lighting guide 5 : lighting for education

Lighting Guide 5:Lighting for education

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© February 2011 The Society of Light and Lighting

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ISBN 978-1-906846-17-6

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Cover illustrations (clockwise from upper left): Warsaw University (photographcourtesy of Thorn Lighting); Southwell Minster School, Southwell,Nottinghamshire (photograph courtesy of Thorn Lighting); Excelsior Academy,Newcastle Upon Tyne (photograph courtesy of Cundall Light4); UsworthSixthform College, Washington, Tyne And Wear (photograph courtesy of ThornLighting).

Note from the publisherThis publication is primarily intended to give guidance. It is not intended to beexhaustive or definitive, and it will be necessary for users of the guidance givento exercise their own professional judgement when deciding whether to abide byor depart from it.

Any commercial products depicted or described within this publication areincluded for the purposes of illustration only and their inclusion does notconstitute endorsement or recommendation by the Society.

Printed on recycled paper comprising at least 80% post-consumer waste

In 1963 the Illuminating Engineering Society published a remarkablemonograph entitled Lecture theatres and their lighting, which became a standardwork of reference. An updated edition was published in 1973 and then in 1991it was updated and published as CIBSE Lighting Guide LG5: The visualenvironment in lecture, teaching and conference rooms. Within a very short period oftime there were a vast array of CIBSE and Department for Education andSchools (DfES) guides available covering all manner of lighting in schools,teaching spaces, lecture theatres and the like, including documents such asBuilding Bulletin 90: Lighting design for schools. In 1995 an addendum to LG5was issued to deal with changes in government funding for schools projects andchanges in European legislation for workplace lighting.

The Department for Children, Schools and Families (previously theDfES) decided in 2008 that it would join with the SLL in updating LG5 toinclude schools.

This Lighting Guide covers not only lecture theatres, but also allteaching spaces and rooms specific to educational premises across schools andfurther education, and extends to committee rooms, conference and multi-purpose rooms. It represents a complete revision but includes relevant materialfrom the original LG5 and BB90 working groups. Our thanks go to many of theoriginal authors whose work is included here, which include R Aldworth, RAnderson, J Baker, L Bedocs, R Bell, C Bissell, K Gofton, J Lambert, D Loe, JLynes, I MacLean, K Mansfield, J Mardaljevic, M Patel, V Rolfe, P Ruffles, ATarrant, R Venning, L Watson and Professor A Wilkins.

LG5 Task Group

I D Macrae (Thorn Lighting) (Chairman)A Bissell (Cundall LLP)R Daniels (Department for Education)B Etayo (Fulcrum First LLP)S Fotios (Sheffield University)P Raynam (University College London)T Ramasoot (Sheffield University)

Director of Information

Jacqueline Balian

Secretary to the Society of Light and Lighting

Liz Peck

Editor

Ken Butcher

Acknowledgement

Permission to reproduce extracts from BS EN 15193, BS EN 12464-2, BS EN1838 and BS EN 12464-1 (draft) is granted by BSI. British Standards can beobtained in PDF or hard copy formats from the BSI online shop:www.bsigroup.com/Shop, or by contacting BSI Customer Services forhardcopies only: tel: +44 (0)20 8996 9001, e-mail: [email protected].

Foreword

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

2 Components of lighting design . . . . . . . . . . . . . . . . .12.1 Objectives and constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

2.2 Lighting for visual function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2.3 Lighting for visual amenity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2.4 Lighting and architectural integration . . . . . . . . . . . . . . . . . . . . . . .4

2.5 Lighting and energy efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

2.6 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

2.7 Lighting costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

2.8 Lighting for health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

3 Lighting options . . . . . . . . . . . . . . . . . . . . . . . . . . . .113.1 Natural lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

3.2 Electric lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

3.3 Integrated daylighting and electric lighting . . . . . . . . . . . . . . . . . .17

3.4 Lightness of the interior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

3.5 Room surface reflectance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

3.6 Lighting the interior space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

3.7 Mean cylindrical illuminance . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

3.8 Modelling index and directional light . . . . . . . . . . . . . . . . . . . . . . .22

4 Lighting design guidance . . . . . . . . . . . . . . . . . . . . .224.1 Daylighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

4.2 Electric lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

4.3 Integrated daylight and electric lighting . . . . . . . . . . . . . . . . . . . .35

4.4 Aids to lighting design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

5 Lighting for particular applications . . . . . . . . . . . . .375.1 Classification of teaching and conference spaces . . . . . . . . . . . . .37

5.2 General performance requirements for learning spaces . . . . . . . . .37

5.3 Lecture theatres and lecture rooms . . . . . . . . . . . . . . . . . . . . . . . .39

5.4 Teaching rooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

5.5 Large conference rooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

5.6 Committee and meeting rooms . . . . . . . . . . . . . . . . . . . . . . . . . . .52

5.7 Multi-purpose rooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

5.8 Adjoining spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

5.9 Waiting areas and lobbies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

5.10 Areas with display screen equipment . . . . . . . . . . . . . . . . . . . . . . .57

5.11 Laboratories, work shops and other practical learning spaces . . . .59

5.12 Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60

5.13 Sports halls and gymnasia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61

5.14 General purpose halls, and drama and dance studios . . . . . . . . . .62

5.15 Lighting for whiteboards and projection screens . . . . . . . . . . . . . .63

5.16 Lighting and visual aids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

5.17 Lighting for pupils with visual and hearing impairments . . . . . . . .65

5.18 Local task lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65

Contents

5.19 Exterior lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66

5.20 Emergency lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

6 Checklist for lighting design . . . . . . . . . . . . . . . . . .776.1 Task/activity lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77

6.2 Lighting and energy efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . .79

7 Lighting maintenance . . . . . . . . . . . . . . . . . . . . . . . .80

8 Management of lecture and conference spaces . . .818.1 Visual clutter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81

8.2 Lecture attendants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81

8.3 Communication between lecturer and projectionist or projector . .82

8.4 Projection rooms and booths . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82

8.5 Preparation and equipment rooms . . . . . . . . . . . . . . . . . . . . . . . .82

8.6 Problems for visiting lecturers . . . . . . . . . . . . . . . . . . . . . . . . . . . .82

8.7 Lectures involving demonstrations . . . . . . . . . . . . . . . . . . . . . . . . .83

9 Lighting costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .839.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83

9.2 Emergency lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83

10 Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8310.1 Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83

10.2 Control gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83

10.3 Lighting controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86

10.4 Disposal of used lighting equipment . . . . . . . . . . . . . . . . . . . . . . .88

11 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

Appendix A1: luminance limits and . . . . . . . . . . .100display screen equipment

Learning, whether by discussion, interaction, practical application or formallecture, requires sufficient light to enable the pupils to see the visibleinformation presented around them. Whether in a primary school classroom ora professional lecture theatre, whether for young or old, the quality of light wechoose to provide in the learning environment will directly affect our learningexperience and indeed our motivation to learn. If we cannot see clearly what iswritten on the board, identify true colours, or read the facial expression andbody language of our teacher, then our learning and our experience will fail tomeet our needs. Above all aspects we can create in a learning space, that of thelighting affects us most. Harsh light creating aggressive facial modelling, orexcessive daylight urging the teacher to draw the blinds and use electric light,impact upon us and our environment. More so now than at any other time in thehistory of lighting, we have to create stimulating and sustainable learningenvironments.

The function of this Lighting Guide is to offer advice on the lighting ofeducational spaces (specifically those not covered elsewhere), lecture theatres,teaching rooms, conference rooms and multi-purpose rooms, and on the visualproblems that may arise. It is therefore necessary to discuss other matters thansimply the lighting equipment and its positioning. The decoration and finishesof such rooms, the sightlines, the positioning of lighting controls and accessdoors all need to be taken into account. The lighting is a vital element in suchrooms and requirements of lighting should be taken into account from the firststages of the planning.

This point cannot be too strongly emphasised. Light is so important tothe functioning of all the premises covered by this Lighting Guide that it mustbe considered from the very outset of the planning process. As lighting designis such a vital part of the success and performance of both space and student thedesigner of such spaces must be able to demonstrate clearly their competence inlighting design for such spaces either by qualification or experience.

By ‘lighting’ it is important to stress that we mean both natural andelectric lighting; experience shows that whilst much thought is given to naturallighting, i.e. window design, planning for electric lighting is often left until fartoo late in the design process. Equally, developments driving sustainablebuildings have often led to natural lighting schemes that introduce otherproblems such as overheating, glare and so on.

That said, natural lighting should be used as far as possible as the primarylight source in all teaching environments. There will be exceptions wheredaylight needs to be excluded but these are few and in most cases simple andfunctional control of daylight ingress when required will suffice.

Lighting design can have many different objectives. Ideally, these objectives aredetermined by the client and the lighting designer in collaboration and coverboth outcomes and costs (Figure 2.1). The most common objective for a lightinginstallation is to allow the users of a space to carry out their work quickly andaccurately, without discomfort. However, this is a rather limited view of what alighting installation can achieve. For educational spaces, the objective oflighting is to facilitate the learning of students by passing on information fromthe teacher or lecturer and via other media. For these tasks the requirements ofthe lecturer will often be different from those of the pupils. In lecture theatresthe task of presenting may require dimmed lighting to enable clear images onthe screen, but the need to take notes may require increased lighting levels,particularly for those with impaired sight. Educational sport facilities are lit atnight to encourage their use in the wider community, but in doing so they mayimpinge upon the residential areas surrounding the school. Most lightinginstallations have to serve multiple functions. When designing lighting it isalways desirable at the outset of the project to identify all the functions that thelighting is expected to fulfil.

1 Introduction

Introduction 1

2 Componentsof lightingdesign

2.1 Objectives andconstraints

As for constraints, an important aspect of lighting design is the need tominimise the amount of electricity consumed, for both financial andenvironmental reasons. It is also necessary to consider the sustainability of thelighting equipment. This means using materials that can be easily replaced andconsidering to what extent the equipment can be recycled at the end of its life.The financial costs, particularly the capital cost, are always an importantconstraint. No one wants to pay more for something than is absolutely necessaryso the lighting designer needs to be able to justify the proposal in terms of valuefor money.

A holistic strategy for lighting design is necessary because without it importantbenefits will be lost, and money and human resources will be wasted. Thestarting point is an in-depth conversation with the client and other members ofthe design team to formulate a design brief. This from a ‘whole building’ designperspective needs to branch out from natural and electric lighting to include theeffects on thermal loading, ventilation and acoustics.

At such a discussion, it will be necessary to address such fundamentalquestions as: what do you want to see and what do you not want to see, what isthe function of the space, what is the proposed architectural style, and what isthe budget?

More formally, six distinct aspects of lighting need to be considered.They are: legal requirements, visual function, visual amenity, architecturalintegration, energy efficiency and sustainability

All these aspects will contribute to the success of a design, but they maynot all carry equal weight depending on the particular application and situation.Also there is no particular order in which they should be considered. Theimportant issue is that all the elements are considered at the inception of theproject and again at each key stage of the design process, perhaps more thanonce, for a satisfactory solution to emerge.

There are a number of legal requirements that apply to all lighting installations.Some are general, e.g. the Construction (Design and Management)Regulations(1). Some are specific about the type and form the lighting thatshould be provided, e.g. emergency lighting in buildings (see chapter 9). Othersinfluence lighting design by the limits they place on the type or amount ofequipment that can be used, e.g. Building Regulations(2–4). Details of therequirements of the Construction (Design and Management) Regulations can beobtained from Health and Safety Executive publications. It is essential that thedesigner and the client are aware of the relevant legal requirements.

The Education (School Premises) Regulations(5) specify minimumstandards for the premises of all maintained schools in England and Wales. The

2 Lighting Guide 5: Lighting for education

Visualfunction

Visualamenity

Lightingdesign

Architecturalintegration

Energyefficiency

Costs(capital andoperating)

Installationmaintenance

Fig. 2.1 Objectives, outcomes andcosts

2.1.1 A holistic strategyfor lighting

2.1.2 Legal requirements

publication Standards for School Premises(6), provides guidance on the SchoolPremises Regulations.

Some of the provisions of the School Premises Regulations also apply toindependent schools. Guidance on legislation applying to independent schoolsis included in the Department for Education’s Registration of Independent SchoolsInformation pack(7). As the UK devolves central government control to individualcountries there may be other Regulations under similar titles to be considered.

Schools are covered by the Building Regulations(2–4). In some cases, DfESBuilding Bulletins are referred to in Building Regulations ApprovedDocuments. Except in these cases, or as otherwise stated, these publications arenon-statutory.

This aspect is related to the lighting required for doing tasks without discom -fort. Recommended illuminance for different tasks is given in the Code forLighting(8) and the SLL Handbook(9), as well as in chapters 5 and 6 of thisLighting Guide. These values apply to the task area and do not necessarily needto apply to the whole working plane. Establishing which values apply to whichtask needs to be done with knowledge of how the space will function both nowand in the future, where this information is available. Equally it is a decisionthat needs to be made with cognisance of all other aspects of the lighting andbuilding design.

The traditional way of lighting a work place has been a regular array ofluminaires. For this approach, minimum task illuminance uniformity(minimum/average task illuminance ≥ 0.7) is recommended. This approach hasthe benefit that the tasks can be carried out on the horizontal plane anywhere inthe work place but does tend to over-light areas not used for the primary taskthat happen to fall within an imaginary work plane. It should be noted that amore visually appealing and stimulating space can be created with additionalenergy saving benefits if the lighting is focused where it is needed. See sections2.3 and 2.5.

In some cases the task will have a colour recognition element. In suchcases it will be necessary to use lamps with a high colour rendering index (CRI).For such tasks it will is appropriate to use lamps with a CRI ≥ 80 but for taskswith a requirement for very good colour discrimination, lamps with a CRI ≥ 90will be necessary.

The human visual system can adapt to a wide range of luminance but itcan cope with only a limited luminance range at any single adaptation state.When this range is exceeded, glare will occur. If a field of view contains brightelements that cause glare it is likely that they will affect performance, or at leastcause stress and fatigue which, in turn, will cause problems. To avoid this willmean using luminaires and windows that have limited luminance within thenormal fields of view relative to the adaptation level. Glare limits for differenttasks are given in the Code for Lighting(8) and the SLL Handbook(9), as well as inchapters 5 and 6 of this Lighting Guide.

There is no doubt that lighting can add visual amenity to a space that can givepleasure to the occupants but whether this provides a more tangibleperformance benefit is uncertain(10). Studies have shown that people respond tothe lit appearance of a room on two independent dimensions, visual lightnessand visual interest(11–13). Visual lightness describes the overall lightness of thespace, which is related to the average luminance of vertical surfaces. Visualinterest refers to the non-uniformity of the illumination pattern or the degree of‘light and shade’. People prefer some modulation in the light pattern rather thanan even pattern of illumination, the magnitude of the modulation depending onthe application. There is some evidence that visual lightness and visual interestare inversely correlated (Figure 2.2).

Components of lighting design 3

2.3 Lighting forvisual amenity

2.2 Lighting forvisual function

Although variation in the light pattern is desirable, it has to be seen asmeaningful in terms of the application and the architecture. To provide randompatches of light in an uncoordinated way for no reason other than to providelight variation would be a poor design solution. Acceptable examples could behighlighting displays within a retail outlet, or a floral display in a hotel lobby.

There remains one further area of visual amenity that needs to beconsidered and that is the colour appearance of the light. A light source with acorrelated colour temperature (CCT) ≤ 3000 K will appear warm, and if it has aCCT ≥ 5300 K it will appear cold (see the SLL Handbook(9), section 1.4.3). Whereon this scale from warm to cool the colour appearance should fall will depend onthe nature of and finishes in the space. In domestic situations a warm colourappearance will be required but in educational interiors a CCT of around 4000 Kis appropriate as it blends reasonably well with daylight. The designer should bewary of the names applied to light sources as these can be misleading and differbetween manufacturers. The best way to choose colour appearance is throughpractical trials.

There is still much to learn about design for visual amenity but it wouldbe negligent to ignore it. The best way to develop an understanding of visualamenity is though personal observations and trial installations.

All elements of a lighting installation form part of the architecture or theinterior design of a building. Understanding the space will be important whendeciding what sort of lighting is to be employed. The dimensions, finishes,texture, colour, materials and the atmosphere to be created are among some ofthe attributes that should be considered.

The most appropriate place to start is with the daylighting, given thepositive impact that well designed sunlit and daylit learning spaces have on theability for individuals to learn and develop(14). The windows and roof lights area fundamental element of the fabric of the building. This means considering theamount and pattern of daylight required for the particular application, andhence the size and positions of windows and rooflights. But windows cannot bedesigned on the basis of the daylighting alone and other visual, thermal, acousticand privacy issues need to be addressed. There is a clear hierarchy for successfulenviron mental design:

(1) Daylight design.

(2) Prevention of summertime overheating.

(3) Design of ventilation.

(4) Acoustic design.


2.4 Lighting andarchitecturalintegration

High

LowLow

Leisure

Industrial

Education andcommercial

Visual lightness (brightness)High

Vis

ual i

nter

est

(deg

ree

oflig

ht n

on-u

nifo

rmit

y)

Fig. 2.2 Map showing the possiblelocations of threeapplication areas on aschematic diagram linkingsubjective impressions ofvisual interest and visuallightness

This is an iterative process but daylight design must come first as itaffects the form of the building. More information on daylighting design can beobtained from the SLL Lighting Guide LG10: Daylighting and window design(15),section 6.3 of the SLL Handbook(9) and section 3.1 of this Lighting Guide.Simple design tools for classroom design are also available, such as ClassCooland ClassVent produced by the Department for Children, Schools and Familiesand available from the teachernet website (www.teachernet.gov.uk/iaq).

Once the daylighting has been determined then the electric lighting canbe planned. To integrate electric lighting with the architecture meansconsidering not only its operation with respect to the daylighting, but theappearance of the luminaires and controls and the way they are incorporatedinto the fabric of the building, as well as the lighting effect produced. Suchintegration may include other building services and could be incorporated intoacoustic raft type lighting systems where appropriate.

Just as the light pattern needs to be meaningful with respect to thebuilding use, the lighting scheme needs to be meaningful with respect to thearchitecture and colour finishes. Profound effects are claimed in learning spacesfrom colour choice, see section 3.5.

It is the responsibility of the lighting profession to use energy as efficiently aspossible but at the same time to provide lit environments that enable people tooperate effectively with comfort. The current estimate for the UK is thatapproximately 19% of the electricity generated is consumed by lighting. Thisamounts to around 64 TW·h/annum. In schools the lighting is responsiblecurrently for one third of carbon emissions in primary schools, and nearly halfin secondary premises, the figure rising significantly for educationalestablishments operating outside of normal daylight hours.

Energy use involves two components: the power demand of theequipment and its hours of use. The lighting industry has worked hard todevelop equipment that has reduced the demand for electricity for lighting byproducing more efficient light sources and their related control circuits as wellas more efficient luminaires. Then there are design options to be considered,such as the use of task/ambient lighting rather than a blanket provision of lightby a regular array of ceiling mounted luminaires. The savings for thetask/ambient approach have been estimated to be up to 50 percent(16).

Good energy efficient lighting design is not just about equipment; it isalso about the use of lighting. Far too often whilst the initial building designseeks to deliver well daylit spaces, as the design progresses other factors such asthermal design, acoustics, cost and ‘buildability’ dominate the solution andreduce the available access to sunlight and daylight. Given the positive impactsunlight and daylight have on the learning environment, and its ability to allowthe electric lighting to be switched off, designing for daylight needs to bepromoted more vigorously throughout the design process. There are also manyexamples where lighting is left on when it is not required. This may be becausethere is adequate lighting through daylighting or because people are not presentand therefore the lighting is unnecessary. This aspect of lighting design needs adramatic change in attitude to improve the energy efficiency of all lightinginstallations. This requires changes to how the lighting is controlled, bothmanually and automatically, as well as how lighting is provided in terms of thedistribution of light, particularly with respect to the daylighting.

It is also necessary to use equipment that is sustainable. This means thatwherever possible the materials used should be from renewable sources,provided by ethical and environmentally sustainable methods, and that at theend of its life the redundant equipment is capable of being disposed of safelywith most of the base materials being recycled. Equipment should also be ‘eco-designed’, allowing for designs that make recycling simple and energy efficient,that minimise material waste and that minimise maintenance and lamprequirements through life. Over the next decade legislation such as the Energy-


2.5 Lighting andenergyefficiency

using Products Directive(17) will drive lamp, gear and luminaire choice and thedesigner should specify in advance lighting that will meet or exceedrequirements.

The most efficient lighting solutions should be procured.Lamp–luminaire combinations are now available that easily exceed theminimum targets required by the Building Regulations(2–4), even consideringthe 2010 levels. Designers should recognise the need to use the most efficientlighting solutions that exceed current energy efficiency targets in documentssuch as Approved Document L(18) (for England and Wales), Part F(19) (forNorthern Ireland) and Part J(20) (for Scotland) and also the Energy Performancein Buildings Directive(21).

Where the usage profile of the building is not known, suitable minimumtargets for luminaire efficacy are given in Table 2.1.


Table 2.1 Energy compliance targets where building usage profiles are not available

Energy efficiency Luminaire efficacy for stated type of space*grade (luminaire lumens per circuit watt)

Teaching spaces, office, Other spaces Display lightingindustrial, storage

Pass 55 55 22

Good 55 55 22

Excellent 55 55 22

* Averaged for all these spaces in the building

Note: ‘Good’ = a minimum of 60% of the installed lighting load must be under daylight control;‘Excellent’ = a minimum of 60% of the installed lighting load must be under daylight andabsence control

Where a new educational building is being provided to replace an existingbuilding, or buildings, it is not acceptable to use the above method except as arough guide. Measurement of the existing building should be taken in order toprovide data for the likely use of the new building and this should be used forthe calculation of the lighting energy numeric indicator (LENI) as a measure ofthe new designs energy efficiency.

The above targets are based on the Building Regulations and includetargets that recognise the important energy savings available from sensibleautomatic control of lighting, but they do not include an overall measure of theefficiency of the luminaires in all applications, so as the preferred method thedesigner should utilise the Energy Performance in Buildings Directive(21)

(EPBD) as a target assessment. As the targets and methodology in BS EN 15193(22) are subject to change

the designer should consider the British Standard. Generally, as schools shouldutilise good daylighting, constant illuminance controls make sense and shouldbe combined with automatic absence detection to most spaces. A sensible ‘pass’grade for the LENI in educational buildings would be taken from Table 2.1 inAnnex 5 of BS EN 15193 (see Table 2.2) but the designer should try and improveon these levels (see Tables 2.3 and 2.4).

Whilst it is possible to achieve a LENI of near 10 kW·h/m2 per annum inclassrooms, the same may not be so easy across a whole building. Similarly, itmay be easy to simply achieve 55 luminaire lumens per circuit watt, either withcurrent or emerging light sources, gear and optical design (based on proposedtargets for England and Wales of 55 luminaire lumens per circuit watt fromOctober 2010) but this ignores significant savings in use. Hence, the designermust consider the careful use of controls, utilising daylight, absence andconstant illuminance measures to limit the use of lighting as well as aspiring touse the best available luminaire designs.

Com

ponents of lighting design7

Table 2.2 ‘Pass’ targets for lighting energy numeric indicator (LENI) for educational buildings (extract from BS EN 15193(22), Annex F, Table F.1, reproduced by permission of the British StandardsInstitution)

Quality Parasitic Parasitic Pn tD tN FC FO FD LENI (limiting value)class energy, Pem energy, Ppc

(W/m2) (h) (h)No constant Constant Manual Auto Manual Auto No constant Constant

(kW·h/m2 (kW·h/m2illuminance illuminance control control control control illuminance illuminance

per year) per year)Manual Auto Manual Autocontrol control control control

* 1 5 15 1800 200 1 0.9 1 0.9 1 0.8 34.9 27.0 31.9 24.8

** 1 5 20 1800 200 1 0.9 1 0.9 1 0.8 44.9 34.4 40.9 31.4

*** 1 5 25 1800 200 1 0.9 1 0.9 1 0.8 54.9 41.8 49.9 38.1

Table 2.3 ‘Good’ targets for lighting energy numeric indicator (LENI) for educational buildings

Quality Parasitic Parasitic Pn tD tN FC FO FD LENI (limiting value)class energy, Pem energy, Ppc

(W/m2) (h) (h)No constant Constant Manual Auto Manual Auto No constant Constant

(kW·h/m2 (kW·h/m2illuminance illuminance control control control control illuminance illuminance

per year) per year)Manual Auto Manual Autocontrol control control control

* 1 5 10.5 1800 200 1 0.9 1 0.9 1 0.8 25.9 20.4 23.8 18.8

** 1 5 14 1800 200 1 0.9 1 0.9 1 0.8 32.9 25.5 30.1 23.5

*** 1 5 17.5 1800 200 1 0.9 1 0.9 1 0.8 39.9 30.7 36.4 28.1

Table 2.4 ‘Excellent’ targets for lighting energy numeric indicator (LENI) for educational buildings

Quality Parasitic Parasitic Pn tD tN FC FO FD LENI (limiting value)class energy, Pem energy, Ppc (W/m2) (h) (h)

No constant Constant Manual Auto Manual Auto No constant Constant(kW·h/m2 (kW·h/m2

illuminance illuminance control control control control illuminance illuminanceper year) per year)

Manual Auto Manual Autocontrol control control control

* 1 5 6 1800 200 1 0.9 1 0.9 1 0.8 16.9 13.7 15.7 12.8

** 1 5 8 1800 200 1 0.9 1 0.9 1 0.8 20.9 16.7 19.3 15.5

*** 1 5 10 1800 200 1 0.9 1 0.9 1 0.8 24.9 19.6 22.9 18.1

To achieve such an improvement, coupled with much higher require -ments for daylight contribution, the designer will need to considerautomatically controlled and/or dimmable luminaires for at least 60% of thebuilding space.

The targets set by the Building Regulations are considered to beminimum standards of performance but these measures do not reflect the actualuse of the space and in some way makes no sense as it allows for efficient lampsand gear in an inefficient luminaire. The designer should use practical controlalong with efficient luminaires to provide best efficacy.

It must be recognised that both daylight and electric light within a building willdepreciate with time. To minimise the effect of this a maintenance programmewill need to be designed and implemented. The maintenance programme willalso affect the lighting design and the designer will need to state the main -tenance programme on which the design has been based, otherwise there couldbe problems when a client is comparing different design proposals. It is essentialfor the client to be provided with a maintenance schedule so that they knowwhat will need to be done. Section 7 of this Lighting Guide discusses the variousfactors that need to be considered when developing a maintenance program.

Cost is always a major concern for any project and it is of course important toconsider these before any work is undertaken. Both the capital cost and therunning or operational costs must be considered at the outset. If the two costelements are not considered together in terms of life cycle costing, then asolution which has a low capital cost but a high operational cost could provesignificantly more costly overall than an installation with a more expensivecapital cost but a low operating cost. A conflict of interests may arise if the twocost elements are paid for from different budgets or organisations. Here the


2.6 Maintenance

2.7 Lighting costs

Table 2.5 Lighting design criteria class for use with Tables 2.2 to 2.4 (reproduced from BSEN 15193(22) by permission of the British Standards Institution)

Criterion Lighting designcriteria class

* ** ***

Maintained illuminance on horizontal visual tasks (Em horizontal) ✓ ✓ ✓

Appropriate control of discomfort glare (UGR) ✓ ✓ ✓

Avoidance of flicker and stroboscopic effects ✓ ✓ ✓

Appropriate control of veiling reflections and reflected glare ✓ ✓

Improved colour rendering ✓ ✓

Avoidance of harsh shadows or too diffuse light in order to provide ✓ ✓

good modelling

Proper luminance distribution in the room (Evertical) ✓ ✓

Special attention of visual communication in ✓

lighting faces (modelling index, Ecylindrical)

Special attention to health issues (see note) ✓

✓ Must comply with required values from Table 5.3 in BS EN 12464-1

✓ Must conform to verbally described requirements from BS EN 12464-1

Note: health issues may even require higher illuminances and therefore higher W/m2

designer needs to present a balanced view of the options to enable the client(s)to decide on the best approach.

The capital costs include the cost of the design process, the equipmentand the installation process, both physical and electrical. It should also includethe commissioning and testing of the installation and training for the buildingoccupier/owner. Allowance must also be made for any builders’ work that formspart of the lighting installation and any other costs that are particular to thelighting design need to be included. It is important that the capital cost is agreedat an early stage if a lot of time is not to be wasted. The capital cost should bechallenged if the client’s expectations seem to be unrealistic.

The operational costs include the cost of the electricity consumed, whichcomprises items such as standing charges, maximum demand charges andelectricity unit costs. They will also include the cost of maintenance, whichincludes cleaning and relamping throughout the life of the installation. In somecases charges may have to be budgeted for the disposal of redundant equipmentalthough this may be borne by the supplier. Note that all electrical equipmentsuppliers must be registered as part of the Waste Electrical and ElectronicEquipment Directive(25) (WEEE) and the designer should provide proof of thisfor any electrical equipment supplied as part of their design.

The designer should consider the full and true life cycle costs, so called‘cradle-to-grave’. This includes elements of the luminaires and other buildingmaterials from the point their raw materials are sourced, to the point they arerecycled into reusable materials. Figure 2.3 shows the elements a design shouldconsider. These include:

— Materials: what material is used from the point it is dug out ofthe ground to the point it is used in a product? For instance, thecreation of plastic from crude oil to the point they are mouldedinto a diffuser whether their type and use makes recycling easyin the future.

— Ecology: the impact on sourcing raw materials and processing itinto a product on the environment, flora and fauna, plus theimpact of the product’s use on the environment.

— Life cycle cost: the financial cost of the product from the point ofraw material to fully recycled, including any manufacture,transport, use and recycling costs.


Health andwellbeing

Lifecyclecost

Ecology

Materials

Transport

Passiveintegration

Recycling

Sustainablelightingdesign

Fig. 2.3 Considerations forsustainable lighting design

— Health and wellbeing: the impact of the lighting on both endusers and those close by who may inadvertently come intocontact with the scheme, for example those using a school sportsfield and those residents nearby who may suffer light nuisancefrom the pitch lighting.

— Recycling: the impact of collecting and treating any waste createdby the lighting and luminaires, including the possibility that theproduct may not be suited for complete recycling but may onlybe down-cycled into other uses.

— Passive integration: the impact of luminaires and the energy theyuse on other services such as heating, cooling and ventilation ofa space. For instance adding electric lighting will reduce theheating load required during winter, but may add to the coolingload during hotter periods.

— Transport: the impact the product has by transporting it in termsof raw materials and by getting it to site, for instance rawmaterials made in South America, manufactured into product inthe Far East and then installed in the UK would have a hightransport impact. Similarly, transport to another country orcontinent for recycling.

Only by considering the true impact of the use of a product can its true cost beunderstood.

Continuing research into the effects of light on health has revealed strongerlinks between access to daylight and effects on both the psychological andphysiological well-being of building occupants. These impacts are not yetsufficiently well understood to safely use electric light to mimic daylight,therefore the designer should be careful when applying colour and intensitychange for all but entertainment.

In all teaching spaces the use of natural light, regulated only by the season,weather and time of day is essential, as it the control of this light when black-out or glare reduction is required.

The role of the circadian system (which controls daily and seasonal bodyrhythms) is to link the functions of the body (e.g. the sleep/wake cycle, andchanges in core body temperature and in hormone secretion) with the externalday/night cycle. Disruption to this system from lack of light can cause problemssuch as depression and poor sleep quality, which could lead to more seriousproblems. Therefore, it is important that occupants of buildings are given accessto high levels of daylight, particularly in the mornings, to reinforce circadianrhythms.

Mood can be modified by lighting. Daylighting is dynamic and variable and isstrongly favoured by building occupants. Adequate access to daylight can havea positive impact on mood especially in situations where people are static forlong periods of time.

A small percentage of people suffer a seasonal mood disorder known as seasonalaffective disorder (SAD) with a further number suffering a mild form known assub-syndromal SAD (S-SAD). Symptoms include depression, lack of energy,increased need for sleep and increased appetite and weight gain, occurring in thewinter when there is little daylight. Such symptoms can be reduced by exposureto daylight.

The ultraviolet (UV) radiation in sunlight can be damaging to the skin.However, with people spending many daylight hours behind glass in buildings,there is the danger of insufficient exposure to UV radiation to maintain healthylevels of vitamin D. A vitamin D deficiency leads to rickets in children andsoftening of the bones in adults. The daylight strategy of educational facilities


2.8 Lighting andhealth

2.8.1 Regulation of thecircadian system

2.8.2 Mood

2.8.3 Seasonal affectivedisorder

Lighting options 11

should include periods of outdoor learning throughout the year to counteractthis.

Exposure to sunlight, even through glass, can kill many types of viruses andbacteria and so can be of great value in winter when there is a high incidence ofrespiratory infections.

Recently links have been made between the UV output of some light sourcesand damage to skin or sight as a result. Designers should note that theluminaires they specify must take due account of these risks in their design,either by use of safe light sources or by other measures that remove any harmfulUV component or limit possible exposure to it. In most cases, for instanceexposure to UV from a conventional fluorescent lamp, there is less risk thanspending a similar amount of time exposed to daylight outdoors, so the user anddesigner should not be overly concerned.

Evidence from research clearly shows increased learning rates, concentrationand comfort amongst students where there is good daylight within the learningenvironment.

Hathaway(26) found significant improvements in health and academicachievement under full spectrum fluorescent lighting, compared to under coolwhite fluorescent or high pressure sodium lighting, in a study of 327 schoolchildren. Mass et al.(27) found that university students doing homework tasksindicated less fatigue and better visual acuity under a daylight simulating lampthan under a ‘cool white’ fluorescent lamp.

Two further studies have investigated the effects of daylighting onchildren, using primary level schools as the children tend to spend all year in thesame classroom. Küller and Lindsten(28) examined 83 children in four Swedishclassrooms, two with and two without windows. The study measured cortisol,behaviour, body growth and sick leave over a year, and concluded thatwindowless classrooms should be avoided.

Heschong(29) surveyed 8000 to 9000 students in each of three districtswithin the US, and reported that students in classrooms with the most daylightshowed a 21% improvement in learning rates (e.g. the change in maths andreading test scores) compared to students in classrooms with the least daylight.

