47p. · For ease of reference, the relevant minimum standards and the constructional standards are reproduced in boxes at the beginning of each section and are summarised on pages

DOCUMENT RESUME

ED 432 905 EF 005 593

AUTHOR Orlowski, Raf; Loe, David; Watson, Newton; Rowlands, Edward;Mansfield, Kevin; Yenning, Bob; Seager, Andrew; Minikin,John; Hobday, Richard; Palmer, John

TITLE Guidelines for Environmental Design in Schools (Revision ofDesign Note 17). Building Bulletin 87.

INSTITUTION Department for Education and Employment, London (England).Architects and Building Branch.

ISBN ISBN-0-11-271013-1PUB DATE 1997-00-00NOTE 47p.AVAILABLE FROM Publications Centre, P.O. Box 276, London SW8 5DT, England,

United Kingdom; Tel: 0870-600-5522; Fax: 0870-600-5533(13.95 British pounds).

PUB TYPE Guides Non-Classroom (055)EDRS PRICE MF01/PCO2 Plus Postage.DESCRIPTORS Acoustics; Climate Control; *Compliance (Legal);

*Educational Facilities Improvement; Elementary SecondaryEducation; Energy Conservation; *Facility Guidelines;Foreign Countries; Lighting; *School Construction;*Standards; Ventilation

IDENTIFIERS England

ABSTRACTBoth existing and new English school premises are required

by law to comply with minimum construction standards published by theDepartment for Education and Employment. This building bulletin providespractical guidance on meeting these standards covering acoustics, lighting,heating and thermal performance, ventilation, water supplies, and energyconsumption. Target bands are also given for energy consumption in terms ofthe carbon dioxide produced. References to more detailed standards andsources of further information are given at the end of each section. Aconcluding section provides a recommended construction standards summarysheet. (GR)

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Reproductions supplied by EDRS are the best that can be madefrom the original document.

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4

U.S. DEPARTMEN I 01- EL.11.11;Al JUNOffice of Educational Research and Improvement

ED CATIONAL RESOURCES INFORMATIONCENTER (ERIC)

This document has been reproduced asreceived from the person or organizationoriginating it.

Minor changes have been made toimprove reproduction quality.

Points of view or opinions stated in thisdocument do not necessarily representofficial OERI position or policy.

PERMISSION TO REPRODUCE ANDDISSEMINATE THIS MATERIAL HAS

BEEN GRANTED BY

G MULLETZ {3 I

_AL Birch

TO THE EDUCATIONAL RESOURCESINFORMATION CENTER (ERIC)

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Departlinl ent forEducation and

BUILDING BULLETIN 87

Guidelines forEnvironmental

Design in Schools(Revision of Design Note 17)

Architects and Building BranchDepartment for Education and Employment

London : The Stationery Office

3

Acknowledgements

DfEE would like to thank the followingresearchers:

Raf Orlowski of Arup Acoustics forSection A;

David Loe, Newton Watson, EdwardRowlands and Kevin Mansfield of TheBartlett School of Architecture, Building,Environmental Design and Planning,University College London for Section B;

Bob Venning of Ove Arup R&D forupdating Section B and John Baker for thesection on lighting for pupils with visualimpairments; and

Andrew Seager, John Minikin,Richard Hobday and John Palmer ofDatabuild Ltd. for Sections C, D and F.

DfEE would also like to thank the membersof the Local Education Authorities whoprovided information on various schoolsand the Society of Chief Electrical andMechanical Engineers (SCEME) for theirhelp with the project.

Particular thanks to:Colin Grindley, Cranfield University;

Chris French, Essex County Council;

Anthony Wilson, Oscar Faber AppliedResearch;

Ian Hodgson, Cleveland County Council;

Alan Yates, Building ResearchEstablishment;

Crown copyright 1997.Published with the permission ofDepartment of Education andEmployment on behalf of the Controllerof Her Majesty's Stationery Office.

Application for reproduction should bemade in writing to The Copyright Unit,Her Majesty's Stationery Office,St Clements House,2-16 Colegate,Norwich NR3 I BQ

ISBN 011 271013 1

Les Fothergill, Building ResearchEstablishment;

Dave Hampton, Building ResearchEstablishment;

Andrew Williams, Building ResearchEstablishment;

Matthew Dickinson, Building ResearchEstablishment;

Miles Attenborough, ECD Energy andEnvironment Ltd;

Duncan Templeton, BDP Acoustics Ltd;

Phil Jones, University of Wales College ofCardiff;

Derek Poole, University of Wales Collegeof Cardiff;

Noel Deam, SCEME;

Fred Harrison, SCEME;

John Goggins, Society of Chief Architectsin Local Authorities.

DfEE Project Team:

Mukund Patel, Head of Architects andBuilding Branch;

Chris Bissell, Principal Architect, Architectsand Building Branch;

Richard Daniels, Senior Engineer,Architects and Building Branch.

4

Contents

Introduction

Section A: Acoustics

Section B: Lighting

(i)

1

8

Section C: Heating and thermal performance 15

Section D: Ventilation 21

Section E: Hot and cold water supplies 23

Section F: Energy (carbon dioxide) rating 26

Energy (carbon dioxide) rating calculation sheet 37

Energy (carbon dioxide) rating spreadsheet formula sheet 38

Summary sheets

The School Premises Regulations summary sheet 39

Recommended constructional standards summary sheet 40

Note: Numbered references in superscript refer toreferences at the end of the relevant section.

1:

introduction

1 See also the companionbuilding bulletin 83 SchoolsEnvironmental AssessmentMethod, SEAM, which usesenergy (carbon dioxide)ratings as part of the overallenvironmental assessment ofboth new and existing schoolbuildings. The StationeryOffice, 1996,ISBN 0 11 27099206,£14.95.

(i)

This publication replaces Design Note 17Guidelines for Environmental Design andFuel Conservation in EducationalBuildings published in 1981.

Both existing and new school premisesare required by law to comply with theminimum standards prescribed in TheEducation (School Premises) Regulations1996. This guidance provides practicaladvice on meeting these standards.

New school premises which are approvedby the Secretary of State are expected tocomply with the constructional standardspublished by the Department forEducation and Employment. Thesespecify Design Note 17 as the standardfor environmental design.

For ease of reference, the relevantminimum standards and theconstructional standards are reproducedin boxes at the beginning of each sectionand are summarised on pages 39 and 40.

Although there are separate sections onthe various environmental factors and onenergy (carbon dioxide) ratings, thedesigner is encouraged to apply anholistic approach to the design.Acoustics, lighting, ventilation, heatingand thermal performance of the buildingconstruction are all interrelated andcannot be thought of in isolation. Inaddition, energy conservation will have amajor effect on most aspects of theenvironmental design.'

Schools and local authorities make theirdesign decisions in the light of theirstatutory responsibilities and their ownassessments of local priorities andresources. It is hoped that the advicegiven in this building bulletin will assistthis process.

The guidelines are aimed primarily at thedesigners of new school buildings, butthey may also be used as a broadframework for the improvement ofexisting buildings. They have purposelybeen kept simple in an effort to be easilyaccessible both to architects and toengineers. However, references to moredetailed standards and sources of furtherinformation are quoted at the end of eachsection. Further detailed advice iscurrently being prepared as separatebuilding bulletins on lighting design forschools and on acoustics in schoolbuildings.


The School Premises Regulations

Each room or other space in a school

building shall have the acousticconditions and the insulation againstdisturbance by noise appropriate to itsnormal use.

GeneralAcoustic design aims to enable people tohear clearly without distraction. This isachieved by:

determining appropriate backgroundnoise levels and reverberation times forthe various activities and room types;

planning the disposition of 'quiet' and`noisy' spaces; separating themwherever possible by distance, externalareas or neutral 'buffer' spaces such asstorerooms or corridors;

using walls, floors and partitions toprovide sound insulation; and

optimising the acoustical characteristicsby considering the room volume, roomshape and the acoustic properties of theroom surfaces.

The architectural planning should takeinto consideration the acoustic conditionsrequired. Particular problems arise whereinsulation between spaces needs to behigh and where there is a desire for openplan arrangements containing a numberof different activities.

The most serious problems found inschools are due to noise transfer and/orexcessive reverberation.

Recommended constructionalstandards

Values for maximum permissiblebackground noise level and minimumsound insulation between rooms aregiven in Tables la and lb. Values forreverberation times are given in Table 2.

PlanningTables la and 1b give recommendedmaximum background noise levels andminimum sound insulation levels betweenrooms for the types of rooms andactivities commonly found in schools.

The tables help to assess the compatibilityof each activity and should be consideredduring the early planning stage of aproject. The tables can help to determinethe layout of the school and the necessarymethods of sound insulation.

It will usually be possible to achieve thenecessary degree of sound insulationbetween two activities by interposing asuitable wall. However, if spaces are verydiverse in their acoustic requirements, forexample a workshop and a lecture theatre,or sports hall and music room, it is seldompracticable to provide the degree of soundinsulation necessary by a single wall. Suchspaces are better positioned well apart,separated by either an external space or a`neutral' area such as a store or circulationspace to act as a buffer between the two.

Noise controlThe noise intruding into the classroom cancome from a number of sources, forexample, activities in adjacent areas,ventilation equipment and road traffic.Dining school hours this noise should notnormally exceed the levels in Table la.

Definition of Background Noise Level

In this document, Background Noise Level,measured in terms of L,QT is the noisegenerated in a space from all sources otherthan those arising from the teaching activitybeing considered. It includes noise from

adjacent areas, ventilation and traffic. It shouldnot be confused with "Background Noise Level"

in BS4142: 1990 where it is defined as thesound pressure level exceeded for 90% of thetime, measured using the 1...,90,T parameter.

1


The background noise level in generalteaching classrooms should not normallybe above 40dBLAN,Ihr.

When external noise levels are higher thannatural ventilation solutions60dBLAcq hr,

as recommended in Sections C and Dmay not be appropriate as the ventilationopenings also let in noise. However, it ispossible to use acoustically attenuatednatural ventilation rather than fullmechanical ventilation when externalnoise levels are high but do not exceed70dBLAN,Ihr.

Where external noises are loud andintermittent eg, aircraft and trains, a noiserating representing the highest levels ofthese events should be used. LA!, thelevel exceeded for 1% of the time period aroom is in use, eg, a lesson, isappropriate. As a general guide, the levelfrom aircraft and trains in teachingclassrooms should not normally exceed55dBLm.

Reference should also be made to PPG24which recommends that, for replacementschools in areas with high aircraft noise,expert consideration of sound insulationmeasures will be necessary.

Where spaces are mechanically ventilatedthe background noise from theventilation system can be used to maskthe noise from neighbouring activities.Thus it is beneficial for the minimumbackground noise level in generalteaching classrooms not to fall below30dBLAcqIhr (the maximum level shouldremain at 40dBLAcq, as stated above).

Impact sound insulation may be neededto control noise created by impacts, eg,footsteps on floors. This is an importantconsideration in upper floors of olderbuildings which have suspended woodenfloors. A good means of control is toreduce the amount of impact energygetting into the floor itself, for exampleby using a resilient surface, such as carpetor resiliently backed vinyl.

2

Definition of acoustical terms

-The equivalent continuous A-weightedITheqT

sound pressure level. This is a notionalsteady sound which, over a defined periodof time T, would have the same A-weighted

acoustic energy as a fluctuating noise, eg,for a 1 hour school lesson this would bedenoted LAe, lhr

A-weighted sound pressure level, dB(A)- The unit in decibels, generally used formeasuring environmental and traffic noise.An A-weighting network can be built into asound level meter so that dB(A) values can

be read directly from the meter. Theweighting is based on the frequencyresponse of the human ear and has beenfound to correlate well with human subjective

responses to various sounds. It is worthnoting that an increase or decrease ofapproximately 10dB(A) corresponds to asubjective doubling or halving of the loudness

of a noise, while a change of 2 to 3dB(A) issubjectively just perceptible.

