environmental rules of thumb

ENVIRONMENTALRULES OF THUMB

R Rawlings

CCB

Technical Note TN 12/99

ENVIRONMENTAL RULES OFTHUMB

Technical Note TN 12/99

Rosemary RawlingsStephen MustowCatherine Pinney

Symon Sterne

B

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ACKNOWLEDGEMENTS

©BSRIA TN 12/99 Environmental Rules of Thumb

ACKNOWLEDGEMENTS

This work was performed under contract to the Department of theEnvironment, Transport and the Regions, under the ‘Partners inInnovation’ programme. BSRIA acknowledges the financial support ofthe Department of the Environment, Transport and the Regions andwould like to thank the following sponsors for their contribution whichled to the production of this Technical Note and to the sister publications,Environmental Code of Practice - Second Edition and Case Studies -Volume 2:

Department of the Environment, Transport and the Regions[DETR ref CI 38/6/129 (cc 771)]NatWest Environmental Management.

John Ahern John Ahern & AssociatesColin Burden Plincke LandscapePeter Charnley NatWest Environmental ManagementDermott Galvin, Iain Paul and Carl

SaxonHereford & Worcester County Council

Bill Gething Feilden Clegg ArchitectsMatthew Hill Leeds Environmental Design AssociatesRod Hughes Lowe Rae ArchitectsRob Jarman and Judy Richmond National TrustKeith Lodge Ecologic LtdLynette Warren University of Luton Research Centre.

Particular thanks are due to Peter Charnley, BSRIA’s external projectassessor, and John Ahern for his contribution to updating the Code andguidance on maintaining a truly inter-disciplinary approach.

BSRIA also gratefully acknowledges the contributions from the manyother people who have provided valuable comments and feedback on useof the Code. Joe Lynes, of the Hull School of Architecture, contributedseveral of the rules of thumb related to lighting.

This publication is issued with the agreement of the DETR and everyopportunity has been taken to incorporate the views of the editorial panel,but final editorial control of this document rests with BSRIA.

EXECUTIVE SUMMARY


EXECUTIVE SUMMARY

This Technical Note contains rules of thumb and other guidance forassessing and addressing the environmental consequences of buildingprojects in the UK. The rules have been collected from the building andconstruction industries and come from a number of sources, includingorganisations, individuals and published material. They cover many ofthe main issues that are likely to be of concern to those involved indesigning, constructing, operating and disposing of/recycling buildings.However, due to the breadth of the subject they do not cover all detailedaspects. Also, because they come from a variety of sources, they do notnecessarily form a coherent set.

The rules of thumb and other notes for attention are categorised into thefollowing sections:

Resource Issues

• Energy• Water• Materials• Landscape

Building Lifecycle

• Pre-design• Design• Construction• Occupation• Refurbishment and recommissioning• Decommissioning, dismantling and disposal. A cautionary note on the indiscriminate use of rules of thumb by theinexperienced is included.

CONTENTS


CONTENTS

1 INTRODUCTION.......................................................................................................................... 1

1.1 Sources.................................................................................................................................... 11.2 Limitations .............................................................................................................................. 1

2 ENERGY ....................................................................................................................................... 2

2.1 Energy Supply ......................................................................................................................... 22.2 Energy Efficient Buildings........................................................................................................ 22.3 Ventilation ............................................................................................................................... 32.4 Lighting................................................................................................................................... 32.5 Transport................................................................................................................................. 42.6 Solar Design ............................................................................................................................ 52.7 Photovoltaics ........................................................................................................................... 62.8 Wind power ............................................................................................................................. 72.9 Waste to Energy....................................................................................................................... 8

3 WATER ......................................................................................................................................... 9

3.1 Taps ...................................................................................................................................... 103.2 Toilets ................................................................................................................................... 103.3 Urinals................................................................................................................................... 113.4 Rainwater & Greywater use ................................................................................................... 113.5 Composting Toilets ................................................................................................................ 123.6 Reedbeds ............................................................................................................................... 12

4 MATERIALS ............................................................................................................................... 13

4.1 Timber................................................................................................................................... 134.2 Masonry Materials................................................................................................................. 144.3 Thermal Insulation Materials.................................................................................................. 144.4 Roofing Materials .................................................................................................................. 154.5 Paint...................................................................................................................................... 154.6 Waste and Recycling.............................................................................................................. 15

5 LANDSCAPE .............................................................................................................................. 17

5.1 Choice Of Plants.................................................................................................................... 185.2 Green Roofs........................................................................................................................... 19

6 PRE-DESIGN............................................................................................................................... 20

7 DESIGN....................................................................................................................................... 21

8 CONSTRUCTION ....................................................................................................................... 22

9 OCCUPATION ............................................................................................................................ 23

9.1 Waste collection..................................................................................................................... 23

10 REFURBISHMENT & RECOMMISSIONING.......................................................................... 24

11 DECOMMISSIONING, DISMANTLING AND DISPOSAL...................................................... 25

CONTENTS

Environmental Rules of Thumb ©BSRIA TN 12/99

TABLES

Table 1 CO2 equivalent for different fuels......................................................................................... 2Table 2 Typical electric lamp efficacies ............................................................................................ 3Table 3 Rules of thumb for solar design............................................................................................ 5Table 4 Photovoltaics: Summary of advantages and disadvantages.................................................... 6Table 5 Estimated annual energy output at wind turbine hub height (in thousand kWh/yr) ................. 8Table 6 Division of water use within residential and office buildings ................................................. 9Table 7 Cheap and easy to install water conservation measures....................................................... 10Table 8 Domestic WC flush amounts.............................................................................................. 10Table 9 Sources of water in order of preference for ease of reuse .................................................... 11Table 10 Reedbed sizing for horizontal flow ..................................................................................... 12Table 11 Embodied energy of different insulating materials............................................................... 14Table 12 Environmental ‘best buys’ for roofing materials ................................................................. 15Table 13 Examples of very drought tolerant plants............................................................................ 18Table 14 Ideal depth of soil for roof gardens..................................................................................... 19Table 15 Loadings associated with green roofs ................................................................................. 19

FIGURES

Figure 1 Energy efficiency of different transport modes in the UK...................................................... 5Figure 2 Increase in power with height above 10 m............................................................................ 7Figure 3 Diagram of European wind distribution patterns .................................................................. 8

INTRODUCTION SECTION 1

©BSRIA TN 12/99 Environmental Rules of Thumb 1

1 INTRODUCTION

It is common practice in the building and construction industries forarchitects, engineers and others to draw on their experience for rapidassessment of issues related to the construction process. Thisaccumulated experience manifests itself as a set of guidelines or rulesknown as ‘Rules of Thumb’. In many cases the derivations of the rulesare not immediately obvious but there is often a sound scientific basis forthem. However, the rules tend not to be quoted in technical articles andbooks and when they do reference is made to only a small number. Thetask of learning the rules is also made difficult by the fact that they aresometimes regarded as commercially confidential or personalinformation.