3 Lightingoptions

3.1 Natural lighting

Fig. 3.1 High level skylights andwindows restrict directglare in this daylit atriumat Brunel University(photograph courtesy of MIDLighting)


They also found no connection between physical classroom characteristics suchas daylight and student health, although this was measured by recording studentattendance, which is not the best indicator of student health.

With this in mind and with the essential drive to design low, or zerocarbon buildings, the strategy for all schools and colleges must be to use daylightas the primary light source and the building design process should be informedfrom the outset as to how that can be achieved. Control of daylight ingressshould be minimised, such that it is reduced or removed from a space only whereprivacy, or at specific times when glare or heat gain are issues. In addition whereit is necessary to have dark for experimentation or presentation then daylightmay need to be completely excluded but only for appropriate periods or time.This of course must be co-ordinated with use of lighting controls and the heatingand cooling design for the building form and early stage in the design.

Providing a well daylit learning environment requires a design balance betweenmany factors. As such the daylight and lighting strategy must be developed earlyin the design process, where the lighting designer works closely with thearchitect and other design team members. Figure 3.2 shows the common factorsthat must be considered such that the daylighting strategy delivers the requiredsolution without negatively impacting on other functional and aestheticrequirements of the building. Whilst the considerations apply to both new-buildand refurbishment, some design elements will be more difficult to achieve withrefurbishment projects due to existing building orientation and form. Howeverthis does not exclude the designer from reviewing every aspect of the buildingand creating the best learning environment achievable.

3.1.1 Designconsiderations

Externalbuilding

obstructions

Roomfunction

Enduser

Buildingfabric

Glazingtype

Surfacereflectance

Shadingsystems

Sunlightredirection

system

Internalblinds and

control

Thermaldesign

Acoustics

Legal andplanning

Buildingorientation

Designingfor daylight

Buildingform

Fig. 3.2 Common factors toconsider in daylightdesign

Understanding the site and the building orientation on the site allows theplacement of room types where the lighting requirements are different, e.g. artrooms that require a higher level of light as opposed lecture theatres or dancestudios. The façade design can also progress as the availability of daylight isestablished and is matched to the requirement of the rooms. Preferred views outand sight lines can also be established. Refer to the BRE Digest 209: Site layoutand planning for daylight and sunlight(30).

Understanding the form and continuing to progress the façade design allowsmore detailed examination of the quality and quantity of daylight that penetratesthe building and individual rooms. A review of both the light and shadows isrequired to establish the quality of the light within the building.

In city centre locations or on more compact sites, external buildings will reducethe availability of daylight and views. Understanding the quality and quantity ofdaylight throughout the building will enable one to advise on adjusting the roompositions, window dimensions, window angles and furniture arrangements toimprove views and daylight levels. The façades of external obstructions also needto be reviewed to identify if a potential reflection discomfort could occur or ifthere is an opportunity to improve the brightness of the building to improve theview.

Typically, art rooms require more daylight and dance studios or lecture theatresrequire less daylight. Equally, some spaces will require balanced light with littlemodelling suggesting a northern aspect is preferred. Computer rooms with highheat loads and high density occupancy could occupy areas within the buildingthat have limited daylight as this would reduce external heat gains.

Different learning environments with their individual types of users will havesome specific requirements from the daylight design. A ‘special education needs’(SEN) school for example will require that some rooms have few distractions and,as such, views may be permanently or temporarily omitted. Higher educationstudents who have more flexibility in their own schedules and travel through abuilding will manage their own visual comfort based on their own preferencesand glare from sunlight will likely be less of an issue, although should not beignored.

The thermal design of the building will drive some elements of the buildingfabric and therefore the wall thickness. The wall thickness will affect thequantity of light which enters the internal space; however it could also act as ashade to reduce heat gains. Where the building fabric creates a wall thickness ofmore than 300 mm then the lighting designer and architect should consider howto make use of the horizontal element as this could effectively be a light shelf.

The glass is a critical element in delivering daylight to the internal spaces. As thefaçade solution is progressed to satisfy the architectural intent, the daylight andthe thermal requirements of the building, the selection of the glass will be fixedto achieve a required light transmittance, thermal and solar transmittance. Careshould be taken to ensure the glazing specification is maintained throughout thedesign process as value engineering can often deliver alternatives that satisfy, say,the thermal performance, but significantly reduce the light transmittance. Inselecting the glazing consideration should also be given to the framearrangement. Some glazing systems are well designed and utilise small framesthat lead to reduced visual and light obstruction.

The quantity of glazing and the arrangement of glazing will have animpact both on the quantity and quality of daylight. The sill and head heightsdesigned to accommodate the end users will deliver good views out and satisfy akey element in delivering good quality daylight spaces. Figure 3.3 shows the

3.1.1.3 External buildingobstructions

3.1.1.4 Room function

3.1.1.5 End users

3.1.1.6 Building fabric

3.1.1.7 Glazing

Lighting options 13

3.1.1.1 Building orientation

3.1.1.2 Building form

main window types and daylight distribution systems employed. These aredescribed below.

(a) Full height glazing: provides very good views out and the maxi -mum level of daylight available through the facade. The highlevel glazing delivers light deep into the space thus creating avisually balanced light distribution. Consideration should begiven to visual security for the lower section of the glazing. Alsoif the furniture is placed adjacent to the glazing then the lowerlevel of glazing will not contribute to the useful daylight withinthe space, therefore any analysis should not include the lowersection of glazing.

(b) Traditional glazing: a solid section of wall makes up the lowerportion of the wall, typically just over desk height, with a solidupper section downstand element. The glazing is horizontal andcan be full width or broken by solid sections. The downstandelement can impact on light reaching the full depth of the room.

(c) Internal glazing (‘borrowed light’): internal glazing will provideviews into the atrium as well as secondary daylight via theatrium. Consideration should be given to the potentialrequirement for privacy into the room or to reduce distractionfor some end users.

(d) Rooflights: the atrium rooflight can provide the quality andquantity of daylight, both within the atrium and within theadjacent rooms. The design of the rooflight and any requiredshading is critical in achieving the quantity and quality ofdaylight.

(e) Clerestory: clerestory windows provide light from the highest andbrightest part of the sky and will not generally be affected byexternal obstructions. They allow a view of the sky but nottypically a view of the immediate outside area. In allowing a viewof the brightest part of the sky the contrast between the insideand outside is likely to be higher than other window types, thuslikely to cause glare. They will provide light deep into the space.

(f) Lightwell rooflight: where site constraints limit external facadesand views, secondary light to a space can be provided via alightwell. Depending on the depth of the lightwell, the light willtypically be diffuse and glare free. The glazing must beacoustically sound to avoid noise transfer to adjacent rooms.

(g) Lightwell window: Semi-translucent glazing can provide a sensea brightness of rooms via the lightwell daylight.

This is discussed in more detail in section 3.5. The more reflective the surfacesthe more light will be distributed around a space. Selecting which surfaces andcolours requires care to ensure that a balance and visual quality exists within thespace. Window walls should always be light to reduce contrast and thus reducethe risk of glare.


(a)

(b) (c)

(d)

(i)

(e)

(g)

(f)

(ii)

(iii)

(iv)

(v)

Fig. 3.3 Main window types anddaylight distributionsystems

3.1.1.8 Surface reflectance

Many types of shading systems exist and are constructed using a variety ofmaterials such as wood, metal, glass, mirrors or a combination of thesematerials. The units are arranged either as vertical elements or horizontalelements and fixed to the outside of the building façade. A study of the sun pathacross the facades of the building at midsummer, midwinter and the equinoxwill show where shading may be required to support other thermal controldevices. The shading devices will typically reduce the quantity of light availablewithin a space but, designed appropriately for their orientation to the sun, theywill provide a high quality of light within the space. The material selectionshould be appropriate to reflect as much light into the space without creatingglare due to high luminance. The devices illustrated in Figure 3.3 are as follows:

(i) Atria shading: with any large glazed roof, at some period of theday and year the sun will penetrate the space and, withoutappropriate shading, this could be a source of glare (dependingon the use of the space and areas adjacent to the atrium). Thesolution could be motorised or manual blinds fixed within theroof glazing panels, external motorised louvres or internallouvres. If internal louvres are used these could be combinedacoustic/shading louvres. The orientation, depth, width andspacing of the louvres will depend on the factors alreadydiscussed in this section, such as building orientation and form.

(ii) Vertical shading: the shading system comprises vertical ‘planks’fixed either perpendicular to the façade or at an angle, depend -ing on the design and requirement of the system. Theorientation, depth, width and spacing of the louvres will dependon the factors already discussed in this section such as buildingorientation and form. Vertical louvres are typically used on theeast and west facades of a building to manage the low angle sunthat occurs on these facades. Motorised louvres provide the idealcontrol scenario, closing to cut out thermal heat gains whenpresent and then opening to allow daylight into the space whenthe thermal gain no longer exists.

(iii) Vertically stacked shading: the shading system compriseshorizontal ‘planks’ stacked one on top of another. Thisarrangement provides a shading system which sits close to thebuilding façade. The view out is partially obstructed, dependingon the detail of the shading system. The orientation, depth,width and spacing of the louvres will depend on the factorsalready discussed in this section, such as building orientationand form. This type of shading system is typically found on thesouth façade to manage the high angle sun.

(iv) Horizontally stacked shading: the shading system compriseshorizontal ‘planks’ stacked one in front of another. Thisarrangement provides a shading system which is clear of thewindow itself leaving good views out, however it extends outfrom the façade making a much more prominent architecturalstatement. The orientation, depth, width and spacing of thelouvres will depend on the factors already discussed in thissection such as building orientation and form. This type ofshading system is typically found on the south façade to managethe high angle sun.

(v) Lightshelf: the function of a lightshelf is twofold; the first is toreflect light onto the ceiling and deep into the space, thusbalancing the level of light between the façade and the back ofthe room. Secondly, as a large solid component, the lightshelfaffects the thermal properties of a room. The scale of thelightshelf and materials of which it is composed will depend onthe façade, building orientation and room dimensions.

Fig. 3.4 Vertical exterior shadingin use at Cardinal HumeCatholic School(photograph courtesy ofCundall Light4)

Lighting options 15

3.1.1.9 Shading systems

Building components that reflect and direct the daylight can be used both toprovide a visually brighter space and a numerically brighter learning environ -ment. These systems are typically used where there exists difficulty achievingthe appropriate lighting quantity and quality.

— Fibre optic light distribution: these system use a series of lightcollectors either mounted on the roof or walls that feed the lightinto fibre optic cables that are routed through the buildingfabric to the room in which the light is required.

— Light pipes: these comprise a highly reflective tube with anexternal and internal lens creating a sealed system. The sunlightenters the top of the unit and reflects multiple times beforebeing emitted into the room. The greater the diameter of thelight pipe the greater the quantity of daylight that will bedistributed into the room and the greater the length of light pipefeasible. Bends in the light pipe should be avoided as theyintroduce losses.

— Reflective surfaces: semi-specular material can be used for ceilingtiles and wall coverings to create areas of higher brightness orreflect more light into another zone, e.g. on the inside of thelightwell, the walls can be lined with a semi-specular material toincrease the quantity of reflected light arriving at the groundfloor.

— Microstructure prismatic materials: this type of material ismanufactured with small prismatic patterns on the surface of ablind or within a glazing unit, to redirect the daylight to reduceor eliminate glare. A common use of these materials is in theupper element of the window system to redirect light onto theceiling and thus to the back of the room.

Internal blinds will be required on nearly all external windows and the majorityof internal windows. This will allow control of the daylight to allow viewing ofpresentations and videos. The blinds will also offer privacy when required. Theselection of internal blinds is critical as too often they are closed to control glareand then left closed when, if opened, they would provide a higher quality,naturally lit, environment and allow the electric lights to be turned off. Blindsthat are easy to control and reliable are more likely to be used. Motorised blindsare expensive and unlikely to be suitable for general use although may beappropriate for high level windows in lecture theatres, halls or drama studios.The transmittance of the blind material should be no more than 10% such thatthe sky brightness and sunlight luminance is reduced to a comfortable level.Some blinds are classed as ‘retro-reflective’, which means they are designed toreflect some heat gain whilst allowing reflected light through and allowing aview out. They may be appropriate for some areas where the heat gain is not sogreat as to require an external louvre system.

Almost all of the components of the building design that affect the daylightdesign will also affect the thermal design. It is therefore essential at the earlieststage of the project to ensure sufficient time is spent examining the most likelysolutions for the site, the building and the spaces within the building. Onlythrough early discussion between the lighting designer, architect and otherdesign team members will all of the opportunities to deliver high quality daylitspaces and energy efficiency be realised.

Depending on the building design and selection of building materials,additional acoustic control may be required within the classrooms and lecturetheatres etc. The position of the acoustic panels/baffles/ceiling tiles must be co-ordinated with the lighting designer to ensure the installation of the equipment

3.1.1.13 Acoustics


3.1.1.10 Sunlight redirectionsystem

3.1.1.11 Internal blinds andcontrol

3.1.1.12 Thermal design

does not interrupt the distribution of the daylight. Typically, if acoustic panelsare to be suspended in a room then an orientation perpendicular to the façadewill have less impact than installation parallel to the façade.

The architect must develop accurate elevation drawings as part of the planningsubmission. It is therefore essential to conclude the daylight strategy, assessmentand analysis early in the design process to ensure all window dimensions, framedetails, shading systems and roof lights are shown on the elevation details andthat the building height is fixed. Changes can be costly and may not be feasiblein some circumstances.

There will be times of the year and times of the day when daylight is insuf -ficient, e.g. on a winters evening for adult education. At such times, or wheredaylighting is specifically excluded, electric light will need to be introduced.Designers should consider carefully the provision of electric lighting levelsaccording to the tables contained in this Lighting Guide (see Table 5.1). Over-provision should be restricted by careful design and by use of suitable lightingcontrols that provide for constant illuminance. The addition of electric light totop-up the daylight should be done carefully, minimising energy use as much aspractical.

Electric light should also be added according to task and, for the majortasks specifically, it would for instance be sensible to light a standard children’sclassroom to only 300 lux given that it is in use for over 35 hours per week toteach children, rather than light it to 500 lux simply because it is used for adulteducation for one or two hours in the evenings. It should also be rememberedthat in most teaching spaces the working plane is rarely simply a horizontaltable surface. The design will have to take into account many vertical and othernon-horizontal surfaces and balance carefully the direction or flow of light. Useof measures such as cylindrical and cubic illuminance may provide betterindicators of good lighting than conventional horizontal and vertical illumi -nance or illuminance ratios between a horizontal work plane and other buildingsurfaces.

Without doubt, the best lighting designs take account of natural and electriclighting, balancing one carefully with the other throughout the working day.Careful design should include electric lighting that reacts to daylight at differentdepths into the room and tries to maximise the penetration of daylight into thespace. The designer would do well to think about minimum and averagedaylight factors in their design and to relate these appropriately to location andorientation of the building, or to use alternative sunlight and daylight metricssuch as useful daylight illuminance (UDI). In either case designers must allow forsuitable daylight sensing and dimming luminaires throughout with simple userfriendly controls.

Education buildings are designed to accommodate many diverseactivities in different interior spaces. The successful interior space designrequires that the designer takes into consideration all the requirements andconstraints. Good lighting is an essential part of the interior space design andwithout it student and staff activity will be seriously impaired and valuableenergy will be wasted. Good lighting ensures that students, teachers and otherstaff can see to carry out their various tasks safely, efficiently and in comfort. Itis important to note that the lighting should not only illuminate the tasks butmust light beyond the horizontal plane and contribute to the quality of thevisual environment and the well-being of the occupants. This needs a holistic orintegrated approach to lighting design considering all criteria and bringingtogether daylight and electric lighting solutions in a well-managed operation.

Climate-based daylight modelling is the prediction of various radiant orluminous quantities (e.g. irradiance, illuminance, radiance and luminance)

Lighting options 17

3.1.1.14 Legal and planning

3.2 Electriclighting

3.3 Integrateddaylightingand electriclighting

3.3.1 Climate-basedmodelling

using sun and sky conditions that are derived from standardised annualmeteorological datasets. Climate-based modelling delivers predictions ofabsolute quantities (e.g. illuminance) that are dependent both on the locale (i.e.geographically-specific climate data is used) and the fenestration orientation(i.e. accounting for solar position and non-uniform sky conditions), in additionto the space’s geometry and material properties. The operation of the space canalso be modelled to varying degrees of precision depending on the type of device(e.g. luminaire, venetian blinds etc.) and its assumed control strategy (e.g.automatic, by occupant, or some combination). The term ‘climate-baseddaylight modelling’ is generally taken to mean any evaluation that is founded onthe totality (i.e. sun and sky components) of time-series daylight dataappropriate to the locale over the course of a year. In practice, this means sunand sky parameters found in, or derived from, the standard meteorological datafiles which contain 8760 hourly values for a full year. Given the self-evidentnature of the seasonal pattern in sunlight availability, a function of both the sunposition and the seasonal patterns of cloudiness, an evaluation period of twelvemonths is needed to capture all of the naturally occurring variation inconditions that is represented in the climate dataset. Standard climate data for alarge number of locales across the world are available for download from severalon-line repositories.

There are a number of possible ways to use climate-based daylightmodelling. The two principal analysis methods are cumulative and time-series.A cumulative analysis is the prediction of some aggregate measure of daylight(e.g. total annual illuminance) founded on the cumulative luminance (orradiance) effect of (hourly) sky and the sun conditions derived from the climatedataset. It is usually determined over a period of a full year, or on a seasonal ormonthly basis, i.e. predicting a cumulative measure for each season or month inturn. Evaluating cumulative measures for periods shorter than one month is notrecommended since the output will tend to be more revealing of the uniquepattern in the climate dataset than of ‘typical’ conditions for that period. Thecumulative method can be used for predicting the micro-climate and solaraccess in urban environments, the long-term exposure of art works to daylight,and quick assessments of seasonal daylight availability and/or solar shading atthe early design stage. Time-series analysis involves predicting instantaneousmeasures (e.g. illuminance) based on each of the hourly (or sub-hourly) valuesin the annual climate dataset. These predictions are used to evaluate, forexample, the overall daylighting potential of the building, the occurrence ofexcessive illuminances or luminances as inputs to behavioural models for lightswitching and/or blinds usage, and the potential of daylight responsive lightingcontrols to reduce building energy usage.

A daylight performance metric would need to be based on a time-seriesof instantaneously occurring daylight illuminances because it is important tocapture the full range of illumination conditions to reliably characterise thedaylighting potential of the space. Whilst the practicalities of climate-baseddaylight modelling are fairly well understood, it remains to be seen which of thehandful of candidate metrics will be deemed most suitable for compliancepurposes. One of the metrics under consideration is called ‘useful daylightilluminance’ (UDI). The useful daylight illuminance scheme was devised toreduce and make readily intelligible the output from a climate-based simulationwithout sacrificing the vital performance-revealing content of the raw data.Rather than analyse the vast amount of simulated illuminance data usingtraditional means, e.g. frequency histograms, cumulative plots etc., the rationalebehind UDI was to approach the data first from a ‘human factors’ perspective,and then reduce it to compact metrics.

Put simply, achieved UDI is defined as the annual occurrence ofilluminances across the work plane that are within a range considered ‘useful’ byoccupants. The range considered useful is based on a survey of reports ofoccupant preferences and behaviour in daylit offices with user-operated shading


devices. Daylight illuminances from 100 lux to the design level value, say350 lux, are considered effective, either as the sole source of illumination or inconjunction with electric lighting. Daylight illuminances from the design levelvalue up to around 2500 lux are often perceived either as desirable or at leasttolerable.

UDI achieved therefore is the defined as the annual occurrence of daylightilluminances that are between 100 and 2500 lux. The UDI range is furthersubdivided into two ranges called UDI-supplementary (or UDI-s) and UDI-autonomous (or UDI-a), taking the design level illuminance as the boundarybetween the two ranges. UDI-supplementary gives the occurrence of daylightilluminances in the range 100 to 350 lux (depending of the design levelilluminance). For these levels of illuminance, additional electric lighting may beneeded to supplement the daylight for common tasks such as reading. UDI-autonomous gives the occurrence of daylight illuminances in the range 350 to2500 lux where additional electric lighting will most likely not be needed. TheUDI scheme is applied by determining at each calculation point the occurrenceof daylight levels where:

— the illuminance is less than 100 lux, i.e. UDI ‘fell-short’ (or UDI-f)

— the illuminance is greater than 100 lux and less than300–500 lux, i.e. UDI-supplementary (UDI-s)

— the illuminance is greater than 300–500 lux and less than2500 lux, i.e. UDI-autonomous (UDI-a)

— the illuminance is greater than 2500 lux, i.e. UDI-exceeded (UDI-e).

For those cases where solar gain in summer must be controlled to minimiseoverheating/cooling, careful attention should be paid to the degree of occurrenceof the UDI-e metric.

When glancing around a room, people take more notice of vertical or nearvertical planes than of working surfaces. The appearance of an interior isaffected by its general brightness, which depends on the distribution of light inthe room and the lightness of room surfaces. The way in which the space isilluminated will affect the environment and character of the space andappearance of objects within. This lighting sets the tone or mood of the spaceand gives it atmosphere and prestige, and provides comfort and stimulation forthe occupants. To create a feeling of visual lightness it is necessary to direct lightonto room surfaces, particularly those surfaces that are prominent in the normalfield of view. Often these will be the walls but the ceiling may also be included,especially in large rooms. Where workstations are employed using verticalpartitions, some light on the partitions will be beneficial and without which theroom can appear gloomy and under-lit. Table 3.1 below gives the range ofilluminance that should be provided on the major surfaces. They will produceacceptable conditions in most situations. For example bright walls will make aroom appear large and spacious whilst dark walls make it appear small andcramped.

Lighting options 19

3.4 Lightness ofthe interior

Table 3.1 Recommended reflectance and illuminance values within an educational space

Room surface Reflectance Illuminancerange

Ceiling 0.7 to 0.9 30–90% of task Illuminance or Eh min > 50 lux; Uo > 0.1

Walls 0.5 to 0.8 50–60% of task Illuminance or Ev min > 100 lux; Uo > 0.1

Task area 0.2 to 0.6 According to task requirement

Floor 0.2 to 0.4 Maintained value of 30–50 lux

Room surface reflectance is the ability of the surface to reflect light that falls onit. The colour appearance of a surface is a function of the surface itself and thetype of light source. It is rare that a lighting designer is allowed to select theroom surface finishes. But when the opportunity arises the designer shouldchoose the hue (or colour), its lightness or darkness and chroma (or saturation).Subdued colours are often chosen where a restful or dignified atmosphere isrequired, whilst strong colours and high contrast are normally used to createlively and exciting effects. The recommended reflectance values together withthe preferred range of illuminance are shown in Table 3.1. These values not onlyprovide for balanced appearance but also help to generate inter-reflected lightmaking the scheme more energy efficient. Experienced designers will of coursebe able to achieve desirable results outside of these limits.

The primary presentation wall, containing the whiteboard, should be ofa different complementary colour and darker hue than the other walls. Thishelps to reduce eye strain as the viewer looks from desk to board-based tasks andback again. Whilst it may be desirable for lighting efficiency to provide higherreflectance surfaces, a deep tone on one wall will provide visual form to the spaceand reduce glare. If the presentation wall is not chosen for the different shade, aside wall (not the main window wall) should have the complementary or darkerhue.

In addition to lighting the task and room surfaces it is important to fill thevolume of space occupied by people with light. It should be remembered that wesee the reflected light from surfaces and hence the choice of colour scheme cansignificantly affect the overall impression of the room. The light will need toilluminate or highlight people and objects, reveal textures and improve theappearance of people within the space. The preferred lighting conditions can bedescribed by the terms ‘mean cylindrical illuminance’, ‘modelling index’ and‘directional lighting’.

Good visual communication and recognition of all solid objects and especiallypeople’s faces requires adequate brightness. The objects require light to reachthem from many directions, see Figure 3.5. In essence, the volume of space inwhich people move should be filled with light. The requirement can be met byproviding sufficient mean cylindrical illuminance in the space at head height.In teaching and circulation areas the recommended maintained meancylindrical illuminance (Ez) should be at least 150 lux at 1.2 m above floor levelwith uniformity of 0.1. Checks should also be made at 0.8 m and 1.6 m abovefloor level to ensure adequate coverage for all ages of the educational staff andstudents.

The cylindrical illuminance in a space can be calculated using proprietarysoftware, often just by selecting the right option so that the calculation surfaceor grid calculates cylindrical rather than horizontal illuminance. The grid sizeis defined in BS EN 12464-1(31) (due for updating) and also BS EN 12193(32).

Grids approximating a square are preferred; the ratio of length to widthof a grid cell should be between 0.5 and 2. The maximum grid size should be:

p = 0.2 ×× 5log d (3.1)

where p ≤ 10 and is the maximum grid cell size (m), d is the longer dimensionof the area (m) if the ratio of the longer to the shorter side is less than 2(otherwise d is the shorter dimension of the area).


3.7.1 Calculation of meancylindricalilluminance

3.5 Room surfacereflectance

3.6 Lighting theinterior space

3.7 Meancylindricalilluminance

The number of points in the longer dimension is given by the nearest oddwhole number of d /p.

The resulting spacing between the grid points is used to calculate thenearest odd whole number of grid points in the shorter dimension. This willgive a ratio of length to width of a grid cell near to 1.

A border of 0.5 m from the walls is excluded from the calculation areaexcept for task areas that are defined and near the wall.

For the immediate surround area the same grid spacing as for the taskarea should be applied. For the background the whole room with a border of0.5 m from the walls, the grid spacing should be in accordance to the room size.

This calculation grid should be applied at 1.2 m above floor level,effectively the seated head height of a typical person. Where the calculation isapplied in rooms predominantly designed for small children, and wherefurniture is such that it specifically designed to suit them, it would be wise tocheck the corresponding mean cylindrical illuminance at about 800 mm.Similarly, where the space is designed for teaching where head height is morecommonly at around 1.5–1.8 m, such as for a formal teaching layout withteaching mainly from a lectern or board, then the mean cylindrical illuminanceat these positions and height should also be calculated.

Approximation of the mean cylindrical illuminance can be made bycalculation the average vertical illuminance at the specified position and heightfor each of the four main vertical planes. In this case:

Ez = 0.25 (Ev1+ Ev2 + Ev3 + Ev4 ) (3.2)

On-site measurement should be carried out at the correct height and to themethod in the Code for Lighting(8) using the grid point spacing as calculatedabove and with the use of a cylindrical illuminance photocell mounted andcalibrated against a suitable light meter, see Figure 3.6.

Where there is no possibility of obtaining such a photocell the usershould measure each of the four main orthogonal vertical planes and average thereadings using the formula for Ez above.

People, and almost everything else in an interior, are three dimensional andneed to be illuminated all around. Modelling describes the ability of light toreveal solid form. Modelling may be harsh or flat and the relative strength ofmodelling is influenced by the directions from which the light comes and thedirection from which the object is viewed. Fairly strong and coherent modellinghelps to reveal three-dimensional shapes as, for example, in display lighting.Good modelling is essential to sculpture display and similar purposes, and canhelp to reveal the detail of many textured tasks. The effectiveness of the light formodelling can be defined by the ratio between mean-cylindrical and horizontalilluminance at the point of interest, see Figure 3.7. A ratio > 0.3 will provide foradequate modelling; this may be closer to 0.5 for teaching spaces used bychildren.

For good modelling there is a need for preferential light to come from onedirection. This directional ‘flow of light’, as produced by daylight through sidewindows or asymmetric and batwing distributions of electric light, can createpleasant highlights and shadows to model objects, texture and people. The flowof light determines where shadows will be cast and how dense they will be. Thelighting should not be too directional or it will produce harsh shadows, neithershould it be too diffuse or the modelling effect will be lost entirely, resulting ina very dull luminous environment.

Lighting options 21

Fig. 3.5 Light falling on the facefrom all sides rather thanjust horizontally is abetter measure of howwell lit the face will be,viewed from any direction

3.7.2 Measurement ofmean cylindricalilluminance

Fig. 3.6 A typical cylindricalilluminance measuringphotocell

3.8 Modellingindex anddirectionallight

Without doubt natural light should be our primary source of light whenever itis available in suitable quantity. The links in research to user performance andcomfort and the obvious link to energy saving of electric light are strong andbuilding designers and architects must include daylight design from the initialbuilding concept right through to completion and post occupancy evaluation.However it is difficult to accurately predict daylight contribution using currentmetrics such as daylight factor, which does not take into account direct sunlightcomponents. Those involved in building design should include in theirconceptual design team an expert in daylight design and consider the latestdesign tools and metrics to include and predict excellent daylight contributionthroughout all learning spaces. Failure to do so at the earliest stages of designwill result in daylight exploitation being very difficult later on.

Once daylight has been incorporated into the building shape andorientation then it should be possible to include electric lighting to complete theoverall lighting and lighting controls strategy to ensure learning spaces performfor both the user and the environment.

The use of daylight as the main means of lighting is recommended and shouldnot be compromised in a learning environment, except in circumstances outsidethe designer’s control. Sometimes site constraints such as adjacent buildings ortrees will mean electric lighting will be the main source, but the designer shouldstrive to avoid this. Daylight provides a less stressful environment for pupils andteachers, improves learning rates and saves energy.

Where we refer to providing daylight within a space we are referring toboth a quality of light and a quantity of light to perform the tasks. The qualityof the light relates to both the direct component (sunlight) and the diffuse


4 Lightingdesignguidance

4.1 Daylighting

(a) Modelling index = 0.1; highly directionaldownlight creates harsh shadows

(b) Modelling index = 0.3; the limit ofacceptable modelling in spaces where goodcommunication is required and still too harshfor some children with special educationalneeds

(c) Modelling index = 0.5; more appropriatefor children’s classrooms

(d) Modelling index = 1.0; except for theatrelighting, it is difficult to get an index muchgreater than 1.0 and values higher than thiswould provide modelling of the face making itdifficult to lip read, for example

Fig. 3.7 Examples of modellingindex (photographs courtesyof Thorn Lighting)

component (skylight). Equally we need to review the quality of the view out ofthe space. In providing a view, most people prefer a view of the naturalenvironment or where this is not possible, e.g. in built-up areas, then a dynamicview is preferred.

Natural light is very variable and in the past the direct component hasbeen excluded from the assessment of daylight quality and quantity. Thecommon measure of daylight has been the daylight factor (an expression of howmuch outside light on an overcast day arrives at a particular place in the room),where the defined luminance distribution of a CIE (Commission Internationalede l’Eclairage) overcast sky is used in the calculation. Within BS 8206-2: 2008:Lighting for buildings, Code of practice for daylighting(33), the principle of climate-based modelling is introduced in section 3.3.1

As discussed in BS 8206-2: 2008, climate-based modelling is currentlybeing developed and, as such, at this time the daylight factor approach tomeasuring daylight quantity must be used. However to deliver the best qualityof spaces, the designer should have studied and have experience in designingspaces utilising sunlight and skylight and controlling these mediums to deliverbright and well lit spaces. In designing a space with appropriate daylight we areproviding a space that allows the reduction in use electric lighting duringdaylight hours. The savings from automatic dimming controls are directlyrelated to daylight factor. As discussed previously, the building form, materials,glazing, façade etc. will affect the daylight factor.

As far as space planning is concerned, natural lighting and naturalventilation are in sympathy. The maximum depths of spaces for naturalventilation are comparable to the maximum depths for effective daylighting.

The depths of individual classrooms should generally be limited toaround 7 m. Beyond this, greater ceiling heights (>2.7 m), skylights, light wells,clerestory windows etc. will need to be employed to improve daylightpenetration. To ensure the focus on daylight as the primary source of light in alleducational spaces it will be preferable to include the above elements in allpossible cases.

A ‘well tempered’ daylit environment is one where the fixed architecturalform provides both good daylighting and effective solar protection. Thusminimising — though in practice rarely eliminating — the need for occupantsto close blinds/shades.

The potential for the fixed form to temper the daylighting of the spacedepends on the building type, specifically on the richness/variety of the fixedarchitectural form. For simple rectangular office blocks (Figure 4.1), the scopeto temper the daylit environment is limited to a few basic building parameterssuch as glazing ratio, window transmissivity etc. Optimisation of these will havesome beneficial effect, but the occupants will still have to resort to frequent useof the blinds/shades to prevent undue ingress of daylight and to prevent glare.The greater the richness and variety in the architectural form (e.g. brise soleil,atria, self-shading etc.) the greater the opportunity for tempering the daylitenvironment through an integrated design approach that combines effectivesolar control with good daylight practice. Often the more successful daylightingdesigns are those that offer a combination of daylighting strategies. Low-risebuildings such as schools (Figure 4.2) offer the greatest opportunity to realise a‘well tempered’ daylit environment because the designs can, in principle,accommodate various daylighting features/devices. In addition to the brise soleiland atria noted above, imaginative low-rise building designs can also featureskylights, clerestory windows, light-wells, re-entrant sections, overhangs, deepself-shading reveals etc.

Window areas and ceiling heights should be chosen to achieve highdaylight factors because the benefit of carbon savings is so significant that theextra cost of larger windows and high ceilings may be effective in terms of costof carbon abatement compared to renewables. They will also aid naturalventilation.

Lighting design guidance 23

Figure 4.1 Simple rectangularbuilding designs offerlittle scope to temperdaylight (illustrationcourtesy of J Mardaljevic)

In all cases where daylight introduces a high thermal load the designershould consider carefully the options. The inclusion of interior and exterior suncontrol is an option that should be considered, carefully linked to all the otherfactors. Its removal on cost grounds is not acceptable if that decision makes theuse of daylight impractical because of its implications for ventilation design andacoustics. In urban and rural locations where noise and air pollution are notsignificant, daylight design must take priority with a higher degree of naturalventilation used to offset heat gains. In city locations where noise and airpollution may be considerable, the daylight quantity may have to be reduced toallow suitable ventilation strategies. However it should be remembered thatoften in built-up locations daylight itself will be restricted by surroundingbuildings and the designer should take this into account.

The average daylight factor is used as the measure of general illumination fromskylights. To achieve the appearance that a room is predominantly daylit theaverage daylight factor should be at least 2%. If the average daylight factor in aspace is at least 5% then electric lighting is not normally needed during thedaytime, provided the uniformity is satisfactory. If the average daylight factor ina space is between 2% and 5% supplementary electric lighting is usuallyrequired.

The strategy should be to create spaces that are daylit to improve learningrates and reduce energy consumption. Therefore good practice would be toachieve 5% average daylight factor and a minimum point daylight factor of 2%.

