bb87 guidelines gor environmental design in schools

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Building Bulletin 87, 2nd Edition Version 1 (May 2003)

Guidelines for EnvironmentalDesign in Schools

This edition replaces Building Bulletin 87 (1997) as referencedin building regulations Approved Document Part L2 2002

School Building and Design UnitDepartment for Education and Skills

© Crown copyright 2003

Produced by the Department for Department for Education and Skills

You may copy extracts from this document for non-commercial or educationalpurposes as long as you mention the source

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Introduction .................................................................................. 3Scope of BB87 (2003) .................................................................... 3Scope of the Building Regulations ............................................... 4

Section 1: BB87 and Approved DocumentPart L2 2002 requirements for schools .................... 5Energy efficiency rating .................................................................. 5Elemental method ............................................................................. 5Whole building method .................................................................... 5Carbon emission calculation method .......................................... 6Interpretation of the elemental methodof AD L2 2002 for schools ............................................................ 6U-values ............................................................................................... 6Lighting efficacy ................................................................................ 6Glazing ................................................................................................. 6External lighting ................................................................................. 6Summertime overheating preventionin schools relating to ADL2 2002 ................................................ 6Building Log-books ........................................................................... 7

Section 2: Heating and Thermal Performance ..... 8Thermal conditions ........................................................................... 9Temperatures in the heating season ........................................... 9Summertime temperatures ............................................................ 9Thermal insulation .......................................................................... 10Heat gains ........................................................................................ 10Heating system design ................................................................. 10Choice of fuel and heating system ........................................... 11Heating Plant Carbon Intensity ................................................... 12Heating control ............................................................................... 12Building Energy Management Systems ................................... 13Frost protection .............................................................................. 14

Section 3: Ventilation and Indoor Air Quality ...... 15Indoor Air Quality (IAQ) ................................................................. 15Purpose of ventilation ................................................................... 15Indoor air quality (IAQ) .................................................................. 15Natural ventilation .......................................................................... 16Mechanical ventilation ................................................................... 16Controlling summertime overheating ....................................... 17

Section 4: Lighting ................................................................ 18Design framework ......................................................................... 18Task/activity lighting ..................................................................... 19Lighting for visual amenity .......................................................... 19Lighting and architectural integration ...................................... 19Lighting and energy efficiency ................................................... 19Lighting maintenance .................................................................... 19Lighting costs ................................................................................. 19

Design criteria ................................................................................ 20Daylighting ....................................................................................... 20Electric lighting ............................................................................... 20Combined daylighting and electric lighting ............................. 21Lighting quality ............................................................................... 21External lighting .............................................................................. 22Emergency lighting ........................................................................ 22Lighting for pupils with visual and hearing impairments ..... 23

Section 5: Hot and cold water supplies ............ 26The School Premises Regulations ............................................. 26Main summary of standards and regulations ......................... 26Cold water ........................................................................................ 26Drinking water ................................................................................. 27Hot water .......................................................................................... 29Legionellaosis (including legionnaires desease) ................... 29Hot and cold water sevices ........................................................ 29Water pollution ................................................................................ 31Lead pipework ................................................................................ 31

The School Premises RegulationsSummary Sheet ...................................................................... 32Acoustics .......................................................................................... 32Lighting ............................................................................................. 32Heating .............................................................................................. 32Ventilation ......................................................................................... 32Water supplies ................................................................................ 32Drainage ........................................................................................... 32

Standards for environmental conditions andenergy conservation for new school buildingssummary sheet ....................................................................... 33Conservation of fuel and power –Energy efficiencyrating ................................................................................................. 33Acoustics .......................................................................................... 33Lighting ............................................................................................. 33External lighting .............................................................................. 33Heating .............................................................................................. 33Thermal performance ................................................................... 33Ventilation ......................................................................................... 34Hot and cold water ........................................................................ 34

References ................................................................................. 35

Bibliography – further reading ..................................... 37

Contents

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Building Bulletin 87 is the Departmentfor Education and Skills’ ConstructionalStandard[Ref.1] for EnvironmentalConditions and the Conservation of Fueland Power.

In addition BB87 contains furtherconstructional standards applying to suchthings as water supplies and theprevention of summertime overheating,and also general design guidance onenvironmental design to achieve energyefficient school buildings.

The Building Regulations Part F:Ventilation and Part L2: Conservation ofFuel and Power apply to all schools sincethe ending of the exemption of LEAmaintained schools from the BuildingRegulations in 2000. The ConstructionalStandards such as BB87 and BB93 whichare mentioned in the ApprovedDocuments are used by Building ControlBodies as the normal means of assessingcompliance with the Building Regulationsfor schools. The Approved Documents(AD) in support of Part F 1995[Ref.2] andPart L2, 2002[Ref.3] both quote BB87 as ameans of compliance with the BuildingRegulations.

This 2003 revision updates BB87 andbrings it in line with the current BuildingRegulations and other legislation such asthe Drinking Water Regulations. In a fewrespects, for schools the ConstructionalStandards refine the recommendationsgiven in certain Approved Documents insupport of the Building Regulations.However, it should be pointed out thatonly the School PremisesRegulations[Ref.4], the BuildingRegulations and other Regulations arelegally binding. In addition to theregulatory requirements, theConstructional Standards for Schoolsincluded in BB87 are often quoted as abasis of funding agreements and BuildingContracts.

For ease of reference, the relevantConstructional Standards and SchoolPremises Regulations can be found at the

Introduction

beginning of each section of BB87. ThoseConstructional Standards which arespecifically mentioned in ADF 1995 orADL2 2002 or other ApprovedDocuments in support of the BuildingRegulations, or other Regulations, arelisted beneath the appropriate ApprovedDocument or Regulation.

The constructional standard for acousticsis now Building Bulletin 93[Ref.5],see www.teachernet.gov.uk/acousticsBB93 is quoted in ADE2003 andsupersedes the acoustics section in the1997 version of BB87.

The standards and guidance given in the1997 edition of BB87 have been largelysuperseded by the requirements of PartL2 of the Building Regulations andhence, this 2003 revision of BB87 hasbeen prepared. This 2nd. Edition of BB87,being the current ConstructionalStandard for schools, therefore replacesthe 1st. Edition of Building Bulletin 87published in 1997. All references to thatdocument, for the purposes ofcompliance with Building RegulationsPart F 1995 and Part L2 2002 and in theDfES Constructional Standards[1], shouldtherefore be considered as references tothe current version of this 2nd edition ofBuilding Bulletin 87. The current versioncan be downloaded from the DfESwebsite http://teachernet.gov.uk/energy

Scope of BB87 (2003)The intention of this document is toprovide advice on the environmentaldesign of schools such that compliancewith Requirements of ADL2 2002 andof ADF 1995 of the Building Regulationsare achieved, and the energy andenvironmental performance of new andrefurbished school buildings is compatiblewith current building standards.

The design guidance relating toApproved Document L2 2002 isformulated in a format similar to that ofADL2 2002, so that it reflects the three

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alternative means of compliance with theEnergy Efficiency Requirements of PartL2 of the Building Regulations.However, BB87 contains some specificConstructional Standards for schoolbuildings which refine and override therecommendations for compliance withBuilding Regulations given in ADL22002 and ADF 1995. For example themeans of avoiding solar overheating givenin Section 1 adds to the guidance on thistopic in ADL2 2002.

Notwithstanding the obligations requiredunder the Building Regulations it shouldalso be borne in mind that The Education(School Premises) Regulations 1999,SI 1999 No.2[Ref. 4] are still in force andcontain minimum environmentalstandards that apply to both new andexisting school buildings. Note thatADL2 2002 also refers to requirementswhen undertaking work on existingbuildings and this applies equallyto schools.

Scope of the Building RegulationsAlthough Building Regulations do notapply to all alteration and refurbishmentwork, it is desirable that such work shouldconsider environmental conditions andenergy efficiency and incorporateupgrading of plant and controls and alsothe building fabric as is appropriate andcost effective. For the application of theBuilding Regulations see Regulations 3and 4 of Building Regulations 2000(as amended).

The exemption of Local EducationAuthority (LEA) maintained schools fromthe Building Regulations has ended andschool Buildings are now subject to theBuilding Regulations and may be subject todetailed design checks and on-siteinspections by the Building Control Bodies.

The Building Regulations apply inEngland and Wales. They apply toboth LEA maintained schools andindependent schools.

Temporary buildings are exempt from theBuilding Regulations. Temporarybuildings are defined in Schedule 2 to theBuilding Regulations as those which arenot intended to remain in place forlonger than 28 days. What are commonlycalled temporary buildings in schools areclassed as prefabricated buildings and arenormally subject to the same buildingregulation requirements as other types ofbuilding. Additional guidance is given inClause 0.6 of ADE, and clauses 0.25 and0.26 of ADL2.

A building that is created by dismantling,transporting and re-erecting thesub-assemblies on the same premises, oris constructed from sub-assembliesobtained from other premises or fromstock manufactured before theappropriate AD came into force, wouldnormally be considered to meet therequirements for school if it satisfies,eg the 1995 edition of ADL.

The Building Regulations Part F 1995and Part L2 2002 apply to most non-domestic buildings. Whereas, BB87applies, and sets the constructionalstandards, for all areas of schoolsincluding nursery and adult/communityeducation within school complexes. Itdoes not apply to nursery schools whichare not part of a primary school, sixthform colleges which have not beenestablished as schools, and Universities orColleges of Further and HigherEducation1. However many of theperformance requirements are desirableand BB87 can be used as a guide to thedesign of these buildings.

Note1 The definition of a school

is given in Section 4 of the1996 Education Act. In thecase of sixth form collegesthe Section 4 of the 1996Act should be read inconjunction with Section 2of the same Act, inparticular subsections (2),(2A) and (4) which dealwith the definition of“secondary education”.

If a sixth form college isestablished as a schoolunder the 1998 SchoolStandards and FrameworkAct then it will be classedas a school under section4 of the 1996 EducationAct and BB87 will apply.Only one sixth formcollege has done this todate. Therefore, mostsixth form colleges areinstitutions in the FurtherEducation sector and arenot schools and henceBB87 will not apply.

In the case of a new sixthform college it will benecessary to contact theLEA to enquire if the sixthform college has beenestablished as a school oras an institute of furthereducation.

Introduction

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Approved Document L2 2002 gives threemethods of compliance for the energyefficiency of a building. ADL2 alsocontains requirements, for example forair tightness testing, provision ofcommissioning logbooks andprevention of summertime overheating.This 2nd. Edition of BB87 gives specificconstructional standards for schoolsrelating to the elemental method andother requirements of ADL2.

Energy efficiency ratingIn addition to the elemental method thereare two further means of complying withPart L2 of the Building Regulation. Thesedeal with the carbon emission of theschool building as a complete buildingrather than the elements of which it iscomposed. The methods are as follows.

Elemental MethodFor the elemental method of compliancethe distinction is generally made between‘offices, industrial and storage buildings’and ‘all other building types’. Specificguidance is given for offices etc, andseparate information for ‘all otherbuilding types’ – which includes schools.

Section 1: BB87 and Approved Document Part L2 2002requirements for schools

Whole Building MethodThe whole building method has beendeveloped to deal with ‘offices’,‘hospitals’ and ‘schools‘. Targets havebeen set for ‘whole-office carbonperformance ratings’, whilst for schools itis stated that:

For schools a way of complying with the require-ments would be to show that the proposedbuilding conforms with the DfEE guidance note.’The guidance note being BB87 (1997).1

The Whole Building Method estimatesthe total annual energy consumption ofthe school taking into account thebuilding fabric, services installed andoperating conditions (including weather).

The calculation procedure is availablefrom the Schools Building & Design Unitwebsite at: http://teachernet.gov.uk/energyThe spreadsheet contains all the datarequired to make calculations of thecarbon rating for the school building.By following the design guidancecontained within BB87 and ADL2 2002,the building should achieve a carbonperformance rating of better than5 kgC/m2 per year.

BB87 Constructional Standard

Summertime overheating

For school buildings it is acceptedpractice to define overheating asoccurring when the internal airtemperature exceeds 28oC.An allowable degree of overheating ina school is that this may occur for upto 80 occupied hours in a year. TheCIBSE test Reference Years fromCIBSE Guides J[Ref. 6] should be usedas the basis of predicting the numberof occupied hours when thetemperature exceeds 28oC.

