“In my architecture I attempt to create a "brighter" world by using natural light to get away from the gloomy."

Henning Larsen

Designed for daylighting?

The Luminous Environment of Malmö Public Library (case study – essay 3)

Beata T Zygarlowska

Previously known as Wroblewska

Malmö Public Library

Malmö is the main city in the region of Scania (Skåne) in south Sweden. It has a population of 262 400 inhabitants.

Four biggest cities in Sweden

Stockholm - 1 660 700

Gøteborg - 796 700

Malmø - 262 400

Uppsala - 191 100

Malmö location

55°37´ N latitude

13°01´ E longitude

Slottsparken

South elevation

Malmö Public Library is situated in the south-eastern corner of the Slottsparken, it consists of two parts, the old part designed by the architect John Smedberg and dating back to 1900. Its red brick building, resembling a 16th century renaissance castle from the region of Scania (Skåne), formerly held the City Museum. The new part of the library was designed by the Danish architect Henning Larsen and was opened to the public in 1997.

This library is the largest in Sweden and designed to accommodate one and a half million visitors a year.

It has an average of almost 5.000 visitors per day and almost 6.000 loans per day.

Collection: 700.000 books, plus periodicals, videotapes, music CD´s etc

View from the Regementsgatan

Based on the old library building’s form and relation to the city park, the new library repeats the existing theme.

The composition consists of three, freestanding masses: the old building (A), the central, cylinder-shaped entrance building (B), and the large, new library building (C) – all held together by glass arcade.

The plan of the main new building, called “Light Calendar”, is based on the old building’s basic square form, with a diagonal shift. It houses a four-storey library hall, whose 17 m high windows facing the park are constituted of 560m2 glass façade supported by grid structure. This glass cube is hold on two sides by an L-shaped, closed building.

Access to the library hall is via a stairway from the access level in the cylinder. It leads into the L-shaped part of the building, which on the lower levels is separated from the library hall by columns, and on the upper floors by square windows facing the hall.

The library hall roof is supported by four, cylindrical columns. A staircase runs up the glass curtain wall on the west side of the building and connects levels of the huge, three storey high “bookshelf”.

The library covers 15 300m2 and is designed to cater to 1.5 million visitors a year.

View from the park

Section

View from the L-shaped part of the building into the Light Calendar

View from the ”bookshelf”

View from the librarian’s offices

View towards the Park

The Calendar of Light

Section aa

L-shaped building, north wing

Stack and reading area

Section bb

L-shaped building, south wing

Stack and reading area

“Daylight plays a special role in the building’s rooms. We have emphasized that daylight should be a simulating, changing element in the building throughout the hours of the day.” p.33 – from competition proposal by Henning Larsen Tegnestue

“Finally light fulfils its role as an indicator of time in the Calendar of Light.” p.37

“It is also obvious that the proposal’s emphasis on light will distinguish the finished building. Daylight – flowing in limitless waves through the large book hall, strainedthrough small openings in the row of administration offices facing Regementsgatan (…) in reality has come to play the leading role in shaping the entire environment, as the competition proposal intended.” p.38

“Light plays also a prominent role in the entrance hall through three interlacing sources of daylight. Direct light floods in from the two entrance sections, in strong contrast to the otherwise compactness of the wall. Around the stairway to the book hall in the new building daylight filters in from the glass-enclosed passageways between buildings.”p.40

“A sudden inrush of daylight through a two-storey window facing south creates a new room in what otherwise, would be the innermost dimness.” p. 41

The architect’s vision, The Calendar of Light

Light Calendar, view from the south-east corner of the offices

Visitors’ activities

Research by library stuff before design proposal was discussed.

Average visit time is 42 minutes, it can vary from 20 seconds to seven hours.

Visitor’s most common activities in public libraries

Lending 61%Searching for material on their own 59%Returning 37%Reading newspapers/magazines 31%Doing computer searches on their own 30%Reading and studying 27%Asking questions at the info desks 25%

Student activities in Malmö Public Library

Borrow course/study literature 45%Study in the library 45%Ask the stuff 25%Search for information 25%

Study areas are mostly filled with students who read material they bring along with them, 80% in fact. Many stay for four to five hours, sometimes up to seven or eight. Also adults come to the MPL to study, they come from high schools*, adult study programmes, study circles and individual studies. Library is becoming a sort of ”open university”.

Characteristics of the luminous environment of Malmö Public Library

- Is new extension of the Library designed for daylighting?