When measuring the average and minimum values it is recognised thatdirectly adjacent to walls the daylight level will be at its minimum and if usedwill disproportionally represent the daylight distribution within the space.Therefore it is recommended to leave a 0.5 m zone around the perimeter of thespace to eliminate these values (see Figure 4.4). As with all calculations, dueconsideration has to be given to furniture layouts. For example, if it is known(and the question should be asked) that desks or task areas will be positioneddirectly against the walls of the room, then the 0.5 m zone should not apply.

The various types of spaces within a school, college or university willrequire different lighting strategies, e.g. a drama space, sports hall, art room orlecture theatre etc. will have specific needs such as mirrored walls, solid wallsand north lights, blackout etc. As such, the 5% average and 2% minimum goodpractice design must be balanced against these specific needs. However, forgeneral teaching spaces, as discussed previously, only external factors outside


4.1.1 Daylight quantity

L

0·5 m

0·5 m

0·5 m 0·5 m

W

H

Fig. 4.4 Average and minimumdaylight factor should becalculated up to 0.5 mfrom each wall

Figure 4.2 Lower level architecturalforms can combineeffective solar controlwith good daylightpractice (illustrationcourtesy of J Mardaljevic)

Fig. 4.3 Deep central atriumproviding daylight to firstfloor classrooms with ICTbreak-out class on lowerfloor (photograph courtesyof Corby Academy; Foster &Partners)

the designer’s control would justify daylight factors less than the good practicefigures.

The importance of the uniformity cannot be underestimated. Too high acontrast and a space will look gloomy from some positions and viewpoints andbe visually uncomfortable or distracting. Controlling uniformity requires theaccess of daylight and distribution of daylight within the room to be balanced.Measures that easily identify if this will be achieved include the ‘no sky line’ androom depth criteria. Calculating the daylight factors throughout the space,either manually or by computer, is also appropriate. These methods arediscussed below.

The figures recommended here aim to improve the learning spaces thatare currently constructed in the UK and, as such, aim to push design forwardand ensure designers recognise the value of daylight to the staff and pupilswithin the learning environment.

A procedure for calculating the average daylight factors is given in BS8206-2: 2008(33) and can be used to calculate the average daylight factor targetsgiven above.

When external obstructions can be defined adequately by two horizontal lines,i.e. the upper and lower limits of the visible sky, the average daylight factor onthe working plane (

––D), expressed as a percentage, is:

T Aw θ––D = ————– (4.1)

A (1 – R2)

where ––D is the average daylight factor on the working plane (%), T is the diffuse

light transmittance of the glazing including the effects of dirt (see BS 8206-2:2008(33), section A.1.2 for typical figures), Aw is the net glazed area of the window(m2), θ is the angle subtended by the visible sky (degrees) (measured in a verticalplane normal to the glass, from the window reference point, see Figure 4.5), A isthe total area of the ceiling, floor and walls, including windows (m2) and R is thearea-weighted average reflectance of the interior surfaces (in initial calculationsfor rooms with white ceilings and mid-reflectance walls, this may be taken as0.5).


4.1.1.1 Calculating daylightfactor for windowsand rooflights withcontinuousobstructions ofuniform height

Fig. 4.5 Angle of visible sky

Windowreferencepoint

0 °

When two or more windows in a room face different obstructions, ordiffer in transmittance, the average daylight factor should be found separately foreach window, and the results summed.

To find the window area above the working plane, in square metres,needed to achieve a given average daylight factor, the equation may be inverted,as follows:

––D A (1 – R2)

Aw = ————––– (4.2)T θ

Note that the window area below the working plane does not significantlyincrease the amount of daylight falling onto the working plane. This is becausethe light from the lower part of the windows has to bounce off at least two roomsurfaces before it reaches the working plane, and it is also common for there tobe obstructions below the working plane. A study has shown that the area of thewindow below the working plane is only about 15% as effective at letting lightonto the working plane as an equivalent area above the working plane.

Limitations of the formula: Equations 4.1 and 4.2 should not be applied whereexternal obstructions cannot be represented by a single angle of elevation, forexample where a window faces into a courtyard. For further information, seeBRE Report: Site layout planning for daylight and sunlight: a guide to goodpractice(34) and Modification of the split-flux formulae for mean daylight factor andinternal reflected component with large external obstructions(35).

This section recommends a procedure for calculating the maximum depth of aside-lit room.

In a room with windows in one wall only, the following inequality shouldbe satisfied:

L L 2— + — <–– ——— (4.3)W H 1 – Rb

where L is the depth of the room from window to back wall (m) (see Figure 4.6),W is the width of the room, measured parallel to the window (m) (see Figure4.6), H is the height of the window head above floor level (m) (see Figure 4.6)and Rb is the area-weighted average reflectance of the interior surfaces (walls,floor and ceiling) in the half of the room remote from the window.

Fig. 4.6 Limiting depth of a side-litroom

L

W

H

4.1.1.2 Room depth criteria

The no-sky line divides those areas of the working plane which can receivedirect skylight from those which cannot. If a significant area of the workingplane lies beyond the no-sky line (i.e. it receives no direct skylight), then thedistribution of daylight in the room will look poor and supplementary electriclighting will be required. The working plane height is relative to the tasks beingundertaken, e.g. desk height. At least 80% of the working plane should have aview of the sky.

The view through a window, or how we perceive the world outside, is a dynamicexperience associated with changes in skylight, sunlight and season. At its lowestlevel, a view satisfies the physiological need of the eye for a change of focus, andprovides an awareness of the environment beyond the building.

View will depend on the location, size, shape and detailing of the window.However stimulating the exterior may be, windows that are too small, break upthe view, or are at a height that inhibits view from normal positions are lessdesirable. There are some spaces where external view may be considered

4.1.1.3 No-sky line

4.1.2 Daylight quality andview


inappropriate as, for example, in a lecture room or theatre where the aim is toencourage occupants to concentrate solely on the task in hand. Nevertheless,there is a general presumption that a view through a window is good, and adaylight strategy that denies a view in any building needs to be questioned. Inbuildings comprising very large spaces, internal views to other daylit areas maysuffice. However in all classrooms a view to the outside should be consideredmandatory.

The view out must be balanced by privacy and the need to keep thestudents’ attention. Low level glazing may require privacy glass, and rooms forteaching that look out onto particularly busy environments may need carefulview control to remove visual distraction (see Figure 4.7).

The question of privacy can be addressed by using curtains or blinds thathave the benefit of avoiding the ‘black hole’ appearance of the window at night.They also provide a means of reflecting electric light back into the room ratherthan losing it to the outside, but this will require a moderately high reflectanceof the inside surface and will dramatically affect daylight contribution. Careshould be taken to specify materials that reduce daylight glare where needed oreliminate it if complete darkness is required. This need for control for purposessuch as interactive whiteboard or image projection should be balanced carefullywith the benefits of having some daylight and view present during daytimehours.

Fig. 4.7 Top: the classroom shownuses a radiant heatingpanel to provide privacybut this also reducesslightly the daylightcontribution from thewindows

Bottom: in this classroomdesperate measures havebeen taken either toreduce glare or view atthe rear window, whereblinds are not available


Care should also be taken in specifying blinds that do not disrupt theventilation strategy. For opening windows, a common strategy is to fix the blindto each window such that the window can be opened and the blind move withthe window, thus allowing the required air flow.

The quality of the view is clearly of importance. Some views are ofexceptional beauty and provide pleasure in themselves, and any experience ofthe world beyond the window that extends our perception of space should beconsidered good. In addition to providing the right quantity of light, daylightgives an interior a particular unique character. Some of this is due to thevariability of the daylight including sunlight; also, the distribution of the lightenhances the visual field. The directional properties of light from side windows(the ‘flow of light’ across the room) are a significant attribute contributing to themodelling of the interior, including objects within it and surface textures, andproviding brightness to vertical surfaces, the amount depending on the reflec -tance. Some variability across room surfaces is also important (see Figure 4.8).

Wherever possible, the shape, size and disposition of the windows shouldbe related to the view, and avoid any deprivation or curtailment of it by theirposition, height or width. A minimum glazed area of 20% of the internalelevation of the exterior wall is recommended for a view. Any seriousobstruction to the view can be annoying and appropriate sill and head heightsare important (see Figure 4.7).

While the view out should preferably have close, middle and distantcomponents, and contain some natural elements, frequently this is not possibleand a popular alternative is the use of courtyards. For these to be successful, theymust be well maintained, preferably with suitable landscaping and some viewsof the sky, and have an adequate view dimension across the courtyard of not lessthan 10 m.

In some instances, a reasonable view of the exterior may not be feasible,and in these cases a long internal view is a useful addition — within a large spaceor possibly through glazed partitions. However, it is preferable to have a feelingof ‘daylight contact’ maybe from roof lights and including atria (see Figure 4.9).On some occasions, a view out can be a disadvantage and cause distraction, andin these circumstances, blinds or curtains should be provided. In addition, thereare situations where there is a need for privacy and here the view into thebuilding needs to be considered.

External shading such as blinds or brise soleil are particularly effective inreducing solar gain. Mid-pane blinds are also very effective. Internal shades orblinds will reduce internal gains but are less effective because once solarradiation has penetrated the glass it will cause some heating of the interior of thebuilding. The blind finish is important; reflective blinds may (with clear glass)reflect heat back out, while absorbing blinds and curtains will become warmquickly.

Fixed devices require careful design for the site to avoid reducingdaylight which could lead to increased use of electric light. Adjustable deviceshave the advantage of allowing maximum daylight penetration while providingsun shading when required. They can be controlled manually or automatically.Manually adjusted blinds or shades can be set by the occupant as required, butthere is a tendency for them to be left down which results in unnecessary use ofelectric light (see Figure 4.10). Automatic blinds overcome this problem, butspecial attention needs to be given to their control to avoid user annoyance withfrequent movement of the blinds. They also need to be silent in operation, andparticular attention needs to be paid to automatic blinds where maintenance isconcerned.

With internal blinds, it is important to take into account potentialproblems that could undermine their effectiveness. Such problems includeinterference with the open window, restricting natural ventilation air flow, blindrattle or sway in the airflow, blinds positioned too far back from the pane


4.1.3 Glare and sunlightcontrol

Fig. 4.9 Internally glazed wallsallow daylightcontribution, a link to theoutside conditions and adistant view (photographcourtesy of Philip Smith)

Fig. 4.8 Variability of daylightacross the room isdesirable (photographcourtesy of Thorn Lighting)

allowing sunlight to fall on the interior window ledge or poor, inaccessible orinconvenient user controls.

Figure 4.11 shows various types of external and internal shading devices.Detailed descriptions and application advice for each of these shading devicescan be found in SLL Lighting Guide LG10: Daylighting and window design(15).

Designers should be careful in the selection of interior shading devicesand the colouration/pattern of the materials used. In recent research theprovision of blinds in 23% of classrooms had spatial characteristics appropriatefor inducing pattern glare(36) which can be a particular problem to those whosuffer from dyslexia and migraine headaches.

One of the most important aspects of obtaining a satisfactory interiorenvironment is to provide a balanced luminance distribution — some contrastbut not excessive. If the luminance of the sky seen through a window is veryhigh and close to the line of sight of a visual task of much lower luminance,disability glare can occur due to a reduction in the perceived contrast, makingdetails impossible to see and thus reducing task performance.

Disability glare will occur where there is a window in a wall on whichthere is a whiteboard and this must be avoided.

Discomfort glare is experienced when some parts of an interior have amuch higher luminance than the general surroundings and this may take sometime to become apparent. Discomfort glare from daylight can be a morecommon occurrence than disability glare, and under most circumstances itsdegree will depend not on the window size or shape, but on the luminance of thesky seen in the general direction of view. Data suggest that, for the UK, anunprotected window will produce uncomfortable glare over a significant periodof the year. It has been predicted that skies with an average luminance exceeding8900 cd/m2 (corresponding to a whole-sky illuminance of 28 000 lux) will causediscomfort glare, and in the UK these are experienced for about 25% of theworking year. Teachers recognise that discomfort glare from daylight andwindows impinges directly on student concentration citing the phrase ‘when thelighting is bad the students stop listening’, hence designers should take greatcare to control overall window luminance.


Fig. 4.10 Blinds closed to reduceglare requiring electriclighting though the classis empty (photographcourtesy of Thorn Lighting)

Fig. 4.11 Types of external(numbers 1–10) andinternal (numbers 11–15)shading devices

3 Fixed vertical screen

4 Fixed louvre system

5 Fixed horizontal

2 Fixed vertical projection

1 Horizontal projection

8 Retractable louvred blind

9 Projecting awning or sun blind

10 Vertical roller blind

7 Vertical non- retractable woven mesh

6 Pivoted non- retractable louvre

13 Fabric roller blind

14 Fabric curtain

15 Venetian blindin double window

12 Vertical louvred retractable blind

11 Venetian blind

Some reduction in the sky glare can be achieved by reducing the contrastbetween the window and its surroundings, for example by the use of splayedlight-coloured reveals or increasing the brightness of the window wall byincreasing its reflectance, or lighting it from a window in an adjacent wall.Window frames should be as light in colour as possible, whether stained orpainted timber, or painted or integrally coloured metal or plastic. However, thereduction of the sky luminance is the major consideration, and where this islikely to be a problem provision should be made for blinds (e.g. horizontal orvertical louvre blinds) or curtains (which can be translucent or opaque, andinternal or external), or retractable screens, canopies or awnings. Permanentfeatures such as roof overhangs may also assist in this matter. However, it hasbeen shown that in the UK, overhangs of more than 300 mm over windowsserve little purpose in terms of shading or improved daylighting(37). If theunderside of the overhang is light in colour, the penetration will be improvedand excessive contrast with the sky can be avoided.

Rooflights can cause discomfort glare for most of the working year if theglazing can be seen directly from normal viewing positions at angles of less than35° above the horizontal (see Figure 4.12). The glare can be ameliorated by usingmeasures similar to those for vertical windows (see Figure 4.13).

Fig. 4.13 Shading styles similarvertical glazing can beused to reduce glare


0<35°

Fig. 4.12 Skylight panels in thefield of view can causediscomfort glare

0<35°

Contrast between the glazing and its surroundings can be reduced byusing coffers with high reflectance sides which also cut off the view of the directsky and by setting the rooflight in a light-coloured ceiling. The luminance of thesky seen can be reduced by adjustable blinds, shades or louvres. The use of apermanent diffusing panel to close in a coffer at ceiling level can provideunsatisfactory conditions; it may become difficult to appreciate that the sourceof light is natural and the feeling of ‘daylight contact’ may be lost, particularly ifthe exterior glazing material is also diffusing. Further, on dull days, there will bea noticeable reduction in the amount of contributed light.

While most of the time sunlight is considered to be an amenity in thiscountry, there are occasions particularly in the summer months when it isnecessary to provide some protection from its inconveniences, such as excessivedirect heat and glare, and shading devices are required. These can usually bedesigned in conjunction with the devices considered for the reduction of skyglare.

It may be undesirable, depending on the climate, to design permanentlyfixed features because they will reduce the amount of daylight entering the roomat all times and this could be particularly undesirable in the winter months.

The protection can be provided by adjustable screening devices such ascurtains and blinds including louvre blinds (Figure 4.11, types 11–15). Foroptimum sun protection, the solar control devices should be placed outside thewindow; retractable screens, canopies or awnings can be used here (Figure 4.11types 1–10). In designing a sunlight control system, it is important that it takesinto account the extent of the use of the school during the summer months.

Emphasis on glare from electric lighting has for a number of years been focusedon the requirements of Lighting Guides LG3(38) and LG7(39), where designershave focused on reducing glare in computer display screens. Technologicaladvances have made some of these recommendations obsolete and designerswould be well advised to absorb the most recent guidance and research beforereaching a definition of suitable glare limits.

The design should also consider that the majority of learning issupported by computers, but not taught via computers; hence the reduction ofglare to computer screens whilst growing in importance is not an over-ridingfactor in most classrooms or lecture theatres. Use of computers will undoubtedlyincrease over the next decade but their use in the majority of cases will belimited, interrupted by other styles of learning, conventional teaching, and forlimited periods. Whilst considering glare to display screens, designers shouldfocus on providing glare control that improves the modelling and lit appearanceof the true teaching surface: the face (teacher, lecturer, student or pupil), text,wall displays and presentation board.

Long established calculations for unified glare rating (UGR) may providethe designer with a numerical method for calculating glare, but the designerwould do well to consider the issues rather than meet a minimum number. Glarecalculated at the mid-position of each wall looking from a seated position mayindicate a worst case but does not apply well to users who are standing, users ofdifferent ages and heights, flexible class or teaching layouts or other teachingspaces outside the norm such as raked lecture theatres. Current research islooking to offer alternative measures for glare using high dynamic rangeimaging converted to luminance maps, though this is still some way fromproviding useful metrics.

Light sources of high luminance and smaller sizes, including smaller,more intense optics, will need careful consideration so that the light sourceluminance is not so intense that even at a small size it impinges on a clear andcomfortable view of the users. This can be achieved by specifying the minimumshielding angles in the field of vision given in BS EN 12464(31) for the specifiedlamp luminance, see Figure 4.14. Minimum shading angles for a range of lampluminance values are given in Table 4.1.

The values given in Table 4.1 do not apply to uplighters or to luminairesmounted below normal eye level.


4.2 Electriclighting

4.2.1 Glare

Table 4.1 Lamp shielding angle limits

Lamp luminance Minimum (kcd/m–2) shielding

angle, α

20 to <50 15°

50 to <500 20°>– 500 30°

α

Fig. 4.14 Lamp shielding angle, α

Research clearly shows flicker from fluorescent and discharge light sourcespowered by switch start or wire-wound gear does influence the comfort of asignificant proportion of the population. To avoid discomfort and hence increaseconcentration and learning rates, the designer should specify high frequency(HF) unless there is a specific special educational need for other systems. Careshould be taken that all control gear should conform to the targets set by theEnergy-using Products Directive(17) and, in the UK, by the Ecodesign forEnergy-Using Products Regulations(40).

Advances in high intensity discharge gear mean that HF gear is becomingmore readily available for these light sources. Where practical and efficient, HF

gear should also be used in these applications.Where the room being lit contains high speed machinery, such as

machine rooms for engineering, industrial technology, or design technologyspaces in schools, then HF equipment must be specified on grounds of safety.Here the fast moving machines combined with switch start gear can createstroboscopic effects that may make the work appear stationary. HF gear operatingat above 30 kHz should minimize this risk. Even so, the designer should carryout a risk assessment of the processes concerned to ensure that the lighting willnot add to any inherent danger.

Care must be taken with the specification and use of LED light sourcesand associated drivers where some poorly designed units have been seen tointroduce an over-riding 100 Hz ripple onto the mains, which may be visible tosome users.

Veiling reflections are high luminance reflections that overlay the detail of thetask. Such reflections may be sharp-edged or vague in outline but, regardless ofform, they may affect the ability to see the task and cause discomfort. Taskperformance will be affected because veiling reflections usually reduce thecontrast of a task, making task details difficult to see.

The two contributors to veiling reflections are any part of the task that isglossy to some degree, and parts of the interior that have a high luminance, suchas windows or luminaires. Generally methods of avoiding veiling reflections areto use matt finishes or to arrange the geometry of the view so that highluminance is restricted, for example by using curtains or blinds on windows.

Gloss finishes should be used with care as they can cause veilingreflections and glare and often when least expected, for instance the use of agloss whiteboard, designed for written presentation but used as a projectionscreen. Here the lamp from the projector itself can become a major source ofveiling reflection and discomfort glare to students seated at many positionswithin the room.

This is less of a problem in most indoor spaces but small intense lightsources such as computer projectors or uncontrolled luminaires such asspotlights can give problems. Such glare will manifest itself in veiling reflectionson whiteboards, glossy computer screens and glossy pages in books.

The primary complaint in classrooms about visual conditions is that ofreflections in display screens(41). This extends to a wider range of media thanjust computer screens. Modern classrooms have for some time used glossfinished whiteboards rather than chalk-based black or green boards. Inherentlythe gloss finish is susceptible to veiling reflections that make it difficult to seethe writing on the board from certain angles. While this problem can becontrolled by the electric lighting, daylight plays a much larger role and suitablecontrol of the luminance from a window will be necessary. Extending this tocurrent technology, it is necessary to include interactive whiteboards dealing notjust with the written message, but projected images as well.

Whiteboards, like green and blackboards before them, require carefullighting. Luminaires placed in the offending zone may cause veiling reflectionsfor pupils, so position and control is important. Windows should not beprovided in either the front wall or back wall of a lecture theatre or lecture room.


4.2.2 Flicker and highfrequency operation

4.2.3 Veiling reflections

The former would produce intolerable glare to the audience and the latter wouldcause serious veiling reflections on the board.

The luminance distribution in the field of view controls the adaptation level ofthe eyes, which affects task visibility. A well balanced adaptation luminance isneeded to increase the visual acuity (sharpness of vision), the contrast sensitivity(discrimination of small relative luminance differences), and the efficiency ofthe ocular functions (such as accommodation, convergence, pupillarycontraction, eye movements etc.).

The luminance distribution in the field of view also affects visual comfortand there are a number of problems to be aware of. Too high luminance may giverise to glare; too high luminance contrasts will cause fatigue because of constantre-adaptation of the eyes. Too low luminance and too low luminance contrastswill result in a dull and non-stimulating working environment. This can be asmuch an effect of the light distribution in a space as the choice of colours usedon the major surfaces.

Figure 4.15 shows a typical classroom where colour is used in the field ofview to add interest to an otherwise bland space. Light surfaces, even the floorcontribute to the overall brightness of the room.

The luminance of all surfaces is important to create a well balancedluminance distribution, and will be determined by the reflectance and theilluminance on the surfaces. Recommended reflectance for the major interiorsurfaces are discussed in section 3.5. In addition, the reflectance of major objects(e.g. furniture, machinery etc.) should be in the range of 0.2 to 0.7.

The surfaces within the room should be effectively lit. For spaces wherecommunication is less important the maintained illuminance on the wallsshould be ≥50 lux with uniformity >0.1; maintained illuminance on the ceilingshould be ≥ 30 lux with uniformity of 0.1.

Applications or activity areas such as offices and teaching areas, wherefacial recognition and communication are much more important, need brightersurfaces. Here the recommended maintained illuminance for walls should be≥ 100 lx and for ceilings ≥ 50 lx.

The designer should consider that illuminance over the complete wallsurface will contribute to the illuminance in the field of view and should beconsidered carefully as a whole.


4.2.4 Luminancedistribution

Fig. 4.15 Classroom exploiting theuse of colour (photographcourtesy of Concord (HavellsSylvania) and RedshiftPhotography)

It is impossible using known technologies to match artificially the properties ofdaylight. Given the fixed spectrum of all light sources it is not possible to matchthe change in sky colour through the day or at different locations with themovement of the sun in azimuth and elevation.

Even the latest red, green, blue colour mixing techniques using LEDscannot match the colour content in terms of spectrum; the best that can beachieved is to fool the psyche into thinking that the artificial solution comesclose. The appearance of a lighting solution or lamp with a colour temperatureclose to that of light from a clear sky at midday may seem excessively blue asevening approaches. The light is also coloured by the materials outdoors fromwhich the light it reflects before entering through the window.

Discrepancies between the colour of electric light and that of daylight canbe reduced by:

(a) using lamps of cool or intermediate correlated colourtemperature (CCT) class of about 4000 K, or

(b) by screening the lamps from the view of occupants.

Caution: research is continuing into the effects of biodynamic lighting on peopleand, until firm research suggests no long-term risk, the lighting designer shouldbe wary of unsubstantiated claims.

It becomes apparent to anyone who walks around educational buildings thatlights are often switched on in places that have more than adequate daylight.Were lighting to be turned off, the occupants would often not notice thedifference. In considering dimming and controls the reasons for switchinglights on must be understood. This may be for a number of reasons such as:

— All lights are turned on because the row of seats furthest fromthe windows is at a lower level of illumination than the windowseats, and the lights are turned on to equalise the illumination.

— The lights were turned on first thing in the morning and, as theday brightens up, the teacher has not noticed they are still on.

— Clouds passing have caused brief interludes of dimness that haveprompted the teacher to turn lights on.

— Glare from the windows has caused the shades or curtains to bedrawn

— Daylit spaces adjacent to classrooms (e.g. corridors) are brightlyilluminated and the classroom appears relatively dim onentering.

Lighting design should make the maximum use of daylight and bedivided into zones of control relative to the amount of daylight present. Usingelectric light to complement daylight should be considered only when daylightis insufficient, and designers should ensure energy efficient electric lighting thatonly operates when it is required (see Figure 4.16). This last point can becovered by the positions of the control devices, by the organisation of thelighting circuits to relate to the daylight distribution and to the function of thespace.

Automatic controls can provide significant energy savings but it isessential that any controls are ‘user friendly’, and should be based aroundautomatic daylight harvesting where daylight is sufficient and absence controlto spaces where lighting is likely to be left on. Absence control requires the userto make the decision to turn on lighting locally and switching circuits andpositions should be included with this in mind. Careful design here will reapmaximum energy savings, minimise control circuit power losses and provide theuser with consistent functionality.


4.2.5 Choice of lamp andluminaire

4.2.6 Lighting control

There is extensive evidence that users do not like or use complex controlsystems, hence the designer should keep it simple, avoiding complex buildingmanagement linked systems (that may be beyond the comprehension of staffand pupils) and use controls that are intuitive in operation and easy to learn.

‘Scene setting’ controls should be used only where absolutely necessary,for instance in conference facilities and lecture theatres, but even here should belimited where possible to a number of simple, practical scenes operated by clearand practically located control panels.

In all cases lighting controls should be commissioned (see CIBSECommissioning Code L: Lighting(42)) by a suitably qualified person and adequatetraining given to users.

In educational buildings most of the spaces should be predominantly daylit,with electric lighting taking over on dull days and at night. There may howeverbe some spaces that have some daylight, but not always sufficient over the wholearea. In these cases, it will be necessary to employ a system combining bothdaylight and electric lighting, which is used as and when required. It isnecessary to consider the distribution of daylight together with the comple -mentary electric lighting distribution to ensure they enhance one another.However, it will not be sufficient to provide a combined lighting system thatgives only a uniform horizontal plane illuminance. It will also be necessary forthe electric lighting installation to create the sensation of brightness in the areasremote from the windows. For this it will be necessary to highlight surfaces,particularly the walls.

When the daylight recommendations cannot be achieved throughout thespace, a supplement of electric lighting should be provided, but it is usual torequire the space to appear predominantly daylit.

The first requirement is for the electric lighting to supplement thedaylight so that the combined illuminance is suitable for the task or activitiesbeing undertaken, and an effective use of controls is necessary to limit theelectric light to no more than is required.

To achieve a satisfactory appearance the luminance of surfaces should bebalanced throughout the space so that surfaces in parts remote from thewindows do not seem dim and gloomy. An appearance that is visually acceptablecan be achieved by preferentially lighting the wall remote from the windowswith lighting that is separate to that required for the task. This wall lighting canbe more effective when some variety is incorporated, as described in section4.2.4. The ceiling will also need to be well lit to avoid a gloomy appearance. Careshould be taken when this wall is partly glazed and open to an atrium orcorridor.


Fig. 4.16 Daylight sensing controlsbarely visible in theceiling centre hold off theartificial lighting duringtimes when sufficientdaylight is available.(photograph courtesy ofThorn Lighting)

4.3 Integrateddaylight andelectriclighting

Bare lamps should, wherever possible, be screened from direct view (seeTable 4.1) to reduce glare and to limit the variation that can occur in the colourappearance of daylight. With regard to discomfort glare for combinedinstallations, and to ensure the degree of glare from the two installationsoperating together is acceptable, it is advised that independently eachinstallation should be designed to be within acceptable limits.

Whilst designing with numbers has its place in quantifying the performance orefficiency of a space, quantifying the lit appearance, the comfort factor is muchmore difficult. As an aid to developing this aspect of design, the designer shoulduse a number of techniques enabling the design possibilities to be iterativelyexplored and proved. These methods could include computer-based modellingand architectural models, particularly for daylight and sunlight studies, but alsoto understand the play of electric light in a space.

Architectural models were commonly used to explore daylightingdesigns, but are often expensive and difficult to achieve given the demands onspecialist equipment and model making; further iterations of models may makethis impractical. However they do render daylight as perceived and viewed bythe eye and therefore are easy to interpret. Computer visualisation (see Figure4.17), whilst easier to achieve given current technology, is more difficult tointerpret, the results being only as good as the software algorithms and thedisplay ability. For example, in order for the screen to render the differencebetween two joined white surfaces, software is forced to render two versions ofgrey, where as the eye would actually see two whites of differing luminance.

For this purpose it is advised that a scale of not less than 1:20 be used andthat models are made from materials that are opaque and have the appropriatesurface reflectance and colour. It is obviously important that models are dimen -sionally correct and that any external obstructions are included. The depth ofdetail that should be modelled will depend on the purpose of the modellingstudy and it may or may not be necessary to model, for example, glazing bars.However, where measurements are to be taken, then items such as glazing barsmust be taken into account. It is important to include any permanent shadingdevices including roof overhangs. Using the correct material finishes, and inparticular for any shading device, is critical where measurements will be taken.Also external obstructions and their reflectance should be modelled.

The model can be used in three ways: to appraise the appearance of thelit space, to measure the daylight distribution and to examine the direct sunlightpenetration. For appearance appraisal it will be necessary to provide viewingslots. These need to be placed at a normal head position and can be used underreal or artificial sky conditions. It is of course important that no stray lightenters the model through the viewing slot. It is often easier and more convenientto use a camera.

When the model is to be used for measuring the daylight distribution,usually under an overcast sky condition, it will be necessary to provide entrypositions for small photocells, but it must be possible to seal these openingswhen the measurements are being made to avoid errors due to light leakage.

It is useful to measure not only the inside values but also an outside,unobstructed, sky value, which will enable the measurements to be quoted interms of daylight factor. The measurements can be made under a real overcastsky, but it is more convenient to use an artificial sky to overcome the problemof light level variability.

Models can also be used to test sun penetration. In this case the model canbe used in conjunction with a spotlamp to represent the sun and a sundial toenable the correct relationship between the model and the spotlight (artificialsun) to be established. With this equipment a range of sun positions can beexplored. An alternative is to use the model in conjunction with a heliodon,which enables the sun/site/building relationship to be explored more easily.


4.4 Aids tolighting design

Whilst few design practices have their own artificial sky or heliodon,these pieces of equipment are commonly available in schools of architecture,university building departments and research establishments.

Calculations for the determination of point daylight factor, illuminanceand luminance are described in the SLL Code for Lighting(8) (2009 edition) andLighting Guide LG10: Daylighting and window design(43), and therefore are notincluded here.

Lighting for particular applications 37

Fig. 4.17 Virtual daylight modelcreated in IES VirtualEnvironment (imagescourtesy of A Bissell, CundellLLP.)


5 Lighting forparticularapplications

5.1 Classificationof teachingand conferencespaces

5.2 Generalperformancerequirementsfor learningspaces

In the last decade a better understanding of learning and changes in teachingmethods, plus the increased demand for sustainable building design, has led tosome innovative educational buildings that provide stimulating and adaptableplaces to learn for children and adults. Some school sites combine school andcommunity use with, for example, an ‘early years’ centre, enhanced sportsprovision, a public library or health centre. Other recent design developmentsinclude the use of innovative glazed facades incorporating sun shading.

Educational spaces need to be designed for present and future learningand teaching styles and organisation; a difficult task given that a school may lastfor over 40 years. But learning spaces should be suitable, safe and secure as wellas attractive and inclusive places in which to learn and work.

Lighting, both electric and natural, plays a key part in the performance ofall these buildings and research suggests that it plays a key part in the learningrates of students. Some of the recent design ideas include: classroom shapesother than rectangular; use of innovative facades including sun shading, glazingand modern construction methods; combined buildings that are suitable forpupils and public inside and outside of school hours (and that may incorporateearly years care); public library spaces; health centres, extending sportscommunity use and so on, in some cases creating multi-use ground floors withmore specialist restricted use upper floors.

Modern learning spaces need to have the flexibility to accommodatedifferent activities and teaching methods. This may be by rearranging furnitureor by merging spaces (e.g. for two or three classes to work together or forcommunity use after school hours). Some large spaces may be multi-functional,each activity requiring different lighting (for example a space used for bothdrama performances and exams). There may be large open-plan spaces wheremore than one teaching activity, formal or informal, takes place at the same time.Lighting, both electric and natural, plays a key part in making these spacesfunction well; it can also benefit students and other users with a sensoryimpairment. Lighting or lighting controls need to be functional in everyscenario.

As teaching experts advocate new methods of interactive learning,perhaps with multi-disciplinary spaces catering for two or three classes andmany teaching staff, we may see so-called flexible learning and teaching spaces,a wider range of spaces, more multi-use of spaces, increased community use (andtherefore a wider range of activities), increased inclusion (and therefore morewith students and users with sensory impairment). Lighting plays a key part inmaking these spaces function well. Importantly these spaces recognise thebenefits teachers and students can gain in having staff close and from being ableto adapt the space for the best learning style and interaction. Each learning andteaching method will create different lighting requirements for the space inwhich they happen.

Table 5.1(44) indicates just some of the lighting measures required for learningspaces. However the designer must not take these in isolation from the othermeasures such as cylindrical illuminance (see section 3.7) and modelling index(see section 3.8) and requirements for children with special educational needs(SEN) (see section 5.17), and will need to consult actively members of the designteam dealing with thermal performance, ventilation and acoustics in particular.

The illuminance uniformity in the task area should not be less than theminimum uniformity values provided in Table 5.2. The illuminance uniformityin the immediate surrounding and in the background area should not be lessthan 0.4.

Daylighting performance for educational buildings is given in Table 5.3.