This Technical Note provides rules of thumb and other guidance forassessing and addressing the environmental consequences of buildingprojects in the UK. It is the second publication of its kind to be producedby BSRIA (Technical Note TN 17/95 deals with rules of thumb for thedesign of building services) and forms one of the outputs of a BSRIAresearch programme. This was undertaken with the support ofgovernment and industry to produce, evaluate and update BSRIA’sEnvironmental Code of Practice for Buildings and their Services.Phases I and II of the project involved drafting, piloting and publishingthe first edition of the Code. Phase III involved evaluation of the Code asused in practice and identified the importance of feedback to the designprocess. As a result a fourth phase was initiated, entitled Feedback,which delivered an updated version of the Code of Practice, case studiesand this publication, Rules of Thumb.

The rules of thumb, together with other points to take into consideration,have been grouped so as to reflect the main resource issues (energy,water, materials and landscape) as well as the various stages of thebuilding lifecycle (design, construction, operation and disposal/recycling).

1.1 SOURCES The information listed has been drawn from a variety of sources,including individuals, organisations and published material. The formerare detailed in the Acknowledgements section of this Technical Note,while full lists of contact organisations and publications are provided inthe second edition of BSRIA’s Environmental Code of Practice forBuildings and their Services.

1.2 LIMITATIONS Where similar rules have come from more than one source, a consensusapproach has been used to select the one included. Although themajority of the rules have come from working designers theirappropriateness for any particular application cannot be guaranteed.Indiscriminate use of rules of thumb by the inexperienced is notrecommended. They should be supplemented by further information orcalculations where necessary.

SECTION 2 ENERGY

2 Environmental Rules of Thumb ©BSRIA TN 12/99

2 ENERGY

Approximately 50% of UK energy consumption is related to buildings.As energy production and consumption have a major effect on theenvironment resulting from acid rain, global warming and habitatdestruction for example, there is increasing pressure for new buildingsand refurbishments to achieve substantially higher levels of energyefficiency.

2.1 ENERGY SUPPLY ♦ Electricity production is only 38% efficient at the point of generation(assuming the UK average generation mix) and may lose a further 3%by the time it reaches your premises.

♦ Almost one third of the UK’s emissions of carbon dioxide (CO2)result from the energy expended in housing.

Table 1CO2 equivalent fordifferent fuels

♦ A range of alternative energy sources/technologies offer low orzero CO2 emissions, including for example photovoltaics, solarthermal, wind energy and energy from waste.

2.2 ENERGYEFFICIENTBUILDINGS

An energy efficient building ‘provides the required internal environmentand services with minimum energy use in a cost effective andenvironmentally sensitive manner’ (CIBSE Guide - Energy efficiency inbuildings). Such buildings are likely to incorporate the followingfeatures:

♦ Improved thermal insulation

♦ Natural ventilation whenever possible

♦ The use of passive cooling techniques in preference to mechanicalcooling

♦ Use of mechanical ventilation and air conditioning only wherenecessary

♦ Maximum use of daylight and ambient energy, ie passive and/or activesolar designs

♦ Exclusion of unwanted solar gain and glare

♦ The use of highly efficient lighting

♦ Local and/or individual control of the internal environment

♦ Use of high efficiency plant and appliances

Fuel Co2 equivalent (kg/kWh)Gas 0.20Oil 0.29Electricity 0.52Coal 0.34Coke 0.43Other solid fuel 0.41

Source: CIBSE Guide: Energy efficiency in buildings (1997 data).

ENERGY SECTION 2


♦ Orientation which optimises the use of solar gains

♦ A shape which optimises heat losses and gains

♦ A design which permits effective maintenance by the tenants

♦ A facility which is simple to manage. Other considerations include:

♦ Energy saving measures not only reduce CO2 emissions but createsavings on annual fuel bills.

♦ Allowing a lower internal air temperature in winter and a higher valuein summer (while still maintaining comfort) will result in energysavings.

♦ The commitment of clients, occupiers and other involved parties cansignificantly reduce running costs.

♦ Simple rules effectively applied can lead to significant resourceconservation.

♦ The use of high thermal mass (eg in floors and internal walls) canprovide thermal storage but can increase embodied energy (ie energyused in production and transport of materials).

♦ An holistic rather than elemental cost approach can justify the use ofpassive systems.

2.3 VENTILATION ♦ To minimise uncontrolled air infiltration, appropriately high levels of

airtightness of the building envelope should be specified andmaintained together with purpose-provided means of adequateventilation.

♦ Internal blinds should be designed and located in such a way that anoise nuisance does not occur in windy conditions.

2.4 LIGHTING ♦ Select efficient lamps and luminaires (see Table 2). There is an ECO

labelling scheme for fluorescent lamps.

Table 2Typical electric lampefficacies

Lumens per wattIncandescent lampsTungsten halogen 20GLS (household lamps) 12Reflector lamps 10Fluorescent lampsT8 triphosphor 88T8 halophosphate 80Compact fluorescent 50Discharge lampsLow pressure sodium 160High pressure sodium 100Metal halide 70

Supplied by Joe Lynes. See also CIBSE Lighting Code for professionalguidance.

SECTION 2 ENERGY


♦ Longer service life reduces consumption of scarce resources (egtungsten, phosphorous).

♦ During the life-cycle of a lamp there is a 5-30% decrease in the lightemitted.

♦ Position fittings so as to maximise available light.

♦ Dust can obscure between 5-30% of visible light, hence regularcleaning of fittings is recommended.

♦ Higher light output means fewer lamps need to be fitted.