- How daylight design associates with building’s functions?

- Does daylight design relate to the artificial light design?

1. Photographic registration of the building, collection of materials. Observation led to the conclusion that following problems may occur: - high illumination levels (artificial lights are on during opening hours, regardless of daylight quality) that can cause discomfort- glare on the working surfaces from both sunlight and artificial light- issues related to visual discomfort such as excessive contrast in computer and working areas (eye strain, headache etc.)- energy consumption- book deterioration

2. Study of existing conditions, used method:- Measuring the illumination levels during day time and in the evening (again: artificial lights are on during opening hours, regardless of daylight quality) - Material characterisation: measurement of reflectance of surfaces: walls, floor, ceiling, furniture etc.-Identification of lighting apertures and lighting system

3. Calculations and comparing of the results to the CIBSE guide for libraries

4. Survey among library users and staff.

5. Defining lighting related problems and proposal of solutions

Methodology

Between stacks in the ”Bookshelf”

Studies of Existing Lighting Conditions

Measurements:- Illuminance level- Luminance and Luminance ratio- Glare

Illuminance of the diffuse sky during investigation was 8900 lux.

Illuminance measurement methodOutdoor illuminance measured every 5 minutes (average of 8900 lux used for calculations) under stable overcast sky conditions. Indoor illuminance was investigated in two sections through the building, section A and B.

The daylight factor are calculated according to the measurementsmade on a working plane (0.80 m from the floor)

Recommended illumination levels (for artificial lighting)According to CIBSE (10), an illuminance much higher than 500 lux will produce difficulty because of the difference in illuminance between the documents and the screen)

Areas of interest Recommended illuminance (lux) Planes of interest

Reading area 300 horizontal (on working plan)Stack area 150 verticalAncillary area:- computer areas 150 vertical (in front of screen)

300 (should not exceed 500) horizontal (for reading documents)- circulation area 100 horizontal

Recommended daylight factors (according to CIBSE (8), if the daylight factor is lower that 2% supplement om electric light is required)

Areas of interest Recommended DF (%) Planes of interest

Average MinimumReading area 5 1.5 horizontalStack area 5 1.5 vertical

Section A

Section B

Illuminance levels – section A

As mention earlier artificial lights are on all the time during opening hours, to define DF and illuminance levels for daylighting measurements were taken firstly between 12.30 and 2.30 pm and after sun set between 6.00 and 8.00 pm.

To define DF and illuminance level for daylight I had to compare illuminance levels during the day (with artificial lights on) with artificial light levels in the evening.

Interestingly lighting levels measured in the evening were close to the recommended values and lied between 150 and 220 in the stack area and about 300 up to 500 in the reading area, where adjustable table lamps are provided .

Light levels during the day, thou, exceeded more then twice the recommended illuminance values.

Interest points- reading area close to the west glass wall (point 2)-“bookshelf” construction (point 3)- reading area (point12)

Section A

Section A, Point 2 Point 3 Point 12

Daylight Factor section A

DF calculation results:Reading areas(recommended 5%)- at point 2 - 20.9% -11%- at point 3 – between 11 and 3.5%- at point 12 – between 1.9-2.7%

- stabile throughout whole space, between 3.5 and 6.9%

-Daylight Levels under Overcast Sky

Assumed lowest sky illuminance 5000 luxRequired illuminance 300 lux- at point 2, for DF= 20.9%

5000 lux x 0.209= 1045 lux (>300lux)*- at point 12, for DF=2.3% (average)

5000 lux x 0.023=115 lux (<300 lux)- at point 3 ”bookshelf”, for DF=7.25%

5000 lux x 0.0725=362 lux (>150 lux)

The above calculation show patterns in light distribution and oncoming problems: - at point 2, always high illuminance levels, sufficient for reading, but that can cause discomfort in sunny periods- at point 12, permanent need for artificial light

* From the equation: DF= Ein/Eout x 100, where Ein - the internal illuminance, Eout – the external illuminance under unobstructed sky

Section A

Required indoor illuminance

Required Sky Illuminance(for inside illuminance of 300 lux)

For lowest daylight factor (in point 12) = 1.9%300 lux / 0.019 = 15,789 lux

For the highest daylight factor (in point 2) = 20.9%300 lux / 0.209 = 1435 lux

For point 3 ”bookshelf”, for DF=7.25%300 lux / 0.0725 = 4137 lux

Availability of Required Sky IlluminanceReading area, For point 2 – 90% of working year

According to the estimate, area close to the western wall has sufficient daylight levels for as much as 90% of a working year.