Table 5.1 Lighting performance for educational premises (reproduced from BS EN 12464-1(31) Tables 5.29, 5.35 and 5.36 by permission ofthe British Standards Institution)

Ref. Type of interior, task or activity Em (lx) UGRL Uo Ra Remarks

1 Nursery school, play school:

1.1 Play room 300 19 0.4 80

1.2 Nursery 300 19 0.4 80

1.3 Handicraft room 300 19 0.6 80

2 Educational buildings:

2.1 Classrooms, tutorial rooms 300 19 0.6 80 Lighting should be dimmable

General: maintained illuminances on the wallshould be 50% of the task area illuminance orEv = 100 lux, and on the ceiling should be aminimum of 30% of the task illuminance orEh = 50 lux

2.2 Classroom for evening classes 500 19 0.6 80 Lighting should be dimmable. The designer and adults education should consider very carefully whether an

elevated illuminance of 500 lux will offer anybenefit or simply be misused when the space isused to teach children

General: illuminances on the wall should be50% of the task area illuminance orEvmin = 100 lux and on the ceiling should be30% of the task illuminance or Ehmin = 50 lux

2.3 Auditorium, lecture halls 500 19 0.6 80 Lighting should be dimmable to suit variousaudio visual needs

2.4. Blackboards (see remarks for 500 19 0.7 80 White and green boards should require lessother colours) light due to higher reflectance, a luminance of

80–160 cd/m2 is recommended

Prevent veiling reflections

The teacher should be illuminated with suitablevertical illuminance

Where used for projection the surface finishshould be carefully considered and lightingshould be dimmable

2.5 Demonstration table 500 19 0.7 80 In lecture halls 750 lx

2.6 Art rooms 500 19 0.6 80

2.7 Art rooms in art schools 750 19 0.7 90 Colour temperature ≥5000 K

2.8 Technical drawing rooms 750 16 0.7 80

2.9 Practical rooms and laboratories 500 19 0.6 80

2.10 Handicraft rooms 500 19 0.6 80

2.11 Teaching workshop 500 19 0.6 80 For specific industry based teaching in further orhigher education additional advice may besought from Lighting Guide LG1: Lighting forIndustry(51)

2.12 Music practice rooms 300 19 0.6 80

2.13 Information technology (IT) rooms 300 19 0.6 80 Artificial and natural lighting should complywith the guidance in Lighting Guide LG7: Officelighting(39)

2.14 Language laboratory 300 19 0.6 80

2.15 Preparation rooms and workshops 500 22 0.6 80

2.16 Entrance halls 200 22 0.4 80

2.17 Circulation areas, corridors 100 25 0.4 80

2.18 Stairs 150 25 0.4 80

2.19 Student common rooms and 200 22 0.4 80assembly halls

2.20 Staff room/office 300 19 0.6 80

2.21 Library: bookshelves 200 19 0.6 80 200 lux on the vertical face of the bookshelf

2.22 Library: reading areas 500 19 0.6 80

2.23 Stock rooms for teaching materials 100 25 0.4 80

Table continues


Table 5.2 Relationship of illuminances of immediate surrounding and background areasto task area (adapted from BS EN 12464-1(31) Table 1 by permission of the British StandardsInstitution)

Illuminance on the Illuminance on immediate Illuminance on task area (lx) surrounding areas (lx) background area (lx)

≥750 500 100

500 300 100

300 200 100

200 Etask 100

150 Etask 100

≤100 Etask Etask

Table 5.1 Lighting performance for educational premises (continued)

Ref. Type of interior, task or activity Em (lx) UGRL Uo Ra Remarks

2 Educational buildings (continued):

2.24 Sports halls, gymnasiums, 300 22 0.6 80 Sports lighting performance requirements areswimming pools detailed in BS EN 12193(32)

2.25 School/college canteens 200 22 0.4 80

2.26 Kitchen 500 22 0.6 80 These may be classed as high risk tasks foremergency lighting

3 Conference and meeting rooms:

3.5 Conference and meeting rooms 500 19 0.6 80 Lighting should be dimmable

Table 5.3 Daylighting performance for educational premises

Ref Type of interior Daylight factor (%) Remarks

Average Minimum point

1 Entrance, Reception 10% 4% This area serves as a transition from the externalenvironment to the internal environment andneeds to provide a lighting level to allow the eyeto adapt. Glare for any permanent staff workingin this area must be considered.

2 Atrium 5–10% 2–4% Classrooms often look into the atria space andas such borrow daylight from the space and usethe brightness of the space as part of the view.Glare into classrooms needs to be consideredcarefully as does privacy.

3 Classrooms, including standard, 5% 2% Daylight should be the predominant lighting science, food preparation, craft component for the majority of the day.and art rooms

4 SEN classroom 5% 2% Due to the nature of SEN children the daylightand view should be considered together, somerooms with daylight and views and some roomswith good daylight but more limited visualstimulation will be required to suit the differentneeds of the children.

5 Lecture theatres 2–4% 1% Daylight keeps people alert and therefore it isessential for all learning environments. Howeverin a lecture theatre the daylight must be able tobe eliminated to suit the presentation style andprojection equipment.

6 Libraries 2–5% 1–2% Delivering good levels of daylight between theshelves is typically difficult; however the readingareas should have good levels of daylight.

7 Sports halls 5% 2% As sports halls are often used for exams thenproviding good levels of daylight to keep thestudents alert is essential. Control of thedaylight will be required for some sports.

8 Dining hall 4–5% 1–2%

9 Offices and meeting rooms 5% 2%

The choice between a lecture room (basically flat, see Figure 5.1) and a lecturetheatre (raked, see Figure 5.2) will be determined by the audience size. If it isless than 60 there is little point in providing a raked room. If it is more than 80,raked seating is essential, unless the lecturer is raised on a stage or podium.


The lighting in a lecture space must reveal the lecturer to the audience and theaudience to the lecturer, and also provide for the other visual tasks involved.These include observing demonstrations, reading what is projected onto thescreen, or written on the whiteboard, and the taking of notes. Note-taking has tocontinue when presentations, video or interactive presentations are used.

The lighting in a lecture theatre may conveniently be thought of in termsof that for the audience area and that for the presentation area (see Figure 5.2)though this distinction should not be pushed too far; in many lecture theatres,especially smaller ones, the audience area lighting may well function as ambientlighting and provide much of the illumination in the demonstration area as well.

These are rooms used for the delivery of formal lectures with raked floors and/orbalconies or galleries and with fixed seating.

For the audience area the basic choice is between incandescent, LED andfluorescent lighting. Incandescent light is readily controllable in intensity anddirection, is often preferred on aesthetic grounds, and may have some benefits interms of reduced noise. However, even in its best form it is inefficient in termsof energy usage and the heat that it introduces to the building has to be removed.Modern fluorescent lamps, with good colour rendering, are very much moreenergy efficient and offer considerable benefits in lamp life, and in those theatreswhich are heavily used, e.g. in schools and colleges, maintenance and energyeconomics will usually dictate their use.

LEDs offer the designer a further choice, though at the time of writing thetechnology is just entering the mainstream. Issues of colour rendering, lightsource life and efficacy are still inconsistent across the industry and the designerwould do well to consider these issues carefully before specifying LED

luminaires; further advice can be found in Guidelines for specification of LED

lighting products(45), issued in August 2009. That said, there appear to be manymanufacturers offering good quality luminaires containing efficient LED sourcesand this technology may offer a long life and fully controllable solution for manylecture theatres, especially where access may be difficult.

Other types of discharge lamp, such as high pressure sodium, are notsuitable due to poor colour rendering, run-up and re-strike times, and flicker.

5.3.2 Lecture theatres

5.3.2.1 Lighting the audience

Fig. 5.1 Flat seating arrangement usinghidden light sources indirectlyto audience, speaker and thewalls (photograph courtesy ofNDYLight)

Fig. 5.2 Raked seating arrangementswith differing approaches toaudience and presenter stagearea lighting; harsh downlightis softened by vertical elementsto the side of the stage(photograph NDYLight)

5.3.1 Lighting and visualneeds

5.3 Lecturetheatres andlecture rooms

Metal halide sources may offer some benefits when dimming technology is fullydeveloped, but at present still cause problems with re-strike times and lamp life.

Whatever type of lighting is used, the luminaires must be positioned soas not to create glare problems either for the audience or the speaker, as shownin Figure 5.3. This means that, unless the ceiling is exceptionally high, theluminaires must be mounted on, or recessed into the ceiling. Figure 5.4 showsthat when the ceiling is not a flat horizontal surface, it may be possible to makeuse of its shape to conceal the luminaires from the direct sight line of theaudience provided that they do not become bad glare sources for the lecturer.The UGR at any point of the audience area should not exceed 19.


A BFig. 5.3 Luminaires at positionssuch as A and B are closeto eye level for back rowstudents and may causesignificant discomfortglare

Fig. 5.4 Luminaires hidden behindelements of the structureor acoustic treatment willcause less glare tostudents but may still be aproblem to the lecturer

When incandescent, LED or compact discharge/fluorescent lighting isused, high direct ratio luminaires with a tight beam angle should be avoided.Although these are often used in theatres and concert halls, they produce poormodelling of peoples’ faces, with the result that the lecturer cannot clearly see orinterpret the reactions of the audience. When surface mounted luminaires areused, they should not produce a harsh distracting halo on the ceiling aroundthem that may itself become a glare source. Care should also be taken withluminaires mounted close to the walls to avoid high luminance on the wall,which can also be distracting.

When fluorescent lighting is used, ceiling mounted luminaires of therecessed or semi-recessed type may be used. The latter are preferred to preventthe ceiling appearing too dark. In order to avoid note-taking shadows, theluminaires should be mounted with their long axis parallel to the rows of seats(see Figure 5.5), though it is not usually practicable to correlate the rows ofluminaires with the rows of seats beneath. The average illuminance on theworking plane (usually 0.85 m above the floor) should be 500 lux, but should alsobe controllable to suit the needs of the audience. Bare fluorescent tubes shouldnot be used if they are visible either to the audience or lecturer.

If the ceiling is white or of a light colour and is of uncluttered design, pureindirect lighting may be used for the audience area, but the energy costs will behigher. This method produces illumination that is quite free of glare, but is feltby some to produce a soporific effect. In practice the light sources usually haveto be concealed in the cornices. Traditional uplighters may cause obstruction tosome of the sight lines and psychologically provide a barrier between the lecturerand some parts of the audience and perhaps are best avoided.


Lamps used should be of colour rendering greater than Ra = 80. Thecommon ‘white’ and ‘warm white’ fluorescent tubes do not meet this require -ment and under the provisions of the Energy-using Products Directive will bewithdrawn from sale in coming years. An efficient solution is offered bytriphosphor T26 or T16 fluorescent lamps.

In small lecture theatres and any theatres that have an unbroken horizontalceiling, it is a good plan to carry the general lighting forward to serve the wholearea and to add additional lighting as described below. This technique does notemphasise any division between the demonstration and audience areas. In verylarge lecture theatres (see Figure 5.5), and especially those where the ceilingheight is reduced at the front, it is advisable to use quite separate lightingsystems for the demonstration and audience areas. The demonstration arealighting needs to be carefully directionally controlled.

In small lecture theatres luminaires designed for display use should beused. In larger theatres luminaires designed for stage lighting may be moreappropriate. The lamps or luminaires should preferably be concealed from theview of the audience. They may otherwise become very obtrusive and give theroom a theatrical look.

The position and angling of luminaires in the demonstration area iscritical. The best alignment for ceiling mounted luminaires is about 45° to thevertical, and between 30° and 45° to the side. If the angle is near the vertical itmay produce grotesque shadows on the lecturer’s face, and if it is near thehorizontal the lecturer may be dazzled when attempting to address the audience.Similar considerations apply to luminaires mounted on the side walls.Illuminance at table-top height in the demonstration area should be higher, butnot more than double those of the audience area. The recommended values are500–750 lux for the demonstration area and 300–500 lux for the audience area.

Lighting provided specifically for the lecturer to read notes while thetheatre is darkened for the purpose of computer projection needs carefulattention. The problems are that light direct from the source, or light reflectedfrom the notes and desk, may fall on the screen and spoil the appearance of theprojection; it takes very little stray light to affect the projected image. The bestsolution is to incorporate carefully shielded low power light sources in thelectern itself. The illuminance of the notes should be kept as low as possible,5–15 lux is sufficient.

Fig. 5.5 Luminaires orientatedwith their long axisparallel to the seatingwith separate lightingoriented perpendicular tothe boards to light thedemonstration area andspeaker (photographcourtesy of Thorn Lighting)

5.3.2.2 Lighting thedemonstration area

In most modern lecture theatres the speaker will primarily use a screen orlaptop computer, which is self-lit. In these cases the lectern is almost alwayswithout an in-built light, or it may be desirable to switch off the lectern lightingaltogether. However, to enable all members of the audience to see the lecturerclearly and be able to discern body language and facial expression, includingimportantly lip reading for those with hearing impediment, there should besufficient light on the speaker. This can be achieved either with theatre lightingpositioned specifically for the task or by additional linear fluorescent lamps orLEDs simply controlled with a dimmer and mounted within the lectern itself.

The first requirements of a lecture space are that the audience shall see thelecturer easily and that the lecturer shall see the audience easily. Lecturetheatres should not be raked too steeply, see Figure 5.6, as this makes theaudience feel uncomfortable and can present problems with image projection.The seating layout is important in raked theatres; if straight rows are used theseats at the ends of the front rows offer a very oblique view.


5.3.2.3 Sight lines

Fig. 5.6 Steeply raked lecturetheatres can causeproblems with projectionand make the audiencefeel uncomfortable

There can be little social contact between different members of theaudience, and this is disadvantageous from two points of view: (a) it discouragesaudience participation and (b) it does not facilitate or encourage discussion andquestions after a lecture.

For these reasons, the curved rows in Figure 5.7 are to be preferred usinga fan shaped plan. This arrangement has the disadvantage that if the room is onlytwo-thirds filled all the audience may be in the back half. Figure 5.8 shows agood design compromise with at least half the length of the side walls parallel soas to limit the length of rows at the back. It is most important in any lecturetheatre that there is an adequate space in the demonstration area. In practicalterms, this means that there should be at least 3 m between the front wall and thefeet of people sitting in the front row.

This not only allows an adequate area for demonstration purposes andimproves the sight lines, but it gives the theatre a spacious quality, see Figure 5.9.If the front wall is too close to the seats the theatre will look cramped, and havea claustrophobic atmosphere.

Fig. 5.7 Fan shaped lecture theatre

Demonstration area

Fig. 5.8 Modified fan shape with morepractical straight rows

Demonstrationarea

These are rooms used mainly for the delivery of formal lectures, generally withlevel floors and often with fixed seating. This category includes rooms with araised step or podium for the lecturer, and rooms with one or two raised stepstowards the rear of the seating.

Because of the smaller dimensions, the audience area lighting in lecturerooms will usually serve the demonstration area as well. It is desirable that thelecturer and the immediate surroundings are a little brighter than the rest of theroom and this can usually be effected by the use of a few spot type luminairesdirected towards the lecturer. However they must be carefully positioned so asto avoid glare to the lecturer. Usually this will mean that they have to bemounted either on the side walls, or on the ceiling adjacent to the side walls; thepositions are shown in Figure 5.10

If a fixed lecture bench is installed luminaires should not be mounteddirectly over it for demonstration purposes. In this position they may causespecular reflections from demonstration equipment which makes it verydifficult to see what is going on. Lighting from the side is equally effective andspotlights may be mounted in the same position as those to light the lecturer.The general lighting should be arranged to produce an illuminance above500 lux at desk level in the audience area. It should be reasonably uniform andif fixed seats are installed right up to the walls the illuminance at desk level atthe wall should not be below 70% of the average illuminance. If there is an aislenext to the wall this does not apply. The lamps used should be of better thanRa = 80. In order that members of the audience may take notes whilst projectedimages are shown, a much lower level of general illuminance in the range of15–30 lux is needed, achieved by dimming.

Lecture rooms are usually rectangular in plan and experience shows that thebest seating plan is that with the lecturing area at one end of the room with rowsof seating parallel to the short dimension as shown in Figure 5.11.

Figures 5.12 to 5.14 show sightlines for typical layouts of lecture rooms.In the case of a lecture room that is basically flat the sight lines may be greatlyimproved by raising the rear half of the audience on one or two steps and raisingthe lecturer on a step. Lecture rooms in general have a much lower ceiling thanlecture theatres, and in the absence of raked seating the sightlines becomecritical. The lighting equipment should be arranged so that the luminaires donot cause serious glare to the occupants of the rear row of seats, as shown inFigure 5.15, or to the lecturer as shown in Figure 5.16. When fluorescentlighting is used the luminaires should be of the recessed or semi-recessed types;if this is not possible they may be provided with the glare shields illustrated inFigure 5.16. It may sometimes be possible to use ceiling ribs as glare shields. Onno account should bare fluorescent tubes be visible to the audience.

The UGR at any seat should be less than 19. It should also be rememberedthat avoiding glare for the audience may create glare for the lecturer; inparticular, the lecturer must not be subjected to disability glare.


Fig. 5.9 Layout of the theatrecreates a feeling of space(photograph courtesy ofNDYLight)

5.3.3 Lecture rooms

Lecturearea

Fig. 5.10 ‘X’ marks possiblepositions for spotlights ina small lecture room onceiling or side walls

Fig. 5.11 A good lecture roomlayout

5.3.3.1 Lines of sight and glare

Almost all presentations will require controlled lighting. For that reason, lecturetheatres and rooms are often built with little or no access to daylight. Equally,people do not like to feel shut in, especially when lectures are given duringdaylight hours, and there are many who have a preference for working undernatural light. In rooms the size of lecture theatres, the provision of natural lightin sufficient quantities for working purposes requires very large areas of glazing.This is not only expensive from the point of view of heat loss, but makes itdifficult to achieve a good blackout. Furthermore, unless the windows are northfacing, or sufficiently shaded externally, there may be severe problems with solarheat gain in summer.


Fig. 5.14 Sight lines can beimproved further byraising the rear seats

A B

Cut offangle

Fig. 5.15 Back row glare in alecture room; luminairesat A and B are very closeto the students’ sightlines, and will causeintolerable glare

Fig. 5.16 Glare shields or louvreswill overcome theproblem of back rowglare

5.3.3.2 Provision of daylight

Fig. 5.12 Sight lines in a lecturetheatre with a flat floor

Fig. 5.13 Sight lines may beimproved by raising thelecturer on a step

The only way in which an adequate blackout can be achieved in suchrooms is by the use of completely opaque blinds, running in grooves at the sidesto provide a light trap. Curtains or venetian blinds are not adequate. Blindsshould be of light colour on the inside, so as not to present a large black areawhen down, and should be motor operated due to the area of window involvedand the need for frequent opening and closing. Blinds should also be of a lightcolour on the outside, to prevent excessive solar heat gain.

It may be desirable to provide occupants a view of the outside world inorder to provide some visual escape rather than to provide lighting. The lecturetheatre shown in Figure 5.5 illustrates that very much smaller areas of windowcan be used, and the problems associated with them are consequently muchreduced. However, the need for a perfect blackout remains and groove-enclosedblinds are needed, though in such cases they may be hand-operated.

Windows should not be provided in either the front wall or back wall ofa lecture theatre or lecture room. The former would produce intolerable glare tothe audience and the latter would cause serious veiling reflections on the board.Skylights should be provided with care; they require elaborate blackoutarrangements and are very difficult to keep clean.

From the point of view of presentation, it may be better for lecturetheatres and rooms to be windowless as this provides less problem controllingglare from sunlight. Since the occupants rarely have to remain in them for morethan an hour without a break, problems of claustrophobia do not arise, althoughthey may well do so in small teaching rooms. Many institutions have madeextensive use of windowless lecture rooms with considerable success. Howeverwindowless lecture theatres and rooms require forced ventilation that may leadto noise problems, but it should be noted that large theatres with extensiveglazing also require forced ventilation. It is preferable, however, that all teachingspaces should allow daylight so the user can retain a link to the time of day andweather. A lack of daylight may adversely affect occupants’ circadian rhythmsand hormone production (though further research is needed), as well as increasethe electrical load in the space due to electric lighting being used when daylightcould be utilised. As with skylights careful and complete blackout blinds shouldbe provided if daylight is permitted.

Light traps (e.g. two sets of doors or other effective means for excludingdaylight) should be provided in all lecture theatres and rooms to preventunwanted light getting in when the theatre is darkened for presentation. This isparticularly so in the case of entrances at the rear of the theatre, which whenopened suddenly by a latecomer may allow full daylight to fall on the projectionscreen. These light traps should also function as sound traps.

Such doors should not be provided with windows, unless essential for firesafety, if it is not possible to provide proper light traps. If automatic door closersare installed they should be of a design that allows the door to be closed quicklyand silently.

The audience should be able to concentrate on the lecturer, screen or board, andthe decoration, furnishings and equipment should not be competing with thelecturer for attention. The lecturer’s desk, board and screen must be so placedthat they do not obstruct the view of the audience. If a computer projector isused, great care must be taken to see that it does not obstruct either theaudience’s view of the lecturer or the lecturer’s view of the audience. Careshould be taken to avoid intense glare to the lecturer from projectors that maylead to eye complaints later in life.

Specular reflections of light sources and windows on the board, soundingboards and glazed portraits should be avoided. Also avoid backgrounds withdisturbing patterns, and backgrounds full of fussy details. The audience’s viewof the front of the lecture room or lecture theatre should be clear and free fromvisual clutter; in particular the front wall should be kept clear of pipework,


5.3.3.3 What the audiencesees

conduits, and ventilation trunking. In some cases the luminaires themselvesmay provide visual clutter and should be carefully chosen and positioned.

It is the decoration and furnishings within a lecture theatre or room which, incombination with the lighting determine its appearance and contribute to thatindefinable quality that is usually called ‘atmosphere’ or ‘character’.

The choice of colours and finishes should be made at an early stage inconjunction with other decorative finishes and furniture. The use of darkercolours on the side walls of theatres will help concentration. The surfaces of theside walls should have some degree of texture, such as that provided by timberpanelling, textile covered panels, slightly textured plastics or recessed-pointingbrickwork.

Shuttered concrete is not recommended as it soon gets dirty and is noteasy to clean. In a lecture room without fixed seating it may not be desirable totreat the side walls as a feature, but darker-toned colour can be used behind thelecturer. Ceilings should be white. Care should be taken to provide some lighteither directly or indirectly onto the ceiling. Walls should be of a differentcolour from the ceiling in order to define the boundaries of the interior spaceand avoid a feeling of claustrophobia.

Matt or semi-matt surfaces are desirable as high gloss areas will causespecular reflection and be distracting.

Colour contrasts of a modest nature are desirable since a bland interiorscheme, combined with dim lighting, tends to cause drowsiness amongst theaudience. These contrasts can usually be obtained by careful choice of thecolours of the seating as this presents a large area of colour; mid-toned coloursare best in a definite but not too strong hue. The flooring colour does notcontribute a great deal to the scheme in a lecture theatre. Whether carpet or hardfinish a neutral colour is the most practical choice.

In any lecture space the lighting controls need to be as simple andcomprehensible as possible — lecturers should be more concerned with theirsubject matter than light switches. In the main, the only lighting settingsneeded in a lecture theatre are:

(a) full lighting, to about 500 lux, for adult use

(b) reduced lighting, to be considered the primary setting, to about300 lux for child and young adult use

(c) audience area lighting reduced to a low level and demonstrationarea lighting off for the purpose of image/video projection, butallowing enough light for the audience to take notes

(d) all lighting off for the projection of specific content, and for thepurposes of visual demonstrations.

Abrupt changes in the lighting are disturbing to the audience, andlighting controls should enable gradual changes to be made in preference toplain switches. A good system is that in which the only controls are fourpushbuttons, corresponding to the states above. On pushing the appropriatebuttons the lighting assumes the appropriate scene. In such installations thetime taken to go from full-on (a) to full-off (d) should not be too long; about fourseconds is sufficient. A lighting scene selection panel should be situatedconveniently for the lecturer and any support staff, with some form of overrideat each entrance, suited to entry and exit from the space. Whilst it may beattractive to include absence detection to ensure lighting is switched off whenthe theatre is empty, the design should take care to ensure any sensor usedcovers the space sufficiently and with a suitable level of sensitivity.

All lecture theatres should be arranged for one-person operation, ascircumstances inevitably arise where a lecturer has to speak without the servicesof an attendant.


5.3.3.4 Decoration andfurnishings

5.3.3.5 Switches, dimmers andcontrols

As most modern lecture spaces use computer based projection, the theatreshould be laid out with sufficient consideration for the use of the projector andaccompanying laptop computer. Inadvertent spill light onto the screen shouldbe avoided especially where older, less powerful projectors are in use. Similarlythe lecturer should have sufficient illuminance onto the computer to enablekeyboard detail to be discerned and to ensure that minimal adaption change isrequired between the view of the audience and the screen in all scenes.

Access doors should not be in the front wall of the lecture theatre or room,where they add to the visual clutter, and distract attention. The same applies tothe doors of preparations rooms, lecturers’ rooms and stores.

All lecture theatres and lecture rooms sooner or later become used forpurposes other than that to which they were originally dedicated. Consequentlyall items in the demonstration area should be movable and removable. Hencethe lighting and control of the lighting to these spaces should be easy to re-aimor re-commission.

Experience shows that when demonstrations are mounted, services otherthan electricity are rarely, if ever, called for and there is little point in installinga fixed bench simply to provide terminal points for water, gas, and other outlets.If such services are needed, they are much better installed in wall cupboardswhere they can be kept both locked and out of sight until they are wanted.

When members of the public may be present, all exits to a lecturetheatre/room be marked with permanently illuminated exit signs, and all exitroutes must have sufficient emergency lighting. Light from such signs falling ona projection screen can ruin the effect of presentations or demonstrations, theyshould therefore be aligned so as to be visible to the audience, but not to throwlight onto the projection screen.

Additional lighting at low level may also be beneficial to aid access andegress during presentations. The glare from such luminaires must be carefullycontrolled to avoid presenting problems to the lecturer.

Possibly because they resemble legitimate theatres in shape, and because theyoften constitute the largest auditorium in a particular institution, lecturetheatres are sometimes chosen as the venue for theatrical presentations.

Such presentations can be greatly helped by the provision of furtherspecial facilities for lighting such as theatre lighting supports and controls. Thefollowing paragraphs describe the additional provisions that should be made ifthe room is to be easily adaptable for these purposes. It is stressed that these areadditional, and it is necessary that the requirements of the previous sections aremet first.

When such rooms are used for theatrical purposes, they will almostcertainly be subject to additional legislation such as additional requirements foremergency lighting; the designer should consult local authorities on suchmatters. Relevant publications and general advice are available from theAssociation of British Theatre Technicians (www.abtt.org.uk), and detailedadvice and planning from members of the Society of Theatre Consultants(www.theatreconsultant.co.uk).

The additional provisions needed in the audience area are:

— The lighting must be dimmable smoothly and without flicker to1% of its maximum level.

— Exit signs as required by BS EN 5266(46). Luminance and spilllight should be restricted to avoid glare and interference withstage lighting effects.

— Light and sound traps on all entrance doors (or at least thoseused by latecomers and for access to toilets). Lighting within alight trap should be primarily from the dimmed house lighting


5.3.3.8 Use for theatricalpresentations

5.3.3.6 Audio-visualconsiderations

5.3.3.7 Access and movement

system, but a low power light from the external system may alsobe needed, and a maintained emergency light.

— Provision for theatrical lighting installation using professionalspotlights rigged on standard 48 mm diameter scaffold tube andconnected using industry standard theatre plugs and sockets.Essential locations are above the seating parallel to the frontcurtain at approximately 45° elevation from 1.8 m above thefront of the stage. Steeper and shallower positions will also beuseful as will positions on the side walls at 45° in plan to centrestage. Safe access for adjustment and relamping must beanticipated. Each socket should be wired suitably for the chosenpower and dimming control systems.

Additional provisions needed in the stage area:

— At least 2 m wing space either side of the stage

— Adequate headroom to allow overhead stage lighting to behidden from sight, i.e. at least 1 m from the upper sightline

— Access to both sides of the stage, not through the auditorium,with sound and light traps and silent closing doors

— Access to dressing rooms

— Access to the auditorium, not via the stage

— Access for scenery from delivery vans

— Provision for front curtain with winch mechanism

— Provision for side and rear masking curtains to hide performersawaiting entrance

— Over-stage rigging for hanging scenery and top masking. Thiscan be basic exposed rolled steel joists (RSJs) and scaffold pipes,with manual or motorised winches, or fully counterweightedflying systems requiring two to three times the visible stageheight.

— Work-lights at both sides, rear and over main stage for settingand changing scenery with local switching and master switch atstage manager position. Fluorescent battens with protectivetrough reflectors and wire guards are usually used for work-lights. Instant operation is essential. Dim, shielded lights arealso required for used during performance but these can berigged as required if full theatrical standards are not specified.

— Provision for theatrical lighting installation using professionalspotlights rigged on standard 48 mm diameter scaffold tube andconnected using theatre lighting industry standard plugs andsockets. Essential locations are above the stage parallel to thefront curtain immediately behind the curtain line, 1 m in frontof rear wall and between at 1 m to 1.5 m intervals. Each socketshould be wired suitably for the chosen power and dimmingcontrol systems.

Control of the lighting and sound systems may be effected from theprojection room or separate lighting and sound control rooms. The lighting inthose rooms should be similar to that for a projection room and the roomsshould be sound-proofed. A good view of the stage is essential in each case.Loudspeaker reproduction of platform sound is essential, and if a headsetcommunication system is used appropriate wiring should be provided.

All systems should be arranged so that they can be operated by a singleperson if necessary. The control rooms should be of sufficient size to cater fordimmer circuits that may be involved. The sound control room should haveconnections to tie-lines for microphones and loudspeakers both on stage and in


the audience area, and also be connected to the headset communication system,the dressing room sound system and the audience hearing aid induction loopsystem if one is installed.

These are rooms used mainly for class teaching purposes, with flat floors and littlefixed furniture except, possibly, cupboards, whiteboards and projection screens.Such rooms will usually have a seating capacity of around 30, but may extend inmodern educational buildings for multiple classes with up to 90 occupants.

Lighting for students with sight problems need careful design and suitable aidsto reading will need to be considered. Bear in mind that for some impairmentshigher illuminance, in itself, may not be the solution. More detail is given insection 5.17.

The designer should still consider the phrase ‘Light the teacher, light the board,light the desk’ but must above all light the face, at whatever height and whateverlocation in the class. Teaching is a mobile interactive activity even in classroomsdesigned around formal instruction, and the student should be able to clearlysee the teacher’s face, and vice versa, from any position. Well applied measuressuch as modelling index (section 3.8) and mean cylindrical illuminance (section3.7) as well as more traditional horizontal task illuminance should be consideredthroughout the class and at appropriate facial heights.

In learning spaces where there is intended to be a high proportion of use ofinteractive whiteboards or display screens with touch sensitive surfaces, thedesigner needs to consider carefully the capabilities of this equipment. Where itis unclear what quality of equipment is to be provided, the designer shouldassume that equipment will be relatively new and capable of good performance.This is acceptable due to the high rate of change in the technology available fordisplay screens and the slower rate of update of lighting in most buildings.

In cases of fully interactive whiteboards, where lit by close offset frontprojection, it is likely that the screen can cope with significant luminance andlighting, except perhaps display spotlights, should not be considered a concern.For self-lit interactive displays such as plasma or LCD monitors with a touchsensitive front surface, the designer may have to consider limiting the luminaireor daylight luminance to as low as 200 cd/m2. In most cases, based on the use forself-lit screens, the designer should apply luminance limits from BS EN ISO9241-307(47). Generally, as interactive screens will use positive polarity software,the application of Case A, see section 5.10.1 (Table 5.4), is sensible.

Where possible, the specifiers of projection equipment should considerthe health and well-being of the presenter or teacher as the glare from poorlyplaced projectors can cause considerable discomfort, and perhaps long-term eyeproblems to those using them. Certainly the projector can affect the presenter’sability to interact with an audience and the layout of any teaching space shouldgive a lecturer room to present without standing in the way of the screen.

These are rooms used regularly for class teaching purposes, without largepermanent pieces of apparatus set up. Such rooms will usually have a seatingcapacity of about 30. This category will include many teaching laboratories.

These are rooms used mainly for conferences and meetings at which people mayaddress the audience from almost any point in the room. Such rooms willusually have a capacity of about 60–120.

The basic visual needs in a large conference room are that all members of theaudience can see the chairman and central officers clearly, and that all personspresent should be able to see each other reasonably well in order that a properdialogue may take place. Many presentations in conference rooms, e.g. the


5.4.2 Rooms intended forpresentation

5.4.3 Rooms intended forinteractive learning

5.4.4 Rooms used forpractical work

5.5 Largeconferencerooms

5.5.1 Basic lighting andvisual needs

5.4 Teachingrooms

5.4.1 Lighting and visualneeds

reading of scientific papers, are essentially formal lectures, and the lightingneeds are similar to those of lecture theatres. However conference rooms are alsooften used as cinemas or theatres and the lighting must be capable of meetingthose purposes also. Specifically the lighting must provide adequateillumination for reading or taking notes at any point, good but not excessivemodelling and good colour rendering.

It must also be flexible and controllable from a single point, must beabsolutely silent and produce no thermal discomfort. Careful co-ordination ofthe lighting design with the interior decoration and with the heating andventilating system is essential. Absolute blackout facilities will be needed.

Large conference rooms have a good deal in common with large lecturetheatres, and much of the information in the previous section applies.Conference rooms usually have a clearly defined presentation area,corresponding to the demonstration area of a lecture theatre, and a clearlydefined audience area. But the activities in a conference room differ from thosein a lecture theatre in these ways:

(a) The audience may be present for long periods, often on severalsuccessive days.

(b) The proceedings although of a formal nature involve interactionbetween members of the audience and they must be able to seeeach other clearly.

(c) Conference participants must be able to move easily between thedemonstration area and the audience area.

(d) Simultaneous interpretation facilities may be required.

Item (a) above requires that participants should be able to move in andout of the room whilst proceedings are in progress with the minimum ofdisturbance and the seating should be arranged accordingly, with a greater ratioof gangway space to seating space than is the case in lecture theatres. It isimportant that participants can both get in and out without disturbing theprojector beam if one is in use.

In the UK it has always been the custom that those who contribute to adiscussion should do so from their seats, but in many countries this is not so. Aperson wishing to speak must seek the chairman’s approval and then get up fromhis seat and go to a central podium to speak.

The points made in the previous sections relating to the layout of theseating apply equally here.

The lighting requirements of the demonstration area of a large conference roomwill be similar to those of a lecture theatre and all luminaires should becontrollable. Large conference rooms may be used for theatrical performancesor entertainment, consequently provision should be made for easily riggingadditional lighting equipment. The particular requirement is that appropriatewiring be provided in the form of numerous circuits terminating in socketoutlets at the points where additional spotlights are likely to be wanted. Thesecircuits may be controlled from a stage lighting control system operated local tothe stage, or from the rear of the room. If it is known that a large conferenceroom will be used for theatrical presentations further special facilities may beadvisable. These are described in section 10.3.