♦ The colour, shape and material of the luminaire affect the distributionof light, eg white reflectors are 60% reflective, foil is 95% reflective.

♦ Highly reflective wall coverings (eg white paint) indirectly increaselighting efficiency.

♦ Low energy lighting systems have high initial costs, but low runningcosts.

♦ Beware of low energy lightbulbs disappearing - they are ‘valuable’items!

♦ Install appropriate control fittings for the dimming or switching oflights, as appropriate.

♦ Design switching arrangements which encourage users to switchelectric lighting off when daylight is sufficient:

⇒ avoid clusters of more than 4 switches, so that a user is not able tolight dozens of lamps with one sweep of the hand

⇒ label every switch clearly⇒ the number of switches in a room should not be less than the

square root of the number of work stations⇒ the maximum distance, in plan, between a luminaire and its switch

should not exceed 3 times the height of the luminaire above thefloor.

♦ Encourage the use of energy-saving lamps:

⇒ provide ‘Green’ switches, distinctively coloured, so that users canknow that when they use these switches they are switching lampswith efficacies exceeding, say, 50 lumens per watt. At present,most users do not know what is wasteful and what isn’t. Greenswitches could be used for other energy saving devices too.

⇒ Not more than 2 incandescent luminaires in any one interior.

2.5 TRANSPORT Energy use associated with transport must be considered:

♦ Transport of people between buildings accounts for 22% of UKenergy use.

♦ Transport of construction materials accounts for 5% of UK energyuse.

♦ For offices the energy consumed in commuting is comparable withthat used for operating the building.

ENERGY SECTION 2


Figure 1Energy efficiency ofdifferent transport modes inthe UK

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

car large diesel

car small diesel (1.8l)

car large petrol (2.9l)

car small petrol (1.1l)

rail intercity electric

rail intercity diesel

rail suburban electric

rail suburban diesel

mini bus

double decker bus

single decker bus

express coach

air domestic

moped

cycle

walk

MJ/passenger kilometre

maximum loading

typical loading

Source: Hughes P. Personal Transport and the Greenhouse Effect: a Strategy forSustainability, Earthscan, London 1993, updated by Stephen Potter, Open University. 1999.

2.6 SOLAR DESIGN ♦ Take advantage of the energy radiated from the sun through carefulchoice of the form, fabric and orientation of the building (see Table 3).

Table 3Rules of thumb for solardesign

♦ External blinds are more efficient than internal blinds for reducingsolar gains.

♦ Some high performance glazing can embody more energy, particularlyin the frame, than is justified by the energy savings achieved.

♦ Although roof lighting allows three times more light into a room, it isalso more susceptible to heat loss.

♦ Unheated conservatories give large energy savings.

♦ Net curtains reduce solar gain by up to 20%.

♦ Active solar water heating provides virtually free (in terms of runningcosts) hot water during daylight hours (although there is a pumpingcost if thermosyphoning is not used).

Form: • create sun spaces, lighting ducts, light shelvesOrientation: • main glazing to face 30 degrees either side of

due south• reduce north glazing• minimise tree over-shadowing• on housing estates build to a density of ≤ 40

properties/ha• design atriums/roof lighting in accordance with the

position of the sun in both summer and winterFabric: • fabric transmission losses may be reduced by

improving insulation or by reducing the meaninside air temperature.

SECTION 2 ENERGY


2.7 PHOTOVOLTAICS ♦ Photovoltaic (PV) cells work most efficiently when they are coldest. ♦ Typical energy output to be expected from PVs (monocrystalline or

polycrystalline) in the UK is 100 kWh/m2/year.

♦ Conversion efficiency for crystalline modules is in the region of 14%and for amorphous thin-film modules is about 5%. The anticipatedlife span of cells is 30 years.

♦ A typical PV-clad facade could generate around 30% of the annualelectricity requirements of a building.

♦ Avoid shading from trees or other parts of the building (vents,chimneys etc). Remember that trees grow!

♦ Small amounts of shading can have a large effect, as groups of cellsmay be by-passed.

♦ If the proposed site for the cells does not receive bright enough sun tocast fairly sharp-edged shadows, it is unlikely that much energy canbe harvested at that location.

♦ Generally speaking, PV arrays that consist of eight or more modulesare best placed on fixed mounts.

♦ Ideally cells should face south (in the northern hemisphere) butorientations between SE and SW are acceptable.

♦ For maximum collection they should be tilted at an angle of betweenplus and minus 15o of the value of the latitude angle (approximately52o for London and 56o for Edinburgh).

♦ Wash PVs in the morning or evening - do not hose off PVs when theyare hot, since uneven thermal shock could break the glass.

♦ The area of roof or facade facing approximately south (in the northernhemisphere) required to provide 1 kW is 20-30 m2 for thin-filmmodules and 8-15 m2 for crystalline modules.

♦ PVs generate DC electricity which requires inversion to AC.

♦ PV arrays produce electricity whenever the sun shines - it is not easyto turn them off!

Table 4Photovoltaics: Summaryof advantages anddisadvantages

Advantages Disadvantages• No moving parts• Ultra-low maintenance• Extremely long life• Non-corrosive parts• Easy installation• Modular design• Universal application• Safe low-voltage output*• Simple controls

• High initial cost• Sensitive to shading• Lowest output during shortest

day length• Low-voltage output difficult

to transmit

*The voltage will depend on the number of cells/modules connected in parallel.

Source: Photovoltaics in Real Goods Solar Living Source Book, John Schaeffer et al, RealGoods Trading Corporation 1996, ISBN: 0 930031 82 2.

ENERGY SECTION 2


2.8 WIND POWER ♦ The site should be well exposed to the wind and free of anyobstructions within 60 m.

♦ If there are any nearby trees, the turbine must be mounted on a tower

at least 10 m above the tallest tree.

♦ Bear in mind that trees often grow taller!

♦ If possible, measure the wind at the site with a recording anemometerover several seasons.

♦ “The taller the tower the greater the power” - The power available to awind machine increases with height. The power available at 24 metresabove the ground is 150% of that at 10 metres.