Note1 The standards and

guidance given in the1997 edition of BB87 havebeen largely supersededby the requirements ofPart L2 of the BuildingRegulations and hence,this 2003 revision of BB87has been prepared. This2nd. Edition of BB87,being the currentConstructional Standardfor schools, thereforereplaces the 1st. Editionof Building Bulletin 87published in 1997. Allreferences to thatdocument, for thepurposes of compliancewith Building RegulationsPart F 1995 and Part L22002 and in the DfESConstructional Standards[Ref.1], should thereforebe considered asreferences to the currentversion of this 2nd editionof Building Bulletin 87.The current version can bedownloaded from the DfESwebsite http://teachernet.gov.uk/energy.

Building Regulations

BB87 and Approved Document Part L2: Conservation ofFuel and PowerEnergy efficiency rating

The designer of a school has three options in the design of a newschool building.1. To use the elemental method as described in Section 1 of ADL2

2002 of the Building Regulations, together with the advicecontained in the revised BB87.

2. To use the Whole Building Method described in BB87 (2003) toestimate the total energy consumption of the building andachieve a carbon performance rating of better than 5 kgC/m2

per year.3. To use the carbon emission calculation method as described in

ADL2 2002. This technique is advised for innovative or passivedesigns that will benefit from detailed whole building simulationprocedures.

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Carbon EmissionCalculation MethodThe carbon emission calculation methodis advised for innovative or passive designsthat will benefit from detailed wholebuilding simulation procedures. It isnecessary to follow the carbon emissioncalculation method as described in ADL22002.

The designer of a school can design a newschool building to comply by any of thesethree methods.

Interpretation of theelemental method of ADL22002 for schoolsThe following recommendations relate tothe standards set by ADL2 2002 forcompliance with the Regulations by theElemental Method.

U-valuesU-values of the building envelope’sconstructional elements shall meet therequirements of ADL2 2002 paragraphs1.7 to 1.16 inclusive, and will provideenergy efficient school buildingenvelopes. Note that these are minimumstandards and higher standards aredesirable for energy efficiency and carbonemission reduction. Although ‘trade-offs’between fabric performance and heatingplant are allowable under the elementalmeans of compliance it is recommendedthat any change is restricted to a trade-offin fabric performance to achieve a moreenvironmentally sensitive design.

Note that ADL2 2002 also refers torequirements when undertaking work onexisting buildings and this applies equallyto schools.

Lighting EfficacyTo provide energy efficient lightingsuggests that a higher lighting efficacycan be specified for school buildings. Aminimum of 65 lamp lumens/circuit wattshould be adopted and therefore the lightsources in table 8 of ADL2 2002 wouldbe appropriate with the exception of“Other; any type and rating with anefficacy of greater than 50 lumens percircuit watt.” All the advice on controlsshould be adopted.

GlazingThe maximum glazed area of 40%, whichis adopted for heat loss purposes, shouldbe accepted and will allow for an elementof passive design and good daylightdesign. If a larger glass area is required itwill be necessary to trade-off any heat lossby increasing the thermal performance ofthe building fabric.

External LightingExternal lighting is not explicitlymentioned in the ADL2 2002 but isbeing increasingly used on schoolpremises for safety and security. It isrecommended that all external lighting isprovided with lamps having an efficacy ofat least 65 lumens per circuit watt that arefitted with both time control and daylightlevel photocell control.

Summertime overheatingrequirements for schoolsrelating to Part L2Schools and their periods of occupancyare different to other building types andthe conventional means of establishingoverheating can be relaxed. For schoolbuildings it is accepted practice to defineoverheating as occurring when theinternal air temperature exceeds 28oC.An allowable degree of overheating in aschool is that this may occur for up to 80

Section 1: BB87 and Approved Document Part L2 2002 requirements for schools

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occupied hours in a year, normally non-heating periods are May to Septemberexcluding August. Simulation has shownthat this can be achieved withconventional natural ventilation designsusing medium to high thermal mass inthe fabric for normal occupancy levels andup to five desktop PCs in a classroom.The glazing distribution as given inTable 4 of ADL2 2002 is a useful guideto avoiding overheating problems.

Appropriate use of shading device andgood facade design, together with use ofthermal mass, helps to limit summertimeoverheating.

Designers wishing to use more than thesuggested glazing to achieve a passiveenvironmentally sensitive design areadvised to adopt the Carbon EmissionCalculation Method for compliance.Passive designs using this amount ofglazing need careful consideration toavoid overheating and would probablyrequire an appropriate design tool.

Currently, it should be assumed thatnatural ventilation will be used forstandard teaching zones with limitedcomputer equipment. For guidance it issuggested that up to five desktop PCswith CRT screens, a laser printer and anOHP/computer projector will constitutethe ICT equipment in a ‘typical’classroom. Above this threshold,additional ICT equipment should beconsidered as a process load and treatedas such in interpretation of the ApprovedDocument.

These internal gains, which provide usefulheat in the heating season, can lead tooverheating in the summer and thereforeshould be reduced as much as possible byselection of efficient appliances with lowheat rejection. Energy labelling schemesfor domestic equipment, such as personalcomputers, cookers and other kitchenequipment, fridges, and washingmachines, indicate bands of energyefficiency. Selecting band A and B ratedequipment will reduce energy

consumption. If less efficient equipmentis used then other elements of thebuilding must be improved tocompensate for the increased equipmentloads. In particular, summertimeoverheating may result from excessiveheat gains from inefficient equipment.Additional information on the efficienciesof equipment can be found from thefollowing websites:

www.ukepic.co.uk

UK Environmental ProductInformation Consortium

www.mtprog.co.uk

Market Transformation Programme

www.sedbuk.com

Boiler efficiency database

When predictions of overheating suggestthat ACMV is required then the existingspecific fan powers are adopted. That is2 W/l/s is allowed for mechanicalventilation in new buildings and 3 W/l/sfor refurbishment. Note: 2 W/l/s is aminimum standard for mechanicalventilation and current good practice is1 W/l/s for new build installations.

In areas with high levels of ICT – ie abovethe basic provision of five PCs and a laserprinter and OHP/computer projector –then mechanical ventilation and comfortcooling may be provided as indicated byADL2 2002 paragraph 1.60d. In thiscase provision should also be made torecord the energy consumption of thisequipment as indicated in paragraph 3.4of ADL2 2002.

Building LogbooksAs indicated in Section 3 of ADL2 2002log-books and manuals for the usershould be available, and a user guideshould tell school staff how to operatethose parts of the heating system overwhich they can and should exercisecontrol.

Section 1: BB87 and Approved Document Part L2 2002 requirements for schools

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Section 2 : Heating and Thermal Performance

School Premises Regulations

(1) Each room or other space in a schoolbuilding shall have such system of heating,if any, as is appropriate to its normal use.

(2) Any such heating system shall be capable ofmaintaining the air temperature, at a heightof 0.5m above floor level, at the specifiedlevel, in the areas set out in the Table below,when the external air temperature is –1oC:

Constructional Standards

The heating system should be capable ofmaintaining the minimum air temperaturesquoted in the School Premises Regulations.The heating system should be provided withfrost protection.

Vertical glazed areas (including clerestory ormonitor lights) should not normally exceed anaverage of 40% of the internal elevation of theexternal wall. However, where a passive ordaylight design strategy has been adopted thepercentage glazing may exceed 40%,provided the insulation of the building fabric isincreased to compensate for the increasedheat loss through the glazing or the heatingplant carbon intensity is traded up accordingly.

Horizontal or near horizontal glazing shouldnot normally exceed 20% of the roof area.

Building Regulations

Central heating systems should haveappropriate controls complying with therequirements in ADL2 2002, in support ofthe Building Regulations.

The air supply to and discharge of products ofcombustion from heat producing appliancesand the protection of the building from theappliances and their flue pipes and chimneysshould comply with Building Regulations,Part J, 2002.

The fabric insulation should comply with therecommended maximum values given in the‘Elemental Method’ in Table 1 of section 1 ofADL2 2002 in support of the BuildingRegulations, 2002.

Area TemperatureoC

Areas where there is thenormal level of physicalactivity associated withteaching, private studyor examinations

Areas where there is a lower thannormal level of physical activitybecause of sickness or physicaldisability including sick roomsand isolation rooms but notother sleeping accommodation

Areas where there is a higherthan normal level of physicalactivity (for example arising outof physical education) andwashrooms, sleepingaccommodation and circulationspaces

(3) Each room or other space which has aheating system shall, if the temperatureduring any period during which it is occupiedwould otherwise be below that appropriateto its normal use, be heated to atemperature which is so appropriate.

(4) In a special school, nursery school orteaching accommodation used by a nurseryclass in a school the surface temperature ofany radiator, including exposed pipework,which is in a position where it may betouched by a pupil shall not exceed 43 oC.

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Thermal conditionsThe thermal conditions withineducational buildings should beappropriate to the activities and clothingof the occupants. Thermal comfort isachieved when a balance is maintainedbetween the heat produced by the bodyand the loss of heat to the surroundings.The rate of heat loss is dependent uponthe amount of clothing worn and thetemperature of the air and surroundingsurfaces. In a normal school environmentthe hourly rate of heat production by thechildren varies with activity. This heat islost to the surroundings by the normalprocesses of convection, conduction,radiation and evaporation. It is thereforenecessary for the designer to take accountof the functions of spaces and theactivities that they contain, and the typeof clothing likely to be worn.

Temperatures in theheating seasonThe air temperatures quoted in TheSchool Premises Regulations are theminimum temperatures that should bemaintained during normal hours ofoccupation throughout the heatingseason, assuming an external temperatureof -1oC. These room temperatures andthis external temperature are not intendedfor use in the design of the heating plant.For sizing of the heating system,reference should be made to CIBSEGuide B[Ref. 7].

Higher air temperatures are often neededin schools to maintain comfort conditionsand for those children with specialeducational needs, or those who may bemore sensitive to the cold.

Excessive vertical temperature gradientsshould be avoided and the temperature at2.0 m should not exceed that at floorlevel by more than 3oC. In schoolbuildings with spaces higher than 3 mtemperatures greater than normal willoccur at ceiling level. In these casesincreased roof insulation should be

considered. Recirculation of warm air tolow level using ‘punka’ or ducted fansmay be worthwhile in the heating season.

Multi-purpose spaces should have heatingcapable of adjustment, so that the space iskept at the temperature required for theactivity and not at a higher or lower levelthan is needed. This is particularly so withsports and assembly halls, which may beused for both strenuous activities andsedentary occupations eg. duringexaminations.

In some establishments like nurseryschools and those for the severelyhandicapped, it is necessary to preventchildren from touching heated surfacesabove 43oC by the use of suitable screensor guards.

Summertime temperaturesAn undesirable rise in temperature duringwarm weather can be caused byuncontrolled incidental and solar heatgains, or by high densities of occupation,eg in lecture rooms. In thesecircumstances sufficient naturalventilation is particularly important.Mechanical ventilation may be necessaryin some instances to help to control airtemperature.

Reflective, white or very light roofsurfaces reduce the solar heat gainthrough the roof as well as reducing thethermal stress in the weatherproofcovering, but will tend to become lesseffective without adequate maintenance.Insulation in the roof and walls also helpsto reduce this solar gain, but will alsoreduce the ability of the excess heat toescape from the space. Increased thermalmass in the conditioned space controlsthe degree of temperature swing.

Excessive solar heat gain throughwindows can be minimised by appropriateorientation and by the use of brise soleilstructural shading, louvres, blinds andcurtains. Shading the glass from theoutside is the most effective method of

Section 2 : Heating and Thermal Performance

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control. However, this calls for carefuldesign of sun shading devices to avoidimpairing the daylighting of a classroom.

Storage temperatures for food, includinglunch boxes need to be considered.

Thermal insulationCompliance with the current BuildingRegulations ADL2 2002 is considered asa minimum requirement that must be metand attempts should always be made toadopt more energy efficient techniqueswhen appropriate.

Adequate thermal insulation of roof andwalls is necessary not only to reduce heatloss, but also to make the internal surfacesof the building warmer and to reduce therisk of condensation. The provisions inADL2 2002 will be adequate to ensurethis in all normal circumstances.

In addition to insulating the building fabricit is important also to insulate adequately allheating mains including valves and hotwater storage tanks. Thermal insulation ofvessels, pipes and ducts according to ADL22002 is sufficient.