The lighting of the audience area and the appearance of the whole arecrucial in a conference room. The audience must not only be able to see eachother clearly, but should not appear grotesque. For that reason downlighters arenot recommended as they produce shadows under the eyes, nose and chin whichare unacceptable, see Figure 3.7(a). If the ceiling is plain white, then recessed orcornice lighting may be used, provided that there is sufficient direct lighting inthe demonstration area to provide a modest degree of ‘sparkle’. If this is not thecase, it is worthwhile introducing a few small luminaires for this purpose. The


5.5.2 Lighting systemsand controls

furnishing and decoration should not be too dark, as light reflected from thefloor and furniture will significantly improve the modelling of participants'faces. The points made about visual clutter in section 5.3.3.3 apply equally toconference rooms.

Strict specifications are laid down for the lighting of interpretation booths, seeISO 2603(48). Care must be taken that light from them does not cause a nuisanceto the audience or speaker, glare or spill onto the projection screen.

These are rooms used for meetings capable of seating up to roughly 30 persons.

The basic functions of the lighting, be it daylight or electric are:

— to enable the committee members to see each other clearly andwithout glare

— to enable members to read their papers and make notes

— to enable committee members to see wall mounted displays.

It should be remembered that committees sometimes have to work under somestress, especially when unpleasant or unpopular decisions have to be made. Theluminaires should be unobtrusive, and glare kept to a minimum.

Committee rooms should always have some natural lighting; windowless roomsare unacceptable for committee purposes. The essential problem of naturallighting in a side-lit committee room lies in the fact that occupants on differentsides of a table are likely to be exposed to different forms of inconvenience.Those facing a window may suffer glare, and see their colleagues opposite withfeatures in shadow silhouetted against a bright sky. Those with their backs to awindow may cast a shadow on their own papers. One possible approach is toensure that the chairman faces the window and can control both the blinds andthe electric lighting. This arrangement ensures that the chairman’s face isclearly revealed, that there is no visual discomfort, and that the faces of otherparticipants can be seen comfortably. If this can be achieved, it is unlikely thatothers will have difficulty in seeing one or another.

Whiteboards and flipcharts should not be placed next to a window sincedisability glare will make them harder to read, even when discomfort glare isacceptable. They should also not be placed where they may reflect an image ofthe window. The prescription above, with the chairman facing the window, alsodeals with these problems. Daylight quantity may need to be strictly limited forcomputer-projected presentations and video conferencing. In the case of thelatter the designer must consider carefully the camera position(s), the modellingof the facial features and the contrast between face and background in bothcolour and luminance terms

The geometry of lighting should correspond to the geometry of the conferencetable, defining it as the focus of activity within the room. This does notnecessarily mean that the table should be the brightest surface; downlights areparticularly unsuitable as they cast harsh shadows, generate shiny reflections ina polished table-top and tend to leave walls and ceilings in relative darkness.The illuminance on the table should be about 500 lux, and the UGR at any pointof the room should be below 19.

The light distribution should produce a modelling index within thelimits recommended in the BS EN 12464-1(44), with suitable cylindricalilluminance at all positions around the meeting table and presentation space.Supplementary display lighting will be required for wall-mounted displays etc.This is governed by the same geometrical constraints as whiteboard lighting.The display lighting should be dimmable. Careful design of a committee room


5.6 Committeeand meetingsrooms

5.6.1 Visual and lightingneeds

5.6.2 Daylight

5.6.3 Electric lighting

5.5.3 Simultaneousinterpretationbooths

will remove the need for portable projection screens, and for ad-hocarrangements of computer projectors and blackout facilities.

The background luminance should ideally be slightly lower than the luminanceof the occupants’ faces. A few small pictures or ornaments can do much toimprove a committee room, but large and complicated features may distract theattention or affect the exposure of video conference equipment and should beavoided.

These are rooms used for a wide variety of purposes, such as school halls, somesports halls, assembly rooms, function rooms, community and church halls.

The lighting designer should be involved with the architect and interiordesigner from the start of the planning process. In attempting to design asuitable installation for a multi-purpose room the first requirement is for thedesigner, in consultation with the client, to draw-up a list of the purposesenvisaged for the room and an order of priorities of use. The prime lightingneeds in terms of illuminance and the controls needed for each separate activitycan thus be tabulated and if any common patterns exist they will be evident;thus the lighting can be designed accordingly. However, in many cases nocommon pattern will emerge and the designer will have to produce acompromise design.


5.6.4 Surface finishes

5.7 Multi-purposerooms

5.7.1 Lighting needs

Fig. 5.17 Ambient lighting providesfor the needs of access,maintenance and someteaching with projectorand screen and also withstage lighting for musicrecital, drama andtheatrical shows(photograph courtesy ofThorn Lighting)

There are a few basic points, discussed below, that should be consideredat the start of the design process. These are the exclusion of daylight, the stagelighting, and accommodating large chandeliers or other lighting supports. Thenext requirement is for the lighting designer to determine what maximum valueof illuminance is required and for how long. This will determine the nature ofthe main light sources. The designer may also have to consider whether a director indirect lighting system is used.

Daylight may sometimes be excluded depending on the function of thespace. If the multi-purpose room requires lighting that is flexible andcontrollable to a high degree then daylight may need to be excluded completely.However, given the imperative to utilise minimal energy in lighting all spaces, ifwindows, roof lights or skylights are to be provided they should be fitted withlight-tight blackout blinds of the type described for lecture theatres in section5.3.3.2. This is particularly so in the case of skylights.

If the room has a definable stage area, then the lighting for it should beregarded as stage lighting and designed accordingly. This may include the needfor ambient lighting to enable set building and general set-up or cleaning of thestage.

If large luminaires such as chandeliers are to be used, they should bepositioned carefully as they can very easily obstruct both sightlines and thebeams of spotlights. Dimming is essential to provide sufficient flexibility in thelit scene.

In the case of rooms whose primary use is for sports (see Figure 5.18) thedesigner may need to consider over-lighting the space for other activities, suchas examinations, along with the associated limitations to uniformity, cylindricalilluminance and modelling posed by these different requirements.

The function of the general lighting in a multi-purpose room is to provide anoverall uniform illuminance of acceptable colour rendering that is free fromglare, and which may be dimmed. The designer should research and indicate theilluminance needed at working plane height, e.g. 0.85 m above the floor for deskbased tasks or floor level for some sports. If no such survey can be made thedesigner should aim for a value of about 150 lux. If it is known that the roomwill be used regularly for examinations then the provision should be for 500 lux.The colour rendering should be of R ≥ 80.


Fig. 5.19 Flexibility in open planallows the space to beused for any number oftasks; the lighting andcontrols needs to accountfor all of these needs andso may be a compromise,in this case perhaps glare.(photograph courtesy ofThorn Lighting)

5.7.2 General lighting

Fig. 5.18 Sports halls are oftendesign for a multitude ofdifferent activities; thismay include regimenteddesk layouts duringexamination time(photograph courtesy ofThorn Lighting)

With the variety of activities that may take place, sightlines may beanywhere, and it is important to avoid glare. This point is very well met if thegeneral lighting is indirect. If a direct system is to be used the luminaires shouldpreferably be fully recessed. If surface mounted fittings are used they shouldhave opaque or diffusing side surfaces, and in no circumstances should barelamps be visible. Suspended luminaires should not be used to provide generallighting unless they are suited to the worst case use such as ball sports. Careshould be taken in avoiding glare not to overdo it; recessed downlighters inparticular give no glare at all but produce both a modelling effect on faces, whichis the reverse of what is wanted for a social occasion, and a gloomy atmosphere.The illuminance produced by the general lighting should have a uniformityratio of a least 0.6 at working plane height, and this may be difficult to achievewith downlighters if the ceiling is low.

The main lighting will almost certainly be fluorescent. In a few cases highpressure metal halide may be used where less control over illuminance isrequired.

Fluorescent lighting may readily be dimmed but, by the nature of thesource, is less flexible. The term fluorescent lighting includes compact sourcefluorescent lamps that can be used in relatively small luminaires. Fluorescentlamps can be used to advantage in an indirect lighting system, especially wherethe tubes can be concealed in cornices, coves, or in the structure of a ribbedceiling.

High pressure metal halide lighting has a relatively long warm-up timeand is thus of restricted value in multi-purpose rooms. However, for somefunctions, e.g. exhibitions, it may be useful, especially if used to provide indirectlighting.

If used for direct lighting the mounting height should be at least 3.5 m.In those rooms that may be used for sports, especially badminton, care shouldbe taken to see that light sources chosen will not cause flicker or stroboscopiceffects; and in most cases HF control gear is essential. Luminaires should besuitably rated for impact resistance with suitable protection of the lamp shouldit become broken. Lighting Guide LG4: Sports lighting(49) should be consultedfor sports applications.

It may be necessary to mount temporary spotlights for many functions andappropriate suspension points should be provided; a space frame ceiling is idealfor this purpose. If the room has a definable stage area then provision should bemade for mounting front-of-house spotlights in the shape of wall brackets orspot bars mounted below the ceiling and in smaller rooms that may suffice forall spotlight mounting. Since wall lighting is often needed for exhibition anddisplay purposes, a ceiling track round the entire room 1.2 m in from the wallmay be a wise provision if ceiling height is less than 4 m.

Where provision is made for spotlight mounting for stage purposes,appropriate wiring runs back to the control point/switchboard must be providedwith separate circuits for each outlet point and provision of cables for a suitablecontrol circuit such as DMX512.

Multi-purpose rooms will generally be regarded as places of public use and thusmay be subject to specific requirements under legislation such as the BuildingRegulations. These may require that the lighting controls be placed such thatthey can only be operated by competent staff, which may prove awkward for theuser.

All of the lighting controls should be grouped together so that oneindividual can have charge of all; the controls are best placed in an adjacentroom with a window or CCTV monitor into the multi-purpose room.

A multiple scene setting control system should be used if possible with anumber of scenes suited to the multitude of uses. This allows complete


5.7.5 Controls

5.7.3 Suitable lightsources

5.7.4 Suspension pointsand wiring

flexibility of control, but also enables pre-set lighting arrangements to be set-upat the push of a button so that it can be used by inexperienced users, such as asimple on/off control for initial entry to the space.

This category includes foyers, ante-rooms, lobbies and corridors immediatelyadjoining those spaces listed above.

The functions of the lighting in spaces adjoining teaching and conference spacesare as follows:

— to provide for the entrance and exit of the users, bearing in mindthat many people may need to get in and out in a short time

— to put users, as they approach, in an appropriate frame of mindfor the activity in which they are about to take part

— in some cases, especially ante-rooms, to provide a socialatmosphere (such spaces are often used as tea and coffee spaces)

— in some cases, to indicate to visitors the route they should taketo reach their destination, e.g. the lecture theatre in a museum;in other cases, e.g. a suite of teaching rooms in a college, this maynot be appropriate

— finally, in many schools there are ‘heart’ or ‘breakout’ areas forgroup interaction or project work.

The lighting of an adjoining space should therefore be designed inparallel with that of the lecture, teaching or conference spaces which they serve.However, this does not necessarily mean that they should be in the same style,or have the same illuminance values.

The circulation routes in a school are its main arteries taking pupils, staff andvisitors from the main gate through to the particular rooms of interest. Theyneed to be functional in that people need to find their way easily and safelythrough the building, even when they are unfamiliar with it. Circulation zonesare often used for chance or ad hoc meetings or as breakout learning spaces (seeFigure 5.20) so these routes also need to incorporate daylight and should be litso that good face to face communication can take place.

They will in most cases need to provide means of escape and this willrequire emergency lighting according to time of availability and user awareness.As school and college use is not restricted to daylight hours, a careful riskassessment should be carried out to determine which access routes are availablefor use during hours of darkness and, therefore, whether they require emergencylighting.

Lighting can provide guidance for the visitor from entrance todestination, that may be done in two ways. First, the geometry of the luminairescan imply a direction. Secondly, by the phototropic effect whereby people areattracted to bright lights. A lighting designer can exploit this tendency byleading visitors towards brightly-lit areas.

Lighting in corridors must provide for safe movement, and shouldprovide an illuminance of at least 100 lux at floor level, with a UGR below 25.There must be appropriate lighting for hazards to be visible; specialconsideration should be given to those with visual impairment, where colourcan be used to provide visual contrast. A particular hazard in corridors withshiny floors is that of water on the floor, which may be present due to spillage,roof leakage, or from melted snow carried in occupants’ shoes.

The rule for staircase illumination is to light the treads and not the risers.A lighting level of 150 lux is appropriate and should be provided by positioningluminaires carefully to avoid distraction. The type and position of luminairesover stairs may be determined primarily by the requirements of emergencylighting and thereafter by the proposed installation and aesthetic requirements.


Fig. 5.20 Breakout spaces openingoff a central circulationspace and stairwell(photograph courtesy ofThorn Lighting)

5.8.2 Circulation

5.8 Adjoiningspaces

5.8.1 Lighting objectives


However, consideration needs to be given to maintenance access whereluminaires are mounted at height or over the stairs themselves (see Figure 5.22).

Waiting areas and lobbies immediately adjoining lecture or conference spacesshould be kept tidy and free of visual clutter. As they may be used as social areas,the illuminance should be about 200 lux and lamps of Ra ≥ 80 should be used.Unless the height is greater than 4 m above the floor, downlighters should beavoided as the harsh modelling they create can hinder face to facecommunication.

Because activities of this kind may go on at the same time as lectures orconference proceedings, there should be two sets of doors at the entrance to theteaching or conference space, to act as both light and sound traps. The designershould consider that latecomers may be entering a much darker environmentand the entrance lobby and walkways to the seating should be lit with care toallow for the adaption of the eye to the new illuminance level.

There should be a rear entrance for latecomers to lecture theatres/roomsand it should be clearly signposted from the main entrance — preferably with asign illuminated when lectures are in progress.

If an ante-room for the lecturer is provided its lighting should be of astandard comparable with a laboratory, office or workshop as appropriate toallow preparation by the presenter.

The lighting for the display screen equipment (DSE) in educational andconference spaces needs to be appropriate for all tasks performed at that locationand for the duration of the task, e.g. reading from screen or printed text, writingon paper, keyboard work.

For these spaces the lighting criteria and system should be chosen inaccordance with activity area, task type and type of interior from the schedule insection 5.2.

The display screen (whether desk mounted, on the speaker’s lectern, orpart of the wall display for interactive teaching) and, in some circumstances, thekeyboard may suffer from reflections causing discomfort glare. It is therefore

5.10 Areas withdisplay screenequipment

Fig. 5.21 Circulation spaces often doubleup as informal learning ormeeting spaces (photographcourtesy of Thorn Lighting)

Fig. 5.22 Adequate illuminance providedin such a way as to cause amaintenance access problem ata later date (photograph courtesyof Thorn Lighting)

5.9 Waiting areasand lobbies

necessary to select, locate and arrange the luminaires, and to control daylight soas to avoid high brightness reflections.

The designer will need to determine the offending mounting zone andchoose equipment with suitable mounting positions or distributions which willcause no disturbing reflections.

Lighting can lower the contrast of the presentation on display screens by eithercausing veiling reflection by the illuminance incident on the displays surface orby luminance from luminaires, windows and bright surfaces reflected in thedisplay. Based on the intended context of use BS EN ISO 9241-307(47) givesrequirements for the visual qualities of displays concerning unwantedreflections. This paragraph describes luminance limits for luminaires that maybe reflected in display screen equipment for normal viewing directions.

Table 5.4 gives the limits of the average luminaire luminance at elevationangles of 65° and above from the downward vertical, radially around theluminaires for work places where display screens, which are vertical or inclinedup to 15° tilt angle, are used.

The effect of higher luminance on the display screen is determined inpart by the display usage. In Table 5.4, ‘Case A’ refers to positive polarity andnormal requirements concerning colour and details of the displayedinformation (e.g. when used in office, school etc.) and ‘Case B’ applies tonegative polarity and/or higher requirements concerning colour and details ofthe displayed information (e.g. when used for computer aided design (CAD),colour inspection etc.).

Some tasks or activities may require different lighting treatment such aslower luminance limits, special shading, individual dimming and so, accordingto the task.


Table 5.4 Average luminance limits of luminaires that can bereflected in flat screens (adapted from BS EN 12464-1(44), Table 4)

Display screen Luminaire luminance limit for stated type screen ‘high state’ luminance

High (> 200 cd/m²) Medium (< 200 cd/m²)

Case A ≤ 3000 cd/ m² ≤ 1500 cd/ m²

Case B ≤ 1500 cd/m² ≤ 1000 cd/m²

Note: for old type CRT screens luminaire luminance limits are200 cd/m² for negative and 500 cd/m² for positive polarity

5.10.1 Luminaireluminance limitswith downward flux

To help establish whether the correct choice of luminance limit has been madethe designer can use the methodology(50) below and the flowcharts given inAppendix A1.

First the designer will need to determine the size of the offending lightsource (luminaire or window, see Figure 5.23. The visual size of the light sourceor the subtended angle (θ ) can be calculated using the equation:

d /2θ = 2 (arctan ——— ) (5.1)

s1 + s2

where θ is the subtended angle or visual size of light source (°), d is the distanceof the light source in the direction of the display screen (m), s1 is the viewingdistance (m) and s2 is the distance between the light source and the displayscreen.

Then the solid angle (Ω) delimited by a cone of apex angle θ can becalculated using the equation:

Ω = 2 π (1 – cos (θ /2)) (5.2)

where Ω is the solid angle in steradians.

5.10.2 Selection of theappropriate limit

The visual size of a luminaire is highly dependent on the luminaire, thedirection of viewing and the distances between the luminaire, the screen and theviewer. A 1° source is about the size of a circular downlight or a fluorescenttroffer viewed crosswise. Other luminaires may be nearer to 3–5°.

The visual size of a window is also variable. Studies of student positionsin typical classrooms indicate window sizes of, typically, 10° and 15°.

The tables given in Appendix A1 use a 95% satisfaction criterion, that isto say by this method of calculation and luminance limit, 95% of users would notexperience problems with display screen equipment veiling reflections.

As screen technology is developing at a faster rate than that of conventionallighting it is far more appropriate to define the performance of the screen that isrequired, rather than compromise the lighting comfort of the user of a space byrestricting the available light. Given that in most learning spaces the computerscreen is not the main disseminator of knowledge, it seems inappro priate tolimit the lighting designer’s choices for lighting the speaker, teacher or pupilsimply due to poor application of display screen technology. To do so would re-create the ‘cave’ effect inadvertently produced in many offices and classrooms ofthe 1980s and 1990s.

Most luminaire manufacturers issue accurate information on theluminance of their equipment at angles above 65° from the downward vertical.Once the lighting designer has reached a lighting solution that provides for theperformance, efficiency and comfort of the users of a learning space, the screenbrightness limitations suited for use in that space should be defined. Forinstance, it should be possible to require suppliers of laptop or desktopcomputers screens for classroom use to provide screens capable of a minimumof 3000 cd/m2 with a matt finish and available tilt of not more than 35°, ratherthan limit the luminaires to 200 cd/m2, based on an inadequate knowledge at thetime of the lighting design as to what display screens may be used. Given alsothat, on average, screens are replaced every 5 years, whereas luminaires may lastin excess of 15 years, this approach makes sense in both economic andsustainability terms in order to provide a good quality lit environment. Lightingcontrol for both the electric lighting and daylighting should still be provided.

Rooms used for practical work, i.e. laboratories, workshops, art rooms, foodtechnology/catering, electronics, craft rooms and similar applied learningspaces, involve visual needs and tasks that are the same as those found inindustry. This is particularly so if the room contains fixed equipment, e.g. aworkshop with lathes and other machine tools.


5.11 Laboratories,workshops andother practicallearning spaces

5.10.3 An alternativeapproach

d

θ

s2

s1

Luminaire

Display screen

Fig. 5.23 Calculation of visual sizein degrees (the luminaireand distance are not toscale but enlarged toshow the angle clearly)

The reader should consult the Code for Lighting(8) for advice onlaboratories, workshops and textiles rooms. However, many rooms used forpractical work have to serve a wide variety of purposes and the visual needs maybe different for each.

In recent years there have been considerable changes in the waytraditional subjects have been taught. Teaching spaces are increasinglybecoming more flexible in use with functions ranging from industrial to officeenvironments. The computer is no longer confined to special rooms — personaland laptop computers may be used almost anywhere.

A very large range of activities are to be found in design and technologydepartments and they may change throughout the course of a year. Theilluminance over the working plane (0.85 m above the floor) should be above500 lux, and UGR 19. The UGR may be raised to 22 for preparation areas and theilluminance should be raised to 750 lux for art rooms in specialist art colleges. Ifwork involving accurate judgement of colour (e.g. art, dyeing etc.) is to be done,the lamps should be of Ra = 80 or better in most educational buildings, but inspecialist art and textile colleges/faculties Ra = 90 would be more appropriate.Visual tasks such as sewing will require local task lighting.

In all these spaces the teacher occupies no fixed position but spends timeat the benches, machines and worktables as needed. The main requirement is forgood supervision with the ability to determine detail and texture beingimportant in most subjects, hence good modelling is required with someflexibility to control the direction of light and to reduce or omit daylight whennecessary. In most rooms there may be a teaching wall from where more formalpresentations will take place with the students sitting or standing by theirmachines, benches or tables, but in some establishments presentations anddiscussions take place in separate spaces with only practical work carried out inspecialist rooms. These separate spaces may be lecture rooms, classrooms,seminar rooms or small group rooms, and the design of these spaces shouldfollow the advice given in earlier chapters.

Laboratories in tertiary education and research will generally have fixedfurniture (see Figure 5.24) but in schools and colleges may take a less formalarrangement with movable tables and fixed wall benches or service pillars sothat a variety of layouts can be provided. In both cases, as with design andtechnology, there is usually a teaching wall. As with other teaching rooms inschools, it is a requirement that they are primarily daylit, but here it is moreimportant that sunlight can be excluded because of disability glare and thedanger of rendering experimental flames invisible.


Fig. 5.24 A typical laboratoryshowing a fixedarrangement, teachingwall and workstationssituated close to daylight(photograph courtesy ofThorn Lighting)

Where fast moving machinery is in use care should be taken to avoidstroboscopic effects by use of high frequency control gear. Where dust ormoisture risk exists the lighting should be a minimum of IP44. In specialistlaboratories in higher education it may be necessary to provide luminaires ofIP65 with a clean room classification. In this case advice should be sought in linewith good practice in the clean room/pharmaceutical industries covered in SLLLighting Guide LG1: Industry(51).

In laboratories some processes may need terminating before evacuation.It is therefore necessary to have adequate high risk emergency task lighting inthose specific locations where a visual task must be performed prior toevacuation. Lighting to the escape routes, or open areas from laboratories andworkshops will be required to ensure safe passage past any risks from machineryor other hazards.

In libraries the designer needs to allow for two main tasks: (a) finding thecorrect book, and (b) reading or study. In addition, there are a number of otherconsiderations such as lighting for using computers and accent lighting fordisplay purposes. Lighting in each case calls for a different approach. Physicallyfinding a book (rather than looking it up on a computer database) requiresvertical illuminance on the spine of the book and, in the worst case, this may bejust above floor level. Therefore, 200 lux on a vertical plane at just above floorlevel is required and the designer should remember that the library user willcreate a shadow when in the vicinity of the shelving, hence light from more thanone direction is important. Use of floor finishes with a relatively highreflectance can help.

For computer and reading based tasks 300 lux is suitable for most usersand in some libraries that are open to the wider adult community this may beraised to 500 lux for reading tasks by the addition of local task lighting whereappropriate, such as at planned reading desks. However, it would not beacceptable to light the entire space to a higher level for a few users who may bepresent only occasionally. Lighting for students with impaired vision needscareful design and suitable aids to reading should be considered. It should beborne in mind that for some impairments higher illuminance, in itself, may notbe the solution.

Care should be taken to incorporate daylight were practical, protectingvaluable reading matter where necessary from heat or ultraviolet damage butmaximising energy savings and providing a higher quality of reading light as faras practicable.


5.12 Libraries

Fig. 5.25 Lighting coordinated withlibrary shelving to providesufficient verticalilluminance to the lowestshelf (photograph courtesyof Thorn Lighting)

It is generally considered that daylight is beneficial in sports halls andgymnasia. However, windows and roof lights are frequently excluded except athigh level because the sun and sky can cause both disability and discomfortglare to users who are moving quickly and often with an upward field of view.Also there is a risk of damage to glazing from some sports. Reflected glare fromshiny surfaces and particularly floors can also be a nuisance. If daylight isprovided, screening facilities for use when necessary should be available. Thereshould be little objection to the use of natural lighting within sports hallsproviding it is well considered and appropriate. The provision of high qualityinternal spaces with attractive daytime environments is a significant aspect inattracting user groups.

There are considerable benefits in terms of environmental sustainabilityand potentially lower running costs in being able to complement electriclighting with natural daylighting. However, using natural light in a sports hallrequires very careful consideration because of difficulties in controlling glareand ensuring reasonably constant and uniform levels of lighting.

Appropriate lighting is vital in sports halls to allow activities to take placethat often demand difficult visual tasks, for instance tracking a fast movingshuttlecock against a similar colour background. The design issues are complexand optimising natural daylight and integrating it with well designed electriclight requires that the form, fabric, internal layout and systems of a building areconsidered holistically. For natural lighting generally, north light is consideredmost appropriate.

To enhance the visual environment, it is suggested that luminaires withboth upward and downward light should be utilised. There should be somecontrol to keep glare to a minimum and the light distribution should provideadequate light on vertical surfaces.

Lamps and luminaires should have wire guards or other impact-resistantprotection. Sports halls and gymnasia in schools are often used for non-sportingevents, including examinations, and therefore consideration must be given tothe lighting required for these events and supplementary arrangementsprovided if necessary. Control strategies should be such as to make it difficultsimply to switch ‘all on’ lighting because it is easy to do so; scene switchingshould be clear and functional.

Because of the high mounting of the luminaires, maintenance of thelighting installation will be difficult unless special access facilities are provided.The use of long life lamps in these circumstances should be examined.Reference should be made to Lighting Guide LG4: Sports lighting(49).


5.13 Sports hallsand gymnasia

Fig. 5.26 It is possible to providedaylight to sports hallswith careful design;electric lighting shouldcater for many differinguses (photograph courtesyof Thorn Lighting)

Very often there will be a need for a large space within an educational buildingto cater for activities ranging from examinations to drama. The design willdepend on the range of activities. Blackout will almost certainly be required fordrama use, as will a degree of flexibility in the lighting dependent on the rangeof uses envisaged and the budget. If the budget is limited, a general lightinginstallation of luminaires that provide both upward and downward light shouldbe used. The installation should meet the most stringent requirements in termsof activity, allowing the luminaires to be simply controlled to provide someflexibility. To complement this there should be a system of wiring that allowssupplementary theatre lighting equipment to be installed when needed.

For teaching of GCSE, A-level and degree level drama courses, a goodstandard of stage and drama studio lighting will be required (see Figure 5.27).


5.14 Generalpurpose halls,drama anddance studios

Front stage barrel(deep stages mayrequire one ormore intermediatebarrels)

Socket for controldesk for setting-uplighting

Possible prosceniumarch location

Wall socketshigh up on wall

Socket for controlboard duringperformance

Dimmer racks

Floor trap with sockets(on stage if fixed stage)

Stage may be wholewidth of hall or beplatform only

Rear stage barrelfor back lighting

Front of stage barrel to light those on fore stage

Window shouldhave full black-out facilities

Sound and light control desk

Pre-wiredlighting barrelsacross entireroom

Fig. 5.27 Mounting positions for(upper) theatre and(lower) drama roomlighting

In halls likely to be used for concerts, theatrical and dance productions itmay be necessary to arrange for an adaptable stage lighting system to be installedso that each event can be appropriately lit. Lighting barrels will need to beplaced above and in front of the stage so that stage lights can be positioned tolight the faces of people performing on all areas of the stage. To achieve this,lighting needs to come from about 45° above and 45° to either side of anyposition on stage. This will involve using wall mounted brackets and additionallighting power and control connections. Where there is a fixed stage, floor-trapswith stage lighting sockets should be located on either side for side-lightingdance, and for special effects lighting. The lighting installed in spaces for musicrecital or performance should be carefully considered in terms of the noise theluminaire components and controls may make. Resistive or inductivecomponents should be mounted outside of the space or within sound insulatingenclosures.

High level, wall mounted and stage sockets should all be wired back to adimmer position on one side of the stage.

For larger halls there may be a need to provide an additional dimmerposition at the back of the hall for controlling the lighting during a production.

Drama and dance studios are used primarily for the teaching of dramawith some need for small dance class use. Whilst windows and daylight are stillrequired to allow flexibility of use for these rooms there may be a need for fullblackout facilities during lessons.

Drama lessons are used to teach group skills, focusing on social andpersonal development, where general mood lighting across the whole studio isneeded, as well as performance and stage craft skills, such as set and lightingdesign, where full theatre lighting is needed for performance use in any area ofthe room.

To achieve this there needs to be a basic structure of lighting points acrossthe space for locating lights in any part of the room. Often the most convenientsolution is to place a series of pre-wired lighting barrels at intervals across thewidth of the room. The lighting sockets should all be wired back to a dimmerposition located in one corner of the room.

The vast majority of educational spaces now use whiteboards (normally with agloss finish) and, in an increasing number of cases, interactive whiteboards.Inherent in these technologies are surface finishes prone to veiling reflectionand, in the latter case, projected images that may struggle to compete with highluminance sources (most commonly sunlight, but in some cases electric orgeneral ambient daylight). It is therefore essential that all whiteboards betreated carefully.

Note that gloss whiteboards cannot satisfactorily be used as projectionscreens as the high gloss will cause veiling reflections from the projector.

To keep reflections to a minimum, whiteboards should be mountedvertically on walls perpendicular to the window wall. They are best lit by ceilingmounted luminaires (see Figure 5.29) or those specifically designed for thepurpose (see Figure 5.30). Where older black chalkboard surfaces are still in use,the illuminance on the surface should average 500 lux, with a uniformity of 0.7;this may be reduced in the case of lighter colour boards to maintain an averageluminance across the board available to the eye of 80–160 cd/m2. Effectivereflectance for coloured boards are: whiteboard 85%, blackboard 5–10%,green/blue 20%, yellow/green 30%.

Where a separate whiteboard luminaire, or luminaires, are fitted theyshould have a manual override switch positioned local to the board for ease ofuse.

Care should also be taken to avoid excessive luminance on the interactivemedia board. In some cases, those based on plasma technology, luminance inexcess of 200 cd/m2 may cause problems. In the case of modern close projectionsystems the luminance may be considerably higher than those imposed for


5.15 Lighting forwhiteboardsand projectionscreens

Fig. 5.28 Dance studios should usedaylight whereas dramamay require completeblackout (photographcourtesy of Cundall Light4)

Visual aids are often used for teaching, most commonly interactive whiteboardsand computer based projectors as well as television and video equipment. Forthe use of these teaching aids it may be necessary to provide a lower level oflighting so that the presentation can be seen comfortably and clearly. Curtainsor window blinds will need to be chosen carefully to match the capabilities ofthe existing equipment and in some cases blackout blinds that fit into slotssurrounding the window reveals may be used. Care should be taken to make surelighting controls and blinds are easy to use to avoid the common ‘blinds closed,lights on’ mentality. Specification of suitable high brightness projectors shouldenable most daylit spaces to retain some natural light contribution at all times.

Sufficient light should be provided to enable notes to be taken during thepresentation, and an illuminance over the seating areas within the range15–30 lux is suitable. High luminance elements from luminaires within the fieldof view may under certain conditions make the viewing of the presentationdifficult and care should be taken, perhaps specifying a required shielding angle,


Where students may sit close to an interactivewhiteboard the board light may need to be switched off to reduce glare

Whiteboard luminaire must be installedwithin the shaded area to avoid reflectionsin the board to the nearest viewer

0

0

Fig. 5.29 Whiteboard luminairesneed to be carefullypositioned

Fig. 5.30 Specific whiteboardlighting positioned toreduce glare and withmatt projection screenmounted separately(photograph courtesy ofThorn Lighting)

laptops and other display screen equipment; in some cases luminance up to6000 cd/m2 may be acceptable but the designer is strongly advised to investigatethe performance of the actual screen to be used.

5.16 Lighting andvisual aids

to make sure a glare-free view of the screen is possible. Also, light should not fallonto the projection screen and it should not be possible to see reflected imagesof luminaires or windows on the screen surface of television monitors.

Lighting must take into account the different needs of children with specialeducational needs (SEN) and disabilities. Children with impaired vision, forexample, need lighting levels that enhance their sight. Those with hearingimpairment need clear visibility for lip-reading and signing, for orientation andusing signage and wayfinding. Safety is a key factor; poor visibility and poorsurface contrast may contribute to accidents. Input from a lighting specialist isrecommended where there are complex visual needs.

A school’s orientation and any natural shading on the site should beconsidered at the outset, including the location of spaces that generate the mostheat and the need for and detailing of shading devices. The Royal NationalInstitute for the Blind (RNIB) and similar organisations can advise on specialistenvironments for children with visual or multiple impairments. Designs shouldavoid glare, silhouetting, reflections, shadows and any other interference thatcauses visual confusion. For instance, a teacher’s or child’s face could be inshadow against a window or bright or highly reflective surfaces, or have shadowscast by electric lighting. Good tonal contrast is important.

There will be times when teachers will want to change the mood of aspace to create a more calming or stimulating environment. Window blinds andelectric dimming can help, as can local controls.

Daylighting is important for all schools, and children with limited mobility inparticular benefit from a connection to the outdoors and a view out. However,some pupils with SEN may be particularly sensitive to glare from direct orreflected sunlight, so it is important to be able to control natural light enteringthe space. This may also be particularly important when providing the rightvisual conditions for viewing whiteboards and projection screens.

The window wall should be light in colour. A brightly lit outdoor viewthrough a window can be glaring against a dark wall — a particular hazard at theend of a corridor. A minimum average daylight factor of 4–5% is considered theoptimum (on the working plane) for schools with children with SEN anddisabilities; an acceptable uniformity ratio should be maintained by providing aminimum point daylight factor of 2% up to 0.5 m from the wall and avoidingunder-lit areas furthest from windows. This applies to learning, circulation andassembly spaces. In deep spaces lit by windows in one wall only, ceilings mayneed to be higher than average with high levels of light reflectance may berequired. Where there is a number of children with visual impairment orsensitivity to light, or where there are conflicting needs, specialist lightingadvice may be needed.