Decibel, dB - The decibel is a unit of soundlevel using a logarithmic scale.

Reverberation - The persistence of soundwithin a space after the source has ceased.

Reverberation time (RT) - The time inseconds required for a sound to decay toinaudibility after the source ceases; strictly,

the time in seconds for the sound level todecay 60dB (The mid-frequency value of RT

is the mean of the values in the octavescentred on 500Hz and 1000Hz).

Room type/activity Activitynoise level

Background Noise Level

Generalcategory

Tolerancelevel

Generalcategory

Maximum backgroundnoise level from adjacentareas, ventilation andtraffic noise

LANIhr (dB)

Music rooms:

Teaching, listening audio High Low 30

Music practice/group rooms High Low 30

Ensemble playing High Low 30

Recording/control room High Low 25

General teaching, seminar and

tutorial rooms and classbases

Average Medium 40

Science laboratories Average Medium 40

Language laboratories Average Low 35

Commerce and typing Average Medium 40

Lecture rooms Average Low 35

Drama, play reading and acting High Low 30

Assembly/multi-purpose halls' High Low 35

Audio-visual rooms Average Low 35

Libraries Low Average Low 40

Metalwork/woodwork High Medium 45

Resource/light craft and practical High Medium 45

Individual study Low Low 35

Administration offices Average Medium 40

Staff rooms Average Medium 40

Medical rooms Average Medium 40

Withdrawal, remedial work Low Low 35

Teacher preparation Low Low 35

Interviewing/counselling Low Low 35

Indoor sports High High 50

Corridors and stairwells High High 50

Coats and changing areas High High 50

Toilets Average High 50

Indoor swimming pools High High 50

Dining rooms High High 50

Kitchens High High 50

Plant rooms High High 65

Box 1: Relationships between differentdescriptors of sound insulation

Sound insulation can be described in terms of a

Sound Reduction Index, symbol R. It is oftenaveraged over the key part of the audiblespectrum and expressed as a single figurevalue, either Rw (weighted index) or Rm (mean

index). The Sound Reduction Index of aconstruction is normally measured underlaboratory conditions and is often quoted inmanufacturers' catalogues. It is a property of the

construction and is independent of its area and

the receiving room reverberation time.

In actual buildings it is appropriate to measurethe Sound Level Difference that can be achieved

between two rooms, symbol D, or Dw for weighted

value. D includes sound transmission via allpaths between one room to another, ie, thedirect path and flanking paths, and it is

representative of the sound insulation achievable

in practice. A value of Dw is commonly quotedin standards eg, BS8233: 1987 and Part E ofthe Building Regulations. Dw is the sound insulation

descriptor adopted in Table lb.


TABLE la:Recommended acousticstandards : Background NoiseLevel

Halls (especially in primaryschools) are multi-functionalspaces used for PE, drama,music and assembly. Largerhalls are used for performingplays and concerts. Halls arealso used for examinations.


Table lb:Recommended acousticstandards : Sound insulation

2 Sound insulation below theselevels is not recommendedbecause of possible futurechange of use.

3 Locating rooms with noisyactivities adjacent to roomswith a low noise toleranceshould be avoided.If inevitable, to achieve 52dB,a heavy masonry constructionor equivalent will be necessary,eg, 200mm dense concreteblockwork walls. To achieve58dB a heavy masonry cavityconstruction with flexible wallties will be necessaryspecialist advice should besought.

Figure 1:Optimum reverberation timesat 'mid-frequencies' for speechand music related to roomvolume for unoccupied spaces

Figure 2:Rooms specifically for music;recommended percentageincrease in reverberation timesat lower frequencies

4

Tolerancelevel inreceivingroom

High

Medium

Low

Minimum sound insulation

D,,

38 28 282

*(48) *(38) *(38)2

48 38 28*(55) *(48) *(38)

523 48 38*(58)3 *(55) *(48)

High Average

Activity noise level in adjacent space

Low

*Values in brackets are for specialist rooms forteaching the hearing impaired. (See page 7)

Note: Where a room is used for more than onepurpose eg, a classroom to be used formusic teaching, the higher sound insulationvalue should be used.

Percentageof valueat 500Hz

160

150

140

130

120

110

100

125 250 500 1000

Frequency (Hz)

2000 4000

411

Reverberation time, RTThe reverberation time of a space affectsthe balance between clarity andreverberance with which a sound is heard.The higher the value of RT the longer thesound takes to decay which shifts thebalance from clarity towards reverberance.

Music activities generally benefit from alonger RT than speech. Figure 1 can beused to set the room volume to provide areverberation time suitable for eithermusic or speech.

Rooms with low acoustic absorption andlong reverberation times can suffer fromhigh ambient noise levels when manypeople try to speak at the same time.There is a tendency for people to increasetheir voice level to make themselves heardwhich exacerbates the situation. This is acommon feature of school dining roomsand design technology workshops.

Recommended reverberation times forthese types of spaces are included in Table 2.

The location of acoustic absorption within aroom is also important. For example,classrooms can benefit from havingabsorbent material on the rear wall but thecentral ceiling area should be hard andacoustically reflective to allow the teacher'svoice to be reflected to all the pupils.

Halls are often used for both speech andmusic and therefore the reverberationtime selected will have to be acompromise to allow for both uses. Agood alternative may be to select areverberation time suitable for music andthen reduce the reverberation time forspeech by using moveable drapes.

Table 2 gives a range of suitable values forRT for the average sizes of various roomtypes.

Type of room Approximate size Recommended unoccupiedmid-frequency 4

Reverberation Time

(seconds)Area (m2) Height (m)

Primary schools:Classroom or class-base 30 65 2.4 3.0 . 0.5 0.8

Library 12 70 2.4 - 3.0 0.5 0.8Music & drama studio/AV room 30 80 2.4 4.0 0.8 1.2

Hall (assembly/PE/movement) 80 200 3.7 6.0 0.8 1.2

Dining Rooms 80 200 2.4 3.2 0.5 0.8

Hall (music, drama, PE, AVA, assembly) 80 - 200 3.7 6.0 0.8 - 1.4

Swimming pool 65 120 3.7 6.0 < 2.0

Kitchens 65 120 2.7 - 4.0 1.5

Secondary schools:General teaching classroom 50 70 2.4 - 3.0 0.5 0.8

Small practical spaces: science, IT,

business studies,

Large practical spaces: art, metalwork,

woodwork, multi-materials, textiles,

electronics, food technology

70 110

80 135

2.4 3.0

2.7 3.0

0.5 0.8

0.5 0.8

Library 90 300 2.4 - 3.0 0.5 1.0

Hall (assembly/rehearsal) 250 550 3.7 7.6 1.0 -1.4

Dining rooms 250 550 3.7 7.6 0.5 0.8

Gymnasium/PE 250 550 5.0 6.0 1.0 1.5

Dance studio 150 2.7 4.0 0.8 - 1.2

Drama studio 80 120 3.7 7.0 0.9 1.1

Swimming pool 100 500 3.0 6.0 <2.0

Music rooms:

Music classroorWrecital room 54 91 2.7 - 3.5 1.0 1.2

Ensemble rooms 16 50 2.7 4.0 0.8 1.2

Small teaching/practice/group room 6 10 2.7 - 3.0 0.4 0.8

Recording/control room 8 15 2.4 - 3.0 0.3 0.8


Table 2:Recommended reverberationtimes for unoccupied spaces

4 Mid-frequency RT is the meanof the 500Hz and 1000Hzoctave band values.


5 A flutter echo is an audibleperception of sound reflectingrepeatedly to and fro betweenparallel walls.

6 A standing wave is causedby interference between twowaves travelling in oppositedirections, often betweenparallel walls. Sound pressuremaxima and minima areformed which can colour theoriginal sound.

6

Open plan areasIn open plan areas it is essential to providegood speech intelligibility at short distances(up to 5m) and to secure freedom fromaural distraction by more distant soundsources and by background noise. Somedegree of privacy is also desirable.

This can be difficult to achieve in practiceand there have been many instances ofdistraction and disturbance between classgroups in open plan areas.

To realise the limited acoustic potential ofopen plan areas, a carpeted floor isrecommended together with an acousticallyabsorbent ceiling. In addition, acousticallyabsorbent screens, of typical height 1.7m,should be interposed between class groups.

A major improvement in the use of openplan areas can be obtained by installing fullheight moveable walls which, if fitted withseals, can provide a moderate degree ofsound insulation between the dividedspaces.

Art, design and technologyspacesThere is often a desire to integrate thevarious disciplines of these subject areaswith insufficient consideration of direct andindirect noise transfer problems.

Areas containing woodwork and metalworkor other noisy machinery can produce highnoise levels and it is advisable to locatethese in spaces separated from quieteractivities such as class instruction in art anddesign.

usic roomsMusic rooms can be the most difficult partof the acoustic design of a school and it isimportant to establish the user'sexpectations of the acoustic performance ofthe spaces. The main problems encounteredare noise transfer between spaces,unsuitable reverberation times, flutter

echoes' and standing waves6, andexcessively high noise levels producingstress and complaints from teaching staff.

There are four basic requirements for goodlistening conditions:

O the background noise level should besufficiently low to permit the fulldynamic range of the music to be heard;

O the reverberation time should be suitablefor the activity and should be constantover the mid to high frequency range.An increase of up to 50% is permissible atbass frequencies as indicated in Figure 2;

O there should be freedom from echoes,flutter echoes, standing waves, focusingand any other acoustic effects whichconfuse or distort the sound;

o the sound should be distributeduniformly throughout the room, both inthe performance and listening areas. It isbeneficial in this respect to model largeflat wall surfaces to a depth of 0.3m ormore. An alternative is to use largeconvex surfaces, in plan and section.

Table lb recommends a minimum D of52dB between music rooms. It is beneficialto increase this to 55dB or higher when thebackground noise level is low, ie, below30dBLAcylhr. This can occur in naturallyventilated rooms on quiet sites where thebackground noise is too low to provideuseful masking of distracting noise fromadjacent rooms.

Design of acoustics forpupils with hearing andvisual impairmentsLighting and acoustic criteria arc veryimportant both to the hearing impaired andto the visually impaired. If one sensorychannel is impaired more reliance is placedon the unimpaired sensory channel, forexample, the use of aural cues by thevisually impaired and lip-reading by thehearing impaired. (See also advice onlighting on page 12).

It is incorrect to assume that schoolacoustics do not matter if the pupils are

12

severely hearing impaired; even profoundlyhearing impaired pupils can detect changesin the intonation and syllabic content ofspeech. Hearing impaired pupils may useresidual hearing as one of a number ofmeans of communication available to themand good acoustic conditions are requiredto give pupils the best opportunity tooptimise their use of residual hearing.

Whilst people with no hearing impairmentcan filter out unimportant backgroundnoise so that they can hear the soundswhich they are interested in (the 'CocktailParty Effect'), this is very difficult for thehearing impaired. In all teaching areas,therefore, low background noise levels arebeneficial for the hearing impaired.

High levels of intrusive noise increase thebackground noise and hence reduce pupils'ability to discriminate between speech andnoise. Careful space planning should becarried out to locate noise producing spacesaway from noise sensitive spaces wherepossible, to reduce the performancerequirements of sound insulatingconstructions.

Staff or pupils with hearing impairmentsmay require special facilities such as hearingaids, radio aids and induction loops.Invasive noise such as mechanicalventilation or the hum of fluorescent lightscan interfere with these. As hearing aidsamplify unwanted sound as well as speech,control of reverberant noise levels inteaching rooms is important for the hearingimpaired. Controlled reverberation timesaid good speech intelligibility.

Specialist accommodationfor pupils with hearingimpairmentsThe following acoustic criteria arerecommended for special schools andspecial units in mainstream schoolsdesigned for teaching the hearing impaired.