For point 12 - 40% of working year

Improvement of daylighting or permanent supply of artificial light is required in this area

For point 3 a ”bookshelf” – 76% of working year

”The bookshelf” has sufficient daylight levels for as much as 76% of a working year. The artificial light can be therefore eliminated for most of the time.

Illuminance levels – section B

DF and illuminance levels defined as earlier.

Errors: DF in point 4 rises up to 19.3% because of the table lamp that was turn on during the day, but turned off in the evening.

DF in point 12 falls down to 0.86%, while measurements were performed artificial light (table lamp) was turned off in both cases, while for all other measurement point, both ceiling lights, daylight and local lighting were turned on.

Section B, Point 2 Point 13 Point 14

Interest points– reading area close to the north glass wall (point2)- reading area in the south wing (point 13)- computer stations (point 14)

Circulation area between point 9 and 10 illuminance – 500 lux, the CIBSE-recommended levels of 100-200 lux.

Section B

Daylight Factor section B

DF calculation results:Reading areas (recommended 5%)- at point 2 - 30%, table lamps are permanently turned on, no possibility for adjustment- at point 13 – 3.6%- at point 14 (Computer stations) close to the window –DF=20.3%- between points 4-9, between book stacks DF - 4,7% and 10%

Daylight Levels under Overcast Sky

Assumed lowest sky illuminance 5000 luxRequired illuminance 300 lux- at point 2, for DF= 30%

5000 lux x 0.3= 1500 lux (>300lux)- at point 13, for DF=3.6% (average)

5000 lux x 0.036=180 lux (<300 lux)- at point 14 (computers), for DF=20.3%

5000 lux x 0.23= 1150 lux (>500 lux)- for book stacks, for DF=7% (average)

5000 lux x 0.07=350 lux (>300 lux)

The above calculation show patterns in light distribution and oncoming problems: - at point 2, always high illuminance levels, that can causediscomfort in sunny periods, plus table lamp that is always on-at point 13, too low daylight level-at point 14 (computer area), (150 lux for vertical- in front of screen,and 300 (should not exceed 500) for horizontal use, illuminance level double then recommended -for book stacks even under overcast sky daylighting seamsefficient

Section B

Required Sky Illuminance(for inside illuminance of 300 lux)

In point 13 daylight factor = 3.6%300 lux / 0.036 = 8,333 lux

In point 2 daylight factor = 30%300 lux / 0.30 = 1000 lux

For book stacks DF=7% (on average) 300 lux / 0.07 = 4285 lux

Availability of Required Sky IlluminanceReading area, For point 13 – 58% of working year

Improvement of daylighting or permanent supply of artificial light is required in this area

For point 2 - 90% of working year

According to the estimate, area close to the western wall has sufficient daylight levels for as much as 90% of a working year.

For book stacks– 72% of working year

Book stacks have sufficient daylight levels for as much as 72% of a working year. The artificial light can be therefore turned off for most of the time.

Required indoor illuminance

Daylighting in Stack Areas

Recommended illuminance level for stack area 150 lux(vertical).

DF recommended 5%, minimum 1.5%

For the Malmö Public Library the average required lighting level per shelf was 300 lux.

”A Library for all Times” p.83

1 2 3

1 2 3

Based on the measurements of the daylight levels in the Light Calendar one can assume that sufficient amount daylight is provided so artificial light should not be necessary, accept for area in the eastern wing of L-shaped building.

Visual comfort

For visual comfort surface reflectance should not greatly exceed the recommended values.

Luminance (cd/m2) of surfaces was investigated.The surfaces reflectances were then calculated by comparing, under tha same lighting conditions, the luminance of surface of interest with the luminance of a gray card, which possesses the calibrated reflectance of 18% on the gray side, and approximately 90% on the white side.

Actual surfaces reflectance: Recommended reflectance. CIBSE (11)

Furniture desk top - laminated wood – 46% Furniture 30-50%Ceiling plastered brick – 80% Ceiling 80%Walls white plaster – 80% Wall 50-80%Floor wooden floor – 21% Floor 20-40%

Table designed as a computer workstation.

Glare is the worst adversary of good visual performance. To avoid visual impairment and to provide visual comfort, environment in library needs to be free from both disability glare and discomfort glare.