Light fittings must be low-glare, with strict avoidance of mains frequencyflicker and unwanted noise. It may be necessary to avoid visible light sources,over changing-beds or therapy couches, for example. Uplighters and use ofcoloured light synchronised to particular time cues or events during the daymay be more suitable for some children with autism.

Automatic sensors that switch off lighting when no movement is detectedmay not be suitable for children who are less mobile. Switches may be useful inteaching children how to use them.

Without doubt there has to be a fundamental change in the use of light in allbuildings. No longer is it ecologically sound to light for the neediest user as ablanket measure. The approach must be one of allowing sufficient light for thenormal users and the most common task. In addition, the designer should allowfor the needs of any other users of the same space through the use of additionaltask lighting. This task lighting can be by the provision of controls, for instance


5.17.2 Electric lighting

5.17 Lighting forpupils withvisual andhearingimpairments

5.17.1 Daylighting

5.18 Local tasklighting

the setting of the normal scene in a classroom to 300 lux, but allowing a scenethat increases this to 500 lux if required. Alternately, the designer could allowfor the lower level using ambient lighting, including daylight, and top-up thislevel local to a particular task; for instance, by providing an ambient 200 luxvertical illuminance in a library with desk mounted reading lighting to 500 luxat reading positions.

Careful design of task luminaires is needed, especially in cases of SEN

students. For all students it will be necessary to ensure power leads are kept outof reach by careful cable management and routing through desks. It will benecessary to limit the temperature of any luminaire components available totouch or likely to be in advertently touched, perhaps whilst leaning over a book.Where luminaires are used in close proximity to students it will be necessary tolimit surface temperatures to below that which will cause skin damage.

Local task lighting should be dimmable and controlled such that thelighting distribution does not extend beyond the intended task and removingthe possibility of glare to other users or equipment. Local switching will berequired, preferably linked to a room override function to ensure lighting isswitched off when not required.

When considering the external lighting the designer should take the oppor -tunity to consider not only the functional requirements of external lighting butalso the amenity aspects and the benefits that good exterior lighting can bring.Advantage should be taken where appropriate to provide landscape illuminationwherever possible and to add a sense of visual enhancement to interestingarchitecture, sculptures or building structures. Overall, though, lighting toeducational buildings will be for safety and security.

Entrances should be treated in the same way as entrances to leisurecentres or retail outlets. The designer should ensure they provide an attractive,welcoming appearance to all the entrances, access routes and surrounding areasfor staff and students alike. Environmental planning will also require thelighting designer to be mindful of the light nuisance that may be caused.Although difficult to alleviate totally, it can be reduced considerably by carefulconsideration of the product design and positioning of luminaires.

Exterior lighting should at the very least provide both pedestrians andvehicular traffic with good visual guidance around the site.


5.19 Exteriorlighting

Fig. 5.31 External lighting shouldguide, welcome andprovide a sense of safetywhilst satisfying the needfor good quality CCTVimages and minimal lightnuisance (photographcourtesy of Cundall Light4)


In addition to the visual tasks it should also be designed to providepedestrians with a ‘psychologically safe’ environment. Colour rendering,installation efficacies and maintenance issues must all be considered as well asthe luminaire positioning relative to CCTV and local residences.

See Table 5.5. Exterior lighting should comply with minimum lamp and gearefficacy targets of 80 lm/W for colour rendering light sources less than Ra = 60and with 70 lm/W for light sources greater than Ra = 60.

Where there is increased use by those with disabilities, the designer maydecide to increase these levels appropriately but only in zones specificallydesigned to ease disabled access.

5.19.2 Sports pitches

Table 5.6 General performance requirements for exterior sports pitches to BS EN 12193(32)

Type of area task or activity Class Em (lx) Ra (min) Uo (min) GRL (max)

Basketball III 75 20 0.50 55

Football (outdoor) III 75 20 0.50 55

Handball (outdoor) III 75 20 0.50 55

Hockey (outdoor) III 200 20 0.70 55

Netball (outdoor) III 75 20 0.50 55

School sports I 750 60 0.70 —II 500 60 0.70 —III 200 20 0.50 —

Tennis (outdoor) III 200 20 0.60 55

5.19.1 General performancerequirements forexterior spaces

Table 5.5 General performance requirements for exterior spaces (source: BS EN 12464-2(52))

Type of area task or activity Em (lx) Ra (min) Uo (min) GRL (max)

General circulation areas:

— walkways exclusively for pedestrians 5 20 0.25 50

— traffic areas for slowly moving vehicles 10 20 0.40 50(max 10 km/h, e.g. bicycles)

— regular vehicle traffic (max 40 km/h) 20 20 0.40 45

— pedestrian passages, vehicle turning, 50 20 0.40 50loading and unloading points

Parking areas:

— light traffic e.g. parking areas of schools 5 20 0.25 55

— medium traffic e.g. parking areas of 10 20 0.25 50colleges or universities, office buildings, sports and multipurpose building complexes

— heavy traffic e.g. parking areas of 20 20 0.25 50major conference venues, major sports and multi-purpose building complexes

The designer should avoid the desire to over-specify sports pitch lighting in theview that it will extend community use. Generally all educational facilities willonly require a maximum of Class III play(32), i.e. suitable for recreation or schoolssports use including physical education. In cases of colleges or universities withspecialist sports courses, the designer may need to increase this sensibly in linewith the needs of the college.

Where the establishment requires lighting to higher than Class III thedesign must provide the additional levels by luminaires on separate controlcircuits enabling a stepped switched approach and giving staff the ability tominimise energy use to the most appropriate level. Lighting controls for thehigher levels should be accessible only to staff.

Generally external sports areas are likely to have a multi-purpose use andthe designer may need to satisfy a number of requirements. Furthermore thedesigner should consider the realistic quality of play, type of material used for

the playing surface and the range of visual acuity issues raised by extendedcommunity use. In such cases the designer may find the guidance levels offeredby Sport England more applicable, see Table 5.7.


Table 5.7 Multi-use games areas to Sport England standards

Surface Game Em (lx) Ra Uo GRL MF CCT(principal

playing area)

Painted open textured macadam

Principal sports Tennis, mini-tennis, basketball 400 65 0.7 50 0.8 4000

Secondary sports Netball 400 65 0.7 50 0.8 4000

Open textured macadam

Principal sports Netball (AENA Category 1 and 2 courts) 400 65 0.7 50 0.8 4000

Secondary sports Tennis, mini-tennis, basketball 400 65 0.7 50 0.8 4000

Polymeric surfaced

Principal sports Netball (AENA Category 3 court) 400 65 0.7 50 0.8 4000

Secondary sports Tennis, mini-tennis, basketball 400 65 0.7 50 0.8 4000

Principal sports Five a-side, football training, athletics training 200 (full — 0.7 — — —lighting and training)

Sand filled/dressed synthetic turf

Principal sports Hockey, football and five-a-side football 350 (full lighting

200 (training) 0.7

Secondary sports Lacrosse, rugby training (not scrummaging), 350 (full and athletics training lighting

200 (training) 0.7

Note: in all cases overall minimum maintenance factor = 0.8, glare rating < 50, colour rendering value (Ra) > 65, colour temperature ≥ 4000 K

In modern exterior design there is very little justification for poor control oflight nuisance from any educational site, especially those that sit within thecommunity. Whilst there are arguments for road lanterns using shallow bowloptical design, to compromise some upward light for maximum spacing andtherefore better overall performance, the case for all other exterior lighting is notas strong.

Particularly for educational premises, the designer should comply withthe requirements of BS EN 12464-2(52) with respect to restricting light nuisance.Furthermore, there is little basis for the decision that new buildings in urban or

Fig. 5.32 Use of zero cut-offlanterns aimed from theperimeter inwards restrictsto the minimum lightnuisance (photographcourtesy of Thorn Lighting)

5.19.3 Light nuisance

suburban zones should be allowed to waste light more than those in ruraldistricts. Hence, for all educational premises, the designer must aim for theminimum limits given against each zone for the technical parameters given inTable 5.8. The zones are defined in Table 5.9.

For colleges and universities specialising in sports the use of zone E4limits may be justified, subject to geographic location for the sports pitchlighting, provided suitable controls are installed to ensure the lighting does notremain on when not required.

Except for high performance sports pitches in specialist colleges anduniversities, exterior lighting should maximise the use of zero cut-off lanterns,those luminaires that emit no upward light when normally installed.


Road lighting requirements are currently detailed in BS 5489-1(53) and BS EN13201: Parts 2 and 3(54,55).

Entrance and exit points will often connect with major traffic routes andthe lighting should be graded, in order to avoid sharp contrast with the externalroadway lighting. Roads lighting standards should be considered based onrealistic vehicle speeds, pedestrian and cyclist usage.

5.19.4 Road lighting

Table 5.9 Classification of environmental zones

Zone Surrounding Lighting environment Examples

E1 Natural Dark National parks and protected sites

E2 Rural Low brightness Industrial or residential rural areas

E3 Suburban Medium brightness Industrial or residential rural suburbs

E4 Urban High brightness Town centres and commercial areas

Table 5.10 Threshold Increment limitations from sports and road lighting installations(reproduced from BS EN 12464-2(52) by permission of the British Standards Institution)

Threshold increment for stated road lighting/road classification

No road lighting Road classification

M5 M4/M3 M2/M1

15% based on 15% based on 15% based on 15% based on adaptation luminance adaptation luminance adaptation luminance adaptation luminanceof 0.1 cd/m2 of 1 cd/m2 of 2 cd/m2 of 5 cd/m2

Table 5.8 Performance requirements to limit light nuisance (adapted from BS EN 12464-2(52)

Table 2, by permission of the British Standards Institution)

Parameter Application conditions Value of parameter for stated environmental zone

E1 E2 E3 E4

Upward light ratio (ULR) Ratio of luminous flux incident 0 0–5 0–15 0–15on horizontal plane just above luminaire in its installed position,to total luminaire flux.

Illuminance in vertical Pre-curfew 2 5 10 10plane (Ev ) (lux) Post-curfew 0 1 2 2

Luminous intensity emitted Pre-curfew 2500 7500 10000 10000by luminaires (I ) (cd) Post-curfew 0 500 1000 1000

Building facade luminance Taken as the product of the 0 5 10 10(Lb ) (cd/m2) design average illuminance

and reflectance factor divided by π

Sign luminance (Ls ) (cd/m2) Taken as the product of the design average illuminance and reflectance factor divided by π or for self-luminous signs the average luminance 50 400 800 2800

Guidance for all types of exterior lighting, including recommended illuminancelevels, can be found in detail in BS 5489-1(53) and summarised in the lightingschedule (Table 5.5). On new installations it is advisable to ensure a that a ‘safeby design’ policy is initiated early in the project. This should include advice onCCTV together with the positioning and type of lighting required. The externallighting should include all entrance and exit points, and all pathways that linkwith buildings. All exterior luminaires should use high output, good colourquality, low energy lamps. Care should always be taken to avoid or minimise anylight nuisance.

All lanterns should be of zero upward light distribution. For smaller carparking areas, it may be possible to provide illumination from the periphery andalso from buildings in the immediate vicinity. Larger areas will require columnsto be located either centrally or on the boundaries of the car parking area. Thelocation of the columns should take into consideration the parking bays. Wherecolumns are used, their height and position relative to adjacent access roadsmust be taken into account. Access for maintenance purposes should also beconsidered and, wherever possible, the column height should be such as to allowon-site maintenance to be carried out without the need for specialist accessequipment.

Footways that are not well illuminated from elsewhere must be provided withadequate illumination to ensure people’s safety during hours of use. Wallmounted luminaires from adjacent buildings or low-level luminaires can beprovided in the absence of street lighting. If low-level luminaires are utilised,these must be of the vandal resistant type and incorporate long life, low energylamps. If CCTV is operational, the minimum illuminance for the CCTV equipmentmust be taken into account, as well as care in the positioning of the luminaires.Particular attention should be given to routes that allow passage to plant roomswhere maintenance staff may require access after dark. These access points,which may be at roof level, must also be adequately illuminated. Similar specialconsideration must be provided for routes to staff on-site residential areas,which may be in regular night-time use.

There are many areas that pose security risks around educational sites,particularly from vandalism or theft. Attention should be given to areas ofdarkness that may encourage unauthorised persons to gain access or linger inthe area.

In all of the rooms covered by this Lighting Guide, large numbers of people maygather together. It is therefore necessary to provide emergency lighting, whichis defined as lighting that will enable people to see their way out of a building inthe event of the normal lighting failing.

It must be stressed that it is not the function of emergency lighting toenable normal activities to continue within a building if the main power supplyshould fail; such lighting is referred to as standby lighting and is not normallyprovided in educational and conference premises.

Certain elements of the Building Regulations put size limitations onrooms inferring that anti-panic lighting is not required. However, the designermust record a risk assessment for the space, specifically under the RegulatoryReform (Fire) Order(56) in England and Wales. It should be noted that wherethere is open access, public assembly, reconfigurable furniture and access afterdark to people unfamiliar with the space the risk of injury on lighting powerfailure is likely to be significant and may be even greater if the likely influencesof age, illness, alcohol or drugs are taken into account.

It is important that all exits, available for use in an emergency, are clearlysignposted and are visible at all material times. The sign should be illuminatedby normal and emergency lighting systems. If exits are not directly visible, route


5.19.5 Car parking

5.20.1 Escape routesignage

5.19.6 Pedestrian footways

5.19.7 Security lighting

5.20 Emergencylighting

indicator signs with an appropriate directional arrow should be used. The styleand details of the safety signs are defined in BS 5499(57,58). ISO 3864(59) gives theinternationally agreed formats of exit signs and safe condition signs. Thedesigns consist of a rectangular or square shaped frame with a white pictogramon a green background. The green area must be more than 50% of the total areaof the sign and the colour must conform to ISO 3864-1(59). As the pictograms candiffer in style and content, it is important to consult the enforcing authority fora particular project on its interpretation prior to choosing the signs. Thepreferred style of escape signs is shown in Figure 5.33, which has beenreproduced from BS 5499-4(57), BS EN 1838(60) and BS 5499-1(58).

A summary of the requirements for safety signs is given in Table 5.11.


5.20.3 Glare

Fig. 5.33 Example pictogram fromBS EN 1838

Table 5.11 Summary of requirements for safety signs

Parameter Requirement

Viewing distance 100 × height of externally illuminated sign200 × height of internally illuminated sign

Mounting height Minimum 2 m above floor

Response time 50% of design value in 5 s100% of design value in 60 s

Minimum duration 1 hour

5.20.2 Escape routeillumination

Escape lighting should provide adequate visual conditions and directions forsafe passage on escape routes and allow occupants to reach escape routes fromopen areas. It should allow fire alarm call points, fire lighting equipment andsafety equipment to be identified. It should allow hazards (stairs, intersections,slopes) and hazardous processes to be identified and made safe duringevacuation.

In general, students will be familiar with the site layout and the safetyprovisions. They should therefore be able to make an orderly evacuation duringan emergency. However, in some educational buildings there may be activitiesand processes that are hazardous and have to be terminated before evacuation.These are referred to as high-risk areas.

In most educational premises there is likely to be public access forextracurricular activities and adult education, therefore there are likely to belarge numbers of people who will be unfamiliar with the premises, layout andescape procedures. Here, much anxiety and confusion may be alleviated bystrategically placed escape signs. At least one sign must be visible from all partsof the premises at all material times. Such signs should permanently indicate thedirections to exits from the premises or places of safety. Escape areas and routesmust also be illuminated adequately and appropriately.

In high-risk areas, a higher illuminance must be provided at positionswhere a visual task has to be performed prior to evacuation or where people haveto pass by these dangers along the escape route.

In all escape areas and spaces, the emergency lighting system should be sodesigned that the light it provides fills the occupied volume of the space used forevacuation.

In addition, the design should be based on the minimum-light-outputcondition of the luminaire and should be based on direct light only. Thecontributions by room surface inter-reflections should be ignored.

However, for lighting systems using indirect luminaires or uplights,where the luminaire works in conjunction with a surface, the first reflection istaken to be the direct light and subsequent reflections should be ignored.

High contrast between a luminaire and its background may produce glare. Inescape route lighting, the main problem will be disability glare, in which thebrightness of the luminaire may dazzle and prevent obstructions from beingseen, see Figures 5.34 and 5.35. Such glare may be created, for example, by the

beam of a twin spot emergency floodlight seen against a very dark backgroundor placed at the end of a corridor.

The disability glare level to which an individual is subjected is related tothe luminous intensities of the luminaires in the visual field. The glare can beminimised by restricting the luminous intensity of all luminaires in the field ofview. The sensitive field of view is taken to be in the zone 60° to 90° (inelevation) for level routes/areas and the whole of the lower hemisphere for non-level routes/areas, as shown in Figures 5.34 and 5.35. The maximum permissibleluminous intensity of an individual luminaire in the glare zone is related tomounting height, and the limits are shown in Table 5.12. The limits have to becalculated for the maximum emergency lighting lumen output.


At points/places of emphasis, position a luminaire at or within 2 m measuredhorizontally:

(a) at each exit door intended for use in emergency

(b) near stairs so that each flight of stairs receives direct light

(c) near any change in level

(d) at mandatory emergency exits and safety signs

(e) at each change of direction

(f) at each intersection of corridors

(g) outside and near each final exit

(h) near each first aid post

(i) near each piece of fire fighting equipment

(j) near each alarm and call point

(k) in lift cars

(l) in toilets, lobbies and closets over 8 m2

(m) in toilets, lobbies and closets less than 8 m2 without borrowedlight

(n) in control and plant rooms

(o) in motor generator rooms use self-contained luminaires

(p) each side of automatically closing doors

(q) immediately outside the exit from the premises to the place ofsafety.

Note: if (h), (i) and (j) is not an escape route or area, a minimum of 5 lx onthe floor should be provided.

60°

Line of sight

Contributory

Glare zone60°

Fig. 5.34 Glare in direction ofescape

180°

180°

Fig. 5.35 Glare on stairs

Table 5.12 Luminaire mounting heights and maximum luminousintensity

Mounting height Maximum luminous intensity, Imax (cd) above floor level,

Escape routes High-risk task h (m)

and open areas area lighting

h < 2.5 500 1000

2.5 ≤ h < 3.0 900 1800

3.0 ≤ h < 3.5 1600 3200

3.5 ≤ h < 4.0 2500 5000

4.0 ≤ h < 4.5 3500 7000

4.5 ≤ h 5000 10000

5.20.4 Luminaire locations

Emergency lighting systems are usually powered from batteries or generatorsthat are automatically triggered by a detection system as soon as the mainssystem fails. The system duration or category is defined by the period the systemis able supply power to the load, usually given as 1 or 3 hours. In mosteducational premises 1 hour duration is sufficient, however for premises used bythose with limited mobility longer durations may be required.

Emergency lighting power systems in educational premises may beintegral or centrally powered; using whichever system makes sense primarilyfrom a safety point of view.

The designer must consider the environmental impact of emergencylighting batteries, lamps and power use, though as a secondary consideration tothat of safety. Consideration of LED emergency solutions may offer reducedquantities of batteries, extended battery life, extended light source life andreduced parasitic power. However, the designer should research carefully theclaimed performance of LED systems and understand the issues until theperformance of such systems is regulated by suitable European standards.

There are a number of ways that emergency luminaires can operate:

— Non-maintained (NM): the lamp is only lit when the mains failand is operated by an emergency power source.

— Maintained (M): the lamp is lit at all material times and ispowered by the mains supply under normal conditions. In anemergency, when the mains fail, an emergency power source cutsin to power the lamp.

In all cases, where a battery is present, it is charged by the mains supply. Wherethe public are present, ‘maintained’ exit signage should be used.

The emergency escape luminaires may be stand-alone bulkhead units orintegrated recessed, surface, pendant luminaires or uplights, but close attentionshould be paid to the positioning and mounting of these luminaires. Luminairesplaced too low, especially along corridors, may be obscured by the movement ofpeople and be subject to vandalism. If placed too high, for example direct on avery high ceiling, the luminaires may be obscured by layering of smoke in theevent of fire. As a general rule, they should be placed at least 2 m above floorlevel and as close to this height as possible. In schemes where provision isplanned for smoke layering at ceiling level (creating a smoke reservoir),consultation with the fire service is advisable and consideration should be givento mounting the luminaires below this zone by using, for example, pendantluminaires. These luminaires, however, should be at least 2.2 m above the floorlevel.

Note that the positions of the escape luminaires can, by themselves, givethe first indication of the escape route.

Escape luminaires should therefore be sited at, or near, positions where itis necessary to emphasise potential hazards on the route or the location of safetyequipment. ‘Near’ is taken to be within 2 m measured horizontally. Theilluminance on the escape route at these positions should be at least 1 lx. If thesepositions are not on the escape route or in an escape area, they should beilluminated to at least 5 lx on the floor.


Fig. 5.36 If this equipment is sitedalong an escape route itwill require 1 lux fromluminaires positionedwithin 2m horizontaldistance

5.20.6 Classification ofsystems

5.20.7 Planning schemes

5.20.5 Choice of systems

See Table 5.13 and Figure 5.37. Escape routes must be clearly defined andpermanently unobstructed.


Table 5.14 Requirements for escape area lighting

Item Value

Area size Generally ≤ 60 m2 except in places of public assembly or where asufficient risk is identified

Design illuminance Minimum design value 0.5 lx on empty floor excluding 0.5 m wideperimeter band

Diversity < 40 (max./min.)

Disability glare Intensity limits: level routes from γ = 60° to 90°

Response time 50% design value in 5 s and 100% design value in 60 s


Colour rendering Lamp Ra ≥ 40

5.20.7.1 Escape route lighting

0·5 lx 1 lx 0·5 lx1 m2 m

Fig. 5.37 Escape route lighting

Table 5.13 Requirements for escape route lighting

Item Value

Route size ≤ 30 m long, up to 2 m wide (each 2 m wide strip if route is wider)

Design illuminance:— on centre line Minimum design value of 1 lx, on the floor along the centre line of

the route— on centre band Minimum design value 0.5 lx, on the floor of the centre band (i.e. at

least 50% of the route width

Diversity Illuminance on centre line < 40 (max./min.)

Disability glare Intensity limits: level routes from γ = 60° to 90° at non-level routes atall angles (γ) in the lower hemisphere

Response time Design value within 5 s of supply failing



5.20.7.2 Anti-panic (escapearea) lighting

0·5 lx

0·5 m 0·5 m

Fig. 5.38 Escape area lighting

See Tables 5.14 to 5.16 and Figures 5.38 and 5.39. These are open or re-configurable areas including teaching spaces, sports/assembly/examination hallsand cafeteria.

It should be noted that there have been changes to the law governing firesafety in a number of countries. In the UK, the Regulatory Reform (Fire Safety)Order 2005(56) makes it the legal responsibility of building designers andowners/occupiers to risk-assess their premises for fire safety. This riskassessment would include emergency lighting for all areas, but in particular itshould be noted that areas smaller than 60 m2, but which may be open to thepublic after dark, may require anti-panic emergency lighting. Recent practice inschools has been to suggest one luminaire near the exit door providing onlypartial illuminance to the room; this is not acceptable.

Fig. 5.39 Emergency task spotlighting

The success of an emergency lighting system depends not only on the design,planning and selection of the correct equipment, but also on the satisfactoryinstallation and maintenance of the equipment throughout its service life. It isvital that the designer specifies equipment that is fit for the purpose.Consideration should be given to the choice of products so that they areserviceable when installed and, if installed in places where access formaintenance will be restricted, will require virtually no servicing during theirproduct life. Regular maintenance, servicing and testing of the emergencylighting installation is very important if it is to be operative when the needarises.

The emergency lighting system should be installed as instructed by thedesigner of the scheme and also in accordance with the equipmentmanufacturer’s instructions. The designer usually provides a schedule ofinstallation, including scheme plans and wiring/piping drawings in which thelocation of equipment, placing of protection devices and the choice and routingof wiring/piping are set out. The schedule or drawings may also give thesequence of fixing and connections, particularly of complex systems, that theinstaller should follow. All such schedules and drawings should be added to thelog book on completion of the installation. These should be updated withinformation of all scheme modifications made during the life of the installation.

Maintenance and servicing of the installation should be made regularly.This work should be carried out by a competent person*, appointed by theowner/occupier of the premises. The designer should provide a maintenanceschedule that lists and gives details of replacement luminaire components suchas lamp type, battery, fuses, cleaning and topping-up fluids.

Caution should be exercised in servicing, as unenergised circuits maysuddenly become energised automatically. Prime movers and generators willalmost always be started without warning in an emergency or auto test, since asensor remote from the plant enclosure initiates the sequence of operations.


Table 5.15 Requirements for lighting in fixed seated areas (i.e. areas in auditoria, sportshalls, conference rooms, lecture theatres having fixed seating)

Item Value

Area size ≤ 60 m2

Design illuminance Minimum design value of 0.1 lx on a plane 1 m above floor/pitch lineover seated areas; gangways should be treated as clearly definedroutes

Diversity < 40 (max./min.)


Response time Design value in 5 s



Table 5.16 Requirements for lighting in high risk task areas (i.e. area where hazardousactivity occurs that is to be made safe or terminated or where people may pass by)

Item Value

Area size As defined by task size, location and plane

Design illuminance Minimum 10% of maintained illuminance on the reference plane butat least 15 lx

Uniformity > 0.1 (min./average)


Response time Design value in 5 s or faster if the risk requires it

Duration Period for which the risk to people exists


Fig. 5.40 Fixed seating area table

5.20.8 Installation, testingand maintenance

* A competent person is someone who has the necessary knowledge, training, experience and abilities to carry out the work (MSLL or equivalent qualification).

The luminaires must be suitable for the environmental conditions in which theyare expected to function. Luminaires and signs should be cleaned at regularintervals that may coincide with the time of inspection. Any defects notedshould be recorded in the log book and rectified as soon as possible. Thecleaning interval is dependent on the atmospheric dirt in the installation.Serviceable components should be replaced by an approved part at the end of therecommended component service life.

Self-luminous signs, such as a tritium-activated phosphor-coated signs,should be replaced at the specified end of service life. Note that these signscontain residual radioactive material and their disposal must be carried out byan authorised contractor.

Photoluminescent signs must be placed such that they are externally litat all times to ensure that the photo luminescent material is fully charged at alltimes.

Inspection and maintenance should be carried out in accordance with asystematic schedule. A typical planned inspection/servicing schedule is asfollows:

— Check that defects recorded in the log book have been corrected.

— Clean the exterior of luminaires and signs.

— Check correct operation of luminaires and internallyilluminated signs by operating the test facility.

— Check correct operation of engine driven generator(s) and carryout the manufacturer’s recommended maintenance.

— Check fuel tanks and oil and coolant levels and top up asnecessary.

— Check level of electrolyte in batteries of central battery systemsand generator starter batteries.

— Check that all indicator lamps are functioning.

— Record data in the log book.

— Check egress path to determine whether architectural andfurniture changes have rendered the emergency lighting systemineffective.

— Check egress path for obstructions that hinder escape during anemergency.

Instructions issued by manufacturers should also be observed and addedto the service schedule.

Routine inspection and testing should be carried out at the intervalsspecified below. Records should be kept of the tests and the results obtained.Where self-testing or remote testing features are being used, those responsiblefor emergency lighting systems should verify that the tests have been conductedon schedule and have given satisfactory results. Details of routine testing aregiven in BS EN 50172(61).

An increasing trend is for emergency lighting to incorporate some form of self-testing facility, or for the luminaires to incorporate a remote monitoring feature.The electrical test should verify that any self-testing system performs asintended, and without impairing the integrity of the lighting design. Where self-testing or remote monitoring systems are used as the basis of compliance withsection 12 of BS 5266-1(46), visual inspection of the installed equipment shouldbe carried out at least annually to verify that it is in good mechanical condition.BS EN 62034(62) gives details of automatic test systems for battery poweredemergency escape lighting.


5.20.11 Self-testing andremote testingsystems

5.20.9 Luminaires

5.20.10 Service schedule

It should be verified that the charging supply to the central battery systems isindicating normal operation. The emergency lighting record log book ormonitoring system should be checked in order that recorded faults may berectified.

A short-duration test should be performed, by simulating a failure of the generallighting power supply, to verify that all emergency luminaires are operating.This applies for both self-contained and centrally supplied systems.

The duration of the function test should be as brief as possible, so as notto discharge batteries unduly or damage the lamps. Engine-driven generatorsshould be checked for automatic starting and to ensure that they energise theemergency lighting system correctly.

A full duration test of all systems should be performed, to verify that theemergency lighting provides its design output for the full design duration.

The duration test should be arranged to occur at a point in time where thetime needed to recharge batteries has the least impact on the occupation of thebuilding. The signs and luminaires are cleaned if required.

A model certificate can be found in BS 5266-1(46).

A maintenance schedule should be prepared as indicated in the service schedule.

Record keeping is an important aspect of maintenance and recording the systemcondition. A log book should be kept on the premises in the care of a competentperson appointed by the owner/occupier of the premises and should be readilyavailable for examination by any duly authorised person. The log book shouldcontain the following information:

— date of any completion certificate, including any certificaterelating to alterations

— a complete set of plans and emergency lighting layouts for thebuilding; a full set of schematics will be required where centralbattery and generator systems are employed

— a schedule of plant and equipment requiring maintenance,including information regarding the frequency of testing

— instructions that highlight planned maintenance tasks and giveguidance on the execution of these tasks

— a schedule of recording the outcome of all maintenanceinspections and tests carried out, defects and remedial action

— manufacturers’ installation and instruction manuals for eachindividual item of the system, and

— a schedule detailing the quantity of each spare component (e.g.lamp, battery, fusing) to be stored on site to enable quickreplacement of failed components; contact details for eachmanufacturer should also be included.

Further guidance can be found in BS 5266(46), BS EN 1838(60) and ISO30061/CIE S 020(63).


5.20.11.3 Annually

5.20.12 Initial inspectioncertificate

5.20.12.1 Maintenanceschedule

5.20.12.2 Log book

5.20.11.1 Daily

5.20.11.2 Monthly

The designer should check systematically that all the factors relevant to thedesign of the lighting installation have been taken into account. In the followingchecklist the headings below indicate the areas to be considered and the mostcommonly occurring questions. In any specific situation there may be otherquestions which need to be considered.

(a) Objectives:

— Safety requirements: What hazards need to be seen clearly? Whatform of emergency lighting is needed? Is a stroboscopic effectlikely?

— Task requirements: Where are the tasks to be performed in theinterior? What planes do they occupy? What aspects of lightingare important to the performance of these tasks? Are optical aidsnecessary?

— Appearance: What impression is the lighting required to create?

(b) Constraints:

— Statutory: Are there any statutory requirements that are relevantto the lighting installation?

— Financial: What is the budget available, and what is the relativeimportance of capital and running costs including maintenance?

— Physical: Is a hostile or hazardous environment present? Arehigh or low ambient temperatures likely to occur? Is noise fromcontrol gear likely to be a problem? Are mounting positionsrestricted, and is there a limit on luminaire size?

— Historical: Is the choice of equipment restricted by the need tomake the installation compatible with existing installations?

(c) Specification:

— Source of recommendations: What is the source of the lightingrecommendations used? How authoritative is this source?

— Form of recommendations: Have all the relevant lighting variablesbeen considered, e.g. design maintained illuminance,uniformity, illuminance ratios, surface reflectances and colours,light source colour, colour rendering group, limiting glare index,veiling reflections?

— Qualitative requirements: Have the aspects of the design whichcannot be quantified been carefully considered?

(d) General planning:

— Daylight and electric lighting: What is the relationship betweenthese forms of lighting? Is it possible or desirable to provide acontrol system to match the electric lighting to the daylightavailable?

— Protection from solar glare and heat gain: Are the windowsdesigned to limit the effects of solar glare and heat gain on theoccupants of the building? Do the window walls have suitablereflectance?

— Choice of electric lighting system: Is general, localised or locallighting for task or display most appropriate for the situation?Does obstruction make some form of local lighting necessary?

— Choice of lamp and luminaire: Does the light source have therequired lumen output, luminous efficacy, colour properties,lumen maintenance, life, run-up and re-strike properties? Is theproposed lamp and luminaire package suitable for theapplication? Is air handling heat recovery appropriate? Will theluminaire be safe in the environmental conditions? Will itwithstand the environmental conditions? Does it have suitable


6 Checklistfor lightingdesign

6.1 Task/activitylighting

maintenance characteristic and mounting facilities? Does itconform to BS 4533(64)/BS EN 60598-1(65) or other appropriatestandard? Does the luminaire have an appropriate appearanceand will it enable the desired effect to be created? Are reliablephotometric data available?

— Maintenance: Has a maintenance schedule been agreed? Has arealistic maintenance factor been estimated based on the agreedschedule or, if not, have the assumptions used to derive themaintenance factor been clearly recorded? Is the equipmentresistant to dirt deposition? Can the equipment be easilymaintained, is the equipment easily accessible, and willreplacement parts be readily available?

— Control systems: Are control systems for matching the operationof the lighting to the availability of daylight and the pattern ofoccupancy appropriate? Is a dimming facility desirable? Havemanual switches or local override facilities been provided, arethey easily accessible and is their relationship to the lightinginstallation understandable?

— Interactions: How will the lighting installation influence otherbuilding services? Is it worth recovering the heat produced bythe lamps? If so, have the air flow rates been checked in relationto the operating efficacy of the lamps?

(e) Detailed planning:

— Layout: Is the layout of the installation consistent with theobjectives and the physical constraints? Has allowance beenmade for the effects of obstruction by building structure, otherservices, machinery and furniture? Has the possibility ofundesirable high luminance reflections from specular surfacesbeen considered? Does the layout conform to the spacing-to-height ratio criteria?

— Mounting and electrical supply: How are the luminaires to be fixedto the building? What system of electricity supply is to be used?Does the electrical installation comply with the latest edition(including any subsequent amendments) of BS 7671:Requirements for electrical installations. IEE Wiring Regulations.Seventeenth edition(66)?

— Calculations: Have the design maintained illuminance andvariation been calculated for appropriate planes? Has anacceptable maintenance programme been specified? Have themost suitable calculation methods been used? Has the glarerating been calculated? Have up-to-date and accurate lamp andluminaire through-life photometric data been used?