Backgrdund noiseIn order to achieve good speech signal/noise level ratios and thus increase thepupils' ability to make the most of theirresidual hearing, it is proposed thatmaximum background noise levels in allrooms for teaching the hearing impairedshould be at least 10dB lower than thestandards quoted in Table la on page 3 forthe equivalent classrooms in mainstreamschools.

Many hearing impaired people make use offrequencies below 500Hz to obtaininformation from speech. Therefore careshould be especially taken to minimise lowfrequency background noise levels.

Sound insulationTable la also recommends Activity NoiseLevel and Tolerance Level categories forvarious teaching spaces. In rooms forteaching the hearing impaired, thesecategories are not changed but therecommended standards for soundinsulation have been adjusted to reflect thelower recommended background noiselevels. The adjusted figures are shown inbrackets in Table lb on page 4, underneaththe figures for mainstream accommodation.

Reverberation timeIn rooms for teaching the hearing impaired,good speech intelligibility is essential. Longreverberation times can lead to poor speechintelligibility and high reverberant ambientnoise levels which make speechdiscrimination difficult. Long reverberationtimes should be avoided.

It is recommended that the unoccupiedmid-frequency reverberation time inclassrooms for teaching the hearingimpaired is between 0.3 and 0.6 seconds.

Specialist audiology facilities may berequired including an audiometry testroom. The acoustic requirements of thisspace are beyond the scope of thisdocument.


Bibliography

Miller, J., Design standards forthe sound insulation of musicpractice rooms. AcousticsBulletin of the Institute ofAcoustics, Vol. 18, No. 6,Nov/Dec 1993, pp 54-58.

Sound control for homes.BRE and CIRIA, 1993.ISBN 0 85125 55900.

Parkin, Humphreys, H.R.and Cowell, J.R. Acoustics,Noise and Buildings, FourthEdition. Faber and Faber,London, 1979.

Noise Control in BuildingServices. Fry, A. (ed.), SoundResearch Laboratories Ltd.Pergamon Press, Oxford,1988.ISBN 0 08 034067 9.

Lord, P. and Templeton, D.Detailing for Acoustics, ThirdEdition. E. & F. N. Spon,London, 1996.ISBN 0 419 20210 2.

Templeton, D.W. andSaunders, D. Acoustic Design.Architectural Press, London,1987.ISBN 0 85139 018 8.

Policy Planning Guide, PPG24,Department of theEnvironment, 1996.

BRE/BRS Building Digests asrelevant.

BS8233: 1987: Code ofPractice for Sound insulationand noise reduction forbuildings, Section 3, Part 9,Educational buildings.

BS5821: Part 1: 1984(ISO 717/1 - 1982): Methodfor rating the airborne soundinsulation in buildings and ofinterior building elements.

BS2750: Part 4: 1980(ISO/1V 1978): Fieldmeasurements of airbornesound insulation betweenrooms.

New DfEE Building BulletinAcoustic Design of Schoolsto be published shortly.

7

Section B: Lighting

References1 CIBSE Code for InteriorLighting, 1994,ISBN 0 900953 64 0.


(1) Each room or other space in aschool building(a) shall have lighting appropriate to

its normal use; and(b) shall satisfy the requirements of

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 are carriedout provision shall be made for amaintained illuminance of not lessthan 500 lux on the working plane.

(4) The glare index shall be limited to nomore than 19.

Note: Since 1994, recommendedilluminance is described as maintainedilluminance, and is defined in the CIBSECode for Interior Lighting, 1994:1 'Theaverage illuminance over the referencesurface at the time maintenance has to becarried out by replacing lamps and/orcleaning the equipment and room surfaces'.

IntroductionA successful lighting installation is onethat satisfies a number of different criteriashown in the following lighting design


Priority should be given to daylight as themain source of light in working areas, exceptin special circumstances. Wherever possiblea daylit space should have an averagedaylight factor of 4-5%.

The uniformity ratio (minimum/averagemaintained illuminance) of the electric lighting

in teaching areas should be not less than0.8 over the task area.'

Teaching spaces should have views outexcept in special circumstances. A minimumglazed area of 20% of the internal elevationof the exterior wall is recommended toprovide adequate views out.

A maintained illuminance at floor level in therange 80 120 lux is recommended forstairs and corridors.

Entrance halls, lobbies and waiting roomsrequire a higher illuminance in the range175 250 lux on the appropriate plane.

The type of luminaires should be chosen togive an average initial circuit luminousefficacy of 65 lumens/circuit watt for thefixed lighting equipment within the building,excluding track-mounted luminaires andemergency lighting.

framework. The criteria will not haveequal weight but all should be consideredto arrive at the best solution.

Design framework

Lightingcosts

Lighting LIGHTINGmaintenance DESIGN

Lightingand energy

efficiency

14

Task/activitylighting

Lighting forvisual amenity

hLighting andarchitecturalintegration

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 ofativities. 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.

Lighting and energy efficiency

This will mean making the maximum useof daylight, using electric light tocomplement daylight, and using energy-efficient 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.2

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 not fixed,eg, track-mounted luminaires areexcluded from this figure.3

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 ensure thatthe lit environment is satisfactory over thewhole maintenance cycle. This will meanliaising with the client to plan a suitablemaintenance programme.

It is worth remembering that use of awide range of different lamp types makessubsequent replacement more complicated.

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.

Section B: Lighting

References2 BRE Information PaperIP6/96, People and lightingcontrols.

3 Approved Document L(Conservation of fuel andpower) in support of theBuilding Regulations,Department of the Environmentand Welsh Office, Section2.4.2 Lighting, HMSO 1995,ISBN 0 11 752933 8, £11.

Section B: Lighting

References4 CIBSE TechnicalMemorandum 10,The Calculation of GlareIndices, 1985.

10

Design criteria

Day lightingNatural 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.

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.

Windows are important as they providenatural variation of light through the day

-and external visual interest. For thewindow area to be adequate for thispurpose, it is recommended that aminimum glazed area of 20% of theinternal elevation of the exterior wall isprovided.

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.

Electric lightingThe electric lighting installation will need tomeet all the requirements shown in thedesign framework.

In terms of task lighting, for most schooltasks, a maintained illuminance of 300 luxwill be appropriate. If the task is particularlydemanding, eg, the task detail content issmall or it has a low contrast, then a valueof not less than 500 lux will be necessary: insome situations, this can be provided by alocal supplement to the general lighting.

A maintained illuminance at floor level inthe range 80 120 lux is recommended forstairs and corridors. Entrance halls, lobbiesand waiting rooms require a higherilluminance in the range 175 250 lux at anappropriate level. Reception areas should belit to a level in the range 250 350 lux onthe working plane.

In terms of avoiding discomfort glare,where a regular array of luminaires is used,the Glare Index shall be limited to no morethan 19.4 It will also be important to avoidvisual discomfort from individual luminairesand from reflected images, on computerscreens in particular.

An additional consideration on visualcomfort is the avoidance of subliminal lampflicker. This can be important as it caninduce epileptic fits in susceptible pupils(see page 14). It can be minimised by theuse of high frequency control gear or usingmore than one phase of a three phasesupply in a lead-lag arrangement. Thestroboscopic effect of lamp flicker must beaddressed in areas with rotating machinery,eg, circular saws.

Colour appreciation is an important part oflearning, and hence it is necessary to useelectric light sources that present coloursaccurately, particularly in art and designrooms. Good colour rendering is not nowvery expensive to achieve. In this respect,lamps with a CIE Colour Rendering Index(R) of not less than 80 are recommended.With regard to colour appearance, lampswith a Warm to Intermediate classification(Correlated Colour Temperature 2800 °K4000 "K) should be used.

16

Switching arrangements should facilitateshared use of spaces where appropriate.

Combined daylighting andelectric lightingA speciallydesigned supplement of electriclighting should be provided when thedaylighting recommendations cannot beachieved throughout a space. In addition toproviding a combined illuminance for thetask or activities being undertaken, asatisfactory appearance should be obtainedby a balance of brightness throughout thespace to cope with relatively brightwindows. This can be achieved bypreferential lighting, and particularly walllighting in areas remote from the window.

In these spaces, it is recommended that thecolour appearance of the lamps used shouldbe in the Intermediate classification with aCorrelated Colour Temperature of about4000"K.

Lighting qualityIn terms of the appearance of the lighting,both natural and electric, it will benecessary to consider the overall lightpattern in terms of 'apparent lightness', ie,the overall lightness of the space and 'visualinterest', ie, a term relating to the degree ofnon-uniformity in the light pattern. Thebright parts can frequently be the highlightareas used for display purposes.

Another aspect that is important is theintegration of the lighting (equipment andlight pattern) with the surface colours andtextures and the overall architecture.

These are attributes which recent researchhas shown are important for the users of aspace, but because they are subjective, theycannot easily be quantified.

However, for the space to have anacceptable 'apparent lightness', it will benecessary to use relatively high surfacereflectances, ie, wall finish reflectance notless than 0.6 with a ceiling finish reflectancenot less than 0.7 and a floor reflectance ashigh as is practicable. Glossy finishes to

Section B: Lighting

ceilings and walls should be avoided tominimise confusing reflections and glare.(Note: since it is common practice forteachers to use the wall surfaces for display,a lower average \van reflectance value, eg,0.3 0.5 will need to be used forcalculations, depending on the wall finishand the amount of display material.)

The choice of surface colours is importantas it affects not only the surface reflectancesbut also the overall visual impression.

External lightingExterior lighting may be needed for:

O roadway/pathway lighting;

O floodlighting of the building at night;

® floodlighting of outdoor sports.

Attention is needed to avoid light trespasswhich causes a nuisance to people anddwellings in the neighbourhood.

Light pollution which affects the localenvironment and atmosphere should also beavoided.

Light trespass can be controlled by suitableselection of the light distribution ofluminaires to avoid 'spill light' and bycareful aiming of floodlights with the use ofshields if necessary.

Generally the intensity of a floodlight beamdiminishes away from the centre. In orderto control glare from light it is oftennecessary to refer to the beam angle withinwhich the intensity of the light falls to onetenth of the peak intensity of the beam.

To prevent light pollution, the light definedby this beam angle must fall within an angleof 70" from the downward vertical. Theseare called full-cut lanterns and usuallyrequire flat 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 Authoritiesespecially concerning effects on local

17 11

Section B: Lighting

References5 DfEE Building Bulletin 78,Security Lighting, HMSO 1993,ISBN 0 11 270822 6

6 New DfEE Building BulletinLighting Design for Schools tobe published shortly.

7 RNIB/GBDA Joint MobilityUnit, 224 Great PortlandStreet, London, W1N 6AA,Tel: 0171 388 1266,Fax: 0171 388 3160.

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

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

12

residents. Planning Departments often turndown proposals which would introducemajor new light sources into areas with onlylow to moderate levels of illumination andwhich would create substantial sky glow.

External lighting without automatic controlis not energy efficient. Some form ofautomatic control should be provided.

Control can be by photocells andtimeswitches or passive infra-red detectors.The types of luminaires and controlsavailable are described in detail in DfEEBuilding Bulletin 78.5

Emergency lightingThe purpose of emergency lighting is toprovide sufficient illumination, in the eventof a failure of the electricity supply to thenormal electric lighting, to enable thebuilding to be evacuated quickly and safelyand 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, except.from 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, gymnasiaand other areas used by the public duringthe hours of darkness the emergencylighting should be of the maintained type.Where part of the premises is licensed it willbe necessary to seek the advice andguidance of the Local Fire Authority.

Emergency Lighting should reveal safepassageways out of the building togetherwith the fire alarm call points, the fire

fighting equipment, escape signs and anypermanent hazards along the escaperoutes such as changes of direction orstairs. Further detail is given in theBuilding Bulletin Lighting Design forSchools. 6

Lighting for pupils with visualand hearing impairmentsLighting 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 alsoadvice on acoustics on page 6.)