Figure 2Increase in power withheight above 10 m

Europe’s wind resource

Wind speed at 50 metres above ground level for differenttopographic conditions

Open At sea Open Hills andplain m/s coasts m/s sea m/s ridges m/s

> 7.5 > 8.5 > 9.0 > 11.5

6.5-7.5 7.0-8.5 8.0-9.0 10.0-11.5

5.5-6.5 6.0-7.0 7.0-8.0 8.5-10.0

4.5-5.5 5.0-6.0 5.5-7.0 7.0-8.5

< 4.5 < 5.0 < 5.5 < 7.0

500 km

Reproduced from the European Wind Atlas (Troen and Petersen, 1989)

Source: Wind Energy in Real Goods Solar Living Source Book, John Schaefferet al, Real Goods Trading Corporation 1996, ISBN: 0 930031 82 2.

♦ Check whether there are any regulations governing wind turbines inthe area and apply for any necessary permits.

♦ If wind power systems are designed and installed with care, they willlast a lifetime.

♦ Energy output is proportional to the velocity cubed therefore anaccurate measurement of average windspeed is very important.

♦ If you know the average annual wind speed on your site, you canquickly size up its potential output.

SECTION 2 ENERGY


Table 5Estimated annual energyoutput at wind turbinehub height (in thousandkWh/yr)

Rotor diameter (m)

Average windspeed (km/h)

1 1.5 3 7 18 40

14.5 0.15 0.33 1.3 7 40 210

16 0.20 0.45 1.8 10 60 290

17.5 0.24 0.54 2.2 13 90 450

Source: Wind Energy in Real Goods Solar Living Source Book, John Schaeffer et al,Real Goods Trading Corporation 1996, ISBN: 0 930031 82 2.(Adapted from: Wind Power for Home & Business, Chelsea Green Publishing, 1993).

♦ The UK has the greatest potential for the use of windpower in Europe.

Figure 3Diagram of European winddistribution patterns

INCREASE IN POWER WITH HEIGHTABOVE 30FT (10M)

40

30

20

10

(feet)

80

100

60

40

20

140

120

160

INCREASE IN POWER

TO

WE

R H

EIG

HT

(F

T)

0 50 100 200150

40

60

80

100

110

120

0

(metres)

Source: Wind Energy - Power for a sustainable future, The British Wind EnergyAssociation, 1996 (reproduced from the European Wind Atlas (Troen andPetersen, 1989). Detailed information on wind distribution patterns in the UKcan be obtained from ETSU.

2.9 WASTE TOENERGY

♦ Waste to energy plants operate CHP systems with the potential togenerate electricity and provide community heating.

♦ A CHP unit can generate useful energy in the form of both electricity

and heat, with an overall efficiency of up to 80-90%.

♦ Waste to energy plants are smaller than landfill sites, so can beoperated within cities.

♦ After incineration, the ash amounts to about 10% of the initial waste.

♦ Plants must perform to very stringent emission standards.

♦ CHP is flexible in both size and fuel source.

♦ CHP can be used in plant of all sizes ranging from 30kW boiler houseupgrades (eg leisure centre, hotel, etc.) to 2000MW in industry.

WATER SECTION 3


3 WATER

It is highly likely that water will become a critical resource issue in manyparts of the developed world early in the 21st century. Thecurrent average water availability in England and Wales is1400 m3/person/year which is already rated as ‘low’ by the WorldResources Institute and is seven times less than the average availability inthe USA. Some regions of the UK (London at 250m3/person/year) arealready rated as ‘very low’.

♦ The average household water use in England and Wales isapproximately 160 litres/person/day (330 litres/household/day) ofwhich less than 10 litres is used for drinking and cooking.

Table 6Division of water usewithin residential andoffice buildings

Adapted from: Edwards K, Anglian Water, Methods of Estimating Water Usagein Unmeasured Households, Minimising Leakage in Water Supply andDistribution Systems Conference, London, 10-11 December 1996; Griggs JC,Shouler MC, Hall J, Water Conservation and the Built Environment, In 21AD:Water, Architectural Digest for the 21st Century, Oxford Brookes University,1998. (Note: “canteen use” in offices was assumed to consist of use for kitchensinks, dishwashers and cleaning, and “washing use” of use for handbasins.) ♦ A typical bath uses 80 litres and a typical shower 30 litres (but power

showers can use as much water as baths).

♦ Metering can encourage customers to use water more efficiently. Themajority of business customers (over 75%) are metered but onlyapproximately 10% of domestic customers.

♦ 95% of all domestic water consumed becomes wastewater; 3% is usedexternally & 2% is lost within the household.

♦ The relative cost of bottling, transporting and distributing bottledwater compared to the use of mains water is more than 1000:1.

To reduce water consumption:

⇒ improve housekeeping

⇒ eliminate leaks

⇒ specify water efficient equipment

⇒ install water saving devices

♦ Water savings of up to 70% can be achieved by water-efficientappliances.

Residentialbuilding

Officebuilding

WCs 35% 43%Urinals 20%Kitchen sinks & dishwashers 19% 10%Washing machines 12%Handbasins 8% 27%Outside taps 6%Baths 15%Showers 5%

SECTION 3 WATER


Table 7Cheap and easy to installwater conservationmeasures

* These figures assume an occupancy of one person and purchase of a single unit.

Source: Pinney, Waggett, Mustow, Smerdon, Water Consumption and Conservation inBuildings: Review of Water Conservation Measures, BSRIA Report 12586B/1,October 1997.

Note: Water fittings approved for bylaw purposes are listed in the Water FittingsDirectory and in information available from the Water Byelaw Scheme on waterconservation devices.

3.1 TAPS ♦ A conventional tap running continuously can discharge an average of1m3 of water per hour.

♦ A dripping tap can waste 25-50 litres of water per day, costing up to£40 per year for 1 tap.

♦ Tap controls are a widely acceptable, easy and fairly cheap way ofreducing water consumption in buildings.

3.2 TOILETS ♦ The measures which have the greatest water saving potential inbuildings are those which cut down the use of water for flushingtoilets.

♦ The Water Byelaws currently stipulate a maximum flush volume of7.5 litres for new toilets and this will be reduced to 6 litres under thenew Water Regulations. Older WCs may have flush volumes of 9litres or more.

♦ The total daily number of domestic toilet flushes during weekend days is

higher than the total daily number of flushes during week days.

Table 8Domestic WC flushamounts

Source: Friedler, Butler & Brown, Domestic WC Usage Patterns, Building &Environment, Vol. 31, No 4, pp 385-392, 1996.