Disability glare - is caused by light scattered into the eye that shines on the retina and reduces the contrast of images that we would normally see clearly without the presence of glare.

Discomfort glare - often occurs when encountering an area that has very high illumination levels. The best solution is to reduce the basic illumination levels.

The existence of glare was observed by eye from sun light and from the artificial light.

Direct glare from direct sunlight can be observed in reading areas.

L-shaped building in south – windows have no blinds or other form for protection.

Visual comfort >< Glare

Adaptive opportunities

Light Calendar – As the whole glass façade had to be made of clear, uncoloured glass external blinds were installed to control potential glare but because of occurring strong winds they were removed and internal louvers were installed at the ground floor and automatic blinds on other storeys.

Library staff is responsible for adjustment of blinds.

Visual Comfort in Computer Areas

Computers are often situated closed to the windows, in the way that users sit frontally to the bright sky of the outside. The bright window without blinds, being at the back of the screen, can make details on the screen difficult to see and distracting.Also stack lights cause problems.

Two types of computer screens, thou are used: ordinary one and anti-glare screen. Anti-glare screens function perfect in every place of the library. Traditional screens cause problems of glare from both daylight and artificial lights (stack light and ceiling light).

Anti-glare computer screens

Traditional and anti-glare computer screens

Lighting system and aperture

Time controlled lighting system:-A time control for emergency light-A time control for library’s equipment (stacks etc)-A time control for ceiling lights-A time control for offices-A photoelectric dimming for outside lighting

Ceiling lights – halogen luminaries integrated into ceiling

Bookshelf’s lights, halogen lamps, one for each segment

Local lamps: adjustable and non-adjustable

The ceiling and stack light are on the whole day, so excessive lighting levels are observed and measured. This situation, which from the energy conservation point of view can be considered a waste of energy, is probably due to the following reasons:-Sky conditions change quite often, making it impractical to turn on or off the ceiling lights-Directional daylight, while western side of the Light Calendar may have sky illuminance high enough to provide sufficient interior daylight levels, the others may not. -Daylight is not well distributed. In some reading areas daylightlevels are sufficient, in some they highly exceed recommended levels, and in the inner areas of L-shaped building’s east corner are comparatively dark, encouraging users to turn the desk lights on.

The Artificial lighting on working planes, with both ceiling lights and local lamps on, is approximately 380 lux, or slightly higher, with possibility of adjusting of table lamps, according to the CIBSE (11) an adequate illuminance.

Picture taken under relatively clear sky at 1.00 pm

Light sources

Adjustable lamps, type A & B

Non-adjustable lamp, type CIlluminance on the desk top reaches 540 lux, during day time 2000 lux

A B

C

Electric light controls

Choosing method for controlling electric light, according to J.Bell and W. Burt

Opening hours1 Jan-31 MarchMo-Th 10-20Fri 10-18Sat12-16Sun12-16

1 April-30 AprilMon-Th 10-20Fri 10-18Sat 12-16

2 May-31 AugustMo-Th 10-19Fri 10-18Sat 12-16

1 Oct-21 DecMo-Th 10-20Fri 10-18Sat 12-16Sun 12-16

Exposure to both natural and artificial light will cause serious harm to books and documents. Not only will inks and colours fade but paper and binding materials will also deteriorate. The amounts of both visible light and of ultra violet emissions from the sun and fluorescent lighting will need to be controlled to a reduce this damage.

All light, particularly that in the ultraviolet (UV) and infrared (IR) regions of the spectrum, induces chemical changes which age materials by degrading them. The most pernicious photochemical damage is caused by UV rays. IR radiation will cause chemical changes, and it accelerates the destructive effect of both UV light and visible radiation. Although not as profound in its destructive capacity as IR or UV, visible light can cause fading or darkening of some pigments. Photochemical deterioration, which occurs in organic objects such as works on paper and textiles, is cumulative and cannot be reversed.

Deterioration of materials

For sensitive materialsSensitive materials include items such as textiles, paper and watercolours.•The brightness of the light should be no greater than 50 lux.•The exposure in one year should be no greater than 200 kilolux hours.•The UV content of the light on sensitive materials should be no greater than 75 µW/lm—microwatts per lumen—and preferably below 30 µW/lm.

This paper is severely damaged: discoloured and very brittle.