The design of specialist accommodationfor the visually impaired is beyond thescope of this document and specialistadvice should be sought.7 &8 However,there are design choices that should beconsidered for all schools. Many of thelow cost or no cost measures can beapplied to existing buildings such as thechoice of decor, tactile surfaces and typeSof luminaires. For a detailed descriptionof possible measures see Building Sightpublished by the RNIB.9

Other measures, such as providing orfacilitating the use of visual aids can beconsidered as necessary. There is no singlesolution and what may assist one personmay well not assist another. The followingnotes are offered as a general guide andshould help in the majority of cases.

Visual impairment can be put into twobroad classifications.

Field defects

Firstly, 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, wouldmean that movement could be made insafety but the ability to perform detailedtasks such as reading or sewing would beextremely difficult if not impossible.

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 acuity

The other main condition is a loss of acuityor a blurring of vision. The extent of theblurring varies widely and some pupils mayhave to bring objects and print extremelyclose to their eves to sec best. There mayalso be an associated loss of colour 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 their ownreading material and the use of a san seriffont of at least 14pt size can be a useful aid.

The effects of low acuity can be aggravatedby glare, and this should be avoided. A`white' board on a dark coloured wall canbe a glare source whereas a traditional`blackboard' would not. Similarly, a view ofa davlit scene through a window can be adisabling glare source.

Both loss of field and loss of acuity canoccur together and, the particulardifficulties which people with visualimpairment experience, and their responsesto light and other environmental features,can vary widely.

The use of higher than normal taskilluminances can be of help to those whoseacuity can be improved by the contractionof the iris, producing a greater depth offield. In some cases, however, such as thosewith central cornea opacities, the iris needsto be dilated so that the student sees`around' the opacity. In such a case morelight will aggravate, not relieve, thecondition.

Positioning

Students with visual impairment should beseated where they can best see the work inprogress. This may mean a position outsidethe normal arrangement, eg, immediately infront of the teacher or board.

It is also important that any visual aids arereadily available for use. These may rangefrom hand-held or stand mounted opticalmagnifiers to CCTV magnifiers. Local tasklighting may also be used as an aid.

It may be necessary to allow the student tochange position within the teaching spaceto accommodate access to an electricalsupply, cope with excess daylight or use anyother aid that is available.

Use of colour

Colour and contrast are particularyimportant to the visually impaired and thehearing impaired.9 For example,downlighters in reception or teaching areasproduce harsh shadows which obstruct lipreading.

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 degree ofcolour blindness and it is important thatcontrast should be introduced in luminanceand not just colour. For example, pale greenand pale cream may be clearly distinguishedby the normally sighted but be seen as asingle shade of grey even by some pupilswhere an impairment has not beenidentified.

Contrast in the decor should be used to aidorientation within a space. For instance,using a darker colour for the architravearound a door will aid location of the doorand a handle which clearly contrasts withthe surface of the door will indicate whichway it swings.

While in some spaces orientation may beestablished by the furniture arrangement orby windows during daylight hours, in othersit can be aided by making one wall distinctly

19)

Section B: Lighting

Section B: Lighting

References1 CIBSE Code for InteriorLighting, 1994,ISBN 0 900953 64 0.

2 BRE Information PaperIP6/96, People and lightingcontrols.

3 Approved Document L(Conservation of fuel andpower) in support of theBuilding Regulations,Department of the Environmentand Welsh Office, Section2.4.2 Lighting, HMSO 1995,ISBN 0 11 752933 8,£11.

4 CIBSE TechnicalMemorandum 10,The Calculation of GlareIndices, 1985.

5 DfEE Building Bulletin 78,Security Lighting, HMSO 1993,ISBN 0 11 270822 6

6 New DfEE Building BulletinLighting Design for Schools tobe published shortly.

RNIB/GBDA Joint MobilityUnit, 224 Great PortlandStreet, London, W1N 6M,Tel: 0171 388 1266,Fax: 0171 388 3160.

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

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

CIBSE Lighting Guide, Lightingfor Visual Display Units, LG3:Revised 1996.

CIBSE Lighting Guide, Thevisual environment in lecture,teaching and conferencerooms, LG5:1991.

CIBSE Applications Manual,Window Design, AM2: 1987,ISBN 0 900953 33 0.

Energy efficient lighting inschools, BRECSU-OPET,Building ResearchEstablishment.

14

different, perhaps by the addition of a largeclock or a change in colour. Whatevermethod is used, it is best adhered tothroughout the building, ie, the difkrentwall is always to the same side of the mainexit 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 are tobe preferred as some directional reflection isdesirable rather than dead matt surfaceswhich may be difficult to place precisely.

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

Daylight

Generally schools should be designed withdaylight as the principal light source. Thewindow wall should be light in colour, toreduce contrast with the outdoor scene,and window reveals may be splayed toincrease the apparent size of the glazing.

Sunlight can be either a help or ahindrance, depending on the type of visualimpairment, and sonic means of controllingthe quantity should be provided.Traditionally this has been by means ofblinds. The design of fenestration incirculation spaces should minimise glarehazards.

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 ateve 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 the schoolday. Any solar shading device, includingthose for rooflights must, therefore, bereadily adjustable to cater for a range ofconditions. Adjustment of solar shadingshould preferably be at the discretion of thestudents and not the teaching staff whomay not fully appreciate the visualdifficulties of the students.

Electric light

The control of glare from overhead lightingis particularly important to students with avisual impairment.

High frequency electronic ballasts forfluorescent lamps are to be preferred as theyavoid subliminal flicker and also theannoying visible flicker that conventionallyballasted lamps can demostrate at the endof their life. If high frequency ballasts areused, consideration should be given tousing a regulated version which can bedimmed to allow the illuminance level to beadjusted to suit the individual as well as tosave energy. The additional cost for this isusually modest.

It is not normally economic to install morethan the recommended illuminances on theoff-chance that they will be useful some dayto a hypothetical visually impaired student.Additional illuminance can often be readilysupplied when the need arises frOm localtask lighting luminaires.

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

Summary of main points on lighting forpupils with visual impairments

Provide contrast in the decor to aid thelocation of doors and their handles,switches and socket outlets, changes indirection in corridors, changes in floorlevel, stairs and steps.

Avoid glare from windows, rooflightsand luminaires; either distant orimmediately overhead.

Provide facilities for the use of any visualaids, eg, magnifiers, telescopes, etc.

Provide additional illumination byadjustable local task lighting as needed.

20

becvon aung and 2nsrmaii performance


Heating

(1) Each room or other space in a school

building shall have such system ofheating, if any, as is appropriate to itsnormal use.

(2) Any such heating system shall becapable of maintaining in the areas setout in column (1) of the Table below the

air temperature set out oppositethereto, in column (2) of that Table, ata height of 0.5m above floor level when

the external air temperature is -1°C:

Column 1

Area

Areas where there is thenormal level of physical

activity associated withteaching, private study orexaminations.

Areas where there is a lowerthan normal level of physicalactivity because of sicknessor physical disabilityincluding sick rooms and

isolation rooms but notother sleepingaccommodation.

Areas where there is a

higher than normal level ofphysical activity (for

example arising out ofphysical education) and

washrooms, sleeping

accommodation and

circulation spaces.

Column 2

Temperature

18°C

21°C

15°C

(3) Each room or other space which has a

heating system shall, if the temperature

during any period during which it is

occupied would otherwise be belowthat appropriate to its normal use, beheated to a temperature which is soappropriate.

(4) In a special school, nursery school orteaching accommodation used by anursery class in a school the surfacetemperature of any radiator, includingexposed pipework, which is in a position

where it may be touched by a pupilshall not exceed 43°C.


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

The heating system should be provided with

frost protection.

During the summer, when the heating system

is not in operation, the recommended design

temperature for all spaces should be 23°Cwith a swing of not more than +/- 4°C. It isundesirable for peak air temperatures toexceed 28°C during normal working hoursbut a higher temperature on 10 days during

the summer term is considered a reasonablepredictive risk.

The air supply to and discharge of products

of combustion from heat producingappliances and the protection of the building

from the appliances and their flue pipes andchimneys should comply with BuildingRegulations, Part J, 1990.

The recommended maximum values ofaverage thermal transmittance coefficients(calculated using the 'Proportional AreaMethod' used in the Building Regulations,Part L, 1994) are :

W/m2°C WAVoC

Walls 0.4 Roof with

a loft space

Floor 0.4 Doors, windows

and rooflights 2.8

Roof 0.3

0.25

Vertical glazed areas (including clerestoryor monitor lights) should not normally exceed

an average of 40% of the internal elevationof the external wall. However, where apassive solar or daylight design strategyhas been adopted the percentage glazingmay well exceed 40%. Also in areas proneto breakages due to vandalism thereplacement cost may justify the use ofsingle glazing instead of double glazing. Inthese cases the insulation of the rest of thebuilding fabric should be increased tocompensate for the increased heat lossthrough the glazing.

Horizontal or near horizontal glazing should

not normally exceed 20% of the roof area.

71 15

Section C: Heating and thermal performance

References1 CIBSE Guide, Section A2,Weather and Solar Data.

2 DfEE Building Bulletin 77,Designing for pupils withspecial educational needs:special schools, HMSO 1992,ISBN 0 11 270796 3,£14.95

16

Energy conservationIn the design of the thermal environment,due regard should be paid to the need toconserve energy. Particular attention shouldbe paid to the design and orientation of thebuilding so that solar heat gain and energyloss can be optimised.

Thermal conditionsThe thermal conditions within educationalbuildings should be appropriate to theactivities and clothing of the occupants.Good control of the heating system isessential not only to maintain comfortableconditions but also to eliminate waste offuel.

Thermal comfort is achieved when abalance is maintained between the heatproduced by the body and the loss of heatto the surroundings. The rate of heat loss isdependent upon the amount of clothingworn and the temperature of the air andsurrounding surfaces. In a normal schoolenvironment the hourly rate of heatproduction by the children varies withactivity between 70 watts and 100 watts.This heat is lost to the surroundings by thenormal processes of convection,conduction, radiation and evaporation. It istherefore necessary for the designer to takeaccount of the functions of spaces and theactivities that they contain, and the type ofclothing likely to be worn.

Other incidental heat gains (eg, teachingequipment and light fittings) will alsocontribute heat to the space. Allowing forthese and designing suitably responsivecontrols and heating systems will helpne.p toreduce fuel consumption.

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 facade willallow entry of sunlight early in the morningbut will avoid direct sunlight during middayand early afternoon when the solar radiationis more intense.

Temperatures in theheating seasonThe air temperatures quoted in The SchoolPremises Regulations should be maintainedduring normal hours of occupationthroughout the heating season when thereis a minimum provision of 3 litres of freshair per person per second and assuming anexternal temperature of -1 °C. This externaltemperature is not intended for use in thedesigning of the heating plant. For sizing ofthe heating system, Section A2 of theCIBSE guide should be referred to.'

Higher air temperatures are often needed inschools for those children with specialeducational needs who may be moresensitive to the cold.2

Excessive vertical temperature gradientsshould be avoided and the temperature at2.0m should not exceed that at floor levelby more than 3 °C.

In some establishments like nursery schoolsand those for the severely handicapped, it isnecessary to prevent children from touchingheated surfaces above 43 °C by the use ofsuitable screens or guards.

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.

Summertime temperaturesAn undesirable rise in temperature duringwarm weather can be caused byuncontrolled incidental and solar heat gains,or by high densities of occupation, eg, inlectiire rooms. In these circumstancessufficient natural ventilation is particularlyimportant. Mechanical ventilation may benecessary in some instances to help tocontrol air temperature. Reflective, white orvery light roof surfaces reduce the solar heatgain through the roof as well as reducingthe thermal stress in the weatherproofcovering, but will tend to become lesseffective without adequate maintenance.Thermal mass and roof insulation also helpto reduce this solar gain.