♦ As WC pans are often designed to operate with a specific flushvolume, the incorrect use of a cistern dam may result in incompleteoperation and lead to double flushing. To avoid this, access to the damshould be provided for adjustment.

Water conservationmeasure

Typical watersavings (per

person, per year)

Average netpayback time

(person years)*Water displacement bag 3.0m3 0.2Cistern dam 5.5m3 0.6Spray tap 2.5m3 3.0Tap restrictor valve 2.1m3 0.7Push top tap 2.1m3 7.0Shower restrictor valve 1.3m3 6.4Water butt 1.6m3 9.7

Flushes/person(male)/day

Flushes/person(female)/ day

Flushes/person(total)/day

Average no. toiletflushes week-day

3.6 4.2 4.0

Average no. toiletflushes weekend day

4.3 4.9 4.8

WATER SECTION 3


3.3 URINALS ♦ Outdated urinal cisterns may flush continuously, 24 hours a day. Insome cases this can account for up to 70% of the average commercialwater use. Adding control devices or replacing them is likely to beeconomic.

♦ It is now a requirement of the 1986 Model Water Byelaws that all newurinals must be fitted with a time switch or an automated device toensure that the cistern only flushes after it is used.

3.4 RAINWATERANDGREYWATERUSE

♦ An average semi-detached house has a roof area of about 42 m2,which given UK average rainfall of 2.3 mm per day would result inthe potential recovery of 96 litres of rainwater per day (35 m3 peryear).

♦ Rainwater is best suited to use in non-potable applications on an ‘asavailable’ basis. There should always, therefore be a backup

♦ Depending on the level of reliance on rainwater, storage may need to

allow for periods of low rainfall.

♦ The build up of atmospheric particles on roofs can be washed into arainwater collection system by the first rain after a drought. It may beadvisable to divert this first flush to drain to avoid abnormally highlevels of contamination.

♦ If mains potable and rainwater are both used, safeguards are required

to avoid mixing (eg clear labelling, different coloured pipes). ♦ Greywater from handbasins, baths and showers makes up 28% of the

waste water produced in the average dwelling.

♦ Use of greywater for WC flushing can reduce mains waterconsumption by up to 35%.

♦ As greywater is produced regularly within a dwelling, the storagecapacity need not be large. Storage should be sized to meet peakdemands in the morning and evening (250 litres for a typical house).

♦ Greywater requires treatment, which could include biocides such as

chlorine.

♦ If greywater is stored without treatment it will begin to smell.Untreated greywater should not be stored for more than 48 hours.

♦ Greywater pipes must be clearly labelled and the requirements of thewater bylaws met (particularly those related to backflow preventionand accidental cross-contamination between potable and non-potablesupplies).

Table 9Sources of water in orderof preference for ease ofreuse

Order of preference Water sources1 Shower & bath water2 Handbasins3 Washing machine4 Kitchen sink or washer

Source: Grant, Moodie, Weedon, Sewage Solutions, Centre for AlternativeTechnology Publications, 1996.

SECTION 3 WATER


3.5 COMPOSTINGTOILETS

♦ Each use of an unheated composting toilet produces on average 0.25litres of liquid effluent (this can be used as liquid fertiliser). Onethousand uses produces around 4 litres of solid compost.

♦ 90% of what goes into a composting toilet is liquid, which is dealtwith by evaporation.

♦ Composting toilets work best at temperatures of 70oF (21oC) or

higher; at temperatures below 50oF (10oC) the biological processslows to a crawl.

♦ It is okay to let a composting toilet freeze, and normal activity willresume when the temperature rises again.

♦ No compost can be removed from the chamber of an unheated toiletfor at least one year after installation.

♦ If a composting toilet smells bad it means something is wrong.

3.6 REEDBEDS ♦ Horizontal reed beds should be approximately 0.6 m deep and will

require an area of 5 m3/person equivalent for secondary treatment ofsewage.

♦ Vertical reed beds require a fall of at least 1.5 m to provide goodtreatment, and an area of between 1 and 2 m3/person equivalent.

♦ Vertical flow reed beds require at least two beds of the same size, so

that the effluent can be alternated between them. ♦ Reeds don’t grow as densely in vertical flow systems as horizontal

flow systems, due to the lower water level.

♦ Reeds will die off if they don’t get water.

♦ Internal walls within the reedbed should be made water tight.

♦ Never plant reedbeds in the constant shade of trees or near willowtrees.

♦ Removal efficiency of chemicals/nutrients by reeds is high, howeverthe reeds must be harvested to avoid release of the nutrients back intothe reedbed.

Table 10Reedbed sizing forhorizontal flow

Sources: Paul Copper, WRc & Mark Moodie, Camphill Water

Surface area (m2/populationequivalent)

Secondary treatment 5.0Tertiary treatment 0.7Stormwater 0.5Combined stormwater and tertiarytreatment

1-1.5

MATERIALS SECTION 4


4 MATERIALS

Good, sound information is required by designers in terms of theenvironmental cost and characteristics of different materials throughouttheir life-cycle.

♦ Avoid materials which damage the environment either through theirexploitation (eg peat, tropical hardwood from non-sustainable sources,etc) or through their production (eg blown polyboard).

♦ Consider environmental assessment of materials’ sources andproduction.

♦ Materials which are durable or which are manufactured from recycledmaterials should be given preference.

♦ Consider re-use of selected and sound bricks, slate (where applicable),timber, RSJs, soils, etc.

♦ Consider use of recycled plastics for materials packaging, streetfurniture, etc.

♦ Materials should be recyclable wherever possible.

♦ Consider the inclusion of specifications in contracts for the supply ofmaterials to favour suppliers who have sound environmental policies,and/or promote good environmental practice (eg minimum/recyclablepackaging, etc).

♦ Non-hazardous materials should be specified.

♦ Choice of building materials, ventilation and insulation should beconsidered together to avoid sick building syndrome.

♦ The nearer a material is to its natural state, the lower the embodiedenergy.

♦ If you buy a new BMW car around 70% of it is made from recycledmaterial, but if you buy a new building, usually less than 1% isreclaimed.

4.1 TIMBER ♦ The environmental best buy is well detailed, properly seasoned woodwith a protective finish, in buildings designed with adequateventilation and avoidance of moisture sources.