— Verification: Does the proposed installation meet thespecification of lighting conditions? Is it within the financialbudget? Is the power density within the recommended range?Does the installation fulfil the design objectives?

A lighting installation should meet the lighting requirements of a particularspace in an energy efficient manner. An estimation of the energy requirementsof a lighting installation needs to be made according to BS EN 15193: Energyperformance of buildings. Energy requirements for lighting(22). It gives a methodologyfor a numeric indicator of energy performance of buildings. This indicator canbe used for single rooms on a comparative basis only, as the benchmark valuesgiven in BS EN 15193 are intended for complete buildings.

It is important not to compromise the visual aspects of a lightinginstallation simply to reduce energy consumption. Light levels as set in BS EN12464-1(44) are minimum average illuminance values, and need to be obtained.Therefore, to achieve the required energy performance, consideration of

Checklist for lighting design 81

6.2 Lighting andenergyefficiency

appropriate lighting systems, equipment, controls and the use of availabledaylight is essential.

Energy efficiency calculations may also be required to prove compliancewith local building regulations, such as Building Regulations Part L(18) forEngland and Wales.

An energy efficiency checklist would include questions such as:

— Does the lighting design exceed 55 luminaire lumens per circuitwatt for the teaching, office, industrial and storage spaces?

— Do areas other than these also exceed 55 luminaire lumens percircuit watt, including display lighting where practical?

— Are full lighting controls for daylight harvesting installed in allrooms that receive daylight?

— Is manual on/off with absence override detection fitted to allinterior luminaires?

— Are lighting controls commissioned appropriately to thepatterns or daylight and use?

— Does the exterior lighting comply to a minimum of 80 lm/W forcolour rendering light sources Ra < 60 and with 70 lm/W forlight sources with Ra > 60?

— Are suitable daylight and time controls fitted to all exteriorlighting?

— Is high frequency (HF) gear used for all luminaires?

— Where dimming gear is fitted do the ballasts use > 0.5 W whenno light is emitted? (From the year 2017, any new luminaireballasts should use zero power when no light is emitted).

In both lecture and conference spaces it is essential for the lighting equipmentto be properly maintained. Lamps that have failed or are flickering not only failin their function, but convey the impression to audience and lecturer alike thatnobody cares. It is important that lamps that have failed be replaced promptly,and with lamps of precisely the same type and colour.

In raked lecture theatres, access to the luminaires is often difficult frombelow. This is a point that the designer must bear in mind. It is stronglyadvisable for a group replacement scheme to be used, in which all of the lampsare replaced at set intervals. The reader is referred to the SLL Code for Lighting(8)

on the maintenance of lighting systems. Other items such as blackout blinds, projection screens and lighting

controls suffer damage relatively frequently. Any damage of this kind should bemade good promptly. It can largely be avoided by using simple controls withclear instructions adjacent to the item concerned and using equipment ofsufficiently robust construction to withstand the onslaughts of daily use.

During the life of a lighting installation the amount of light it produceswill diminish. This reduction is caused mainly by dirt building-up on thelamps, the luminaires or, in the case of natural lighting, on the windows. Therewill also be a reduction caused by dirt build-up on the internal surfaces of therooms, diminishing their reflectance. Lamp light output will also reduce withageing, some light sources losing more output than others.

These reductions in lighting levels will need to be minimised if energyand money are not to be wasted, and to achieve this it is important to payattention at the design stage to the proper maintenance of the lightinginstallation and of the building itself. This aspect should be discussed inadvance with the users of the building to ensure that they are aware of theproposed maintenance strategy and its implications and obtain their co-operation.


7 Lightingmaintenance

The designer should pay specific attention to the life and lumenprediction graphs for each light source, especially when considering LEDs.Across the range of light sources there are a number of different life measuresfor instance that vary from 90% lumen output to 50% failure of a batch of lamps.

For LEDs, until there is international agreement on this fast developingtechnology, the designer should consult Guidelines for the specification of LED

lighting products(45), which has been produced by a joint committee representingthe SLL, the Institution of Lighting Engineers, the Lighting IndustryFederation, the Professional Lighting Designers’ Association, the InternationalAssociation of Lighting Designers, and the Highway Electrical Manufacturersand Suppliers Association.

For the purposes of managing lecture theatres there are three categories:

(a) those supposedly devoted to a single subject or singledepartment of an educational institution, e.g. the ‘nuclearphysics’ theatre

(b) those in common use by a wide variety of departments in aneducational institution; often very heavily used

(c) those in research institutes, professional institutions, museums,galleries and so on; usually relatively lightly used.

In practice, all lecture theatres are on occasions used for purposes otherthan those intended, sometimes on a hire basis.

Mention has already been made in section 5.3.3.3 of the need to keep lecturerooms free of visual clutter, which means keeping them free of unwantedparaphernalia that serves only to distract the attention of the audience from thespeaker. It is an essential part of managing a lecture theatre or conference roomto see that unwanted paraphernalia is kept out, see Figure 8.1 below.

Lecture theatres of category (a) are particularly prone to these intrusions;wall charts, glass cased specimens and glazed portraits of the great men of thesubject serve to distract rather than inspire. Such items should only bepermanently displayed if there is a real need to refer to them frequently, e.g. theperiodic table in a chemistry lecture theatre.

The absence of visual clutter is also welcome in lecture rooms andclassrooms, where it can be equally distracting.

Management of lecture and conference spaces 83

8 Managementof lectureandconferencespaces

8.1 Visual clutter

Fig. 8.1 A large lecture theatrekept clear of clutterthough the wall behindthe lecture station isrelatively busy in designterms (photograph courtesyof Thorn Lighting)


8.4 Projectionrooms andbooths

8.5 Preparationand equipmentrooms

The term ‘lecture attendant’ refers to those individuals who actually assist in theperformance of lectures. The job of such lecture attendants is to see that thelecturer’s needs are fulfilled, e.g. that the lights are raised or lowered at the righttime, the sound is correct and so on. To do this, it is necessary for the attendantto give undivided attention to assisting the lecturer and to avoid distraction.

Where there is a control booth or room for the lecture assistant, careshould be taken that stray light and sound do not distract the audience from thepresentation and that the assistant, who may be visible, does not cause distrac -tion to the lecturer.

To limit light nuisance, the assistant should be provided with a carefullyshielded task light. Care should be taken to see that light from the audience areadoes not cause glare to the assistant, either on their equipment or within theirview field of view of the lecture theatre.

In the majority of lectures in which images are shown, a laptop computer underthe direct control of the lecturer is used. In these cases often the lecturer hascomplete control of the room and the controls available to them should be clearlymarked, sufficiently distinct to be visible in near-darkness. The controlsavailable to the lecturer should also include an on/off switch for any projector, asit often happens that there are long periods when projection is not required andthe fan noise may distract and annoy the audience.

Lighting controls are similar; it is best if they can be operated directly bythe lecturer, but again the controls must be simple and clearly marked. Someduplicate controls for the lights should be provided near the main entrancedoor(s).

There are occasions when control of the projection, sound and lightinghas to be in the hands of an attendant, for example when a large array ofdemonstrations is presented or for a full day’s conference containing manydifferent presenters and media. In this case the lecturer should have a speaker’sscreen showing an image and perhaps speaker’s notes of the slide that theaudience is currently viewing. There should also be a controller for advancingthe presentation, though commonly these are now wireless.

The traditional projection room adjacent to a lecture room is nowadays usedmore often as a control room than a projection room. Experience shows that sucha room is essential in any lecture theatre seating more than 150. Besides housingthe projection equipment, it may also be needed to house sound amplifyingequipment, lighting controls, image recording and projection equipment, andpossibly controls for the air conditioning system. A projection booth within alecture theatre is not recommended unless situated where there is no risk ofdistraction or difficulty of access once an audience is seated.

The multiplicity of audio/visual aid techniques of recent years have nowconverged normally to a single projector and sound system with, in some cases,an interactive screen. The need for separate lockable equipment rooms is lessthan before but some form of storage should be provided for the relevant cablesand power extensions often required by visiting presenters.

In large lecture theatres there should ideally be a large equipment roomadjacent to and on the same floor as the demonstration area, which can be usedto house items needed for only part of the presentation. The lighting in theserooms needs to be sufficient for safe set-up and removal of these items, whichmay include fine detail tasks, but should be suitably shielded from the mainspace so as to limit distraction to the audience. This can normally be achievedeither through lighting controls in the equipment room, or by a suitable lobbybetween rooms.

Lighting control sensors in these rooms should be positioned carefully todetect fine movement possibly shadowed by the body of the technician.

8.3 Communicationbetweenlecturer andprojectionist or projector

8.2 Lectureattendants

The main problem facing the visiting lecturer is unfamiliarity with the lightingcontrols, and seeing that the audio/visual aids chosen will work satisfactorily onthe apparatus provided, for instance that the presenter’s laptop computerconnects to the projector.

Reference has already been made to the necessity for lighting andprojector controls to be clearly marked. They should be few in number andshould be grouped separately from other controls. A control panel resembling acomplex computer interface does nothing to ease the lecturer’s task unless it isblatant in its simplicity of operation.

Access to the theatre/room from cars or vans is required. Demonstrationequipment intended to be seen by large numbers of people must itself be large,and may obstruct the view of some members of the audience of either theprojection screen or the lecturer. This is particularly the case in lecture roomsand conference rooms as distinct from raked lecture theatres. To avoid thisproblem the presentation area should be devoid of any fixed furniture, usingloose tables or benches combined with the provision for additional theatricalstyle lighting where required.

The cost of lighting can be divided into three parts: (a) the capital cost of theequipment, including its installation, (b) the running costs, which include bothmaintenance and the cost of energy, and (c) the environmental or sustainabilitycosts.

It is important that all aspects are considered when the lighting is beingdesigned. In terms of capital cost, the amount will be small compared to the totalcost of the building and yet lighting has a major effect on its appearance andoperation, and economies need to be considered carefully to ensure that they arenot false economies. Energy and maintenance costs are a continuing burden onthe operation of any educational building and need to be taken into account atthe design stage to ensure that they can be kept at an acceptable level. Thesustainability costs will include items such as recycling and replacement, forinstance the cost of obtaining raw materials, transport and manufacture ofreplacement luminaires and that or returning the failed components to arecycling point and converting them into re-usable materials.

For many buildings, the capital and running cost elements may be borneby different bodies, which can result in conflict. It is important therefore thatthe lighting designer produces a scheme which takes a balanced view of energyand cost efficiency, considering the true life cycle costs.

Emergency lighting, by its very nature, introduces additional running costs.Even as a safety system it is important to consider the technologies used andmake rational decisions about the life cycle costs. For instance the provision oftraditional 8 W bulkheads for emergency lighting may introduce significantmaintenance and environmental costs in lamp and battery replacementcompared to well designed LED emergency lighting fittings, which have a longerlight source life and use less battery material.

Testing and maintenance of emergency lighting is essential and thedesigner should consider carefully the cost to building managers of the testingand regular maintenance visits necessary. The use of self-test and central testemergency products may negate the need to provide staff to test emergencysystems and may regulate the number of maintenance visits to just those whencomponents are reported as faulty.

Where such self-test systems are used the provision of training andoperation manuals that are simple to understand is essential.

Characteristics of the main lamp types are summarised in Table 10.1.

Lighting costs 85

9.2 Emergencylighting

8.7 Lecturesinvolvingdemonstrations

9 Lightingcosts

9.1 General

8.6 Problems forvisitinglecturers

10 Equipment10.1 Lamps

86Lighting G

uide 5: Lighting for education

Table 10.1 Summary of lamp types

Lamp type Format Nominal size Power Control gear Efficacy Colour Colour appearance Dimming Suitable for centralrange (lm/W) rendering (K) options control system(W) group

Linear fluorescent T16 (T5) 600–1500 mm 14–80 Electronic 60–95 1A–1B 2700–4000 Yes Yes(16 mm diam.) 6000 (limited options)

Linear fluorescent T16 (T5) miniature 150–530 mm 4–13 Electronic/magnetic 35–65 3 3500 No No(16 mm diam.)

Linear fluorescent T26 (T8) 600–1800 mm 18–70 Electronic/magnetic 55–95 1A–1B 3000–4000 Yes Yes(26 mm diam.) 6000 (limited options)

Compact fluorescent Various Various 16–120 Electronic 64–88 1B 3000–4000 Yes Yes

Compact fluorescent Various Various 18–70 Electronic 64–76 1B 3000–4000 Limited Yesamalgam

Metal halide* Single ended Various 20–2000 Electronic/magnetic 70–115 1A–2B 3000–4000 Very limited Yes; not suitable fortubular, double 6000 (limited options) frequent switchingended and reflector

High pressure sodium* SON tubular Various 50–1000 Electronic/magnetic 65–125 4 2000 Very limited No(up to 150 for 600/1000 W lamps)

* Metal halide and SON lamps can take several minutes to run up to full output and, immediately after being switched off, can take several minutes to re-strike. Some low wattage options can be run atreduced output on special electronic control gear but dimming range is limited and colour variations can occur.

A wide range of lamps require control gear of some kind to ensure correctrunning and starting of the lamp. This gear in various lamps controls either thevoltage or the current and may itself operate at differing voltages andfrequencies.

Where available the designer should specify the most appropriate and efficientcontrol gear for all lighting. In general this would imply high frequency (HF) orelectronic control gear for all luminaires. Control gear should comply with theminimum targets set by the Energy-using Products Directive(17) for lighting.

Generally electromagnetic gear used in fluorescent circuits is consideredinefficient when compared to high frequency circuits, and causes userdiscomfort through 100 Hz flicker. In all teaching/learning buildings highfrequency control gear should be used as standard except where a suitable casecan be made on health and safety grounds or if alternative technologies aredeveloped that remove the problem of flicker and improve the sustainable casefor this technology.

Operating fluorescent lamps at high frequency has a number of advantages andmost modern control gear is now of this type. Most electronic ballasts forfluorescent lamps are integrated into a single package that performs a number offunctions including limiting the amount of harmonic distortion, controlling theamount of radio frequency interference, and protecting the ballast against highvoltage mains peaks. Where high frequency ballasts are used with in-builtprotection fuses there will be no need to fit additional fused terminal blocks.

In some ballasts it is possible to dim the lamp by use of an additionalcontrol signal, either analogue or digital signals. The designer should lookcarefully at the features and benefits that the various types offer, weighing up thetrue cost or energy implications. For instance, while it may be beneficial to dimrather than switch a luminaire in response to daylight, offering considerableenergy savings in some installations, the parasitic power absorbed by the ballastand control system must be taken into account.

There are many types of high intensity discharge (HID) lamp, with differentelectrical requirements and a limited range of frequencies in which they can beoperated. Also many lamp types do not show a significant gain in efficiencywhen operated on high frequencies. However, it is possible to gain a number ofbenefits from electronic gear for HID lamps. These include increased lamp life,elimination of visible flicker, better system efficacy, less sensitivity tofluctuations in mains voltage or temperature and the possibility of dimmingwith some lamp types.

Not all these benefits are possible for all lamp types and all control gearcombinations. However, the availability and quality of electronic gear availablefor HID lamps is rapidly increasing.

Many tungsten–halogen lamps are designed to run on low voltages the mostcommon of which is 12 volts. Thus they need a device to reduce the supplyvoltage. The traditional way to do this was by using a transformer.

As well as reducing the voltage, the transformer also isolates the lampsupply from the mains. This means that even under a fault condition the voltagein the secondary circuit will not rise significantly above the nominal outputvoltage and so it will always be safe to touch the conductors on the low voltageside. In all educational buildings transformers for halogen lamps should be ofthe electronic type with a minimum circuit efficacy of 22 lumens per circuit watt(lm/W) for a ‘pass’ rating, 29 lm/W for ‘good’ and 36 lm/W for ‘excellent’.

LEDs need to be run at a controlled current to ensure proper operation. Toprovide this drivers are used. Most drivers take mains power and provide a

Equipment 87

10.2.1.4 Electronic gear for HIDlight sources

10.2.1.2 Electromagneticcontrol gear forfluorescent lightsources

10.2.1.3 Electronic control gearfor fluorescent lightsources

10.2 Control gear

10.2.1.1 General principles

10.2.1.5 Transformers for lowvoltage light sources

10.2.2 Drivers for LEDs

constant current output. However, it is possible to control some drivers so thatoutput current is varied so that the LED may be dimmed. In more complexsystems it is possible to dim three separate channels separately, so that when red,green and blue LEDs are used together it is possible to make colour changes.Most LED drivers can maintain their constant current output over a range ofvoltages so it is often possible to connect a number of LEDs in series on onedriver. The designer should take care to avoid flicker inherent in cheaper LED

drivers. For LED circuits to be considered efficient they should meet or exceedthe same efficacy targets for other lighting.

Wherever practical lighting controls should be included to provide scene settingfunctionality where required and energy saving where users are unlikely toswitch off lighting when not required. In daylit spaces lighting should becircuited according to the amount of daylight likely to occur in the area lit bythe luminaire. Luminaires in daylight zones should then be switched, accordingto the daylight present. Preference must be given to systems that dim accordingto daylight and hence also provide for constant illuminance control from theluminaires.

There are a number of factors that need to be considered in any control system;these are the inputs to system, how the system controls the lighting equipmentand what is the control process that decides how a particular set of inputs willimpact on the lighting. Thus for a control system to function it must have inputdevices such as switches, presence detectors, timers and photocells. Controlprocesses may consist of a simple wiring network through to a computer-basedcontrol system. The system may control luminaires in a number of ways, fromsimply switching them on and off to dimming the lamp and, in more complexsystems, causing movement of spotlights and colour changes.

Lighting controls require a number of inputs to make them function, broadlythey are classified as follows.

These vary from simple switches used to turn the lights on though dimmerswitches and remote control units that interface to a control system to lightingcontrol desks that are used in theatres. The point of these units is to allow peopleto control the lighting and care is always needed in the application of suchdevices to ensure that users of the system can readily understand the function ofany such control.

Most presence detectors are based on passive infrared (PIR) detectors. Howeversome devices are based on microwave or ultrasonic technology. PIR devicesmonitor changes in the amount of infrared radiation that they are receiving. Themovement of people in a space will be detected by them and this can be signalledto a control system. Thus if a device detects the presence of a person this can beused to signal the control system to switch the lights on, but if no persons havebeen detected for some time this can be used to signal that the lights can beturned off.

It is strongly recommended that these detectors, when used ineducational spaces, should be used for absence detection with a manual overridefor teaching staff. This enables sufficient flexibility for teaching purposes, butalso offers the maximum energy savings.

In order to achieve an excellent efficiency rating in an educationalbuilding, more than 60% of luminaires need to be controlled for daylight andabsence using controls within the parasitic power limitations set in the Energy-using Products Directive(17).

Most computerised control systems have timers built in so that they can turn thelighting on or off at particular times. However, there are also a large number of


10.3 Lightingcontrols

10.3.1 Options for control

10.3.2 Input devices

10.3.2.1 Manual inputs

10.3.2.2 Presence detectors

10.3.2.3 Timers

time switches available that can turn lamps on and off at given times. Timers forexternal lighting are available that change the time at which they operatethroughout the year, so that the lamps are switched at dawn and dusk.

Timers should be carefully considered and only those used that respondalso to ambient conditions or time of year and so offer maximum energy savings.

There are many different types of photocells used to control lighting. Thesimplest to use are those that switch on at one illuminance value and switch offat another and are often used outdoors for car park, security and amenitylighting. Some photocells communicate the illuminance value detected to acentral control system, which uses the information to adjust the lighting insome way. Some photocells are mounted on ceilings with shields around themso that they only receive light reflected from the working plane; this allowsthem to act like luminance meters and, provided the reflectance of the workingplane remains constant, they can be set to provide constant illuminance.

Photocell control should be considered essential for all teaching spaces asconsiderable daylight will be available. They should also be fitted to all externallighting and to lighting elsewhere in the space where daylight is sufficient. Astheir use in occupied spaces may lead to nuisance switching the designer shouldconsider the use of dimming luminaires where this is more appropriate.

In the case of simple control systems these are generally configured as someform of automated switching in the power supply to a luminaire or group ofluminaires. However, more complex systems are generally configured as anetwork of devices including luminaires, sensors and control inputs. In mostsystems the devices are physically connected using some form of cabled networkor based on the local area network (LAN).

There are several systems in common use for lighting systems and careneeds to be taken to specify the correct type for each component in the system.The most common systems offer differing levels of functionality and speed ofresponse. The designer should consider carefully the needs of the controlssystem, for instance the speed of response and number of channels availablewould make the DMX512 protocol an obvious choice for theatre, drama andsome conference rooms, whereas DSI or DALI would be more appropriate forclassrooms. In all cases a control strategy needs to be developed and this shouldconsider primarily the efficiency savings possible and the comfort needs of theoccupants. Too complex a system will often render the system inoperable to allbut the most determined user.

The minimum controls provision recommended for various types of space aregiven in Table 10.2 below.

The WEEE Regulations(25) make business users, manufacturers and retailers ofelectrical and electronic equipment (EEE) responsible for making sure theirgoods do not end up in landfill or incineration, where the toxic chemicals,metals and associated solders, glues and plastics can cause environmental andhealth problems.

Original equipment manufacturers (OEMs) now have cradle-to-graveresponsi bility for their electrical products, having to pay for the treatment andrecycling of all affected products. The designer should ensure that anyequipment they specify is suited to recycling and that the producer, who may bethe wholesaler, electrical contractor, importer or OEM, complies with the WEEERegulations. The installer who removes old equipment, or purchases new,should ensure that all obsolete luminaires or other EEE is dealt with accordingly.

Equipment 89

10.3.4 Recommendedminimum controlsprovision

10.3.2.4 Photocells

10.3.3 Control processesand systems

10.4 Disposal ofused lightingequipment

The definitions and explanations given in this glossary are intended to helpreaders to understand this Lighting Guide. They are based on BS EN 12665:Light and lighting. Basic terms and criteria for specifying lighting(67), which should beconsulted if more precise definitions are needed.

adaptation

The process by which the state of the visual system is modified by previous andpresent exposure to stimuli that may have various luminances, spectraldistributions and angular subtenses.

adjoining spaces

Foyers, ante-rooms, lobbies and corridors immediately adjoining teachingspaces listed in this Lighting Guide.

chromaticity

The property of a colour stimulus defined by its chromaticity coordinates, or byits dominant or complementary wavelength and purity taken together.


11 Glossary

Table 10.2 Recommended minimum controls provision

Type of space Description Recommended minimum controls

Owned space A space such as a small room for Manual switch by the door with one or two people who control absence* override. Separate circuit the lighting, e.g. a cellular office for daylight dimming, or switching, or tutorial room. of luminaires close to the window in

daylight spaces.

Shared space A multi-occupied area, e.g. Manual switch by the door with classroom, common room, an absence* override. Separate circuits open-plan office or craft area. for daylight dimming or switching of

luminaires in appropriate zonesaccording to the amount of daylitfor daylight spaces.

Temporarily owned A space where people are Local manual control with absence* space expected to operate the lighting override. Sensor(s) should be

controls while they are there, suitably mounted to pick up the e.g. a lecture or meeting room. movement of occupants and

speaker.

Occasionally visited A space where people generally Manual on with absence* override.space stay for a relatively short period Presence detection may be

of time when they visit the space, acceptable provided sensors use no e.g. a storeroom or toilet. more than 0.5 W.

Un-owned space A space where individual users Time switching, or manual on with require lighting but are not absence* override, or presence expected to operate the lighting provided individual sensors use no controls, e.g. a corridor or atrium. more than 0.5 W.

Separate circuits for daylightdimming or switching of luminairesin appropriate zones according tothe amount of daylight for daylitspaces.

Managed space A space where lighting is under Time switching, scene setting or the control of a responsible central switching by a responsible person, e.g. a conference room, person.theatre or sports hall.


* Absence sensors should be circuited such that they switch themselves off and hence use zeropower when the lighting is off.

stroboscopic effect

The apparent change of motion of an object when illuminated by periodicallyvarying light of appropriate frequency. This periodic motion is especiallynoticeable in the light from discharge lamps with clear bulbs operating onalternating current.

teaching rooms

Rooms used mainly for class teaching purposes, with flat floors and no fixedfurniture except possibly chalkboards and projection screens. Such rooms willusually have a seating capacity of less than 60.

uniformity

See illuminance uniformity

veiling reflections

Specular reflections that appear on the object viewed and that partially or whollyobscure the details by reducing contrast.

visual acuity

The capacity for seeing distinctly fine details that have very small angularseparation.

visual comfort

A subjective condition of visual well-being induced by the visual environment.

visual field

The area or extent of physical space visible to an eye at a given position anddirection of view.

visual performance

The performance of the visual system as measured for instance by the speed andaccuracy with which a visual task is performed.

1 The Construction (Design and Management) Regulations 2007 StatutoryInstruments No. 320 2007 (London: The Stationery Office) (2007) (available athttp://www.opsi.gov.uk/si/si200703) (accessed October 2010)

2 The Building Regulations 2000 Statutory Instruments 2000 No 2531 as amended byThe Building (Amendment) Regulations 2001 Statutory Instruments 2001 No. 3335and The Building and Approved Inspectors (Amendment) Regulations 2006Statutory Instruments 2006 No. 652) (London: The Stationery Office) (dates asindicated) (London: The Stationery Office) (2007) (available at http://www.opsi.gov.uk/stat.htm) (accessed October 2010)

3 The Building (Amendment) Regulations (Northern Ireland) 2006 Statutory Rules ofNorthern Ireland No. 355 2006 (London: The Stationery Office) (2006) (available athttp://www.opsi.gov.uk/sr/sr200603) (accessed October 2010)

4 The Building (Scotland) Amendment Regulations 2009 Scottish StatutoryInstruments No. 119 2009 (London: The Stationery Office) (2009) (available at http://www.opsi.gov.uk/legislation/scotland/s-200901) (accessed October 2010)

5 The Education (School Premises) Regulations 1996 Statutory Instruments 1996 No.360 (London: Her Majesty’s Stationery Office) (1996) (available athttp://www.opsi.gov.uk/si/si199603.htm) (accessed October 2010)

6 Standards for School Premises (London: Department for Education and Schools)(undated) (available at http://www.teachernet.gov.uk/docbank/index.cfm?id=3928)(accessed October 2010)


References

7 Registration of independent schools — information pack (London: Department forEducation) (2010) (available at http://www.dcsf.gov.uk/reg-independent-schools)(accessed October 2010)

8 Code for Lighting (CD-ROM) (London: Society of Light and Lighting) (2009)

9 SLL Lighting Handbook (London: Society of Light and Lighting) (2009)

10 Boyce P R Human factors in lighting ch. 4 (Oxford: CRC) (2003)

11 Hawkes R J, Loe D L and Rowlands E A note towards the understanding of lightingquality’ J. Illum. Eng. Soc. 8 111–120 (1979)

12 Loe D L, Mansfield K P and Rowlands E ‘Appearance of a lit environment and itsrelevance in lighting design: Experimental study’ Light. Res. Technol. 26 119–133(1994)

13 Loe D L, Mansfield K P and Rowlands E ‘A step in quantifying the appearance of alit scene’ Light. Res. Technol. 32 213–222 (2000)

14 Heschong L Daylighting in Schools: An Investigation into the Relationship betweenDaylighting and Human Performance (Fair Oaks, CA: Heschong Mahone Group) (1999)

15 Daylighting and window design CIBSE Lighting Guide LG10 (London: CharteredInstitution of Building Services Engineers) (1999)

16 Loe D L ‘Quantifying lighting energy efficiency: a discussion document’ Light. Res.Technol. 35 319–329 (2003)

17 Directive 2005/32/EC of the European Parliament and of the Council of 6 July 2005establishing a framework for the setting of ecodesign requirements for energy-usingproducts and amending Council Directive 92/42/EEC and Directives 96/57/EC and2000/55/EC of the European Parliament and of the Council Official J. of the EuropeanUnion L191 29–58 (22.07.2005) (available at http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32005L0032:EN:HTML) (accessed October 2010)

18 Conservation of fuel and power in new buildings other than dwellings Building Regulations2000 Approved Document L2A (London: The Stationery Office) (2006) (available athttp://www.planningportal.gov.uk/england/professionals/en/1115314231806.html)(accessed August 2008)

19 Conservation of fuel and power in buildings other than dwellings The Building Regulations(Northern Ireland) 2000: Technical booklet F2 (London: The Stationery Office)(2006) (available at http://www.opsi.gov.uk/legislation/northernireland/ni-srni.htm)(accessed October 2010)

20 The Scottish Building Standards — Technical Handbook: Non-Domestic (Edinburgh:Scottish Building Standards Agency) (2008) (available at http://www.sbsa.gov.uk/tech_handbooks/tbooks2008.htm) (accessed October 2010)

21 Directive 2002/91/EC of the European Parliament and of the Council of 16 December2002 on the energy performance of buildings (‘The Energy Performance of BuildingsDirective’) Official J. of the European Communities L1 65–71 (4.1.2003) (Brussels:Commission for the European Communities) (2003) (available at http://ec.europa.eu/energy/demand/legislation/buildings_en.htm)

22 BS EN 15193: 2007: Energy performance of buildings. Energy requirements for lighting(London: British Standards Institution) (2007)

23 BREEAM: the environmental assessment method for buildings around the world (website)(Garston: BRE Global) (2009)

24 Conservation of fuel and power in buildings other than dwellings Building Regulations2000 Approved Document L2 (London: The Stationery Office) (2002) (superseded;see reference 18)

25 The Waste Electrical and Electronic Equipment Regulations 2006 StatutoryInstruments no. 3289 2006 (London: The Stationery Office) (2006) (available athttp://www.opsi.gov.uk/si/si200632) (accessed October 2010)

26 Hathaway W E ‘A study into the effects of types of light on children — a case ofdaylight robbery’ Proc Conf. 101st Annual Convention of the American PsychologicalAssociation, Canada, August 1993 (1993)

27 Mass J, Jayson J and Kleiber D ‘Quality of light is important, not just quantity’American School and University 46(12) 31 (1974)

28 Küller R and Lindsten C ‘Health and behaviour of children in classrooms with andwithout windows’ J. Environmental Psychology 12 305–317 (1992)

References 97


29 Heschong L Daylighting in Schools: Reanalysis Report (Sacremento CA: CaliforniaEnergy Commission) (2003) (available at http://newbuildings.org/daylighting-schools-reanalysis-report) (accessed October 2010)

30 Littlefair P Site layout planning for daylight and sunlight — a guide to good practice(Garston: BRE) (1998)

31 09/30206726 DC: BS EN 12464-1: Light and lighting. Lighting of work places. Part 1.Indoor work places (draft for public comment) (London: British Standards Institution)(2009)

32 BS EN 12193: 2007: Light and lighting. Sports lighting (London: British StandardsInstitution) (2008)

33 BS 8206-2: 2008: Lighting for buildings. Code of practice for daylighting (London: BritishStandards Institution) (2008)

34 Littlefair P Site layout planning for daylight and sunlight: a guide to good practice(Garston: BRE Press) (1991)

35 Tregenza P R ‘Modification of the split-flux formulae for mean daylight factor andinternal reflected component with large external obstructions’ Lighting Res. Technol.21(3) 125–128 (1989)

36 Winterbottom M and Wilkins A ‘Lighting and discomfort in the classroom’ J.Environ. Psychology 29(1) 63–75 (2009)

37 Passive solar schools — a design guide Department for Education Architects andBuilding Division Building Bulletin 79 (London: Her Majesty’s Stationery Office)(1994)

38 Visual environment for display screen use CIBSE Lighting Guide LG3 (London:Chartered Institution of Building Services Engineering) (1996) (out of print)

39 Office lighting SLL Lighting Guide LG7 (London: Society of Light and Lighting)(2005)

40 The Ecodesign for Energy-Using Products Regulations 2007 Statutory Instruments2007 No. 2037 (London: The Stationery Office) (2007) (available at http://www.opsi.gov.uk/si/si200720) (accessed October 2010)

41 Ramasoot T and Folios S A ‘Acceptability of screen reflections: lighting strategies forimproving quality of the visual environment in classrooms of the future’ Proc. conf.PLEA Dublin 2008: Towards zero energy building, University College Dublin, October22–24 2008 (2008)

42 Lighting CIBSE Commissioning Code L (London: Chartered Institution of BuildingServices Engineers) (2003)

43 Daylighting and window design CIBSE Lighting Guide LG10 (London: CharteredInstitution of Building Services Engineers) (1999)

44 BS EN 12464-1: 2002: Light and lighting. Lighting of work places. Indoor work places(London: British Standards Institution) (2002)

45 Guidelines for specification of LED lighting products (Society of Light andLighting/Institution of Lighting Engineers/Lighting Industry Federation/International Association of Lighting Designers/Professional Lighting DesignersAssociation/Highway Electrical Suppliers & Designers Association) (2009) (availableat http://www.cibse.org/index.cfm?go=page.view&item=369) (accessed October2010)

46 BS 5266-1: 2005: Emergency lighting. Code of practice for the emergency lighting of premises(London: British Standards Institution) (2005)

47 BS EN ISO 9241-307: 2008: Ergonomics of human-system interaction. Analysis andcompliance test methods for electronic visual displays (London: British StandardsInstitution) (2010)

48 ISO 2603: 1998: Booths for simultaneous interpretation — General characteristics andequipment (Geneva, Switzerland: International Organization for Standardization)(1998)

49 Sports lighting SLL Lighting Guide LG4 (London: Society of Light and Lighting)(2006)

50 Fotios S and Ramasoot T ‘Developing a model to predict user acceptability of displayscreen reflections’ Proc. Conf. Lux Europa, Istanbul, 9–11 September 2009 513–520(2009)

References 99

51 Industry SLL Lighting Guide LG1 (on Code for Lighting (CD-ROM)) (London: Societyof Light and Lighting) (2009)

52 BS EN 12464-2: 2007: Lighting of work places. Outdoor work places (London: BritishStandards Institution) (2007)

53 BS 5489-1: 2003 + A2: 2008: Code of practice for the design of road lighting. Lighting ofroads and public amenity areas (London: British Standards Institution) (2003/2008)

54 BS EN 13201-2: 2003: Road lighting. Performance requirements (London: BritishStandards Institution) (2003)

55 BS EN 13201-3: 2003: Road lighting. Calculation of performance (London: BritishStandards Institution) (2003)

56 The Regulatory Reform (Fire Safety) Order 2005 Statutory Instruments No. 15412005 (London: The Stationery Office) (available at http://www.opsi.gov.uk/si/si200515)(accessed October 2010)

57 BS 5499-4: 2000: Safety signs, including fire safety signs. Code of practice for escape routesigning (London: British Standards Institution) (2000)

58 BS 5499-1: 2002: Graphical symbols and signs. Safety signs, including fire safety signs.Specification for geometric shapes, colours and layout (London: British StandardsInstitution) (2002)

59 09/30197377 DC: BS ISO 3864-1: Graphical symbols. Safety colours and safety signs. Part1. Design principles for safety signs and safety markings (draft for public comment)(London: British Standards Institution) (2009)

60 BS EN 1838: 1999, BS 5266-7: 1999: Lighting applications. Emergency lighting (London:British Standards Institution) (1999)

61 BS EN 50172: 2004, BS 5266-8: 2004: Emergency escape lighting systems (London:British Standards Institution) (2004)

62 BS EN 62034: 2006: Automatic test systems for battery powered emergency escape lighting(London: British Standards Institution) (2007)

63 ISO 30061: 2007 (CIE S 020/E:2007): Emergency lighting (Geneva, Switzerland:International Organization for Standardization) (1998)

64 BS 4533-102: Luminaires. Particular requirements (4 sections) (London: BritishStandards Institution) (1990)

65 BS EN 60598-1: 2008: Luminaires. General requirements and tests (London: BritishStandards Institution) (2009)

66 BS 7671: 2008: Requirements for electrical installations. IEE Wiring Regulations.Seventeenth edition (London: British Standards Institution) (2008)

67 BS EN 12665: 2002: Light and lighting. Basic terms and criteria for specifying lightingrequirements (London: British Standards Institution) (2002)

68 Glare and uniformity in road lighting installations CIE 31 (Vienna, Austria: InternationalCommission on Illumination) (2002)

69 Glare evaluation system for use within outdoor sports and area lighting CIE 112 (Vienna,Austria: International Commission on Illumination) (1994)

70 Discomfort glare in interior lighting CIE 117 (Vienna, Austria: International Commissionon Illumination) (1995)


Allpolarities

< 200 cd/m2

200–300cd/m2

300–500cd/m2

500–1000cd/m2

Alltypes OK to use

Change display polarity or surface finish

OK to use if LB > 700 cd/m2 or change finish

Change display polarity

OK to use


OK to use if LB > 600 cd/m2







1000–1500cd/m2

Size oflight source

Brightness oflight source

DSEtype

DSEpolarity

Suggestion

GlossyLCD

GlossyLCD

GlossyLCD

GlossyLCD

MattLCD

MattLCD

MattLCD

MattLCD

ProjectIWB

ProjectIWB

ProjectIWB

ProjectIWB

Negative

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive


OK to use

OK to use

OK to use

OK to use



OK to use

OK to use


OK to use


Positive

Angulardiameter 15°

Abbreviations and symbolsLB = background luminance on display screen (cd/m2); LCD = liquid crystal display; IWB = interactive white board;‘Positive’ polarity means dark text on light background; ‘Negative’ polarity means light text on dark background

Appendix A1: luminance limits and display screen equipment

The following flowcharts offer suggestions to ensure that the luminance isappropriate to the type of display screen equipment in use, see section 5.10.2.They use a 95% satisfaction criterion, i.e. 95% of users would not experienceproblems with veiling reflections at the luminance limits indicated.