22

Excessive solar heat gain through windowscan be minimised by appropriateorientation and by the use of 'brise soleil'structural shading, louvres, blinds andcurtains. Shading the glass from the outsideis the most effective method of control, butweather conditions in this country fluctuatein a way that calls for careful design of sunshading devices so as not to unduly impairthe daylighting of a classroom.

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

Thermal insulationAdequate 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.

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 Part Lof the Building Regulations is sufficient.'

Temperatures greater than normal willoccur at ceiling level in buildings withspaces higher than 3m. In these casesincreased roof insulation should beconsidered. Recirculation of warm air tolow level using 'punka' or ducted fans maybe worthwhile.

U-valuesU-values should be calculated using theproportional area method of Part L of theBuilding Regulations which takes accountof thermal bridging. Table 7 of Part L givesindicative values of U-values for windows,rooflights and doors which may be used.Thermal bridging around openings shouldalso be reduced by compliance with Part L.

Where higher percentage glazed areas arerequired than recommended, doubleglazing should be used and the fabricinsulation should be increased tocompensate for the increased heat lossthrough the windows using one of thecalculation methods listed in Part L.


Double glazing reduces the risk ofcondensation and improves comfortconditions. However the replacement costof broken units can be prohibitive in areasprone to breakages.

Every opportunity should be taken toimprove the thermal insulation of existingbuildings so that they are as close asreasonably possible to the standards for newbuildings.

Heating installationThe installation should be capable ofachieving the temperatures recommendedin The School Premises Regulations.Occupancy and solar gains may provideadditional heat. However, the heatingsystem must be responsive enough to adjustto these gains.

The choice of heat emitter is an importantdesign decision. It will depend on thethermal mass of the construction, the use ofsolar heat gain, the type of ventilation andthe level of fabric insulation, etc.

Radiators are generally the most suitable forteaching spaces. In some primary schoolswhere extensive use is made of the floor hotwater underfloor heating is preferred. Thisis not appropriate where the floor area islikely to be covered, eg, with insulatingmats or 'bleacher' seating.

Large infrequently used spaces such as hallscan benefit from a faster response and fanconvectors or low temperature radiantpanels are often used. Low temperatureradiant panels can be fixed to ceilings ratherthan taking up valuable wall space.However, they can produce thermalstratification and this should be consideredat the design stage. Underfloor heating issometimes used in halls to keep walls clearand to avoid background noise.

Wall space is often a priority in schools andfan convectors can then be used inpreference to radiators. However, it shouldbe remembered that fan convectors have ahigh maintenance cost. The backgroundnoise level of the fan convectors should notbe too high for the planned activities.

References3 Approved Document L(Conservation of fuel andpower) in support of theBuilding Regulations,Department of the Environmentand Welsh Office, 1994,ISBN 0 11 752933 8,£11.

2 _q 17


References4 Department for Education,Broadsheet 22, Use of HeatPumps in Rural Schools, DFEPublications Centre, P.O.Box2193, London, E15 2EU.

18

The shorter the heat-up period prior tooccupation, the less fuel is used. This is thecase particularly in buildings withintermittent occupancy such as schools. Toachieve an effective and efficient heat-up,optimum start controls should generally beprovided. Similarly, an optimum-off facilityshould be provided to minimise the heatingoverrun at the end of the school day.

Careful design of the number and size ofboilers to match load variations is requiredto ensure optimum efficiency throughoutthe heating season and to have a reasonablestandby capacity when implementing majorboiler maintenance.

It should be remembered that plant sizedfor steady-state design conditions always hasexcess capacity when outside conditions areless severe than design conditions. Plantover-sizing in excess of 25% of steady-statedesign requirements is unlikely to bejustified unless very substantial deviations inflow temperatures are required. Referenceshould be made to Sections A2, A3, and A9of the CIBSE Guide when calculating theheat losses and designing the heatingsystem.

Where multiple boiler installations are beingdesigned, condensing boilers should beconsidered for the lead boilers to takeadvantage of hot water loads and the longrun time for the base load of the spaceheating.

Small stand-alone gas-fired boilers or directgas-fired heaters used in remote classroomscan allow more flexible use of the buildingsthan large central boiler plant.

Heat pumps' may be a viable option for theheating in rural schools away from gas mainnetworks. Heat pumps can be air to air, airto water, or water to water. Supplementaryheating is normally required when externaltemperatures fall below around 3 °C. Thiscan be by use of a heat store and off -peakelectric heating.

24

Choice of fuelThe selected fuel should be that giving thelowest net present value taking into accountcapital, maintenance and running costs. Inpractice the selection procedure iscomplicated by the unpredictability of fuelprice trends and fuel availability.

Fuel choice in relation to the total carbondioxide produced is covered in Section F.In the choice of heating systems the optionshould be kept open where possible tochange from one type of fuel to anotherduring the life of a building. Dual fuelburners for oil and gas are readily availableand allow the site manager to choose thecheaper fuel. Where oil tanks already existthe extra cost is small.

Electric off-peak storage heater installationscannot be adapted to any other fuel use,whereas systems where heat is delivered byhot water or warm air can possibly beconverted to coal, gas, oil or electricity.Electric storage heaters are alsounresponsive to changing heat gains.

Heating controlThe type of space heating control and theway in which it is operated have asignificant influence on fuel consumption.Investing in control equipment can producea relatively quick pay-back, and zonecontrol of buildings can help with lettingsand out of hours use.

Space heating controls should be user-friendly, reliable and as far as possibleautomatic. Simple and inexpensive controlsare now available which provide variabletime control with optimum start. Thesecontrols are economic even in the smallestof schools. Adjustable components (such astemperature sensors) should be tamper-proof.

Tamper-proof thermostatic radiator valves(TRVs) have been shown to give good localcontrol of heat emitters to minimiseoverheating and underheating of areas withdifferent thermal mass and incidental heatgains.

It is preferable if a member of the schoolstaff can easily change heating periods, setholidays, change temperatures according touse and extend heating periods.

Good design of heating controls alone isnot sufficient to ensure fuel economy. It isalso necessary for the controls to beproperly commissioned and maintained ingood working order. Manuals for the usershould be available along with training forthe site staff and provision of back-upservice advice should it be required.

A user guide should tell school staff how tooperate those parts of the heating systemover which they can and shduld exercisecontrol.

Where a building energy managementsystem is provided it can be used tomonitor eleCtrical and thermal energy aswell as water consumption. It can also helpto monitor running costs.

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 of awell designed new installation.Improvements that may be worthwhilerange from the re-design and renewal ofplant to the re-assessment of its operatingpattern. Fuller details are given in BuildingBulletin 73.5

Heating zones should be chosen to suit thesolar and incidental heat gains and to allowout of hours use of selected zones.

A particular problem is offices which maybe the only part of the building occupiedduring the holidays. Here, electric heatingcan be used as an alternative to the mainheating system.

Control strategies forprimary schoolsOptimum start/stop controls andautomatic frost protection will normally beprovided. Zoning and individualtemperature sensors should be provided toaccount for orientation and pattern of use.


Occupancy sensors and manual override toallow occasional use out of hours shouldalso be considered. Weather compensationshould be used where the boiler plantcapacity exceeds 100 kW and may also beusefully applied to smaller heating zones,eg, to allow for aspect zoning. Weathercompensation may be of the central plant orthe local zones. It is not advised on circuitsserving fan convectors.

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

Hot water generation should be on aseparate circuit or a separate system to themain heating.

Depending on diversity and out of hoursuse a building energy management systemmay be considered. This will only besuccessful where a member of staff isavailable who is fully conversant with itsoperation and ensures the system is runningcorrectly.

An economic assessment of cost savings andpayback periods should be made beforeinstalling complex control systems. Thecalculations should include maintenancecosts of the control equipment and itsanticipated life expectancy.

Control strategies for largesecondary schoolsIn addition to the points covered above forprimary schools, large secondary schoolsrequire careful design of the control systemto take account of the greater range ofoperating hours and diversity of useincluding possible out of hours use by thelocal community .

A number of zones may be provided toallow only the areas that are used to beheated. Care should be taken to ensure thatthe heat 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.

References5 Department for Education,Building Bulletin 73, A guide toenergy efficient refurbishment,HMSO, 1991,ISBN 0 11 270772 6,£8.50.

25 19

Section C: Heating and thermal pertormance

ReferencesCIBSE Guide, Section A2,

Weather and Solar Data.

2 DfEE Building Bulletin 77,Designing for pupils withspecial educational needs:special schools, HMSO 1992,ISBN 0 11 270796 3,£14.95

3 Approved Document L(Conservation of fuel andpower) in support of theBuilding Regulations,Department of the Environmentand Welsh Office, 1994,ISBN 0 11 752933 8,£11.

4 Department for Education,Broadsheet 22, Use of HeatPumps in Rural Schools, DFEPublications Centre, P.O.Box2193, London, E15 2EU.

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

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

BRE IP 12/94, ThermalBridges, Assessingcondensation risk and heatIosss at thermal bridgesaround openings, BuildingResearch Establishment.

BS 6880: 1988 Code ofpractice for low temperaturehot water heating systems ofoutput greater than 45kW.

CIBSE Applications ManualAM1:1985, Automatic controlsand their implications forsystems design.

20

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 located ina position which cannot be affected bysunlight to bring on all pumps bothheating and hot water service. Thisshould be set to 2 °C (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 °C. 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°C. This temperatureshould be adequate for most buildingswhere condensation is not a problem.

Where pipework runs externally or theboilerhouse has a poorer level ofinsulation than the heated spaces, thestage 1 and 2 themostats 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 the boilerplant.

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 up'

mheating 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 °C.

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.

26

Section 0: Ventilation


(1) All occupied areas in a school building

shall have controllable ventilation at aminimum rate of 3 litres of fresh air per

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 air per

second for each of the usual number of

people in those areas when such areas

are occupied.

(3) All washrooms shall also be capable of

being ventilated at a rate of at least six

air changes an hour.

(4) Adequate measures shall be taken toprevent condensation in, and removenoxious fumes from, every kitchen and

other room in which there may besteam or fumes.

Wherever possible school buildingsshould be naturally ventilated. However,supplementary mechanical ventilationmay be required in spaces with highfunctional heat gains, eg, kitchens, homeeconomics rooms, and some types oflaboratories, and areas producing watervapour or fumes.

Where mechanical ventilation is requiredheat recovery can reduce heat losses by50%. However, there will be additionalelectricity used by the fans; and filters,ductwork and grilles will needmaintenance. Ventilation systems mustbe designed together with any fumecupboards so that they do not disturb theoperation of the fume cupboards.'

Natural ventilation is driven by thecombined wind and stack effect. Therates of natural ventilation required byThe School Premises Regulationscorrespond to the design conditions ofaverage wind speed and average inside to


The heating system shall be capable ofmaintaining the required room airtemperatures with the minimum averagebackground ventilation of 3 litres per secondof fresh air per person.

Spaces where noxious fumes or dust aregenerated may need additional ventilation.Laboratories may require the use of fumecupboards, which should be designed inaccordance with DfEE Design Note 29.Design technology areas may require localexhaust ventilation.

All washrooms in which at least 6 air changes

per hour cannot be achieved on average by

natural means should be mechanicallyventilated and the air expelled from thebuilding.

outside temperature difference. Inpractice, adequate ventilation rates may behigher or lower than the rates quoted.Less ventilation will be required where theuse of a space is intermittent, where thevolume of a space is large, providing alarge dilution effect, or where rapidventilation occurs between teachingperiods, eg, by opening of externalwindows and doors. As it is difficult topredict the actual rates required, theemphasis should be on the provision ofeasily adjustable openings whether theyare windows, slot ventilators or air grilles.