♦ Only a small proportion of the timber industry can justifiably bedescribed as being anywhere near to ‘truly sustainable’ in its widestsense. Buy certified timber if available, but buy locally - especially ifsuitable certified timber is not available.

♦ Wood is less likely to rot if the timber is not sealed and is able tobreath.

♦ Dry rot, wet rot and many wood-boring insects will only occur indamp timber. Solve your damp problems and you have gone a longway to solving your pest problem.

SECTION 4 MATERIALS


♦ Only use treated timber if the risk of damage and /or the consequencesof that damage are significant. There is always a potential riskassociated with the use of any hazardous chemical and unnecessaryuse should be avoided.

♦ Use factory treated timber in preference to applying treatment on site.If preservatives have to be applied on site care must be taken to ensurethe conditions of use are strictly followed.

4.2 MASONRYMATERIALS

♦ The best overall environmental option for building masonry walls isto use reclaimed brick or stone, with a pure lime mortar.

♦ Fuel costs are the major part of brick and cement manufacturersexpenses.

♦ Around 10 or so old bricks embody the energy equivalent of a gallonof petrol.

♦ Use soft mortars to enable reuse of bricks.

♦ Ready-mixed mortars and concrete may present less risk to theenvironment - the mixing and storing of cements on building sites isprone to accident, spillage and wastage, whilst ready-mixed productscan be made under much more controlled conditions.

4.3 THERMALINSULATIONMATERIALS

♦ The insulation materials with the lowest environmental impact arethose most closely associated with natural products, eg wool andcellulose fibre.

♦ The embodied energy of insulation is low compared to life cycleenergy transmitted and substantial thickness of insulation is justifiedon environmental grounds. (The figures given in Table 11 are forillustration, as methods of calculating embodied energy are stillevolving.)

Table 11Embodied energy ofdifferent insulatingmaterials

♦ Products made specifically for insulating purposes will probably savemore energy during their life than is consumed in their production.

Material Embodied Energy(GJ/m3)

‘Plastic insulation’ 4.05Foamed glass (a) 2.70Mineral wool (Rockwool) 0.83Cellulose fibre (Warmcell) 0.48Wool (b) 0.11

Cited in Green Building Digest 2,Thermal Insulation Materials, February 1995Sources: Environmental Building B4, Pat Borer, Centre for Alternative Technology,1994, except (a) The Ecological & Energy Balance of Foamglass Insulation,Pittsburgh Corning 1992, & (b) Klober Ltd.

MATERIALS SECTION 4


4.4 ROOFINGMATERIALS

♦ Well designed interlocking slates and tiles which have a small overlapbetween units will use less material, and are thereforeenvironmentally preferable to tiles which require a large overlapbetween units.

Table 12Environmental ‘best buys’for roofing materials

♦ Consider using the roof for other things:

⇒ Utilise rainwater-catching devices for irrigation or potable water.⇒ Planted roofs create green space and roofing materials last longer

under a layer of soil and vegetation.⇒ Photovoltaic systems for energy production.

4.5 PAINT ♦ Avoid paint containing heavy metal derivatives.

♦ Paint is treated as controlled waste. Waste disposal contractors arereluctant to collect containers due to risk of spillage when compacted.

♦ Some local councils run repaint schemes, where unused or part fullcans are collected and redistributed to local charities and schools.

4.6 WASTE ANDRECYCLING

♦ Waste is a misplaced or misused resource. Waste and pollutionshould be reduced as much as possible from the building developmentprocess and the building use.

♦ In waste management priority should be given to reducing the amountof waste, then to reuse, followed by recovery and finally disposal.

♦ To manage waste effectively and ensure legal compliance, the typeand quantities of waste must be known. The first step is to assesswhich wastes will arise as a result of the project and to estimate thequantities.

♦ Of prime importance is the identification of any hazardous wastes.

♦ Unnecessary wastage on site can be reduced through improved sitemanagement including better control and auditing of materials.

♦ It is greatly more cost effective to reuse a product rather than torecycle its constituent materials.

♦ Use secondary materials as much as possible.

♦ Should sufficient quantities of waste with a value be present, egcopper piping, lead flashing, then segregation and resale may beappropriate.

♦ The contractor has a duty of care for all wastes that leave a buildingsite.

Roofing MaterialsBest buy: Reclaimed tiles/slates or certified wooden

shinglesSecond choice: Natural slatesThird choice: Clay/cement based tiles

Source: Green Building Digest 11, Roofing Materials, June/July 1996

SECTION 4 MATERIALS


♦ The Site Manager must ensure that only licensed waste carriers areused to take waste from sites and that the waste is being taken to adisposal site licensed to take the type of waste removed from site.

♦ Rising landfill costs are encouraging consideration of alternatives (egmaximising reuse and recovery and incineration extracting energy).

♦ Design-in separation facilities for waste, eg storage in kitchens fordifferent materials such as glass, paper, cans, etc.

♦ Bear in mind that when the relevant building regulations were lastupdated in 1985, the average UK household had only one dustbin,whereas now a wide range of domestic waste disposal systems,including wheely bins, blue boxes and composting bins are used.

♦ 60% of domestic refuse might be recoverable, worth £2 billion peryear.

♦ The government are committed to recycling or composting 25% ofhousehold waste by 2000.

♦ Recyclates have commercial value.

♦ Domestic composting schemes can remove 200-400 kg/household perannum from the waste stream.

♦ Organic composts have commercial value.

LANDSCAPE SECTION 5


5 LANDSCAPE

Construction does not have to reduce the ecological value of a site.Indeed, through careful development and management of the landscapethe ecological value of the site can be enhanced.

♦ Utilise and create natural landscape features for maximum shelter tobuildings and open spaces and afford maximum winter solar gain.Avoid winter shadow to living quarters and open space or to buildingsutilising active and passive solar gain.

♦ Avoid the creation of wind vortices around building entrances,cycleways and seating areas. Special care should be taken in thedesign of high rise buildings to minimise high wind speeds at groundlevel.

♦ Perforated wind breaks are more effective than solid ones as theydissipate rather than deflect the air flow.