Heat gainsIncidental heat gains (eg solar, teachingequipment and light fittings) will alsocontribute heat to the space. Allowing forthese and designing suitably responsivecontrols and heating systems will help toreduce fuel consumption. With theincreasing use of InformationCommunication Technology (ICT) inschools these incidental gains becomeincreasingly significant and may requirespecial consideration.

Solar gains can be beneficial if carefulconsideration is given to the design andorientation of the building, but excessivesolar gains may lead to overheating.Windows on a south-east facing facadewill allow entry of sunlight early in themorning but will avoid direct sunlightduring midday and early afternoon when

the solar radiation is more intense. Westand south-west facing glazing leads to thegreatest risk of overheating.

Heating system designThe heating installation should becapable of achieving the temperaturesrecommended in The School PremisesRegulations. Occupancy and solar gainsmay provide additional heat. However,the heating system must be responsiveenough to adjust to these gains. Goodcontrol of the heating system is essentialnot only to maintain comfortableconditions but also to eliminate waste offuel.

Consequently, the choice of heatingsystem and heat emitter is an importantdesign decision. Among other factors, itwill depend on the thermal mass of theconstruction, the use of solar heat gain,the type of ventilation and the level offabric insulation.

Radiators are generally the most suitableheat emitters for teaching spaces. In someprimary schools where extensive use ismade of the floor hot water underfloorheating is preferred. This is notappropriate where the floor area is likelyto be covered, eg with insulating mats orbleacher seating and should not be theonly form of heating in spaces such asnurseries, where doors are often openedfor outside activities even during theheating season.

Large infrequently used spaces such ashalls can benefit from a faster responseand fan convectors or low temperatureradiant panels are often used. Lowtemperature radiant panels can be fixed toceilings rather than taking up valuablewall space. However, they can producethermal stratification and this should beconsidered at the design stage.

Underfloor heating is sometimes used inhalls to keep walls clear and to avoidbackground noise but its thermalresponse is slower than for other systems.

Section 2: Heating and Thermal Performance

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Wall space is often a priority in schoolsand fan convectors can then be used inpreference to radiators. However, itshould be remembered that fanconvectors have a high maintenance cost.The background noise level of the fanconvectors across the frequency spectrumshould not be too high for the plannedactivities, see Building Bulletin 93.

To achieve an effective and efficient heat-up, optimum start controls shouldgenerally be provided. This is the caseparticularly in buildings with intermittentoccupancy such as schools. Similarly, anoptimum-off facility should be providedto minimise the heating overrun at theend of the school day.

Careful design of the number and sizeof boilers to match load variations isrequired to ensure optimum efficiencythroughout the heating season and tohave a reasonable standby capacity whenimplementing major boiler maintenance.

It should be remembered that plant sizedfor steady-state design conditions alwayshas excess capacity when outsideconditions are less severe than designconditions. Plant over-sizing in excess of25% of steady-state design requirementsis unlikely to be justified unless verysubstantial deviations in flowtemperatures are required. Referenceshould be made to Sections A2, A3, andA9 of the CIBSE Guide[Ref.8] whencalculating the heat losses and designingthe heating system. Design loads shouldtake into account the considerableincidental heat gains that are available inoccupied schools. This is particularlyimportant in determining ventilation heatloads, the majority of which will onlyoccur during occupied periods whenthere are high heat gains to offset partof the heat loss.

Pupils in a classroom will compensate forall fabric losses and a major part ofventilation heat losses. Equipment andsolar gains further reduce the heatingdemand. During pre-heat the ventilationloss will be minimal.

Where multiple boiler installations arebeing designed, condensing boilersshould be considered for the lead boilersto take advantage of hot water loads andthe long run time for the base load of thespace heating. Small stand-alone gas-firedboilers or direct gas-fired heaters used inremote classrooms can allow more flexibleuse of the buildings than large centralboiler plant.

Heat pumps may be a viable option forthe heating, particularly in rural schoolsaway from gas main networks. Heatpumps can be air to air, air to water, orwater to water. Supplementary heating isnormally required when externaltemperatures fall below approximately3 oC. This can be by use of a heat storeand off-peak electric heating.

Choice of fuel and heatingsystemThe choice of fuel and heating systemshould be based on calculations of thecarbon efficiency of the system and its netpresent value, taking into account capital,maintenance and running costs. Inpractice the selection procedure iscomplicated by the unpredictability offuel price trends and fuel availability.

In the choice of heating systems theoption should be kept open wherepossible to change from one type of fuelto another during the life of a building.Systems where heat is delivered by hotwater or warm air can possibly beconverted to coal, gas, oil or electricity.Dual fuel burners for oil and gas arereadily available and allow the sitemanager to choose the cheaper fuel.(Where oil tanks already exist the extracost is small.)

Modular boilers (perhaps using acondensing lead boiler) should beconsidered. Smaller installations caneconomically use condensing boilers withunderfloor heating systems.


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Hot water generation should be on aseparate circuit or a separate system to themain heating. Point of use systems can bethe most energy efficient option.

Electric off-peak storage heaterinstallations cannot be adapted to anyother fuel use, and electric storageheaters are also unresponsive to changingheat gains.

Electricity that is derived from renewablesources, but supplied from the grid (suchas ‘green tariff’ electricity) is notconsidered as an appropriate way ofmeeting the carbon emission calculations.

One of the most effective ways ofconserving energy in existing schools is toimprove the efficiency and responsivenessof the heating installation so that it comesas close as possible to the performance ofa well designed new installation. Beforeany improvements are considered theoperation of existing plant and controlsshould be checked. Simple re-commissioning of systems often leads tolarge fuel savings, for little or no cost.Improvements that may be worthwhilerange from the re-design and renewal ofplant to the re-assessment of its operatingpattern. Fuller details are given inBuilding Bulletin 73[Ref.9].

When designing new buildings to improveenergy efficiency it is important to considerthe inclusion of systems based uponrenewable energy and other innovativetechnologies eg micro CHP (CombinedHeat and Power) systems. For furtherinformation see the following websites:

• DTI PhotovoltaicDemonstration programmewww.solarpvgrants.co.uk

• Renewable energy capital grantswww.dti.gov.uk/renew/eoi.htm

• Community and householdrenewable energy grantswww.clear-skies.org

The EU Directive on EnvironmentalPerformance of buildings1 which will beincluded in the Building Regulations by

2006 asks member states to ensure thattechnical, environmental and economicfeasibility studies of alternative systemsare carried out.

Heating Plant CarbonIntensityThe level of carbon (C) produced bydifferent fuels varies according to theinitial proportion of carbon in the fossilfuel. ADL2 2002 refers to the ‘CarbonEmission Factor’ of the fuel. They areprovided in Table 6 of the ApprovedDocument and included in a table in theBB87 calculation spreadsheet. As can beseen for each unit (kWh) of electricitydelivered more than twice the amount ofcarbon is produced as for natural gas.

However, the conversion of the fossil fueldelivered to the school takes place at lessthan 100% efficiency and this has to betaken into account. This is achieved bycalculating the heating plant carbonintensity, in kgC/kWh of useful heat.The elemental method sets an overallmaximum value for the carbon intensityof the heating plant. It is this value thatcan be traded-off against fabric insulationlevels, although this is not recommendedfor schools other than to achieve a moreenvironmentally sensitive design.

(Note: for conversion from kg of carbonto kg of CO2 multiply the carbon figureby 44/12.)

Heating controlADL2 2002, paragraph 1.33recommends space heating controls suchthat the required temperature is onlymaintained when required in areas in use.The type of space heating control and theway in which it is operated have asignificant influence on fuelconsumption. Investing in controlequipment can produce a relatively quickpay-back, and zone control of buildingscan help with lettings, out of hours useand catering contracts.


Note1 EU Directive on the Energy

Performance of Buildingsadopted in January 2003http://europa.eu.int/eur-lex/en/com/pdf/2001/en_501PC0226.pdf

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Space heating controls should be user-friendly, reliable and as far as possibleautomatic. Simple and inexpensivecontrols are now available which providevariable time control with optimum start.It is preferable if a member of the schoolstaff can easily change heating periods, setholidays, change temperatures accordingto use, and extend heating periods. Thesecontrols are economic even in the smallestof schools.

Adjustable components (such astemperature sensors) should be tamper-proof. For the most accurate control, andimproved energy efficiency, electronicthermostats (rather than bi-metallic stripdevices) should be specified. Similarly,tamper-proof thermostatic radiator valves(TRVs) have been shown to give goodlocal control of heat emitters to minimiseoverheating and underheating of areaswith different thermal mass and incidentalheat gains.

Good design of heating controls alone isnot sufficient to ensure fuel economy. Itis also necessary for the controls to beproperly commissioned and maintained ingood working order.

Zoning and individual temperaturesensors should be provided to account fororientation and pattern of use. Heatingzones should be chosen to suit the solarand incidental heat gains and to allow outof hours use of selected zones.

Large secondary schools require carefuldesign of the control system to takeaccount of the greater range of operatinghours and diversity of use including possibleout of hours use by the local community.Care should be taken to ensure that theheat load required in these areas can beprovided from the heating system efficientlyby avoiding long distribution runs andensuring the boiler plant can operateefficiently at part load.

A number of zones may be provided toallow only the areas that are in use to beheated. A particular problem is officesthat may be the only part of the building

occupied during the holidays. Here,electric heating can be used as analternative to the main heating system.

Building EnergyManagement SystemsDepending on diversity and out of hoursuse a building energy management systemmay be considered. Building energymanagement systems (BEMS) arebecoming increasingly common and cansignificantly improve both theperformance of the building and itscontrollability. Within the BEMS,optimum start/stop controls andautomatic frost protection will normallybe provided. Occupancy sensors andmanual override to allow occasional useout of hours should also be considered.Weather compensation should be usedwhere the boiler plant capacity exceeds100 kW and may also be usefully appliedto smaller heating zones, eg to allow foraspect zoning. Weather compensationmay be of the central plant or the localzones. It is not advised on circuits servingfan convectors.

The use of BEMS will only be successfulwhere a member of staff is available whois fully conversant with its operation andensures the system is running correctly.There should be provision of training forthe site staff and a back-up advice serviceshould be provided if required.

Where a building energy managementsystem is provided it can be used tomonitor electrical and thermal energy aswell as water consumption. Remote meterreading is likely to provide quick paybacksas it allows staff to identify waste by real-time monitoring of consumption. It canalso help to monitor running costs.

Meter reading software is available at lowcost where there is no control BMS andsome of this software has been designedfor curriculum use, eg mathematics.

An economic assessment of cost savingsand payback periods should be madebefore installing complex control systems.


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The calculations should include predictedmaintenance costs of the controlequipment and its anticipated lifeexpectancy.

Frost protectionWhen unoccupied, a building should beheated only for frost protection or duringthe pre-occupation heat-up period. Frostprotection is for the hot and cold waterservices and the heating system only,unless there is a need to preserve thestructure, as with wooden panels inancient buildings.

A three-stage frost protection isrecommended for larger heating systems.Designs often omit stage 2 or 3 but thecost saving is small. The set points quotedare for bimetallic thermostats. Electronictemperature sensors have much smallerswitching differentials allowing set pointsto be lower which saves energy.

Stage 1. An outside thermostat locatedin a position, which cannot be affected bysunlight, to bring on all pumps bothheating and hot water service. Thisshould be set to 2 oC (just abovefreezing).

Stage 2. An immersion/strap-onthermostat should be fitted in thecommon return from the heating and hotwater service which will bring intooperation the boiler plant. This should beset at 5 oC. Conventional optimisers oftenprovide this function. The watertemperature should rise high enough toprevent freezing of remote pipework dueto very low outside temperatures and toprevent back-end corrosion of oil boilers.This can be achieved by providing a timerto ensure that the plant runs for 30-60minutes dependent on the size of thesystem.

Stage 3. A standard low temperaturethermostat installed in a normally heatedroom with maximum exposure should beset to bring the boiler plant intooperation when the internal temperaturedrops below 5 oC. This temperatureshould be adequate for most buildingswhere condensation is not a problem.

Where pipework runs externally or theboiler house has a poorer level ofinsulation than the heated spaces, thestage 1 and 2 thermostats may need to beset to higher temperatures.

Suitable indicators should be provided toshow on the boiler control panel that thevarious stages of frost protection areworking.

An outside air temperature sensor shouldnot be used to directly bring on theboiler plant.

This method of protection assumes thatdomestic hot water and cold waterservices are within the insulated buildingenvelope. If they are not, additional frostprotection for these services may beneeded.