The ventilation system should be designedto ensure that air movement at theoccupants' level is at such a temperatureand velocity as to ensure comfort; windowdesign is important for this. Backgroundventilation is required whenever spaces areoccupied. Trickle vents controlled by theoccupants are an effective way ofproviding this by natural ventilation.

27

References1 DfEE, Design Note 29, FumeCupboards, (to be revised).

21

aeCt10111 II,J; VUFR1111111U11

ReferencesDfEE, Design Note 29, Fume

Cupboards, (to be revised).

2 Department for EducationBuilding Bulletin 79, Passivesolar schools, a design guide,1994, ISBN 0 11 270876 5,£19.95.

3 Approved Document F(Ventilation) in support of theBuilding Regulations,Department of the Environmentand Welsh Office, 1994,ISBN 0 11 752932 X,£4.50

4 Approved Document L(Conservation of fuel andpower) in support of theBuilding Regulations,Department of the Environmentand Welsh Office, 1994,ISBN 0 11 752933 8,£11.

BRE Digest 399, NaturalVentilation in non-domesticbuildings, 1994,ISBN 0 85125 645 7.

CIBSE Applications ManualAM10: Natural Ventilation inNon-Domestic Buildings, 1997,ISBN 0 900953 77 2,£45.

22

Where appropriate, consideration shouldbe given to the design of the building sothat natural ventilation can be driven bythe solar induced stack effect. This willencourage ventilation on days with littleor no wind.

Measures to limit solar gain should beconsidered as part of the ventilationdesign. The ventilation rates for coolingin summer need to be excessively high ifno measures are taken to prevent solargains.2

Natural ventilation designs forbackground and rapid ventilation usingthe openable areas quoted in Table 2 ofPart F of the Building Regulations3should satisfy the requirements forventilation except in the case of deep planspaces where more complex designmethods are required to predict thenatural ventilation rates.

The methods range from manualcalculations of air flow through windowsor across a space to simple single zonecomputer models through multi-zonemodels to computerised fluid dynamicmodels. An alternative which has alsobeen used to good effect is to use scalemodels with salt solutions to model theair flows.

In a well insulated building, ventilationheat losses account for a major part of theenergy consumed. Infiltration throughjoints in the external envelope, arounddoor and window openings and servicepenetrations can represent a large part ofthese losses and should be reduced as faras possible.` Draught lobbies, auto-closing doors and internal fire doors canall play their part in reducing infiltration.

The design should ensure ease ofmaintenance. This includes thereplacement of filters, the cleaning ofextract grilles and the cleaning ofventilation ductwork.

Section E: hot and coid water suppkas


Water Supplies

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

(2) Water closets and urinals shall havean adequate supply of cold waterand washbasins, sinks, baths andshowers shall have an adequate

supply of hot and cold water.

(3) The temperature of hot watersupplies to baths and showers shallnot exceed 43°C.

Drainage

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

Cold waterTanks should be as small as possiblecommensurate with the requirements ofthe local water supply company. In dayschools it should not be neccessary toexceed 25 litres per occupant. Theminimum recommendeek5 storagecapacities per pupil for different types ofschool are shown below. The figuresallow for 24 hour storage. Some watersupply companies do not require this andthe figures can then be reduced.

The size of water meter should also be assmall as possible, as standing chargesincrease with the meter size.

An adequate supply of drinking watershould be accessible to staff and pupilsthroughout the school day.°

.,;


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

All water fittings should be of a type approved

by the WRC (Water Research Centre), and all

installations should comply with the WaterSupplies Byelaws.'

Where a temperature regime is used toreduce the risk of legionellosis hot waterstorage temperatures should not be lowerthan 60 °C. However for occupant safety, to

reduce the risk of scalding, The SchoolPremises Regulations require that thetemperature at point of use should not beabove 43°C for baths and showers and where

occupants are severely disabled. This maybe achieved by thermostatic mixing at thepoint of use. It is also recommended that hot

water supplies to washbasins in nursery and

primary schools are limited to 43°C. Particular

attention should be given to the provision offacilities to ensure the effective maintenance

of systems.2"

Unvented hot water storage systems shouldcomply with Building Regulations, Part G3,1992.

Day schools

Nursery and primary 15 litres per pupil

Secondary 20 litres per pupil

Boarding school 90 litres per pupil

Hot waterThe use of a decentralized hot watersystem may help to minimise energywastage. Wherever possible a separateboiler, hot water generator or point of usewater heater should be used to providehot water. Plant sizing curves for hotwater in schools are given in Section B4of the CIBSE Guide.5

Numbers of sanitary appliances fordifferent types of schools are given in TheSchool Premises Regulations, 1996.

29

Table 3

OQ

Section E: Hot and cold water supplies

Legionellosis (includinglegionnaires' disease)Inhalation of the legionella bacteria cangive rise to legionellosis, but the risk ofinfection is low. Aerosols produced bywater services such as showers and spraytaps are potential routes of infection.

Although there have been no knowncases of legionnaires' disease in schoolsthis is no reason for complacency. Schoolsneed to be aware of the dangers and theirresponsibility to maintain water systemsproperly.

In accordance with the HSC ApprovedCode of Practice The prevention or controlof legionellosis', risk assessments arerequired for certain water systems. Wherea reasonable foreseeable risk is assessed,management plans should be drawn upand maintained to minimise the risk byregular inspection, maintenance, cleaningand treatment procedures.

Whilst 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 risk ofinfection is addressed by the applicationof good engineering practice to ensurethe bacteria are prevented fromproliferating. A considerable amount ofguidance has been issued on the risks.Compliance with HS(G)70 The control oflegionellosiss and HSC Approved Code ofPractice The prevention or control oflegionellosis is a minimum requirement.Good practical guidance on procedures isalso available.2 &3

Steps should be taken to minimise theopportunity for growth of legionella. Itmultiplies in warm water (approximately20 to 45 °C) and will thrive in thepresence of biofilms, scale or debris. Thetemperature at cold water outlets shouldbe not more than 3 °C higher than thecold water storage temperature, whichcan be as high as 25 °C, the highest

24

temperature at which the WaterCompanies can supply water.Consequently quick water turnover instorage tanks is crucial in preventing theproliferation of legionella.

Where a temperature regime is reliedupon to control legionella hot watershould be stored at a temperature of 60 °Cor above and distributed at a minimumtemperature of 50 °C.

However for occupant safety, to reduce therisk of scalding, The School PremisesRegulations require that the temperature atpoint of use should not be above 43 °C forbaths and showers and where occupants areseverely disabled. This may be achieved bythermostatic mixing at the point of use. It isalso recommended that hot water suppliesto washbasins in nursery and primaryschools are limited to 43°C.

Because the organism thrives in warm(but not hot) water, the length of pipingcarrying hot and cold water (eg, after athermostatic mixer valve) must be kept toan absolute minimum, certainly less than2 metres. Preferably each shower headshould have its own mixer valve.Similarly, the length of pipes feedingwashbasin hot taps should be minimised,especially with spray head taps whichcould generate an aerosol containinglegionella; point of use water heaters maybe preferable to centralised hot watersystems.

Recent research on silver/copperionisation water treatment has shown thatthis can be a successful alternative to atemperature regime, to controllegionellosis9 . The research has alsoestablished that copper pipework isnaturally biocidal particularly at slightlyacid pH values. Copper can inhibit theformation of biofilms which are thebreeding ground for legionella and otherbacteria. Copper pipework must havewater passing through it in the first fewmonths for the natural inhibition to takeplace. It should not be left empty for longperiods. As a result of this research theHSE are issuing a supplement toHS(G)70.8

30

Past outbreaks of legionnaires' diseasehave usually been associated with systemsthat have been neglected, or where theroutine operation has changed. Frequentmonitoring of the operation of thesystem and factors encouraging rapidmultiplication of bacteria are thereforevital control measures.

Excessive periods of stagnation (in tanksor 'dead legs') should be avoided, andstorage tanks must be maintained in aclean condition. Water tanks shouldcomply with the Water Supplies Byelaws.i.

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 HS(G)70 recommendedconcentrations and chlorination times.

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

On the other hand, monitoring generalwater quality can provide a fair indicationof system conditions. This, together witha package of other routine measuresrecommended by HSE, will drawattention to potential problems as theydevelop.

Section E: Hot and cold water supplies

References

Water Research Council,Water Supplies Byelaws Guide,2nd edition, 1989, £7.95,ISBN 0 90215671 3.(Note: the Byelaws are to bereplaced by the WaterRegulations.)

See also the Water ResearchCouncil publication, The WaterFittings and MaterialsDirectory.

2 Chartered Institution ofBuilding Services Engineers(CIBSE), TechnicalMemorandum 13, 1991,Minimising the risk ofLegionnaires disease,ISBN 0 900953 52 7.

3 Guide to Legionellosis,Temperature measurementsfor hot and cold waterservices, BSRIA ApplicationGuide AG4/94, N.L. Pavey,ISBN 0 86022 3.

4 BS 6700: 1987, BritishStandard Specification forDesign, installation, testing andmaintenance of servicessupplying water for domesticuse within buildings and theircurtillages,ISBN 0 580 15769 5.

5 CIBSE Guide, Section B4:Water Service Systems, 1986,ISBN 0 9009533 30 6.

6 Workplace (Health, Safetyand Welfare) Regulations1992, Guidance for theEducation Sector, LeafletIAC(L)97, HSE Books.

Health and Safety Executive,HSC Approved code ofpractice, L8, The prevention orcontrol of Legionellosisincluding Legionnaires'disease, 1995.

8 Health and Safety Executive,HS(G)70, The control oflegionellosis includingLegionnaires' disease, 1994(supplement to be issued),ISBN 0 1 882150 4.

9 Ionisation water treatment forhot and cold water services,BSRIA Technical Note TN 6/96, N.L.Pavey,ISBN 0 86022 438 4.

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

Section F: Energy (carbon dioxide) rating

26

Recommended constructionalstandard

In the design of a new building the calculated

Annual CO, Production Value should bebelow the top of band D shown in Figure 1

or 2, when the environmental standards inSections B and C have been achieved.

GeneralIn the sections dealing withenvironmental conditions a number ofmeasures for conserving energy have beenrecommended.

There are a variety of calculation methodsavailable to predict the annual energyconsumption and the amount of CO,produced by new buildings.

The most sophisticated are computerisedreal time models which use recordedweather data to simulate the actualperformance of the building. Thesemodels require the input of a lot ofparameters and are most useful at thelater stages of design when the form ofthe building is known in some detail.

At the early stage of design whenassessing different options a steady statecalculation method can be more useful.

Such a method follows. It allowsalternative designs to be ranked in termsof their cost-effectiveness and theirenvironmental impact in terms of CO2production. It provides a procedure forcomparison of alternative methods ofheating and lighting. Calculated energyconsumptions in kWh per square metrefloor area are converted into kgCO2/m2using the conversion factors of the variousfuels.

Design procedureThe calculation procedure enables theenergy requirements to be estimated at anearly stage in the design.

Kitchens and swimming pools arc notincluded and their areas and energyconsumptions must be excluded from thecalculations. Craftwork and homeeconomics loads are also not included.

,,-

The calculation procedure derives anAnnual CO2 Production Value by thesummation of the heat requirement of thebuilding and the energy used for otherpurposes such as lighting, small power, hotwater, and the circulating pumps for theheating system. The heat requirement iscalculated from the theoretical heat lossminus the heat displaced by adventitiousgains such as lighting, occupancy, smallpower use, and solar gains. Using this basisthe annual energy uses are calculated over amodel year and converted to kgCO2 /m2.

The total Annual CO2 Production Valueis calculated and compared with thetarget bands in Figures 1 and 2 forprimary and secondary schoolsrespectively. The figures show bands ofannual energy consumption in terms ofkgCO2 per square metre of the gross floorarea (GFA) that is heated.

As the design of the building develops,alternatives (eg, in the choice of fuel, fuelefficiency or the methods of heating andlighting) may present themselves.