♦ Maximise planting on surfaces, walls and roof space for insulation,amenity and wildlife value, utilising hardy species appropriate to eachspace. Wherever possible, try to use native species associated with thelocal areas to create the planting ‘structure’.

♦ Grassed areas (eg playing fields) require a year to establish beforethey can be used.

♦ Create networks of interlinked open spaces which integrate public,semi-public and private open space, providing enhanced recreation,wildlife and education opportunities.

♦ Consider landscape materials by their impact on the environment atsource of exploitation, processing and transport.

♦ Avoid the use of peat and tropical hardwoods in landscape works.

♦ Energy savings by planting shelter belts typically range between 3-9%, but can reach 15%.

♦ Planting may reduce dust in city streets by a factor of four (onehectare of forest may bind up to 68 tonnes of dust per annum), and incombination with open space noticeably reduces ‘heat island’ effects.

♦ Planting and mounding may absorb unwanted noise.

♦ Design landscapes with maintenance in mind and remember thatmaintenance is long-term.

♦ Avoid specifying the use of chemical herbicides in groundsmaintenance. The alternatives include the use of membranes to coverthe soil, preventing weed growth and also retaining moisture.Membranes can be covered with bark mulch, chippings or granular fillfor aesthetic purposes.

♦ Wherever possible, allow water penetration to the soil rather than tosurface run-off piping. Incorporate reedbed technology to clean up anypotentially toxic urban runoff.

SECTION 5 LANDSCAPE


♦ The principles and practice of self-sustaining horticulture(permaculture) can be used by anyone, anywhere.

♦ Determine the requirements for the quality and quantity of light forplant growth for interior planting by involving a landscape architect atan early stage of the building design.

♦ A tree requires 2000 lux minimum over 12 hour periods to be able tosurvive indoors.

5.1 CHOICE OF

PLANTS♦ It may be useful to study the natural growth habit of local vegetation

and to note the particular species of which it is composed.

♦ Appropriate selection should be applied to all plant groupings toachieve minimal maintenance, but avoiding bland monocultures ofsingle species. However, no one aspect should be allowed to dominateto the exclusion of all else, and designing purely for ease ofmaintenance alone could be as disastrous as ignoring this aspectaltogether.

♦ Low-maintenance plants should be in the majority as pruning can be amajor cost.

♦ Native planting is not necessarily low maintenance.

♦ Include those that are not susceptible to pests and diseases andtherefore require little or no pesticide or fungicide treatment.

♦ People’s perceptions of natural/native planting is that of beingunkempt and messy, this can lead to a disrespect of an area anddamage occurs.

♦ Specimen planting is usually single clear stem trees allowing the windto pass through unhindered near ground level, whereas group plantingprovides vegetation cover at all heights therefore slowing wind down.

♦ Plants are most vulnerable in summer. Try to avoid moving them then.

♦ Seek advice from local experts.

♦ The use of drought-tolerant plants can reduce the need for watering indry conditions. (See Table 13 for examples of very drought- tolerantplants.)

Table 13Examples of very droughttolerant plants

Trees and shrubs • Corokia• Elaeagnus angustifolia• Helianthemum nummularia (rock rose)• Perovskia (Russian sage)

Perennials • Armeria (thrift)• Heliopsis helianthoides (perennial

sunflower)• Eryngium (sea holly)• Geranium ‘Wargrave Pink’

Annuals • Gazania• Helichrysum bracteatum (strawflower)• Ipomoea (morning glory)• Portulaca grandiflora

Source: Gardening Which, June 1996

LANDSCAPE SECTION 5


5.2 GREEN ROOFS ♦ Roof ‘gardens’ may be accommodated on specially reinforced, sealed,irrigated and drained flat and sloping roofs.

♦ Besides providing additional habitat for flora and fauna, rooflandscape will ‘green’ urban landscape, reduce urban peak runoffflows, reduce urban air-borne dust, improve air quality and reduceglare. Breathing grass roofs are good CO2 sinks and camouflage.

Table 14Ideal depth of soil for roofgardens

♦ Every roof has a particular load-bearing capacity. Adding vegetationand all the associated layers of waterproofing and insulation will addconsiderable weight.

Table 15Loadings associated withgreen roofs

Depth of soil/mmGrass 200-250Herbaceous plants and shrubs 500-600Trees 800-1300

Source: Building Green, Johnston & Newton, London Ecology Unit

Weight of roof(kg/m2)

Special light-weight green roof 25-30Bauder system for extensive green roofs 65-80Typical extensive green roof on gravel 80-150

Source: Building Green, Johnston & Newton, London Ecology Unit

SECTION 7 PRE-DESIGN


6 PRE-DESIGN

Ensuring that environmental issues are firmly on the agenda from thebeginning of a project will increase the likelihood of environmentalobjectives being met, and will reduce the risk of radical changes in designbeing required at a later stage. Multi-disciplinary design teams working inan integrated fashion are most suited to the task of identifyingenvironmental issues and they should ensure that the client is fullyinformed of these. It is important that the outline brief which is developedis clearly defined and that environmental objectives are included within it.

♦ Demonstrate commitment to environmental matters and ensure thatthese are firmly on the agenda of the initial project meeting.

♦ Always consider the option of retaining, extending or adaptingexisting buildings before deciding to demolish and rebuild.

♦ The layout of any new development should seek to retain and enhanceexisting landscape features, buried earthworks or built features ofspecial interest, such as archaeological remains.

♦ New development should preserve and respect the local architectureand the character, scale, density and massing of adjacent development.

♦ The special local character of the environment can be emphasisedthrough the use of local materials.

♦ If the development is on land that is contaminated or has specialground conditions, advice must be sought from appropriate bodies (theLocal Planning Authority will be able to give advice on the bodies tocontact).

♦ Full and careful consideration of several potential sites or buildingscan greatly improve the final building design.

♦ Radical thinking at this stage will be rewarded later on.

♦ Critically appraise the “back of envelope” feasibility solution - thefeasibility stage is about options, not solutions.

DESIGN SECTION 6


7 DESIGN

Full and comprehensive consideration of environmental issues should takeplace in the design stage and the results of this must be incorporated intothe detailed design. Options for all components of the building andsurroundings should be taken into account, including the building fabricand structure, building services and landscape. The options should beassessed in terms of the full lifecycle of the building, which also includesdownstream events such as dismantling, demolition, recycling anddisposal.