Single stage frost protection, omittingstages 1 and 2 is adequate for smaller gasfired heating systems.

In a building with high thermal storage,the use of night setback operation shouldbe considered for unoccupied hoursduring term time. This would top upheating as required but rely mainly onstored heat in the fabric to avoid frostdamage. This could use less energy thanthe frost thermostat protection andreduce boost heating requirements onstart up for this type of building.

In some highly vulnerable areas,consideration should be given to usingself-regulating tracer cable as a last resort.This should be switched on and off by athermostat set at 2 oC.

Where air, via fresh air inlets, is heated byhot water heater batteries, provision offrost temperature sensors to protect themis essential. When the plant is notoperational, the control valve should beopen to the coil and the associateddampers closed.

Cold water tanks and pipework need tobe insulated to prevent freezing as well asto prevent overheating in summer. (seeSection 5).


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Purpose of VentilationIt should be remembered that theprimary purpose of ventilation is toprovide good indoor air quality in bothwinter and summer. The supply of freshexternal air, at a level required to meetthe need for odour control and adequateindoor air quality, suggests that 8 litre persecond per person (l/s/p) are provided.In the summer it may be desirable toprovide more than this to removeunwanted heat gains that may lead tooverheating. In winter lower ventilationrates are usual. This together withincidental heat gains limits the wintertimeheat demand.

Indoor Air Quality (IAQ)There are many factors which influenceIAQ in schools, such as damp conditions,allergens from dust mites in carpets,

Section 3 : Ventilation and Indoor Air Quality

School Premises Regulations(1) All occupied areas in a school building

shall have controllable ventilation at aminimum rate of 3 litres of fresh airper second for each of the maximumnumber of persons the area willaccommodate.

(2) All teaching accommodation, medicalexamination or treatment rooms, sickrooms, isolation rooms, sleeping andliving accommodation shall also becapable of being ventilated at aminimum rate of 8 litres of fresh airper second for each of the usualnumber of people in those areas whensuch areas are occupied.

(3) All washrooms shall also be capableof being ventilated at a rate of at leastsix air changes an hour.

(4) Adequate measures shall be taken toprevent condensation in, and removenoxious fumes from, every kitchen andother room in which there may besteam or fumes.

Constructional StandardsIt is recommended that in all teaching accommodation, medicalexamination or treatment rooms, sick rooms, isolation rooms, sleepingand living accommodation, ventilation systems, whether natural ormechanical, are capable of providing a minimum of 8 litres per second offresh air for each of the usual number of people in those areas whensuch areas are occupied.

All other areas, such as corridors, halls and circulation spaces, shall becapable of being ventilated to a minimum of 3 litres per second of freshair for each of the maximum number of persons the area willaccommodate.

Natural ventilation is the preferred method of ventilation in schools and itshould be easily and readily controlled by the occupants.

Spaces where noxious fumes or dust are generated may need additionalventilation. Laboratories may require the use of fume cupboards, whichshould be designed in accordance with DfES Building Bulletin 88[Ref.10].Design technology areas may require local exhaust ventilation.

All washrooms in which at least 6 air changes per hour cannot beachieved on average by natural means should be mechanically ventilatedand the air expelled from the building. Heat recovery fans can be used.

During the summer, when the heating system is not in operation, therecommended design temperature for all spaces should be 24 oC with aswing of not more than +/- 4 oC. It is undesirable for peak airtemperatures to exceed 28 oC during normal working hours but a highertemperature for 80 hours during the summer term is acceptable.

volatile organic compounds, dirt ormould in mechanical ventilation systemsdue to poor maintenance and externalpollution. Increasing numbers of childrenare reported to be asthmatic and/orsensitive to some of these contaminants.

Much research has recently been done onIAQ in school classrooms, which usuallyhave high occupancies. It has been foundthat the concentration of carbon dioxidein the air in a classroom is a goodindicator of the IAQ. For this reasonlimiting carbon dioxide concentrationsare increasingly being used in design. Forexample, in Finland, design guidelinesrecommend that in classrooms, naturalventilation systems should achieve aconcentration of carbon dioxide of lessthan 1500 parts per million (ppm) underdesign conditions and mechanicalventilation systems achieve aconcentration of less than 1000 ppm. In

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normal classroom occupancy, aconcentration of 1000 ppm correspondsto a ventilation rate of approximately 8litres per second per person of fresh airwhereas a concentration of 1500 ppmcorresponds to 4.5 l/s/p.

Carbon dioxide concentrations of 2000to 3000 ppm are often found in schoolclassrooms and levels of up to 3500 ppmare considered perfectly safe. (Note: Thethreshold limit value for an adult forcontinuous eight hour exposure tocarbon dioxide is 5000 ppm.) Exposureto this level is not dangerous but mayaffect performance.

A simple cost effective measure is toprovide visual CO2 indicators and to giveguidance to teachers that high CO2 levelsare likely to lead to a fall off in theconcentration of pupils.

Natural ventilationGenerally it is assumed that schoolclassrooms can be ventilated to 8 l/s/pby natural means alone and naturalventilation is taken to be the defaultdesign solution for the ventilation ofschool classrooms. Some supplementarymechanical ventilation will be required inmost schools, for example, in toilets,changing rooms and spaces with highfunctional heat gains, such as kitchensand home economics rooms, and also insome laboratories, and areas producingwater vapour or fumes.

Given that natural ventilation is driven bythe combined wind and stack effect, therates of natural ventilation provided shouldbe calculated to give good indoor airquality in the typical conditions of windspeed and inside to outside air temperaturedifference. The minimum designrequirement of 3 l/s /p, for spaces otherthan those defined as teachingaccommodation, offices, medicalexamination or treatment rooms, sickrooms, isolation rooms, sleeping and livingaccommodation, is based on the

assumption that these will be either: usedintermittently; large volume spacesproviding a dilution effect; or have highlevels of ventilation occuring betweenteaching periods, eg in circulation spaces byopening of external windows and doors.

As it is difficult to predict the actual ratesrequired, the emphasis should be on theprovision of easily adjustable openingswhether they are windows, slot ventilatorsor adjustable grilles. The ventilationsystem should be designed to ensure thatair movement at the occupants’ level is atsuch a temperature and velocity as toensure comfort; window design isimportant for this. Ventilation suitable forthe occupancy level is required wheneverspaces are occupied. Window-vents andextract grilles to ventilation stacks,controlled by the occupants are aneffective way of providing naturalventilation. In practice, adequateventilation rates may be higher or lowerthan the rates quoted.

In classrooms designed to be ventlated byopening windows trickle vents should alsobe fitted. This is particularly importantwith modern airtight construction.

Mechanical VentilationIn a well insulated building, ventilationheat losses account for a major part of theenergy consumed and any mechanicallyventilated part of the building shouldinclude, wherever possible, heat recovery,as this can reduce ventilation heat lossesby up to 80%. The potential savings fromheat recovery systems will only be realisedif a building is very airtight, thereforewhere heat recovery is used there isincreased need for airtightness.Infiltration through joints in the externalenvelope, around door and windowopenings and service penetrations canrepresent a large part of these losses andshould be reduced as far as possible[Ref.11].Draught lobbies, auto-closing doors andinternal fire doors can all play their part inreducing infiltration.

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Although internal gains may provide forheat losses the incoming air will still needto be tempered to avoid draughts, for thisthe heat recovery can be beneficial. Smallinput/extract fan units including heatrecovery are now available for use intoilets and smaller rooms, these areeconomical and give good energy savings.However, there will be additionalelectricity used particularly in larger heatrecovery systems, by the fans and filters,ductwork and grilles. Also, these items allneed maintenance. One hundred percentfresh air mechanical ventilation systemswith heat recovery by thermal wheelsminimise the potential for IAQ problemsassociated with recirculation systems andcan have heat recovery efficiencies of 80%.

Ventilation systems must be designedtogether with any fume cupboards andlocal exhaust ventilation systems so thatthey do not disturb the operation of thefume cupboards or exhaustventilation.[Ref.10]

Whichever ventilation system is selected itis important to note that IAQ is highlydependent on the cleanliness of thespaces and ductwork for a mechanicalsystem. Therefore, cleaning of carpetsand room surfaces such as bookshelves tolimit the contaminants is as important forgood IAQ as adequate fresh airventilation rates.

Controlling summertimeoverheatingOne of the main design problems facedby the designers of modern schools is theprevention of overheating. Classroomscan be subject to substantial heat gainsfrom electrical equipment, the pupils andfrom solar gain. Electronic white boardprojectors and overhead projectors are inuse for a large part of the school day insome schools. When in use, blinds areusually drawn to provide easier vision ofthe board and this again increases theheat load from the electric lights.

In addition to ensuring that all internalgains are reduced to a minimum it isnecessary to control solar gains.For those sensitive areas that cannot beoriented to the north, some form ofsolar shading may be required - eitherusing special glass or blinds or acombination of the two.

The first means of removing theunwanted heat is by natural ventilation.The ventilation rate for cooling insummer is significantly more than thatrequired for the hygiene of theoccupants. Therefore, particularconsideration should be given to thedesign of the building so that naturalventilation can achieve these supply rates.

Deep plan spaces should be avoided andclassrooms should have the provision forcross-ventilation. As the worst situation islikely to be at times of high solarradiation it may be possible for theventilation to be driven by a solarinduced stack effect - solar chimneys areone way to utilise this effect. This willencourage ventilation on days with littleor no wind. It may be useful tosupplement the natural ventilation withfan assistance in a hybrid system for thosetimes when the design requirements (eitherfor fresh air for IAQ or reduction ofinternal temperatures) are not being met.

Simple methods can be used to calculatethe size of opening vents in classrooms.In the case of deep plan spaces morecomplex design methods are required topredict the ventilation rates [Refs.12 & 13].


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Constructional StandardsWhere possible, priority should be given to design for daylight as the mainsource of light in working areas.

The uniformity ratio (minimum/average daylight factor) of the daylight shouldbe in the range 0.3 to 0.4 for side-lit rooms. Where spaces are top-lit, eg,atria, then higher uniformities should be expected of the order of 0.7.

The uniformity ratio (minimum/average maintained illuminance) of the electriclighting in teaching areas should be not less than 0.8 over the taskarea[Ref.14].

Teaching spaces should have views out except in special circumstances. Aminimum glazed area of 20% of the internal elevation of the exterior wall isrecommended to provide adequate views out.

A maintained illuminance at floor level in the range 80 - 120 lux isrecommended for stairs and corridors.

Entrance halls, lobbies and waiting rooms require a higher illuminance in therange 175 - 250 lux on the appropriate plane.

The type of luminaires should be chosen to give an average initial circuitluminous efficacy of 65 lumens/circuit watt for the fixed lighting equipmentwithin the building, excluding track-mounted luminaires and emergencylighting. In all other respects the lighting efficiency and controls shouldcomply with Approved Document Part L2, in support of the BuildingRegulations.

External lighting is not explicitly mentioned in the ADL2 2002 but is beingincreasingly used on school premises for safety and security. It isrecommended that all external lighting is provided with lamps having anefficacy of at least 65 lumens per circuit watt that are fitted with both timecontrols and daylight level photocell control.

The School PremisesRegulations(1) Each room or other space in a

school building -

(a) shall have lighting appropriateto its normal use; and

(b) shall satisfy the requirementsof paragraphs (2) to (4)

(2) Subject to paragraph (3), themaintained illuminance of teachingaccommodation shall be not lessthan 300 lux on the working plane.

(3) In teaching accommodation wherevisually demanding tasks arecarried out provision shall be madefor a maintained illuminance of notless than 500 lux on the workingplane.

(4) The glare index shall be limited tono more than 19.

Note: Recommended illuminance isdescribed as maintained illuminance, andis defined in the CIBSE Code forLighting, 2002[Ref. 14] as: ‘The averageilluminance over the reference surface atthe time maintenance has to be carriedout by replacing lamps and/or cleaningthe equipment and room surfaces’.

Section 4 : Lighting

Design frameworkThis section of BB87 is based on themore detailed design advice given inBuilding Bulletin 90, Lighting Design forSchools [Ref.15]. A successful lightinginstallation is one that satisfies a numberof different criteria shown in the lightingdesign framework. The criteria will nothave equal weight but all should beconsidered to arrive at the best solution.