Realistic estimates of the options and theconsequent life cycle costs for operationand maintenance are required so thatdesign decisions can be based on bothcost and environmental impact.

A spreadsheet calculation for an exampleschool is given on pages 32-35. A blankspreadsheet and a spreadsheet formulasheet are included on pages 37 and 38.

The Annual CO2 production value targetbands were first published in the Schools'Environmental Assessment Method(SEAM), Building Bulletin 83 in October1996. These target bands have now beenrevised in the light of a survey of 1995/96 energy consumption in 2000 primaryschools and 300 secondary schools from17 local authorities.

Bands E and F (shown dotted) now applyonly to existing schools. Previously onlyband F applied to existing buildings andnot to new buildings. The revised targetbands and numbers of points awardedshould now be used in the SEAMassessment.

32


100

90

80

70

60

E

O 50-00A

40

30

20

10

0

-L-F

E

D

C

B

A

500 100

I I I

1500 2000 2500 301000 3000

Gross floor area/m2

3500

100

90

80

70

60

F

O 50OOA

40

30

20

10

0

... ...... ...... ...... --------- F

E

D-

C

B

A

1,500 3,000 4,500 6,000 7,500 9,000 10,500 12,000 13,500 15,000

Gross floor area/m2

Band

New buildings

Existing buildings

A

7

11

B

5

9

C

3

7

D

1

5

E

3

F

1

33

Figure 1:Annual CO, production valuetargets: primary schools

Figure 2:Annual CO, production valuetargets: secondary schools

Key to figures 1 and 2

BAND COMMENT

D Upper line of bandindicates the maximumpermissible Annual CO,Production Value fornew buildings.

C and B Improvement upon themaximum permissibleAnnual CO, ProductionValue.

A Good low energydesign.

Table 4:The table shows the revisednumbers of points to beawarded in the SEAM method,bands E and F now only apply toexisting buildings


Table 5:Degree-days.

Degree-days are a measure ofhow cold the weather is duringthe heating season(1st September to 30th Aprilfor schools).

The number of degree-daysequals the sum of the numberof days times the number ofdegrees that the temperatureis less than the basetemperature.

The table gives 20 yearaverage degree-days (for 1975to 1995) to a base of 15.5°Cfor each of the recognisedzones within England andWales.

Degree-days are usuallyquoted to a base temperatureof 15.5°C. This is lower thanroom temperature and allowsfor occupancy andmiscellaneous gains. Howeverthis calculation method doesnot apply this correction anduses a base temperature equalto the room temperature of18°C for classrooms. Note:current annual and 20 yeardegree-day figures should beused if available.

ReferencesCIBSE Guide B18

Installation and EquipmentData, 1988.

2R

Location Zone Degree-days

Thames Valley 1 1678

South East 2 1838

Southern 3 1792

South West 4 1512

Severn Valley 5 1588

Midlands 6 2014

West Pennines 7 1980

North West 8 2040

Borders 9 2110

North East 10 1977

East Pennines 11 1938

East Anglia 12 1897

Wales 16 1732

Average 1856

Model Year - Hours ofoperation' of space heatingIt is necessary to construct a model yearon which.to base calculations so thatcomparisons can be made. For thispurpose a normal school day is used.Evening and holiday use is excluded asthis varies from school to school.Likewise, kitchens, swimming pools andother proceSs loads are excluded from thecalculations. The length of heatingseason, 1st September 30th April, is 176working days. The number of schooldays, including 8 days for cleaning andmaintenance is 144.

The average value of degree-days, Dd forEngland and Wales over the school heatingseason for normal working hours is 1856(use local figure for Dd from Table 5).

Assuming a medium weight building (asmost school buildings are) andintermittent use of plant and disregardingoccupancy and other miscellaneous gains,the base temperature equals the internaldesign temperature (Section Crecommends 18 °C for classrooms).

In order to correct the degree days forother base temperatures, the figure forbase temperature of 15.5 °C should beadjusted by the relevant factor in TableB18.9 of CIBSE Guide Section B18':

Base temperature = 18 °C

ratio Dd/D15.5 = 1.30

The following equivalent hourscalculation is based on the CIBSEGuide.' Box 1 explains this calculationand the correction factors which must beapplied for mode of operation.

Average equivalent annual operation:

E= 24 x x 1.30

19

Correction for mode of operation

(a) 5 day week (for school use)

W x DR = 0.8 x (144/176)= 0.65

(b) intermittent use R = 0.70(c) 7.5 hour day DI = 0.96

Corrected Ec = 24 x D1; x 1.30/19x 0.65 x 0.70 x 0.96

Box 1: Corrected equivalenthours of operation

The method uses local degree-days andthe design temperature to represent thespace heating requirement in terms of theequivalent number of hours at full loadoperation.

Where:

E=

E. 24 xDdAtd

Equivalent hours of operation at full load.

Dd = Seasonal total of degree days to thebase of the design internal temperature.

Ltd = Design internal temperature minusdesign external temperature.

Correction for mode of operation

The calculated equivalent hours isadjusted by a series of correction factors(detailed below) appertaining to thebuilding's mode of operation, whichproduces a corrected equivalent hours ofoperation. This value is used to determinethe heating requirement of the building.

= ExWxDRxR0(0,

= Corrected equivalent hours of operationat full load.

W = Factor for length of working week.

DR = Ratio of school operating days to officeoperating days.

Rp = Factor for the response of the buildingand plant.

D, = Factor for the length of the school day.

34

a. Length of working week (W)Schools are most commonly mediumweight buildings when a factor of 0.8 isused for a 5 day working week.

The,values of W in Table 6 were designedfor office buildings which have 176working days during the defined heatingseason (September to April inclusive).

Ratio of school to officeoperating days (DR)Schools operate for fewer days thanoffices over the same heating season andtotal school operating days, including 8days for cleaning, are generally 144.Therefore a further correction has to beapplied to make the factor W suitable forschool buildings.

The factor DR is obtained by a ratio ofthe number of operating days.

For school use: the additional factor, DRis generally: (144/176) = 0.82.

b. Response of building andplant (Rp).

Most schools are intermittently heated,although the heating may be responsiveor have a long time lag and considerationshould be given to the type of systemwhen using these correction factors. SeeTable 7.

c. Length of working day (D1)Educational buildings commonly have adaily occupancy of 7.5 hours. See Table 8.

Recommended design dataThe values in the boxes that follow arerecommended in the absence of moreaccurate information. More accuratefigures, eg, lighting gains based on theactual lighting design, should be usedwhen they become available.


In the tables that follow the buildings arecategorised into light, medium, and heavyweight buildings, this refers to their thermalcapacity which may include considerationsfor the buildings' contents as well as theirconstruction.

Definition of light, medium and heavy,weight buildings.

Heavy weight:

buildings of curtain walling, masonry orconcrete, especially multi-storey, with solidinternal walls, eg, inner city, particularlyVictorian, two and three storey buildings.

Medium weight:

traditional brick-built, single-storey orconcrete multi-storey with large windows.

Light weight:

system or temporary buildings with light

weight partitions and external walls.

Working Type of constructionweek

Light Medium Heavy

weight weight weight

7 day 1.0 1.0 1.0

5 day 0.75 0.80 0.85

Type of

heatingType of construction

Light Medium Heavy


Intermittent-

responsive

plant

0.55 0.70 0.85

Intermittent-

plant with

long lag

0.55 0.70 0.85

Continuous 1.0 1.0 1.0

Occupied Type of constructionperiod

(hours) Light Medium Heavy


4 0.68 0.82 0.96

7.5 0.96 0.98 0.99

8 1.0 1.0 1.0

12 1.25 1.14 1.03

Table 6:Factor W for length of workingweek.

Table 7:Factor Rp for response ofbuilding and plant.

Table 8:Factor D, for length of workingday.

nn


Table 9:Building fabric U-values

Figure 3

Opaque areas Watts /m2 / °C

Walls 0.4

Floor 0.4

Roof 0.3

Roof with a loft 0.25

U-values for windowsSingle glazed (timber) 4.7

Double glazed (timber) 2.8

Rooflights 2.8

Annual lighting energy consumption in relation to vertical glazed area of external

walls, for various average room depths.

14

13

12

Eu

Io

04

To 8

<

6

5

0

15m

12m

m

m

10 15 20 25 30 35 40 45 50 55 60 65 70 75

% glazing of internal area of external walls

The graph above is based upon the following assumptions:

Lights are switched on and off in response to daylight levels;

electric lighting is needed for the number of hours that the daylight is below 300 Luxas given in the table below for different design daylight factors;

Daylight Factor (DF)

DF below 0.5

DF 0.5 to 1.0

DF 1.0 to 2.0

DF 2.0 to 4.0

DF over 4.0

Number of hours whendaylight is below 300 Lux

1640 hours

1600 hours

1280 hours

700 hours

250 hours

a minimum maintained illuminance for general teaching spaces of 300 Lux, which canbe provided at a loading of 8 W/m2;

reflection factors: walls 30% (average including pinboard areas),ceiling 70%, floor 15%; and

floor-ceiling height 2.4m, window height 1.5m, cill height 0.9m.

If rooflights are used, their glazed area is multiplied by 180 degrees minus the angle ofthe rooflight to the horizontal, divided by 90 degrees, eg, 1m2 horizontal rooflight isequivalent to 2m2of vertical window. This equivalent area is then added to the area ofthe vertical glazing to determine the percentage glazing of the internal face of theexternal walls.

Occupancy gainsFor this calculation procedure, a constantrate of heat production from theoccupants is used. The total heatproduced is estimated from the numberof occupants within the building.

Typical rate of heat production

70 watts per pupil

Electric lightingThe average room depth should becalculated. For example, a daylit buildingwould have an average room depth offrom 6 9m. The average room depthsand percentages of glazing on the internalareas of the external walls are used to findthe lighting energy in kWh/m2 usingFigure 3 on the left.

The prediction of annual lighting energyuse obtained from Figure 3 is based on adesign load of 8 W/m2 and a designminimum maintained illuminance of 300lux at desk height. More accurateinformation for the proposed design maybe used if available.

Typical load

8 watts/m2 for an illuminance of 300 Lux

Ventilation lossesThe background ventilation (infiltration)rate will depend upon the type of windowsystem used and the air leakagecharacteristics of the buildingconstruction.

If a heat recovery system is used, theventilation losses can be reduced by 50%.However, there will be additionalelectrical energy used for fan power and aneed for maintenance of filters, ductworkand grilles.

Minimum ventilation requirement

3 litres/second/person of fresh air

Typical ventilation rate

4 6 litres/second/person of fresh air

36

Hot water serviceHot water energy use varies according tothe type and use of the building.However as an approximation the figurebelow may be used.

Typical rate 2 watts/m2

This value does not include hot water use for

kitchens

Heating circulatorsFans and pumps for use in the heatingsystem are often located outside of thebuilding in which case they will producean electrical load but no heat gain.

Typical load 2 watts/m2

Miscellaneous power gainsIncluded in the figure below, are all smallpower teaching uses such as computersand audio-visual equipment. It is alsointended to include the use of generalcleaning equipment.

Individual high load equipment such askilns and cooking appliances are notincluded in the calculation.

Teaching and cleaning

equipment 5 watts/m2

Solar GainsMost buildings benefit from solar heatgains to some extent. If carefulconsideration is given to the use of solargains at the design stage these benefitscan be optimised2 (see Section C).

Design and methods of using solar gainsare many and varied and separateindependent calculations or computersimulations can be used to assess theeffects of different designs. However, asimple method of accounting for theeffect of direct solar gains on spaceheating is included in this calculationprocedure.The solar gains are calculatedusing a solar utilitization factor related tothe area of glazing, the orientation of thewindow and the type of glazing used


(ie, single, double or triple). This methodis based on Section B5.2 of the CIBSEApplications Manual on WindowDesign(3).