Lighting related problems

Lack of balance between daylight and artificial lighting

• Inappropriate artificial lighting control system• Insufficient daylight levels in some areas under the standard overcast sky• Glare problems on computer screens and in reading areas• Danger of material deterioration• Energy waste

Pointed problems are caused by:Building design• Lack of design consequences – daylight playing special role• Aesthetics dominating design strategy without consideration of function• Deep plan building• Interior design – layout, location of reading areas and computer areas• openings in south façade• lack of blinders in south facing windows

Lighting system• conflict between quantity and quality of light• inflexible control system • Circulation areas are more lit that necessary

Adaptive opportunities• lack of influence from the users side on shading devices

• well-informed building occupants - librarians.

Proposal of solutions

Improvement of lighting control system- Time control system dividing ceiling light in zones will make possible to control lighting according to different sky conditions and direction of sun light- Photocells and dimmer switches would permit adjustment of illumination levels in accordance to changing sky illuminance- Efficient control of stack lighting

Proposed zones for ceiling lighting

Energy

Electrical power within hall of Light Calendar17 m above the floor ceiling lighting is turnedon probably 24 hours a day

The electrical loads can be calculated as follows:100 luminaires (fluorescent) a 18 Watt 1800 Watt

Energy required1800 x 24 x 356 = 15MWhours per annum

If used only after sunset e.g. 6.00 pm to 6.00 am50% would be saved

576 stack lights (halogen) 50 Watt each 28800 Watt

Energy required28800 x 7(hours a day on average) x 356 = 70.56 MWhours per annum

Availability of Required Sky Illuminance 72-76% of the working hours.

Only 24-28% of energy would be required if daylight levels were considered.

Proposal of solutions

Insufficient daylight levels in reading areas under the standard overcast sky can be improved by changes in interior layout.

To be consider:The blue square – represents the best area from the daylight point of view for reading, DF on average 5%

The wall dividing space on the east side obstructs daylight access.

GlareEasily operable blinds to avoid glare from windows should be introduced in south. It would prevent glare and provide visual comfort for computer users. More efficient use of blinds on the west side of Light Calendar should be considered.

Computers with traditional screens should be adjusted so sunlight would not be reflected to users’ eyes.

Stack light reflects in computers screens, therefore new layout should be proposed.

Book deterioration•incorporating UV absorbing filters into windows and fluorescent lighting. • Curtains and blinds •If illumination is necessary then lighting must be carefully chosen• It should be remembered though that all light falling on an object for any length of time will cause damage.

The Malmö Public Library

- Conflict between architect’s concept and lighting performance of the building

- Poetic and intuitive design dominates while lighting performance is not considered

- Impressive architecture that needs improvements

- Visual comfort and energy efficiency should be considered in early design stages

- Function of the building is often forgotten in the name of the aesthetic experience

- Relation between lighting and users’ behaviour - mostly occupied area is close to the western glass wall

- Beautiful view suppresses inconvenience of light qualities

Bibliography

-A Library for All Times, Swedish National Council for Cultural Affairs, Malmö, 1997-Baker, N. and Steemers, K., Energy and Environment in Architecture: A Technical Design Guide, London, 1999-Fontoyont, M., Daylight Performance om Buildings, European Commission 1999-Lechner, N., Heating, cooling, lighting:design methods for architects, John Wiley & Sons, 1991-Chartered Institution of Building Services Engineers, The Environmental Criteria for Design, CIBSE Guide Volume A, 1988-Chartered Institution of Building Services Engineers ,The Codes for Interior Lighting, CIBSE, London, 1994-Bell, J., and Burt, W., ”Design buildings for daylight, CIBSE, 1995-Phililps Gloeilampenfabriken, Eindhoven, Lighting Manual, A Handbook of lighting installation design, The Netherlands, 1975The Institute of Paper Conservation - Manual, Upton-upon-Severn, UK- Lighting for Buildings, Part 2. Code of practice for daylighting, British Standard BS8206, 1992

Articles:-”Mjukfogar och demokrati”, MAMA – Magasin for Modern Arkitektur, 1997-”Svenak & Danska Brustna Hjärtan”, Forum, 1997/4-”Tower of Learning”, Frame, 1999/8-”Malmö Masterpiece”, The Architectural Review, June 1998, No 1216-”Malmö Stadsbibliotek”, Arkitektur DK, 1997/6-"Care from a Connoisseur," Nancy Harrison, Senior Vice President and Director of the 19th Century European Paintings Department at Sotheby's New York