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Lighting and energy efficiencyThis will mean making the maximum useof daylight, using electric light tocomplement daylight, and using energyefficient electric lighting that onlyoperates when it is required. This lastpoint can be covered by the positions ofthe control switches, by the organisationof the lighting circuits to relate to thedaylight distribution and to the use of thespace. Automatic controls can provideuseful energy savings but it is essentialthat any controls are user friendly, ie theydo not hinder the use of the space.[Ref.16]

The type of luminaires should be chosento give an average initial circuit luminousefficacy of 65 lumens/circuit watt for thefixed lighting equipment within thebuilding. Both emergency lightingsystems and equipment which is notfixed, eg track-mounted luminaires areexcluded from this figure.

Lighting maintenanceAll lighting will deteriorate with time dueto dirt build-up on the lamps andluminaires, on the windows, on thereflecting surfaces of the space and alsodue to lamp light output depreciation.The designer will need to consider thesematters in making decisions to ensurethat the lit environment is satisfactoryover the whole maintenance cycle. Thiswill mean liaising with the client to plan asuitable maintenance programme.It is worth remembering that use of awide range of different lamp types makessubsequent replacement morecomplicated.

All lighting elements including windowsshould be easy to clean and maintain.

Lighting costsBoth capital costs and running costs willneed to be considered to ensure a costeffective design. This is particularlyimportant if the two costs are to be metby different budgets.


Task/activity lightingHere the designer needs to examine thefunctional requirements of the particularspace. It is necessary to consider theamount of light and the type of lightingrequired to ensure that the users of thespace can carry out their particular taskswithout visual difficulty and in acomfortable visual environment. Hencethe first consideration here is to analysethe activity requirements for particularspaces.

It may be necessary to provide flexibilityin the lighting to allow for a variety ofactivities. Local task lighting can be veryuseful for specific tasks. Safety should beconsidered in choosing the type of localtask light, eg surface temperature of thefitting.

An increase in the size or contrast of thetask detail, eg typeface may be analternative to higher levels of illuminanceparticularly for the visually impaired.

Lighting for visual amenityThis aspect of lighting addresses theappearance of the lit scene, the aim beingto create a ‘light’ environment that isvisually interesting and pleasant. Thismeans creating a light pattern that hasluminance variation and a sensitive use ofsurface colour.

Lighting and architecturalintegrationIt is important that a lighting installation,both natural and electric, appears anintegrated part of the architecture. Thiswill apply both to the lighting elements(windows and luminaires) and the lightpatterns they produce.

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Design criteria

DaylightingNatural light should be the prime meansof lighting during daylight hours. A spaceis likely to be considered well lit if there isan average daylight factor of 4-5%. Forthe daylight illuminance to be adequatefor the task, it will be necessary to achievea level of not less than 300 lux, and forparticularly demanding tasks not less than500 lux. When this cannot be achieved,the daylight will need to be supplementedby electric light. Light exterior surfacescan sometimes be used to increasereflected light. Light shelves and specialrefractive glazing can be used to redirectlight from perimeter windows deeper intospaces to increase the uniformity of thedaylight [Ref. 17].

The design of the fenestration shouldrelate to the layout and activities plannedfor the internal space, eg, to avoidsilhouetting effects and excessive contrastsin brightness.

Discomfort and disability glare arepossible from daylight, and in particularfrom direct sunlight. This potentialproblem can often be solved by carefuldesign of the fenestration to minimiseglare. Alternatively, adjustable blinds canbe provided to screen the glare sourcewhen necessary. Blinds can also improvethe thermal environment by reducingheat gains. Although they are moreexpensive than internal blinds, externalblinds are more effective in preventingsolar heat gain. Internal blinds are oftendifficult to maintain and are a source ofnoise when windows are open.

A low maintenance solution is a tripledglazed window with an internal doubleglazed unit and an interstitial blindlocated between this and the externalsingle glazed element. This gives a verylow U-value of around 1.6 W/m2 0Cwithout using specialised double glazedunits and also enables the outer pane tobe easily replaced in the event ofbreakage. The external cavity can also beventilated to dissipate heat gains.

Windows are important as they providenatural variation of light through the dayand external visual interest. For the windowarea to be adequate for this purpose, it isrecommended that a minimum glazed areaof 20% of the internal elevation of theexterior wall is provided.

Windows, in addition to being treated as alighting source and providing a view out,need to be considered in terms of otherenvironmental factors, eg, the thermal andacoustic performance together with theenergy efficiency of the building.

Where windows are used for ventilation,the openings need to be controlled toprovide the necessary ventilation withoutdraughts.

Electric lightingThe electric lighting installation will needto meet all the requirements shown in thedesign framework.

In terms of task lighting, for most schooltasks, a maintained illuminance of300 lux will be appropriate. If the task isparticularly demanding, eg, the task detailcontent is small or it has a low contrast,then a value of not less than 500 lux willbe necessary: in some situations, this canbe provided by a local supplement to thegeneral lighting.

A maintained illuminance at floor level inthe range 80 - 120 lux is recommendedfor stairs and corridors. Entrance halls,lobbies and waiting rooms require ahigher illuminance in the range 175 - 250lux at an appropriate level. Receptionareas should be lit to a level in the range250 - 350 lux on the working plane.

In terms of avoiding discomfort glare,where a regular array of luminaires isused, the Glare Index shall be limited tono more than 19. It will also beimportant to avoid visual discomfort fromindividual luminaires and from reflectedimages, particularly on computer screens.


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An additional consideration on visualcomfort is the avoidance of subliminallamp flicker. This can be important as itcan induce epileptic fits in susceptiblepupils. It can be minimised by the use ofhigh frequency control gear or usingmore than one phase of a three phasesupply in a lead-lag arrangement. Thestroboscopic effect of lamp flicker mustbe addressed in areas with rotatingmachinery, eg lathes, cnc machines, bandsaws and circular saws.

Colour appreciation is an important partof learning, and hence it is necessary touse electric light sources that presentcolours accurately, particularly in art anddesign rooms. Good colour rendering isnow not very expensive to achieve. In thisrespect, lamps with a CIE ColourRendering Index (Ra) of not less than 80are recommended. With regard to colourappearance, lamps with a Warm toIntermediate classification (CorrelatedColour Temperature 2800oK - 4000oKshould be used).

Switching arrangements should facilitateshared use of spaces and changes to thelayout of spaces, where appropriate.

Combined daylighting andelectric lightingA specially designed supplement ofelectric lighting should be provided whenthe daylighting recommendations cannotbe achieved throughout a space. Inaddition to providing a combinedilluminance for the task or activities beingundertaken, a satisfactory appearanceshould be obtained by a balance ofbrightness throughout the space to copewith relatively bright windows. This canbe achieved by preferential lighting, andparticularly wall lighting in areas remotefrom the window.

In these spaces, it is recommended thatthe colour appearance of the lamps usedshould be in the Intermediateclassification with a Correlated ColourTemperature of about 4000oK.

Lighting qualityIn terms of the appearance of thelighting, both natural and electric, it willbe necessary to consider the overall lightpattern in terms of ‘apparent lightness’, iethe overall lightness of the space and‘visual interest’, a term relating to thedegree of non-uniformity in the lightpattern. The bright parts can frequentlybe the highlight areas used for displaypurposes.

Another aspect that is important is theintegration of the lighting (equipmentand light pattern) with the the surfacecolours and textures and the overallarchitecture.

These are attributes which recent researchhas shown are important for the users of aspace, but because they are subjective,they cannot easily be quantified.

However, for the space to have anacceptable ‘apparent lightness’, it will benecessary to use relatively high surfacereflectances, which requires a wall finishreflectance not less than 0.6 with a ceilingfinish reflectance not less than 0.7 and afloor reflectance as high as is practicable.Glossy finishes to ceilings and wallsshould be avoided to minimise confusingreflections and glare1.

The choice of surface colours is importantas it affects not only the surfacereflectances but also the overall visualimpression.


Note1 Since it is common

practice for teachers touse the wall surfaces fordisplay, a lower averagewall reflectance value of0.3 - 0.5 will need to beused for calculations,depending on the wallfinish and the amount ofdisplay material.

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External lightingExterior lighting may be needed for:

• roadway/pathway lighting;

• floodlighting of the building atnight;

• floodlighting of outdoor sports.

External lighting is not explicitlymentioned in the ADL2 2002 but isbeing increasingly used on schoolpremises for safety and security. It isrecommended that all external lighting isprovided with lamps having an efficacy ofat least 65 lumens per circuit watt that arefitted with both time control and daylightlevel photocell control.

Attention is needed to avoid light trespasswhich can cause a nuisance to people anddwellings in the neighbourhood. Lightpollution which affects the localenvironment and atmosphere should beavoided.

Light trespass can be controlled bysuitable selection of the light distributionof luminaires to avoid 'spill light' and bycareful aiming of floodlights with the useof shields if necessary.

Generally the intensity of a floodlightbeam diminishes away from the centre. Inorder to control glare from light it isoften necessary to refer to the beam anglewithin which the intensity of the lightfalls to one tenth of the peak intensity ofthe beam.

To prevent light pollution, the lightdefined by this beam angle must fallwithin an angle of 70o from thedownward vertical. These are calledfull-cut lanterns and usually requireflat glasses.

To achieve the correct uniformity in carparks or playing fields higher columns orcloser spacing may be required.While there is no legislation concerninglight pollution it has become a majorplanning issue with Local Authorities

especially concerning effects on localresidents[Ref.18]. Planning Departmentsoften turn down proposals which wouldintroduce major new light sources intoareas with only low to moderate levels ofillumination and which would createsubstantial sky glow.

External lighting without automaticcontrol is not energy efficient. Some formof automatic control should be provided.Control can be by photocells andtimeswitches or passive infra-reddetectors.

Emergency lightingThe purpose of emergency lighting is toprovide sufficient illumination, in theevent of a failure of the electricity supplyto the normal electric lighting, to enablethe building to be evacuated quickly andsafely and to control processes,machinery, etc, securely.

In schools, emergency lighting is onlyusually provided in areas accessible to thegeneral public during the evenings. Theseinclude halls and drama spaces used forperformances. Emergency lighting is notusually provided on escape routes, exceptfrom public areas, as the children aregenerally familiar with the buildings andthere is only a relatively small part of theschool year during the hours of darkness.

Exceptions where emergency lightingmight be considered are upstairs escapecorridors, escape stairways, corridorswithout any windows and areas withdangerous machinery.

It is recommended that for halls,gymnasia and other areas used by thepublic during the hours of darkness theemergency lighting should be of themaintained type. Where part of thepremises is licensed it will be necessary toseek the advice and guidance of the LocalFire Authority.


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Emergency Lighting should reveal safepassageways out of the building togetherwith the fire alarm call points, the firefighting equipment, escape signs and anypermanent hazards along the escaperoutes such as changes of direction orstairs. Further detail is given in BuildingBulletin 90, Lighting Design forSchools.[Ref.15]

Lighting for pupils withvisual and hearingimpairmentsLighting and acoustic criteria are veryimportant both to the hearing impairedand to the visually impaired. If onesensory channel is impaired more relianceis placed on the unimpaired sensorychannel. For example, the use of auralcues by the visually impaired and lip-reading by the hearing impaired. See alsothe advice on acoustics in Section 6 ofBuilding Bulletin 93.[Ref.5]

The design of specialist accommodationfor the visually impaired is beyond thescope of this document and specialistadvice should be sought.[Refs.19 & 20]

However, there are design choices thatshould be considered for all schools.Many of the low cost or no cost measurescan be applied to existing buildings suchas the choice of decor, tactile surfaces andtypes of luminaires. For a detaileddescription of possible measures seeBuilding Sight published by theRNIB[Ref.21].

Other measures, such as providing orfacilitating the use of visual aids can beconsidered as necessary. There is nosingle solution and what may assist oneperson may well not assist another. Thefollowing notes are offered as a generalguide and should help in the majority ofcases.

Visual impairment can be put into twobroad classifications.

Field defectsFirstly, there are conditions where what isseen is seen clearly but the visual field isrestricted. It may be that only the centralpart of the field is seen (tunnel vision). Inthis case mobility would be impairedalthough reading and the ability to dofine work would be largely unaffected.The converse, loss of central vision,would mean that movement could bemade in safety but the ability to performdetailed tasks such as reading or sewingwould be extremely difficult if notimpossible.

In all types of field defect the quantity oftask illumination is generally unimportantproviding normal recommendations arefollowed. Glare should be avoided (seesection on loss of acuity below) and decorcan help rapid orientation (see section onuse of colour below).