♦ Simplest is best, but usually difficult to achieve.

♦ You get what you pay for - poor brief, poor design.

♦ Review decisions continuously.

♦ Keep it user friendly.

♦ Involve the people who will have to run and maintain the building inthe design process.

♦ Over-design can contribute substantially to the waste of resources andenergy without necessarily prolonging the life of the building. It canalso lead to loss of flexibility.

♦ Environmentally friendly products, including buildings, willincreasingly carry an eco-label or some other form of productassessment or certification by approved bodies which will state levelsof performance achieved.

♦ The amount of fresh air, natural daylight and the quantity ofpollutants are recognised as having significant impacts on the health,productivity and well-being of building occupants.

♦ Building form can contribute substantially to good environmentaldesign.

♦ Green buildings do not have to look unusual.

♦ It is possible to achieve low capital cost and low running costsimultaneously.

♦ BSRIA’s Environmental Code of Practice can be used effectively incollaborative design and build projects.

♦ Appraise short and long term environmental implications of designoptions intended to accommodate future changes of conditions or use.

♦ The design life of buildings is generally too short.

♦ Try to design a flexible building which can adapt to future change.

♦ Design for deconstruction. Recycling philosophy can be applied to theinitial design process, whereby the specification and design ofmaterials, components, building elements and entire buildings takeinto consideration their possible future reuse.

SECTION 7 CONSTRUCTION


8 CONSTRUCTION

The environmental aims and objectives developed during the designstages and incorporated in the environmental policy will be developedfurther and implemented during this phase, which involves preparing tobuild, the main construction stage, completion, commissioning andhandover. It is vitally important that the environmental strategy remainshigh on the agenda throughout and that other priorities do not weaken theenvironmental targets.

♦ Integrate environmental issues into all procedures/documentation.

♦ Identify contractors who can best satisfy client priorities and who willbe able to fulfil environmental aims.

♦ Encourage contractors to present their environmental approach priorto tender.

♦ M&E subcontractors should be invited to tender for maintenancecontracts during the defects liability period. If problems occur they arethen dealt with by the same people.

♦ Monitor induction of personnel.

♦ Material delivery, vehicle size, type and frequency of use should all bethoroughly assessed to reduce unnecessary vehicle movements.

♦ Minimise noise, dust and fumes from the site. Low frequency noise isthe most difficult to eliminate. Choose appropriate units for noisespecification.

♦ Waste products must be properly disposed of at appropriate wastedisposal sites or through registered waste carriers.

♦ Give particular care to avoiding pollution of water courses.

♦ Minimisation of waste will reduce costs.

♦ Commissioning generally takes longer than the time available.

♦ Do not let the rush to handover/accept/move in obscure theenvironmental objectives.

♦ All warranties, maintenance guidance, manuals, etc. should beobtained as soon as possible.

OCCUPATION SECTION 9


9 OCCUPATION

Many of the environmental benefits gained as a result of careful planningand management during the design and construction stages can be dilutedor lost following handover if the building is poorly managed andmaintained. It is therefore important that an environmental strategy forfacilities management should be developed and that this should have high-level support, including a commitment to provide adequate funding.

♦ Aim to reinforce the environmental policy.

♦ Both BSRIA’s Environmental Code of Practice for buildings and theirservices and environmental management systems provide a systematicapproach to environmental issues associated with buildings.

♦ Aim to upgrade when any maintenance, replacement, or alteration iscarried out.

♦ Simple checks can precede full audits.

♦ The requirement of COSHH risk assessments will affect day to dayoperations.

♦ Periodic environmental reviews can ensure that aspirations are beingmet or exceeded.

♦ Evaluation must involve those able to make a difference.

♦ A stitch in time saves nine.

♦ Cleaning the windows regularly will maintain the efficiency of naturallighting.

♦ Specify low energy lighting.

♦ Bad lighting causes headaches, eyestrain, fatigue, stress and blurredvision. Common problems include glare on computer screens,flickering fluorescent lights and lack of natural light.

♦ The easiest solutions: moving desks to reduce glare, softeningfluorescent tubes using desk lamps, and using uplighting.

9.1 WASTECOLLECTION

♦ The gestation period of the blowfly is ten days, thus fortnightlyemptying of dustbins may be too infrequent if nuisance is to beavoided.

♦ The standard family wheely bin has a capacity of 240 l. Localcouncils can also offer small lightweight 120 l wheely bins,appropriate for single residents, and 360 l versions for large families.

♦ Low-rise domestic dwellings require access to a wheely bin/disposalcontainer.

♦ Containers should be no more than 30 m from the house, and less than25 m from the point of vehicle access.

SECTION 10 REFURBISHMENT & RECOMMISSIONING


10 REFURBISHMENT & RECOMMISSIONING

The environmental issues associated with refurbishment andrecommissioning are generally a sub-set of those encountered at otherpoints in the building lifecycle, although they may be brought into sharperfocus during this stage.

♦ Retain, extend or adapt existing buildings wherever possible, ratherthan demolish and rebuild.

♦ Aim for a balance between old and new.

♦ Aim for upgrade where reasonably achievable.

♦ Advances in technology can assist in generating better buildings and abetter local and global environment.

DECOMMISSIONING, DISMANTLING AND DISPOSAL SECTION 11


11 DECOMMISSIONING, DISMANTLING AND DISPOSAL

These are increasingly important stages in the lifecycles of buildings, dueto the rising costs of waste disposal measured in both financial andenvironmental terms. There are also significant health and safety issuesrelated to these processes, particularly when hazardous materials, such asasbestos, are present in the building. However, these issues can bemitigated through best practice and by maximising opportunities for thereuse and recycling of materials.

♦ Expect the unexpected - existing installations can be unpredictable!

♦ Historical records concerning the buildings use may help to identifypotential health hazards during demolition.

♦ Do not cancel agreements, licences, etc - they may be needed at thedemolition stage.

♦ Keep neighbours informed.

♦ Verify routes and methods of waste disposal.

♦ Well organised dismantling can achieve as much as 99% materialrecovery for recycling.

♦ Always use licensed waste disposal operators.

♦ The various methods of dismantling: hand, machine, explosives andcutting, should be considered in the wider sense, to achieve maximumenvironmental benefit.

environmental rules of thumb

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