Fig. A1.1 Evaluation and correctionof glare in display screenequipment (DSE) for largelight sources (15° angulardiameter) such as largewindows or atria

Appendix A1: luminance limits and display screen equipment 101

Allpolarities

< 300 cd/m2

300–500cd/m2

500–700cd/m2

700–1000cd/m2

Alltypes OK to use



OK to use

OK to use


OK to use




OK to use



1000–1500cd/m2

Size oflight source


DSEtype

DSEpolarity

Suggestion

GlossyLCD

GlossyLCD

GlossyLCD

GlossyLCD

MattLCD

MattLCD

MattLCD

MattLCD

ProjectIWB

ProjectIWB

ProjectIWB

ProjectIWB

Negative

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive



OK to use

OK to use


OK to use


OK to use

OK to use


OK to use


Positive

Angulardiameter 10°


Fig. A1.2 Evaluation and correctionof glare in display screenequipment (DSE) formedium sized lightsources (10° angulardiameter) such as smallwindows or skylights


Allpolarities

< 500 cd/m2

500–700cd/m2

700–1000cd/m2

1000–1500cd/m2

Alltypes OK to use



OK to use

OK to use


OK to use



OK to use

OK to use


OK to use

1500–3000cd/m2

Size oflight source


DSEtype

DSEpolarity

Suggestion

GlossyLCD

GlossyLCD

GlossyLCD

GlossyLCD

MattLCD

MattLCD

MattLCD

MattLCD

ProjectIWB

ProjectIWB

ProjectIWB

ProjectIWB

Negative

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive

Negative

Positive


OK to use

OK to use

OK to use

OK to use

OK to use


OK to use

OK to use

OK to use

OK to use


Positive

Angulardiameter 1°


Fig. A1.3 Evaluation and correctionof glare in display screenequipment (DSE) for smalllight sources (1° angulardiameter) such asluminaires

In 1963 the Illuminating Engineering Society published a remarkablemonograph entitled Lecture theatres and their lighting, which became a standardwork of reference. An updated edition was published in 1973 and then in 1991it was updated and published as CIBSE Lighting Guide LG5: The visualenvironment in lecture, teaching and conference rooms. Within a very short period oftime there were a vast array of CIBSE and Department for Education andSchools (DfES) guides available covering all manner of lighting in schools,teaching spaces, lecture theatres and the like, including documents such asBuilding Bulletin 90: Lighting design for schools. In 1995 an addendum to LG5was issued to deal with changes in government funding for schools projects andchanges in European legislation for workplace lighting.

The Department for Children, Schools and Families (previously theDfES) decided in 2008 that it would join with the SLL in updating LG5 toinclude schools.

This Lighting Guide covers not only lecture theatres, but also allteaching spaces and rooms specific to educational premises across schools andfurther education, and extends to committee rooms, conference and multi-purpose rooms. It represents a complete revision but includes relevant materialfrom the original LG5 and BB90 working groups. Our thanks go to many of theoriginal authors whose work is included here, which include R Aldworth, RAnderson, J Baker, L Bedocs, R Bell, C Bissell, K Gofton, J Lambert, D Loe, JLynes, I MacLean, K Mansfield, J Mardaljevic, M Patel, V Rolfe, P Ruffles, ATarrant, R Venning, L Watson and Professor A Wilkins.

LG5 Task Group

I D Macrae (Thorn Lighting) (Chairman)A Bissell (Cundall LLP)R Daniels (Department for Education)B Etayo (Fulcrum First LLP)S Fotios (Sheffield University)P Raynam (University College London)T Ramasoot (Sheffield University)

Director of Information

Jacqueline Balian

Secretary to the Society of Light and Lighting

Liz Peck

Editor

Ken Butcher

Acknowledgement

Permission to reproduce extracts from BS EN 15193, BS EN 12464-2, BS EN1838 and BS EN 12464-1 (draft) is granted by BSI. British Standards can beobtained in PDF or hard copy formats from the BSI online shop:www.bsigroup.com/Shop, or by contacting BSI Customer Services forhardcopies only: tel: +44 (0)20 8996 9001, e-mail: [email protected].

Foreword

The definitions and explanations given in this glossary are intended to helpreaders to understand this Lighting Guide. They are based on BS EN 12665:Light and lighting. Basic terms and criteria for specifying lighting(67), which should beconsulted if more precise definitions are needed.

adaptation

The process by which the state of the visual system is modified by previous andpresent exposure to stimuli that may have various luminances, spectraldistributions and angular subtenses.

adjoining spaces

Foyers, ante-rooms, lobbies and corridors immediately adjoining teachingspaces listed in this Lighting Guide.

chromaticity

The property of a colour stimulus defined by its chromaticity coordinates, or byits dominant or complementary wavelength and purity taken together.


11 Glossary

Table 10.2 Recommended minimum controls provision

Type of space Description Recommended minimum controls

Owned space A space such as a small room for Manual switch by the door with one or two people who control absence* override. Separate circuit the lighting, e.g. a cellular office for daylight dimming, or switching, or tutorial room. of luminaires close to the window in

daylight spaces.

Shared space A multi-occupied area, e.g. Manual switch by the door with classroom, common room, an absence* override. Separate circuits open-plan office or craft area. for daylight dimming or switching of

luminaires in appropriate zonesaccording to the amount of daylitfor daylight spaces.

Temporarily owned A space where people are Local manual control with absence* space expected to operate the lighting override. Sensor(s) should be

controls while they are there, suitably mounted to pick up the e.g. a lecture or meeting room. movement of occupants and

speaker.

Occasionally visited A space where people generally Manual on with absence* override.space stay for a relatively short period Presence detection may be

of time when they visit the space, acceptable provided sensors use no e.g. a storeroom or toilet. more than 0.5 W.

Un-owned space A space where individual users Time switching, or manual on with require lighting but are not absence* override, or presence expected to operate the lighting provided individual sensors use no controls, e.g. a corridor or atrium. more than 0.5 W.


Managed space A space where lighting is under Time switching, scene setting or the control of a responsible central switching by a responsible person, e.g. a conference room, person.theatre or sports hall.


* Absence sensors should be circuited such that they switch themselves off and hence use zeropower when the lighting is off.

colour appearance (see also colour temperature)

A term used of a light source. Objectively the colour of a truly white surfaceilluminated by the source. Subjectively, the degree of warmth associated withthe source colour. Lamps of low correlated colour temperature are usuallydescribed as having a warm colour appearance and lamps of high correlatedcolour temperature as having a cool appearance.

colour rendering

The effect of an illuminant on the colour appearance of objects by conscious orsubconscious comparison with their colour appearance under a referenceilluminant.

CIE 1974 general colour rendering index (Ra)

The mean of the CIE 1974 special colour rendering indices for a specified set ofeight test colour samples. In some cases R8 or R14 references are quotedindicating use of the original 8 reference colour or a wider range of 14 referencesamples.

colour temperature (Tc )

The temperature of a Planckian radiator whose radiation has the samechromaticity as that of a given stimulus (unit: K).

correlated colour temperature (Tcp)

The temperature of the Planckian radiator whose perceived colour most closelyresembles that of a given stimulus at the same brightness and under specifiedviewing conditions (unit: K).

committee rooms

Rooms used for meetings capable of seating up to roughly 30 persons.

contrast

In the perceptual sense: assessment of the difference in appearance of two ormore parts of a field seen simultaneously or successively (hence brightnesscontrast, lightness contrast, colour contrast, simultaneous contrast, successivecontrast etc.)

contrast rendering factor

The ratio of the contrast of a task under a given lighting installation to itscontrast under reference lighting conditions.

cut-off

The technique used for concealing lamps and surfaces of high luminance fromdirect view in order to reduce glare.

cut-off angle (of a luminaire)

The angle, measured up from nadir, between the vertical axis and the first lineof sight at which the lamps and the surfaces of high luminance are not visible.

cylindrical illuminance (at a point, for a direction) (Ez)

The total luminous flux falling on the curved surface of a very small cylinderlocated at the specified point, divided by the curved surface area of the cylinder.The axis of the cylinder is taken to be vertical unless stated otherwise (unit: lux).

Glossary 91

It is defined by the formula:

where Ω is the solid angle of each elementary beam passing through the givenpoint, L is the luminance at that point and ε is the angle between the elementarybeam passing through the given point and the given direction (unless otherwisestated, that direction is vertical).

daylight factor (D)

The ratio of the illuminance at a point on a given plane due to the light receiveddirectly or indirectly from a sky of assumed or known luminance distribution,to the illuminance on a horizontal plane due to an unobstructed hemisphere ofthis sky, excluding the contribution of direct sunlight to both illuminances.

diffused lighting

Lighting by means of luminaires having a distribution of luminous intensitysuch that the fraction of the emitted luminous flux directly reaching theworking plane, assumed to be unbounded, is 40–60%.

direct lighting


directional lighting

Lighting in which the light on the working plane or on an object is incidentpredominantly from a particular direction.

emergency lighting

Lighting provided for use when the supply to the normal lighting fails.

emergency escape lighting

That part of emergency lighting that provides illumination for visibility forpeople leaving a location or attempting to terminate a potentially dangerousprocess before doing so.

flicker

The impression of unsteadiness of visual sensation induced by a light stimuluswhose luminance or spectral distribution fluctuates with time.

fusion frequency

The frequency of alternation of stimuli above which flicker is not perceptible.

general lighting

Substantially uniform lighting of an area without provision for special localrequirements.

glare

The discomfort or impairment of vision experienced when parts of the visualfield (e.g. sky or lamps) are excessively bright in relation to the generalsurroundings.

E Ls rz

= ∫14π

επ

sin dΩ


glare, disability

Disability glare may be expressed in a number of different ways. If thresholdincrement (TI) is used the following values of TI shall be used (see CIE 31(68)):5%, 10%, 15%, 20%, 25%, 30%. If glare rating (GR) is used the following values ofGR shall be used (see CIE 112(69)): 10, 20, 30, 40, 45, 50, 55, 60, 70, 80, 90.

glare, discomfort

Discomfort glare may be expressed by means of a ‘psychometric scale’ derivedfrom psychophysical experiments. If it is expressed using the unified glarerating the following values of UGR shall be used (see CIE 117(70)): 10, 13, 16, 19,22, 25, 28.

illuminance (at a point of a surface) (E)

The quotient of the luminous flux dφ incident on an element of the surfacecontaining the point, by the area dA of that element (unit: lm·m–2).

illuminance, average (E)

The illuminance averaged (mean average) over the specified area (unit: lx).

illuminance, maximum (Emax )

The highest illuminance at any relevant point on the specified surface (unit: lx).

maintained illuminance (Em)

The value below which the average illuminance on the specified area should notfall (unit: lx). It is the average illuminance at the time maintenance should becarried out.

illuminance, minimum (Emin)

The lowest illuminance at any relevant point on the specified surface (unit: lx).

illuminance, initial (Ei )

The average illuminance on the specified surface when the installation is new(unit: lx).

illuminance uniformity

In this Lighting Guide this is taken as the ratio of minimum illuminance(luminance) to average illuminance (luminance) on (of) a surface.

immediate surrounding area

A band with a width of at least 0.5 m surrounding the task area within the fieldof vision.

indirect lighting

Lighting by means of luminaires having a distribution of luminous intensitysuch that the fraction of the emitted luminous flux directly reaching theworking plane, assumed to be unbounded, is 0–10% intensity.

installed loading

The installed power of the lighting installation per unit area (for interior andexterior areas) or per unit length (for road lighting) (unit: W·m–2 for areas;kW·km–1 for road lighting).

Glossary 93

keystone effect

The distortion of an image caused by projection onto a surface not at rightangles to the projector beam. It commonly occurs when a projector is tiltedupwards to throw an image on a vertical screen, causing the top of the image tobecome wider than the bottom and can be easily corrected on most modernprojectors.

lamp lumen maintenance factor

The ratio of the luminous flux of a lamp at a given time in its life to the initialluminous flux.

lamp survival factor

The fraction of the total number of lamps that continue to operate at a giventime under defined conditions and switching frequency.

large conference rooms

Rooms used mainly for conferences and meetings at which people may addressthe audience from almost any point in the room. Such rooms will usually havea seating capacity of more than 60.

lecture rooms

Rooms used mainly for the delivery of formal lectures, with basically flat floorsand fixed seating. This category includes rooms with a raised step or podium forthe lecturer, and rooms with one or two raised steps towards the rear of the seating.

lecture theatres

Rooms used for the delivery of formal lectures with raked floors and/orbalconies or galleries and with fixed seating.

lighting energy numeric indicator (LENI)

A numeric indicator of the total annual lighting energy required in the building(unit: kW·h.m–2 per annum).

light output ratio (of a luminaire)

The ratio of the total flux of the luminaire, measured under specified practicalconditions with its own lamps and equipment, to the sum of the individualluminous fluxes of the same lamps when operated outside the luminaire withthe same equipment, under specified conditions.

local lighting

Lighting for a specific visual task, additional to and controlled separately fromthe general lighting.

localised lighting

Lighting designed to illuminate an area with a higher illuminance at certainspecified positions, for instance those at which work is carried out.

luminance (L)

Luminous flux per unit solid angle transmitted by an elementary beam passingthrough a given point and propagating in a given direction, divided by the areaof a section of that beam normal to the direction of the beam and containing thegiven point (unit: cd·m–2).


luminaire lighting fitting (deprecated)

Apparatus that distributes, filters or transforms the light transmitted from oneor more lamps and which includes (except the lamps themselves) all the partsnecessary for fixing and protecting the lamps and, where necessary, circuitauxiliaries together with the means for connecting them to the electrical supply.

luminaire maintenance factor

The ratio of the light output ratio of a luminaire at a given time to the initiallight output ratio.

mounting height

The vertical distance between the luminaire and the ground or floor, or betweenthe luminaire and a defined task plane (working plane).

multi-purpose rooms

Rooms used for a wide variety of purposes, such as school halls, assembly rooms,and function rooms.

reflectance (ρ)

The ratio of the reflected radiant or luminous flux to the incident flux in thegiven conditions.

room index

An index related to the dimensions of a room, and used when calculating theutilisation factor and other characteristics of a lighting installation:

L × WK = —————–

Hm (L + W)

where K is the room index, L is the length of the room, W is the width of theroom and Hm is the height of the luminaires above the floor or other relevanthorizontal plane. Consistent units must be used for the dimensions.

rooms for practical work

Rooms used regularly for class teaching purposes, without large permanentpieces of apparatus set up. Such rooms will usually have a seating capacity of lessthan 60. This category will include many teaching laboratories.

semi-direct lighting

Lighting by means of luminaires having a distribution of luminous intensitysuch that the fraction of the emitted luminous flux directly reaching theworking plane, assumed to be unbounded, is 60–90%.semi-indirect lighting


spacing/height ratio

The ratio of spacing of the geometric centres of the luminaires to their heightabove the reference plane.

Glossary 95

stroboscopic effect

The apparent change of motion of an object when illuminated by periodicallyvarying light of appropriate frequency. This periodic motion is especiallynoticeable in the light from discharge lamps with clear bulbs operating onalternating current.

teaching rooms

Rooms used mainly for class teaching purposes, with flat floors and no fixedfurniture except possibly chalkboards and projection screens. Such rooms willusually have a seating capacity of less than 60.

uniformity

See illuminance uniformity

veiling reflections

Specular reflections that appear on the object viewed and that partially or whollyobscure the details by reducing contrast.

visual acuity

The capacity for seeing distinctly fine details that have very small angularseparation.

visual comfort

A subjective condition of visual well-being induced by the visual environment.

visual field

The area or extent of physical space visible to an eye at a given position anddirection of view.

visual performance

The performance of the visual system as measured for instance by the speed andaccuracy with which a visual task is performed.

1 The Construction (Design and Management) Regulations 2007 StatutoryInstruments No. 320 2007 (London: The Stationery Office) (2007) (available athttp://www.opsi.gov.uk/si/si200703) (accessed October 2010)

2 The Building Regulations 2000 Statutory Instruments 2000 No 2531 as amended byThe Building (Amendment) Regulations 2001 Statutory Instruments 2001 No. 3335and The Building and Approved Inspectors (Amendment) Regulations 2006Statutory Instruments 2006 No. 652) (London: The Stationery Office) (dates asindicated) (London: The Stationery Office) (2007) (available at http://www.opsi.gov.uk/stat.htm) (accessed October 2010)

3 The Building (Amendment) Regulations (Northern Ireland) 2006 Statutory Rules ofNorthern Ireland No. 355 2006 (London: The Stationery Office) (2006) (available athttp://www.opsi.gov.uk/sr/sr200603) (accessed October 2010)

4 The Building (Scotland) Amendment Regulations 2009 Scottish StatutoryInstruments No. 119 2009 (London: The Stationery Office) (2009) (available at http://www.opsi.gov.uk/legislation/scotland/s-200901) (accessed October 2010)

5 The Education (School Premises) Regulations 1996 Statutory Instruments 1996 No.360 (London: Her Majesty’s Stationery Office) (1996) (available athttp://www.opsi.gov.uk/si/si199603.htm) (accessed October 2010)

6 Standards for School Premises (London: Department for Education and Schools)(undated) (available at http://www.teachernet.gov.uk/docbank/index.cfm?id=3928)(accessed October 2010)


References

This page has been reformatted by Knovel to provide easier navigation.

INDEX

Note: page numbers in italics refer to figures; page numbers in bold refer to tables.

Index Terms Links

A

absence control 34 88

access doors see entrances

acoustic considerations 16–17 24

adaptation, visual 3 90

adjoining spaces 57–58 90

ante-rooms 57 58 84

anti-panic (escape area) lighting 76 76 77

architectural form and daylighting 13 23–24 24

architectural integration 4–5

architectural models 36–37

area lighting see exterior lighting

area-weighted average reflectance 25

art rooms 39 60–62

artificial sky 37

assembly halls see auditoria

atria 14 15 23 24

40

audience lighting 41–43 52

audio-visual presentation 49

auditoria 39 77

see also conference rooms; lecture theatres

automatic controls see controls

average illuminance 3 21 93

awnings 29 30

B

battery powered emergency lighting 75 78–79

biodynamic lighting 34

blackout arrangements 47 66

blinds 28–29

see also external blinds; internal blinds

‘borrowed light’ 14

Index Terms Links


brise soleil 23 28

British Standards

BS 5266-1 78 79

BS 5489-1 71

BS 5499 73

BS 8206-2 23 25

BS EN 1838 73

BS EN 5266 49

BS EN 12193 20

BS EN 12464 20 31 70 81

BS EN 13201 71

BS EN 15193 6 7 8 81

BS EN 50172 78

BS EN 62034 78

BS EN ISO 9241-307 59 59

BS ISO 3864 73

building fabric, and daylight design 13

building facades 13–14 15

building form see architectural form

building obstructions 13 25 25

building orientation 13 67

Building Regulations 3 6 8

C

canopies 29 30

canteens 40

capital costs 9 85

car parking 69 72

CCTV surveillance 72

ceiling heights 23

checklist for lighting design 80–81

chromaticity 90

CIE 1974 general colour rendering index 91

circadian system 10

circulation areas

exterior 68–69 69

interior 39 57–58

classification of spaces 38

Index Terms Links


classrooms 51

colour interest 33

daylight design 27 40

depths and heights 23

design tools 5

electric lighting 17

natural lighting benefits 11–12

performance requirements 39

veiling reflections and glare 32 60

clean room classification 62

clerestory windows 14

climate-based daylight modelling 17–19

colour appearance 4 20 91

colour interest 20 33 48

colour recognition 3

colour rendering 91

colour rendering index (CRI) 3 39–40 91

colour temperature 4 34 91

committee rooms 53–54 91

common rooms 39

computer display screens see display screen equipment (DSE)

computer modelling 36–37

computer projection 47 49 66–67 84

see also interactive whiteboards/display screens

computer visualisation 36–37

concert halls 65

conference rooms 40 51–53 77 82

94

Construction (Design and Management) Regulations 2

contrast

ambient/task lighting 40

definition 91

room surfaces 20 25

window walls 14 30

see also luminance distribution

contrast rendering factor 91

control rooms 50–51 84

controls 34–35 88–89

blinds and shades 28

checklist 81

Index Terms Links


controls (Cont.)

conference rooms 52

configuration 89

control gear 87–88

daylight sensing 34 35

energy efficiency 5

input devices 88–89

integrated daylighting and electric lighting 17

internal blinds 15

lecture rooms/theatres 48

multi-purpose rooms 56–57

recommended minimum provision 90

special educational needs 67

correlated colour temperature (CCT) 4 34 91

corridors 39 57

costs 8–10 85

courtyards, daylighting 28

craft rooms 39 60–62

curtains 27 30

cut-off 91

cut-off angle 31 31 91

cylindrical illuminance 20–21 91–92

D

dance studios 64–65

daylight design 4–5 11–17 12 22–31

committee/meeting rooms 53–54

daylight modelling 17–19

daylight quantity 24–26

lecture rooms 46–47

lighting controls 5

multi-purpose rooms 54

performance requirements 40


sports halls and gymnasia 63

daylight factor 24 24–25 40 67

92

daylight matching lamps 34

daylight quality 26–28

daylight sensing controls 34 35

Index Terms Links


demonstration areas 39 43–44 49

demonstration equipment 85

design and technology areas 32 39 60–62

design checklist 80–81

design objectives and constraints 1–2

diffused lighting 92

dimmers 48

dining halls 40

direct lighting 92

directional lighting 21 22 92

disability glare 29 93

discharge light sources

flicker 32

fluorescent lights 32 86 87

high frequency 32

discharge light sources

high intensity discharge (HID) lamps 32 87

high pressure sodium lamps 41 86

metal halide sources 42 56 86

discomfort glare 29 36 93

display lighting 53 56

display screen equipment (DSE) 58–59

luminance limits 59 59–60 60 100–102

veiling reflections and glare 31 32 60


disposal of used equipment 89

drama studios 64 64–65

E

Education (School Premises) Regulations 2–3

efficacy see luminance efficacy targets

efficiency, energy see energy efficiency

electric lighting 17 31–35

electrical supply 81

emergency lighting 75 78–79

electromagnetic control gear 87

electronic control gear 87

emergency escape lighting 72–79

anti-panic (escape area) lighting 76 76 77

costs 85

Index Terms Links


emergency escape lighting (Cont.)

definition 92

laboratories and workshops 62


emergency power supplies 75

end user needs and preferences 13 17

energy consumption 5

energy efficiency 5–8 81–82

design criteria classes 8

requirements 5–6

targets 6 6–8 7

Energy Performance in Buildings Directive (EPBD) 6

Energy-using Products Directive 5–6

entrance halls 39 40 57

entrances

exterior lighting 68

to lecture rooms/theatres 47 49 58

environmental design 4–5

passive integration 10

see also daylight design

EPBD (Energy Performance in Buildings Directive) 6

equipment disposal 89

equipment rooms 84

escape area lighting 76 76 77

escape route lighting 73–76 74 76 76

escape route signage 72–73

exhibition lighting 56

exit signs 49 72–73

exterior lighting 68–72 69

external blinds 28 29

external building obstructions 13 25 25

external shades 28 29 29 30

external view 26–28

F

facade design 13–14 15

fibre optic light distribution 16

fire risk assessment 76

flicker 32 92

flip charts 53

Index Terms Links


floodlighting 69–71

fluorescent lights 32 86 87

footways 72

foyers see entrance halls

full height glazing 14

full spectrum fluorescent lighting 11

furnishings 48 52–53

G

games areas 69 69–70 70 71

general colour rendering index 91

general lighting 3 92

general purpose halls 64–65

glare, definition 92

glare control

daylighting 28–31

electric lighting 31

escape route lighting 73–74 74

lecture rooms/theatres 42 45 46

multi-purpose rooms 56


glazed roofs see rooflights

glazing see windows

gloss finishes 32

gymnasia 40 63

H

handicraft rooms 39 60–62

hazardous situations 62 73 76 77

health issues

natural lighting benefits 10 11–12

ultraviolet (UV) radiation 10

hearing impairment 67

heliodon 37

high frequency discharge lamps 32

high intensity discharge (HID) lamps 32 87

high pressure sodium lamps 41 86

high risk task areas 62 73 76 77

horizontally stacked shading 15

Index Terms Links


human visual system 3

I

illuminance

definition 93

recommended 19 19 39–40

uniformity 25 38 93

see also daylight factor; luminance

immediate surrounding area 93

independent schools 3

indirect lighting 19 93

information technology (IT) rooms 39

initial illuminance 93

inspection, emergency lighting 78–79

installation, emergency lighting 77

installed loading 93

integrated daylighting and electric lighting 17 34 35–36 88

interactive whiteboards/display screens 32 51 65–66

interior decoration

colour interest 20 33 48

conference rooms 52–53


internal blinds 28–29 29 47

internal glazing 14 28 28

internal shades 28 29 29

interpretation booths 53

ISO 2603 53

IT (information technology) rooms 39

K

keystone effect 94

kitchens 40

L

laboratories 39 60–62

lamp lumen maintenance factor 94

lamp survival factor 94

lamps

choice of lamp and luminaire 34 41–42 86

Index Terms Links


lamps (Cont.)

correlated colour temperature (CCT) 4 34 91

luminaire efficacy 6 8

shielding angles 31 31 31

see also discharge light sources; LEDs (light emitting diodes)

language laboratories 39

lecture attendants 84

lecture rooms 39 41 45–51 94

lecture theatres 41–51

daylighting 40

definition 94

lighting and projection control 84 85

lighting maintenance 82

management 83–85

performance requirements 39 77

LEDs (light emitting diodes) 32 41 75 83

drivers 87–88

legal requirements 2–3

daylight design 17

energy efficiency 6–8

libraries 39 40 62

life cycle costs 9

light nuisance 70–71 71

light output ratio 94

light pipes 16

light pollution 70–71 71

light traps 49–50

light trespass 71

lighting controls see controls

lighting energy numeric indicator (LENI) 6 7 94

lighting scenes 35 48

lightshelves 15

lightwells 14

lines of sight see sight lines

lobbies 57 58

local lighting 94

localised lighting 67–68 94

see also task lighting

log books, emergency lighting 79

louvre blinds 29

Index Terms Links


low voltage light sources 87

luminaires

cut-off angle 31 31 91

emergency lighting 74 74 75 78

light output ratio 94

lighting fitting 95

maintenance factor 95

mounting height 56 58

selection checklist 80–81

spacing/height ratio 95

task lighting 68

see also lamps

luminance

definition 94

for display screen equipment 59 59–60 60 100–102

see also illuminance

luminance adaptation 3 90

luminance distribution 3–4 29 33

daylighting 24–25 28

modelling 36

task/ambient lighting 5 40

luminaire efficacy targets 6 6 8

M

machine rooms 32

mains ripple 32

maintained illuminance 39–40 93

maintenance 8 82–83

checklist 81

emergency lighting 77–79

maximum illuminance 93

mean cylindrical illuminance 20–21

meeting rooms 40 53–54

metal halide sources 42 56 86

microstructure prismatic materials 16

mnimum illuminance 93

modelling 36–37

modeling index 21 22

motion detectors see presence detectors

Index Terms Links


mounting height 95

emergency lighting 74 75

luminaires 56 58

safety signs 73

multi-purpose halls 64–65

multi-purpose rooms 54–57 95

music practice rooms 39

musical performances 65

N

natural lighting

design considerations 12–17

learning and health benefits 11–12

see alsodaylight design

natural ventilation 23 24

no-sky line 26

O

offices 40

operational costs 9 85

orientation of building 13 67

outdoor learning 11

outdoor lighting 68–72 69

P

parking areas 69 72

passive integration 10

pedestrian footways 72

performance requirements 38 39–40

escape area lighting 76 77

exterior lighting 69 71

photocell control 89

photoluminescent signs 78

planning submissions 16

power supplies for emergency lighting 75 78–79

practical work, rooms for 39 51 60–62 95

preparation rooms 39 58 84

presence detectors 88

Index Terms Links


presentation areas

lecture rooms/theatres 43–44 47–48

teaching rooms 51

presentation walls 20 29

privacy problems 27

projection screens 65–67

see also computer projection

psychological effects 10–11

R

raked seating 42 44 44

reception areas 40

recycling 9 10 89

reflectance, definition 95

reflective surfaces 14 16 19 20

Regulatory Reform (Fire) Order (2005) 76

remote testing, emergency lighting 78–79

retractable screens 29 30

road lighting 71 71

roof overhangs 30

rooflights 14 15

daylight factor 24

daylight factor calculation 25

discomfort glare 30 30

lecture rooms 47

room depth 23 26 26

room function and daylight design 13

room index 95

room surfaces

colour 20 33

reflectance 14 16 19 20

wall lighting 35

S

safety signs 72–73 73

‘scene setting’ controls 35 48

science laboratories 39 60–62

seasonal affective disorder (SAD) 10–11

security lighting 72

Index Terms Links


self-luminous signs 78

self-testing, emergency lighting 78–79

semi-direct lighting 95

service schedules, emergency lighting 78–79

servicing, emergency lighting 77–78

shading, and architectural form 23

shading systems 15 30

see also blinds; external shades; internal shades

sight lines, lecture rooms/theatres 44 45 46

signage, escape routes 72–73

sky luminance 29 30

skylights see rooflights

solar design 23–24 28–31 36

space planning 23

spacing/height ratio 95

special educational needs (SEN) 13 40 67

splayed reveals 30

sports halls 40 55 63 77

sports pitches 69 69–70 70 71

spotlights 45 50 56

staff rooms/offices 39

stage areas 49–50 56

staircases 39 57–58 74

stock rooms 39

stroboscopic effects 32 62 96

sunlight

human exposure to 11

penetration into building 36

redirection systems 16

shading systems 15

see also solar design

supplier registration 9

surface finishes 32 48 54

surface reflectance 14 16 19 20

95

sustainability issues 5 9 9 85

swimming pools 40

switches see controls

Index Terms Links


T

task lighting 67–68

and ambient lighting 5 40

design checklist 80–81

emergency 62 73 76 77

teaching rooms, definition 96

technical drawing rooms 39

television equipment 66

testing, emergency lighting 77

theatrical lighting 50 64 64–65

theatrical presentations 49–51 65

thermal design, and daylight design 13 15

timers 88–89

transformers, for low voltage light sources 87

U

ultraviolet (UV) radiation 10

unified glare rating (UGR) 31 39–40

useful daylight illuminance (UDI) 18–19

V

veiling reflections 32–33 96

ventilation 23 24 28 47

vertical shading 15

video equipment 66

view (outlook) 26–28

virtual daylight models 36 37

vision, human 3

visual acuity 96

visual aids 66–67

visual amenity 3–4

visual clutter 83

visual comfort 19 33 96

visual field 96

visual function 3

visual impairment 67

visual interest 3–4 4

see also colour interest

visual lightness 3–4 4 19

Index Terms Links


visual performance 96

W

waiting areas 58

wall lighting 35

wall thickness, and daylight design 13

Waste Electrical and Electronic Equipment (WEEE) Regulations 9 89

whiteboards 53 65–66

lighting design 32–33

luminaires 65–66 66

presentation walls 20 29

veiling reflections 32


window walls 14 30

windows 4 30

daylight design 13–14 14 23 25–26


view 26–28

wall contrast 14 30

see also rooflights; shading systems

workshops 39 60–62