Loss of acuityThe other main condition is a loss ofacuity or a blurring of vision. The extentof the blurring varies widely and somepupils may have to bring objects and printextremely close to their eyes to see best.There may also be an associated loss ofcolour vision.

Large print will, and higher illuminancemay, be of assistance depending upon thecause of the loss of acuity. Many schoolsnow have the facility to produce theirown reading material and the use of a sanserif font of at least 14pt size can be auseful aid.

The effects of low acuity can beaggravated by glare, and this should beavoided. A ‘white’ board on a darkcoloured wall can be a glare sourcewhereas a traditional ‘blackboard’ wouldnot. Similarly, a view of a daylit scenethrough a window can be a disablingglare source.

Both loss of field and loss of acuity canoccur together and, the particulardifficulties which people with visual


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impairment experience, and theirresponses to light and otherenvironmental features, can vary widely.

The use of higher than normal taskilluminances can be of help to thosewhose acuity can be improved by thecontraction of the iris, producing agreater depth of field. In some cases,however, such as those with centralcornea opacities, the iris needs to bedilated so that the student sees ‘around’the opacity. In such a case more light willaggravate, not relieve, the condition.

PositioningStudents with visual impairment shouldbe seated where they can best see thework in progress. This may mean aposition outside the normal arrangement,eg immediately in front of the teacher orboard.

It is also important that any visual aids arereadily available for use. These may rangefrom hand-held or stand mounted opticalmagnifiers to CCTV magnifiers. Localtask lighting may also be used as an aid.It may be necessary to allow the studentto change position within the teachingspace to accommodate access to anelectrical supply, cope with excessdaylight or use any other aid that isavailable.

Use of colourColour and contrast are particularyimportant to the visually impaired and thehearing impaired[Ref.21]. For example,downlighters in reception or teachingareas produce harsh shadows whichobstruct lip reading.

Careful use of the colour scheme can helppupils recognise and identify a location. Itcan be more important than an elaboratelighting installation.

Some visual impairments involve a degreeof colour blindness and it is importantthat contrast should be introduced in

luminance and not just colour. Forexample, pale green and pale cream maybe clearly distinguished by the normallysighted but be seen as a single shade ofgrey even by some pupils where animpairment has not been identified.

Contrast in the decor should be used toaid orientation within a space. Forinstance, using a darker colour for thearchitrave around a door will aid locationof the door and a handle which clearlycontrasts with the surface of the door willindicate which way it swings.

While in some spaces orientation may beestablished by the furniture arrangementor by windows during daylight hours, inothers it can be aided by making one walldistinctly different, perhaps by theaddition of a large clock or a change incolour. Whatever method is used, it isbest adhered to throughout the building,ie, the different wall is always to the sameside of the main exit from the space.

High gloss finishes should be used withcare as they can appear as glare sourceswhen they reflect bright lights such assunlight. In general, eggshell finishes areto be preferred as some directionalreflection is desirable rather than deadmatt surfaces which may be difficult toplace precisely.

Changes in the tactile qualities of surfacescan also be useful to reinforce visualcontrasts. They are most important inschools for the blind.

ICT and display equipmentThe use of ICT by the visually impairedcan be made easier or more difficult bythe choice of font and backgroundcolours, screen brightness, font size andstyle, the type and level of room lighting,and the control of solar glare [Ref. 22].

Individual display screens also provide theopportunity to set up a work space anddisplay screen to cater for an individual’sparticular needs. It can take a


25


considerable amount of effort to set up adisplay screen but research is going oninto ways of automating at least part ofthe set up process for example the choiceof font and background colour.

DaylightGenerally schools should be designedwith daylight as the principal light source.The window wall should be light incolour, to reduce contrast with theoutdoor scene, and window reveals maybe splayed to increase the apparent size ofthe glazing.

Sunlight can be either a help or ahindrance, depending on the type ofvisual impairment, and some means ofcontrolling the quantity should beprovided. Traditionally this has been bymeans of blinds. The design offenestration in circulation spaces shouldminimise glare hazards.

Large areas of glazing can be hazardousto the visually impaired unless they can beclearly seen. To avoid accidents they canbe marked with a contrasting feature ateye level. This should be visible in lowlight levels.

In the UK the greatest problems, bothvisual and thermal, are caused by lowaltitude sunlight at either end of theschool day. Any solar shading devices,including those for rooflights must,therefore, be readily adjustable to caterfor a range of conditions. Adjustment ofsolar shading should preferably be at thediscretion of the students and not theteaching staff who may not fullyappreciate the visual difficulties of thestudents.

Electric lightThe control of glare from overheadlighting is particularly important tostudents with a visual impairment.

High frequency electronic ballasts forfluorescent lamps are to be preferred asthey avoid subliminal flicker and also theannoying visible flicker that

conventionally ballasted lamps candemostrate at the end of their life. If highfrequency ballasts are used, considerationshould be given to using a regulatedversion which can be dimmed to allowthe illuminance level to be adjusted tosuit the individual as well as to saveenergy. The additional cost for this isusually modest.

It is not normally economic to installmore than the recommendedilluminances on the off-chance that theywill be useful some day to a hypotheticalvisually impaired student. Additionalilluminance can often be readily suppliedwhen the need arises from local tasklights.

Escape routes should be clearly identifiedand alarm systems (visual and acoustic)should be adequate.

Summary of main points onlighting for pupils withvisual impairments

• Provide contrast in the decor to aidthe location of doors and theirhandles, switches and socket outlets,changes in direction in corridors,changes in floor level, stairs andsteps.

• Avoid glare from windows,rooflights and luminaires; eitherdistant or immediately overhead.

• Provide facilities for the use of anyvisual aids, eg magnifiers, telescopes,display screens, etc.

• Provide additional illumination byadjustable local task lighting asneeded.

26

Main summary of standardsand regulationsWater storage is not a mandatoryrequirement of schools and need not beincorporated where mains pressures cannormally be maintained throughout theoccupied period sufficient to supply alloutlets. However, where storage is notinstalled the School Authorities should bereminded that the affected buildingshould cease to operate in periods ofmains failure unless satisfactory sanitaryfacilities can be provided in adjacentbuildings.

Cold water storage capacity in day schoolsshould not exceed 25 litres per occupant.

All water fittings and installations shouldcomply with The Water Supply (WaterFittings) Regulations 1999.Ref: 23

Where a temperature regime is used toreduce the risk of legionellosis hot waterstorage temperatures should not be lowerthan 60oC. However for occupant safety,to reduce the risk of scalding, The SchoolPremises Regulations require that thetemperature at point of use should not beabove 43oC for baths and showers andwhere occupants are severely disabled.This may be achieved by thermostaticmixing at the point of use. It is also

recommended that hot water supplies towashbasins in nursery and primaryschools are limited to 43oC. Particularattention should be given to theprovision of facilities to ensure theeffective maintenance of systems.Ref: 24&25

Unvented hot water storage systemsshould comply with Building RegulationApproved Document G3, 1992.

Drainage and waste disposal shouldcomply with Building RegulationApproved Document H, 2000 (2002Edition).Note 2

Cold water storageIf water is stored, the cold water storagecistern capacity should be designed withconsideration towards providing theminimum amount of storage sufficient toenable the school to function during aninterruption to the water supply. In dayschools it should not be necessary toexceed 25 litres per pupil. Theminimum recommendedRef. 26 & 27 storagecapacities per pupil for 24 hour storagefor different types of school are shown inTable 3.

Section 5 : Hot and cold water supplies

Water Supplies

(1) A school shall have a wholesomesupply of water for domesticpurposes including a supply ofdrinking water.

(2) Water closets and urinals shallhave an adequate supply of coldwater and washbasins, sinks,baths and showers shall have anadequate supply of hot and coldwater.

The School Premises Regulations

(3) The temperature of hot watersupplies to baths and showersshall not exceed 43oC. Note 1

Drainage

(1) A school shall be provided with anadequate drainage system forhygienic purposes and the generaldisposal of waste water andsurface water.

Notes1 In the TMV2 scheme 46oC

is appropriate for showersand baths.

2 In Scotland and NorthernIreland other regulationsapply.

27

These figures assume that meals areprovided on site. In many schools this isnot the case. In practice 8 hours storageis more realistic and 4 hours should besufficient in most cases. The watersupplier should be consulted beforefinalising cold water storage cisterncapacities.

In mainland Europe it is normal practicenot to provide any water storage inschools. This is often possible in Englishschools. The installation will depend onthe supply pressure available from thewater supply company. Where the supplypressure is low, a storage vessel with abooster pump may be required. Watersupply pressures vary with location,however water supply companies mustprovide a minimum level of service of1 bar (10 metres head) at 12 litres/minute. Generally a pressure of 1.5 baris set as a minimum standard with anormal operational pressure of 2 bar(20 metres head).Note 3

The size of water meter should be assmall as possible, as typically standingcharges increase with the meter size.As a rule of thumb it should be possibleto down size existing older type meters toone size smaller than the diameter of thesupply pipe to the premises. However,although water for fire fighting purposesis supplied free of charge, some schoolsmay have a fire hose reel fed by themetered supply. In these cases, or if indoubt, the local fire officer should beconsulted if a reduction in the watermeter size is considered.

Remote metering allowing easy, possiblyreal-time monitoring of waterconsumption is now a cost effectivepossibility. Sub-metering can be includedas appropriate, for example forindependent facilities such as, kitchensrun by outside caterers, swimming pools,sports facilities and nurseries.

By monitoring actual consumption onsite, storage cistern and meter sizes canoften be further reduced. Observationsof the meter readings can be made over aperiod of time or electronic dataloggerscan be used but note that consumption isusually less in winter. Water companiesmay help to conduct a water audit andestablish peak demand flows for accuratesizing.

Drinking WaterHealth and safety legislation and theSchool Premises Regulations require thatadequate supplies of wholesome drinkingwater are accessible to staff and pupilsthroughout the school day.Ref: 28 All wateroutlets should be labelled as ‘Drinking’ or‘Not for drinking’.Note 4

Water fountains are quite often used tosupply drinking water but can be prone tovandalism unless they are located in areassuch as corridors that are easily observedby staff.

Fountains that discharge waterdownwards are more hygienic than thosethat discharge upwards. Fountains canalso be fitted with in-line water filters toremove chlorine, etc and a facility forcooling water. Water coolers, includingthose plumbed directly to the watersupply may also be considered fordrinking water purposes, howeverconsideration should be given tomaintenance and the number of pupilsusing the facility.


Table 3

Day schools

Nursery and primary 15 litres per pupil

Secondary and technical 20 litres per pupil

Boarding school 90 litres per pupil

Reference BS 6700: 1998Ref. 26

Notes3 This may fluctuate during

the day due to the drawoff pattern of the supplynetwork. Compensationcan usually be claimedfrom the water supplier ifwater pressure drops to70% of the minimum levelof service, ie 0.7 bar.

4 Within public buildings it isoften not possible todetermine whether tapsare connected to thesupply main or to storagecisterns and it is possiblethat the microbiologicalquality of the water instorage may deteriorate.Therefore, unless the tapis clearly labelled assuitable for drinking, itshould not be assumedthat the water from anytap is safe to drink. The1998 Drinking WaterDirective contained newprovisions to ensure thatthe water supply withinpublic buildings remainswholesome and is notadversely affected by thedomestic plumbingsystem. The variouselements of the Directiveare due to be implementedbefore the end of 2003.

28

Disposable paper cups can be provided atdrinking water outlets, to make themmore comfortable to use, but havehygiene and maintenance consequences.Where Local Authorities removefountains they must ensure that there is asuitable alternative source of drinkingwater for pupils.

Drinking water taps and fountains intoilet facilities are not recommended innew facilities but do exist in some schoolsand should always be clearly labelled.It is quite acceptable to supply drinkingwater from a “well managed” cisternsupply, installed to the standards of theWater Regulations 1999; previously calleda “Water Byelaw 30 tank”, when theWater Byelaws were in force. This iscommon practice in schools andrecommended by water supplycompanies.

However these cisterns need to bedesigned and maintained correctly.Key elements to ensure the preservationof water quality are:-

• cleanliness

• maintenance of cool conditions

• the regular use of water to preventstagnation

• system design; and

• materials used in the construction ofthe cistern should not contaminate thestored water (eg materials listed in theWater Fittings and Materials Directory,published by the Water RegulationsAdvisory Scheme (WRAS)).

The water inside the cold water storagecisterns should be kept as cool as possible.To minimise the risk of proliferation ofbacteria, cold water temperatures shouldbe maintained below 20oC. If thetemperature is between 20oC and 25oC,then caution should be exercised. If thetemperature is above 25oC, action shouldbe taken to lower the temperature asbacteria will multiply.

These temperatures can be achieved inpractice but require all cisterns to be fullyinsulated and will require the ventilationof roofs or other spaces containing,cisterns, which are subject to solar gain.

Good practice requires that the watershould not remain static for a longperiod. Automatic flushing urinals andcaretaker use in holidays is usuallysufficient to ensure this and preclude theneed for annual draining and cleaning,which is a difficult procedure and bestavoided if at all possible. If this cannotbe achieved then the cistern should becleaned, and disinfected annually asrecommended. Cleaning is veryimportant in order to remove eveninorganic debris which could provide ahabitat for bacteria, including legionella;and the cistern must be periodicallysampled to ensure that too many bacteriaare not present (depending oncircumstances, between two and fourtimes a year is normally advised).

Some Local Authorities do howeverroutinely carry out annual draining andcleaning of their water cisterns.

The difficulty of meeting all theconditions for water quality in a schoolsituation means that it is preferable ifdrinking water supplies in schools can beconnected directly to the cold water mainwherever possible.

An alternative is to use bottled watersupplies, as are often used in offices.However the cost will usually beprohibitive for school use and bacterialcounts in bottled water are often higherthan in mains cold water, because bottledwater is not chlorinated. Also it ispossible to supply a mains fed watercooler which does not require a bottledwater supply.

Water cisterns that are not up to thestandard of the Water Regulations; ie,without tight-fitting lids, uninsulated orwithout insect screens on the vent andoverflow pipes, do exist in some schoolsand drinking water should not be


29

supplied from them. They should beupgraded as soon as possible even if theydo not supply drinking water outlets asthere is no guarantee in the schoolenvironment that children will not drinkfrom any available cold water tap. Note 5

Hot waterThe use of a decentralised hot watersystem may help to reduce energywastage. Wherever possible a separateboiler, hot water generator or point ofuse water heater should be used toprovide hot water. Plant sizing curves forhot water in schools are given in Section2 of the CIBSE Guide, Public HealthEngineering. Ref : 27

The minimum numbers of sanitaryappliances for different types of schoolsare given in The School PremisesRegulations, 1999.

Consideration should be given to theproblem of build up of limescale on heatexchanger surfaces in hard water areas.This can especially be a problem for directsystems and maintenance issues need tobe considered. Also, the use of watersofteners has on-going consumable costs.

Legionellosis (includinglegionnaires’ disease)Inhalation of the legionella bacteria cangive rise to legionellosis, but the risk ofinfection is low in children unless they areimmuno-compromised or have respiratoryproblems, eg smoking. Aerosolsproduced by water services such asshowers and spray taps are potentialroutes of infection.

Although there have been no knowncases of legionnaires’ disease in schoolsthis is no reason for complacency.Schools need to be aware of the dangersand their responsibility to maintain watersystems properly.

In accordance with the HSC ApprovedCode of PracticeRef : 29, risk assessmentsare required for certain water systems.Where a reasonable foreseeable risk isassessed, management plans should bedrawn up and maintained to minimise therisk by regular inspection, maintenance,cleaning and treatment procedures.

Hot and cold water servicesWhilst surveys have shown legionella tobe present in quite large numbers ofwater systems such as those found inhospitals, schools and office blocks, onlyrarely do these appear to give rise toinfection. It is generally not possible tocompletely and permanently eradicate thebacteria. Therefore, in practice, the riskof infection is addressed by theapplication of good engineering practiceto ensure the bacteria are prevented fromproliferating. A considerable amount ofguidance has been issued on the risks.Compliance with the HSC ApprovedCode of PracticeRef :29 is a minimumrequirement. Good practical guidanceon procedures is also available.Ref : 24 & 25

Hot and cold water systems of all sizes arecovered by the ACoP. Steps should betaken to minimise the opportunity forgrowth of legionella. It multiplies inwarm water (approximately 20oC to45oC) and will thrive in the presence ofbiofilms, scale or debris. Thetemperature at cold water outlets shouldbe not more than 3oC higher than thecold water storage temperature, whichcan be as high as 25oC, the highesttemperature at which the watercompanies can supply water.Consequently quick water turnover instorage tanks is crucial in preventing theproliferation of legionella. Features ofcistern fed hot water systems whichinfluence the risk of exposure tolegionella include having open cisternsand larger than required cistern capacities.These risk features can be removed byreplacing such hot water systems withdirect feed water systems using unvented

Note5 If lawfully installed before

the 1 July 1999 watercisterns are not requiredto meet the WaterRegulations requirements.However, such tanksshould not supply drinkingwater outlets.


30

hot water storage. Other problems suchas maintaining distribution temperaturesthroughout the system can be reducedthrough the installation of instantaneoushot water heaters.

Where a temperature regime is reliedupon to control legionella hot watershould be stored at a temperature of60oC or above and distributed at aminimum temperature of 50oC.However for occupant safety, to reducethe risk of scalding, The School PremisesRegulations require that the temperatureat point of use should not be above43oC for baths and showers and whereoccupants are severely disabled. This maybe achieved by thermostatic mixing at thepoint of use. It is also recommended thathot water supplies to washbasins innursery and primary schools are limitedto 43oC. This may be achieved byinstalling a thermostatic mixing valve(TMV) close to the terminal fitting.Valves meeting the requirements of theBuildcert TMV scheme give assured levelsof scalding protection to either TMV2or TMV3 standards.

Because the organism thrives in warm(but not hot) water, the length of pipingcarrying hot and cold water (eg, after athermostatic mixing valve) must be keptto an absolute minimum, certainly lessthan 2 metres where possible. Where thefinal pipework supplying shower heads islonger than this it should be regularlypasteurised as a precautionary measure.It is recommended that this is done everytime the showers are out of use for morethan 5 days. Self draining shower headscan also be fitted as a precautionarymeasure. Similarly, the length of pipesfeeding washbasin hot taps should beminimised, especially with spray headtaps which could generate an aerosolcontaining legionella; point of use waterheaters may be preferable to centralisedhot water systems.

Research on silver/copper ionisation watertreatment has shown that this can be usefulin the control of legionellosis.Ref: 30

The research has also established thatcopper pipework is naturally biocidalparticularly at slightly acid pH values.However acidic water is uncommon.Copper can inhibit the formation ofbiofilms which are the breeding groundfor legionella and other bacteria.Copper pipework must have waterpassing through it in the first few monthsfor the natural inhibition to take place. Itshould not be left empty for long periods.

Past outbreaks of legionnaires’ diseasehave usually been associated with systemsthat have been neglected, or where theroutine operation has changed. Frequentmonitoring of the operation of the systemand factors encouraging rapidmultiplication of bacteria are thereforevital control measures. Excessive periodsof stagnation (in tanks or ‘dead legs’)should be avoided, and storage tanksmust be maintained in a clean condition.Water cisterns should comply withThe Water Supply (Water Fittings)Regulations.Ref. 23

GRP tanks usually contain biofilmstherefore annual chlorination followed bycleaning is recommended. Chlorinationof copper pipework should be avoided asit strips off the natural protection of thepipe and can cause corrosion.

Chlorination of hot and cold waterservices should be done in accordancewith the concentrations and chlorinationtimes recommended in the ACOP.Ref: 29

As sampling for legionella will often yieldpositive results, it is not advocated as aroutine measure because it can causeeither unnecessary alarm and anxietyto all concerned, or complacency andrelaxation of standards. Sampling isexpensive, and since no firm conclusionscan be drawn from the results, therandom sampling for legionella does not


31

represent good value for money.CIBSE Technical Memorandum TM 13recommends that a thermal pasteurisationregime is the most appropriate form oflegionella control for hot and cold watersystems.Ref : 24 On the other hand,monitoring general water quality canprovide a fair indication of systemconditions. This, together with a packageof other routine measures recommendedby HSE, will draw attention to potentialproblems as they develop.

Water PollutionThe Control of Pollution (Oil Storage)(England) Regulations 2001 administeredby the Environment Agency controlsecondary containment of oil storagetanks dependant on a risk analysis.Bulk storage tanks greater than 200 litressupplying a generator or “day tank”come within the scope of the Oil StorageRegulations as the oil is being stored)not used.

Lead PipeworkLead pipework for drinking water suppliesis a hazard. This is increased in areas withplumbosolvent water, ie soft water,particularly where the water is acidic.In schools built before the early 1950s,where there is a likelihood of the presenceof lead pipework, its extent should beassessed and a programme drawn up forits removal.

The European Drinking Water Directivecame into force in December 1998.Most of the new standards must beimplemented by the end of 2003. Waterwithin buildings is the responsibility ofthe owner. The new maximum lead levelof 10 microgrammes/litre is expressed interms of an average weekly consumption.

Currently, there is no practical way ofmeasuring this except through laboratoryanalysis. Monitoring of water supplies atthe dietetic tap will be required in schoolsto demonstrate compliance with theDirective. Further guidance is awaited.

Up till around 1975 lead-based solderswere used on copper pipework fordrinking water supplies. This can lead tobreaches of the 10 microgrammes/litrelevel therefore testing of copper systemsof this age will be necessary in some areas.

The Drinking Water Inspectorate (DWI)recommends the replacement of leadpipes however if this is not feasible DWIrecommends that if water is left standingin lead pipework for an extended durationthat a volume is drawn off (for a non-drinking or food preparation purpose)before consumption. Guidance can befound on the DWI website(www.dwi.gov.uk).


32

These are the minimum environmental standards thatapply to all school buildings, both new and existing.

AcousticsEach room or other space in a school building shallhave the acoustic conditions and the insulation againstdisturbance by noise appropriate to its normal use.

Lighting

(1) Each room or other space in a school building -

(a) shall have lighting appropriate to its normaluse; and

(b) shall satisfy the requirements of paragraphs(2) to (4).

(2) Subject to paragraph (3), the maintainedilluminance of teaching accommodation shall benot less than 300 lux on the working plane.

(3) In teaching accommodation where visuallydemanding tasks are carried out, provision shallbe made for a maintained illuminance of not lessthan 500 lux on the working plane.

(4) The Glare Index shall be limited to no more than19.

Heating

(1) Each room or other space in a school buildingshall have such system of heating, if any, as isappropriate to its normal use.

(2) Any such heating system shall be capable ofmaintaining the air temperature, at a height of0.5 m above floor level, at the specified level, inthe areas set out in the Table below, when theexternal air temperature is –1oC:

Area Temperature oC

Areas where there is the normal levelof physical activity associated withteaching, private study or examinations

Areas where there is a lower thannormal level of physical activity becauseof sickness or physical disabilityincluding sick rooms and isolationrooms but not other sleepingaccommodation

Areas where there is a higher thannormal level of physical activity (forexample arising out of physicaleducation) and washrooms, sleepingaccommodation and circulationspaces.

The School Premises Regulations Summary Sheet

(3) Each room or other space which has a heatingsystem shall, if the temperature during any periodduring which it is occupied would otherwise bebelow that appropriate to its normal use, beheated to a temperature which is so appropriate.

(4) In a special school, nursery school or teachingaccommodation used by a nursery class in aschool the surface temperature of any radiator,including exposed pipework, which is in aposition where it may be touched by a pupil shallnot exceed 43 oC.

Ventilation

(1) All occupied areas in a school building shall havecontrollable ventilation at a minimum rate of 3litres of fresh air per second for each of themaximum number of persons the area willaccommodate.

(2) All teaching accommodation, medicalexamination or treatment rooms, sick rooms,isolation rooms, sleeping and livingaccommodation shall also be capable of beingventilated at a minimum rate of 8 litre of fresh airper second for each of the usual number of peoplein those areas when such areas are occupied.

(3) All washrooms shall also be capable of beingventilated at a rate of at least six air changes anhour.

(4) Adequate measures shall be taken to preventcondensation in, and remove noxious fumes from,every kitchen and other room in which there maybe steam or fumes.

Water supplies

(1) A school shall have a wholesome supply of waterfor domestic purposes including a supply ofdrinking water.

(2) Water closets and urinals shall have an adequatesupply of cold water and washbasins, sinks, bathsand showers shall have an adequate supply of hotand cold water.

(3) The temperature of hot water supplies to bathsand showers shall not exceed 43oC.

Drainage

(1) A school shall be provided with an adequatedrainage system for hygienic purposes and thegeneral disposal of waste water and surface water.

18

21

15

33

The main provisions of BB87 (2003) to be used inconjunction with Approved Document Part L2, insupport of the Building Regulations, or quoted byDfES as constructional standards are given below.

Conservation of Fuel and PowerEnergy efficiency ratingThe designer of a school has three options in thedesign of a new school building.

1. To use the elemental method as described inSection 1 of ADL2 2002 of the BuildingRegulations, together with the advice containedin the revised BB87.

2. To use the Whole Building Method described inBB87 (2003) to estimate the total energyconsumption of the building and achieve a carbonperformance rating of better than 5 kgC/m2 peryear.

3. To use the carbon emission calculation method asdescribed in ADL2 2002. This technique isadvised for innovative or passive designs that willbenefit from detailed whole building simulationprocedures.

AcousticsSee Building Bulletin 93 Section 1, which is quoted byApproved Document Part E in support of BuildingRegulations as a means of compliance for schools withRequirement E4 of the Building Regulations.

LightingWhere possible, priority should be given to design fordaylight as the main source of light in working areas.

The uniformity ratio (minimum/average daylightfactor) of the daylight should be in the range 0.3 to0.4 for side-lit rooms. Where spaces are top-lit, egatria, then higher uniformities should be expectedof the order of 0.7.

The uniformity ratio (minimum/average maintainedilluminance) of the electric lighting in teaching areasshould be not less than 0.8 over the task area.

Teaching spaces should have views out except inspecial circumstances. A minimum glazed area of20% of the internal elevation of the exterior wall isrecommended to provide adequate views out.

Standards for environmental conditions and energy conservation for newschool buildings summary sheet

A maintained illuminance at floor level in the range80 - 120 lux is recommended for stairs and corridors.Entrance halls, stairs, lobbies and waiting roomsrequire a higher illuminance in the range 175 - 250lux on the appropriate plane.

The type of luminaires should be chosen to give anaverage initial circuit luminous efficacy of 65 lumens/circuit watt for the fixed lighting equipment within thebuilding, excluding track-mounted luminaires andemergency lighting.

In all other respects the lighting efficiency and controlsshould comply with ADL2 in support of the BuildingRegulations.

External LightingIt is recommended that all external lighting is providedwith lamps having an efficacy of at least 65 lumens percircuit watt that are fitted with both time control anddaylight level photocell control.

HeatingThe heating system should be capable of maintainingthe minimum air temperatures quoted in the SchoolPremises Regulations. The heating system should beprovided with frost protection.

Central heating systems should have appropriatecontrols complying with the requirements in ADL22002, in support of the Building Regulations.

The air supply to and discharge of products ofcombustion from heat producing appliances and theprotection of the building from the appliances andtheir flue pipes and chimneys should comply withBuilding Regulations, Part J, 2002.

Thermal performanceThe fabric insulation should comply with therecommended maximum values given in the‘Elemental Method’ in Table 1 of section 1 of ADL22002 in support of the Building Regulations, 2002.

Vertical glazed areas (including clerestory or monitorlights) should not normally exceed an average of 40%of the internal elevation of the external wall. However,where a passive or daylight design strategy has beenadopted the percentage glazing may exceed 40%,provided the insulation of the rest of the buildingfabric is increased to compensate for the increased heatloss through the glazing or the heating plant carbonintensity is traded up accordingly.

34

Horizontal or near horizontal glazing should notnormally exceed 20% of the roof area.

VentilationIt is recommended that in classrooms, ventilationsystems, whether natural or mechanical, are capable ofproviding approximately 8 litres per second of fresh airper person.

Spaces where noxious fumes or dust are generated mayneed additional ventilation. Laboratories may requirethe use of fume cupboards, which should be designedin accordance with DfES Building Bulletin 88. Designtechnology areas may require local exhaust ventilation.

All washrooms in which at least 6 air changes per hourcannot be achieved on average by natural meansshould be mechanically ventilated and the air expelledfrom the building. Heat recovery fans can be used.

During the summer, when the heating system is notin operation, the recommended design temperaturefor all spaces should be 24 oC with a swing of notmore than +/- 4 oC. It is undesirable for peak airtemperatures to exceed 28 oC during normal workinghours but a higher temperature for 80 hours duringthe summer term is acceptable.

Standards for environmental conditions and energy conservation for new school buildings summary sheet

Hot and cold waterCold water storage capacity in schools should notexceed 25 litres per occupant.

All water fittings should be of a type approved by aWRC (Water Research Centre), and all installationsshould comply with the Water Supply (Water Fittings)Regulations 1999.

Where a temperature regime is used to reduce the riskof legionellosis, hot water storage temperatures shouldnot be lower than 60oC. However, for occupantsafety, to reduce the risk of scalding, The SchoolPremises Regulations require that the temperature atpoint of use should not be above 43oC for baths andshowers and where occupants are severely disabled.This may be achieved by thermostatic mixing at thepoint of use. It is also recommended that hot watersupplies to washbasins in nursery and primary schoolsare limited to 43oC.

Particular attention should be given to the provisionof facilities to ensure the effective maintenanceof systems.

Unvented hot water storage systems should complywith Building Regulations Part G3, 1992.

35

1. See the Regulatory Information section of theDepartment for Education and Skills’, SchoolsBuildings and Design Unit’s website atwww.teachernet.gov.uk/schoolbuildings forcopies of The School Premises Regulations, andthe Constructional Standards for Schools (to berevised) and guidance on their application.

2. Approved Document F (Ventilation) in support ofthe Building Regulations,Department of the Environment and WelshOffice, 1994, ISBN 0 11 752932 X, £4.50.

3. Approved Document L2 (Conservation of fueland power) in support of the BuildingRegulations, Department of the Environment andWelsh Office, 2002, ISBN 0 11 753610 5, £15.

4. The Education (School Premises) Regulations1999, SI 1999 No. 2, The Stationery Office,1999, ISBN 0 11 080331 0, £3 and on websitewww.legislation.hmso.gov.uk/si/si1999/19990002.htm

5. Building Bulletin 93, Acoustic Design of Schools,DfES, The Stationery Office,ISBN 0 11 271105 7, to be published in 2003and availble as a download fromwww.teachernet.gov.uk/acoustics

6. CIBSE Guide J : Weather, solar and illuminancedata (CD-Rom), 2002, £176.25,see www.cibse.org

7. CIBSE Guide B18 - Installation and EquipmentData, 1988, see www.cibse.org

8. CIBSE Guide A - Environmental Design, 1999,see www.cibse.org

9. Department for Education, Building Bulletin 73,A guide to energy efficient refurbishment,HMSO, 1991, ISBN 0 11 270772 6, £8.50.

10. DfEE, Building Bulletin 88, Fume Cupboards inSchools, ISBN 0 11 271027,The Stationery Office, 1998, £14.95.

11. CIBSE Technical Memorandum 23: Testingbuildings for air leakage, 2000, £30,see www.cibse.org

References

12. CIBSE Applications Manual AM10: NaturalVentilation in Non-Domestic Buildings, 1997,ISBN 0 900953 77 2, £45.

13. BS 5925: 1991 Code of Practice for Ventilation,Principles and designing for natural ventilation.

14. CIBSE Code for Lighting, 2002,ISBN 1 903287 22 7, available on CD-Rom or asprinted version, see www.cibse.org

15. DfEE Building Bulletin 90,Lighting Design for Schools,ISBN 0 11 271041 7,The Stationery Office, 1999, £22.95.

16. BRE Information Paper IP6/96, People andlighting controls.

17. See www.serraglaze.redbus.co.uk

18. The Institution of Lighting Engineers, Guidancenotes for the reduction of light pollution,1994, available from ILE,Lennox House,9 Lawford Road,Rugby,Warwickshire, CV21 2DZ.

19. RNIB/GBDA Joint Mobility Unit,224 Great Portland Street,London,W1N 6AA,Tel: 0171 388 1266,Fax: 0171 388 3160.

20. The Partially Sighted Society,62 Salusbury Road,London,NW6 6NS,Tel: 0171 372 1551.

21. Building Sight, Peter Barker, Jon Barrick,Rod Wilson, RNIB, ISBN 011 701 993 3,HMSO, 1995, £35.

22. The visual environmeent for display screen use,LG03: 1996 and addendum 2001,ISBN 0 900953 71 3.

36

23. The Water Supply (Water Fittings)Regulations 1999Schedule 1: Fluid CategoriesSchedule 2: Approved Document.

See also the Water Regulations Advisory Schemepublication, The Water Fittings and MaterialsDirectory available from the Water RegulationsAdvisory Scheme, ISSN 0954-3643.

24. Chartered Institution of Building ServicesEngineers (CIBSE), Technical Memorandum 13,2002, Minimising the risk of Legionnaires disease,ISBN 1 903287 23 5.

25. Guide to Legionellosis, Temperaturemeasurements for hot and cold water services,BSRIA Application Guide AG4/94, N.L. Pavey,ISBN 0 86022 3.

26. BS 6700: 1997, British Standard Specification forDesign, installation, testing and maintenance ofservices supplying water for domestic use withinbuildings and their curtillages,ISBN 0 580 26817 9.

References

27. CIBSE Guide Public Health Engineering,Section 2: ISBN 0 900953 87 X.

28. Workplace (Health, Safety and Welfare)Regulations 1992, Guidance for the EducationSector, Leaflet IAC(L)97, HSE Books.

29. Health and Safety Executive, HSC Approved codeof practice and guidance, L8, Legionnaires’disease - The control of legionella bacteria inwater systems, HSE Books, 2000.

30. Ionisation water treatment for hot and cold waterservices, BSRIA Technical Note TN 6/96,N.L.Pavey,ISBN 0 86022 438 4.

Legionella and Building Services,G.W.Brundrett,Buttersworth Heinemann,ISBN 0 7506 1528 1.

37

Bibliography – further reading

Building Bulletin 83, SchoolsEnvironmental Assessment Method(SEAM), The Stationery Office, 1996,ISBN 0 11 27099206, £14.95.

Building Bulletin 90. Lighting Designfor Schools. ISBN 0 11 2710417,TSO 1999, £22.95

CIBSE Lighting Guides:The visual environment in lecture,teaching and conference rooms,LG05:1991.

The outdoor environment,LG06: 1992, ISBN 0 900953 53 5.

Daylighting and window Design,LG10:1999,ISBN 0 900953 98 5.

Energy efficient lighting in schools,BRECSU-OPET, Building ResearchEstablishment.

Department for Education, BuildingBulletin 79, Passive Solar Schools, adesign guide, HMSO 1994,ISBN 0 11 270876 5, £19.95.

Good Practice Guide 16 - Guide forinstallers of Condensing Boilers inCommercial Buildings - Energy EfficiencyOffice Best Practice Programme, 1990.

BRE IP 12/94, Thermal Bridges,Assessing condensation risk and heatloss at thermal bridges around openings,Building Research Establishment.

BS 6880: 1988 Code of practice for lowtemperature hot water heating systemsof output greater than 45 kW.

CIBSE Applications Manual AM1:1985,Automatic controls and their implicationsfor systems design.

BRE Digest 399 Natural Ventilationnon-domestic buildings, 1994,ISBN 0 85125 645 7.

Note1 WRAS are producing a

water supply industryplumbing installationsguide for schools,colleges & further andhigher education premiseson the design andmanagement of watersupplies in schools.

BRE Digest 457,The Carbon PerformanceRating for Offices.

DfEE Building Bulletin 77, Designing forpupils with special educational needs:special schools, HMSO 1992,ISBN 0 11 270796 3, £14.95

BRE Report BR262 Thermal Insulation:Avoiding risks, Building ResearchEstablishment, 1994,ISBN 0 11 701792 2, £16.50.

Water Regulations AdvisoryScheme publications:

The Water Fittings and MaterialsDirectory.1

• Reclaimed Water Systems, Informationabout installing, modifying ormaintaining reclaimed water systems,Information and Guidance Note9-02-04, 1999.

• Precautions against freezing of water inplumbing systems, Information andGuidance Note 9-02-02, 1998.

• Conservation of Water an IGN forArchitects, Designers and Installers,Information and Guidance Note9-02-03, 1999.

The Water Regulations AdvisoryScheme,Fern Close,Pen-y-Fan Industrial Estate,Oakdale,Gwent, NP11 3EH

Tel: 01495 248454

Fax: 01495 249234

E-mail: [email protected]

Website: www.wras.co.uk