The solar gains are calculated from theformula:

Solar gain = I([areas x solar utilization] xAtd x Ec) /(gross floor areax 1000)

Where solar utilisation3 = 1000fT TS

and:

f = 0.65

T

0.24Dd

= 0.87(single) or 0.76 (double) or0.66 (triple glazing)3

T = 0.8

The average solar radiation on a verticalsurface

S = 1.5 (north),

4.31 (south),

2.43 (east & west),

3.96 (horizontal)

Dd = 1.3 x D15.5

The equation reduces to:

Solar gain = I,(areas x S x 100 x f x x Tx W x DR xR x Di) /(gross floor area)

Values for S, f, Ts and T are taken fromSection B5 of the CIBSE ApplicationsManual which describes the calculationmethod in more depth and gives tablesfor these factors.

W, OR R and D are from the CIBSEdetermination of the Model Yeardescribed on pages 28 and 29.

(See example calculation on page 33,paragraph f. Solar gains).

Other gains and energy usesThe period of full occupancy at 5 hoursper day is taken for metabolic gainsduring the heating season,(ie, 136 x 5 = 680 hours). [5 hours isused in preference to 7.5 hours to allowfor lunch and other breaks and for classchangeover]

37

References2 Department for Education,Building Bulletin 79, PassiveSolar Schools, a design guide,HMSO 1994,ISBN 0 11 270876 5, £19.95.

3 CIBSE Applications ManualWindow Design AM2: Section85.2 Useful Heat Gains 1987,ISBN 0 900953 33 0.


Hot water and miscellaneous powerrequirements are assumed for 1500 hoursper annum = (7.5hrs x 200days); usefulheat gains from them are provided onlyover the heating season for 1020 hours =(7.5hrs x 136days). [136 days is the fullyoccupied part of the heating season, ie,minus the 8 cleaning days]

Heating circulators and fans operate overthe heating season only, for 1080 hoursper annum = (7.5hrs x 144 days).

It is assumed that 80% of the lighting isused over the heating season and that thiscontributes useful heat to the space.

Table 10

Type of system

Space heating:

Electric

Fan assisted electric off-peak heaters

Direct electric floor and ceiling systems

Gas/Oil boiler type

Automatic centrally fired

radiator or convector system

Automatic centrally firedwarm air ventilation system

Seasonal efficiency %

Conventional

63

60

Domestic hot water heating:Gas and oil fired boiler/storagecylinder

Off-peak electric storage with

cylinder & immersion heater

Instantaneous gas multi-point heater

Instantaneous electric multi-point heater

District heating with central calorifiers anddistribution

90

95

High performance

76

73

56

80

62

95

56

Condensing

87

84

Table 11 KgCO2 per kWh of delivered energy

Electricity 0.58

Natural gas 0.21

Solid fuel 0.34

Oil 0.29

Sustainable wood orbiomass fuel

0.01

In the case of systems using heat pumps, the CO2conversion factors for whichever fuel is used bythe heat pump, should be divided by the coefficientof performance of the heat pump.

Kilogrammes of carbon dioxide can be convertedto tonnes of carbon by multiplying by 0.048

Seasonal system efficienciesaveraged over the heatingseasonui4 (based on grosscalorific values of fuels)The design heating requirement isdivided by the seasonal efficiency of theheating system to obtain the deliveredfuel equivalent, ie, the amount of gas, oilor electricity supplied to the school. SeeTable 10.

Carbon dioxide (CO2)emissionsThe level of CO2 produced by differentfuels varies according to the initialproportion of carbon and the degree ofprocessing required to arrive at thedelivered fuel.

The delivered energy of a fuel ismultiplied by the carbon dioxideconversion factor to give the carbondioxide equivalent. Factors for typicalfuels are given in Table 11.

Note that each unit of electricitydelivered consumes three times as muchprimary energy and emits three times asmuch CO2 as a similar unit of gas due toconversion losses at the power station

Example calculationTo calculate the annual CO2 ProductionValue for a 450 place, single storeysecondary school building with a gross floorarea of 3565m2 and a perimeter of 432m.

Assume a gas-fired central boiler withradiators and hot water storage cylinder,Temperature differenceAtd = 19°C (internal 18°C, external -1 °C).

Given:

Local 20 year average for the Midlands

Dd = 2014.

Floor-ceiling height = 2.4m

Overall height = 3.0m

Room depth (Figure 3) = 8.0m

Overall window : wall ratio = 0.29

(internal elevation of external wall)

38

The building is medium weight. Theoverall percentage glazing is distributedas follows :

North 25%

South 45%

East 25%

West 25%

Heating is intermittent with responsiveplant, Rp = 0.70.

U-values and installed loads are asrecommended earlier in this section.

Double glazing and a ventilation rate of15m3/person/hour (4.2 litres/second/person) have been used.

In the example calculation that followsthe default values, as in the recommendeddesign data on pages 29 to 32, forU- values (maximum values), incidentalgains, domestic hot water loads, lightingloads, miscellaneous power and heatingcirculator loads have been used.

In practice these values can beconsiderably improved on and defaultvalues should be replaced by actual valueswhere available.

a. Fabric losses

Fabric losses = E(Area x U-value) x Atdgross floor area

example:wall losses = [(735 x 0.4) x 19]/3565

=1.57 W/m2

b. Ventilation losses

Ventilation losses= [1113/person/hour x 0.33 x Atd ]

(density of occupation)

example:ventilation losses = [15 x 0.33 x 19]/

(3565/450) = 11.87 W/m2

c. Miscellaneous power gain

Miscellaneous power= [installed load (W/m2)] x [hours of

operation] /1000

example:miscellaneous power = (5 x 1020/1000)

= 5.1 kWh/m2


d. Lighting gain

The value for electric lighting is takenfrom Figure 3, using the overall glazingratio and the average room depth. Of thislighting use, 80% is assumed to be duringthe heating season. This is a useful spaceheating gain and is used to off -set theheating requirement.

O example:

lighting gain = 0.8 x 8 = 7.04 kWh/m2

e. Occupancy gain

Occupancy gain= [metabolic rate (W/m2) x number of

occupants x hours occupied] /(floorarea x 1000)

example:occupancy gains = [70 x 450 x680]/

(3565 x 1000) = 6.01 kWh/m2

f. Solar gains

Solar gain = E[(areas x S) x 100 x f x T,xTxWx DR x R x D1] / (gross floor area)

Values for f, T and T are from page 31.T = 0.76 for double glazing. W, DR, DIare from page 29.

example:R = 0.70 from above

solar gain= [(65x1.5)±(104x4.31) +(65x2.43) +

(65x2.43)1x (100 x 0.65 x 0.8 x0.76 x 144/176 x 0.7 x 0.96)/3565

= 4.20 kWh/m2

The spreadsheet on page 34 shows thatfor the example school, the predictedannual Carbon Dioxide Production Valueis 19.51 kgCO2 /m2 of gross floor area.This has been plotted in Figure 4 on page35 on the target graph for new secondaryschools. The result is just inside band Afor good low energy design.

ReferencesCIBSE Guide B18 Installation

and Equipment Data, 1988.

4 Good Practice Guide 16Guide for Installers ofCondensing Boilers inCommercial Buildings EnergyEfficiency Office Best PracticeProgramme, October 1990.


Energy (carbon dioxide) rating calculation sheetExample Calculation

Floor area

Factors for use with

3565

Figure 3 in lighting calculationAverage room depth 8

Window : wall ratio 0.29

Occupancy 450Density of occupancy 7.92

Design temperature Internal 18 °C

External -1 °C

Temperature difference 19 °C

square metres excluding kitchens and swimming pools

metres

percentage glazing on internal elevation of external wall

persons

square metres of gross floor area per person

Local 20-year degree day average 2014

Model year factors page 28 W 0.8 School days in heating season 144 DR 0.82 Rp 0.70 DI 0.96

Losses Area

Opaque area page 33(a) Walls 735Roof 3565Floor 3565

Windows North 65South 104East 65.

West 65

Rooflights

Ventilation rate 15 m3/hour/person

U-value Watts/m2

0.4 1.570.3 5.700.4 7.602.8 0.942.8 1.502.8 0.942.8 . 0.94

Ventilation loss page 33(b) 11.87 Watts/m2

Convert to kWh/m2: (divide by 1000 and multiply by corrected equilvalent hours of operation 1455 ) 4539 kWh /m2

GainsIncidental Installed load (W/m2) Hours of operation kWh/m2

Miscellaneous power page 33(c) 5 1020 5.10Lighting from Figure 3 page 33(d) 7.04

Metabollic rate

(W/person)

Hours of

occupancy

Occupancy page 33(e) 70 680 6.01

Factors for solar gain calculation page 31Transmission of glazing T 0.76 Utility factor f 0.65 Shadow factor Ts 0.8

Solar gain factor 0.0048Solar gain pages 31 and 33(f) Area Average solar radiation Solar gain kWh/m2

North 65 1.5 0.48

South 104 4.31 2.19

East 65 2.43 0.77

West 65 2.43 0.77

Roof lights 0 3.96 0.00

Sum of solar gains 4.20

Total gains 22.35 Oft/m2

Heating requirement: losses -gains 23.04 kWh /m2

Delivered fuel equivalent: (divide by heating system efficiency 0.63 ) 35.57 kwh/m2

Carbon dioxide equivalent: (multiply by carbon dioxide conversion factor 0.21 ) 7.68 KgCO2/m2 (i)

Other uses Installed Load (W/m2) Hours of operation kWh/m2

Domestic hot water 2 1500 3

Delivered fuel equivalent: (divide by hot water system efficiency 0.56 ) 5.36Carbon dioxide equivalent: (multiply by carbon dioxide conversion factor 0.21 ) 1.13 KgCO2/m2 (ii)

Electrical energy Installed Load (W/m2) Hours of operation kWh/m2

Lighting (Figure 3) 8.8

Miscellaneous power 5 1500 7.5

Heating circulators 2 1080 2.16

Total electric 18.46 kwh/m2

Carbon dioxide equivalent: (multiply by carbon dioxide conversion factor 0.58 ) 10.71 KgCO2/m2 (iii)

Total Annual Carbon Dioxide Production Value(heating + hot water + electrical) (i + li + iii) 19.51 Kg carbon dioxide per square metre of gross floor area

2/1 40


Figure 2:Secondary Schools

E

Oao

100

90

80

70

60

50

40

30

20

10

0

1,500 3,000 4,500 6,000 7,500 9,000 10,500 12,000 13,500 15,000

Gross floor area/m2

However there is still scope forimproving the energy efficiency of thedesign.

If the predicted annual CO2 ProductionValue had been above the maximumpermitted(ie, the top of band I)), thenthe design would have been reconsideredin order to identify the factors whichproduced the excess energy consumption.These factors would then be altered toimprove the design so that it met thedesign target.

The calculation was repeated with thefollowing energy. saving features:

improved U-values of

roof

walls and floor

= 0.25 W/m2/"C,

= 0.35 W /m2 / °C,

triple glazed timber framed windows= 0.8 W/m2/"C;

Total solar radiant heat transmission oftriple glazing, T = 0.66a condensing boiler;

a direct gas-fired hot water generator;

the minimum ventilation rate of10m3/person/hour;

photoelectric lighting controls; and

a reduced miscellaneous power demandof 3W/m2.

The resulting annual CO2 ProductionValue was 12.92 KgCO2 /m2, animprovement of 34% on the previouscalculation putting the design well insideband A.

This example shows the value of thiscalculation in early design decisions andthat highly energy efficient designs arepossible using current constructiontechniques.

U

Figure 4:The predicted annual CO2Production Value, at 19.51kgCO2/m2 gross floor area, isin band A considerably betterthan the maximum permittedDesign Target.

References1 CIBSE Guide B18 Installationand Equipment Data, 1988.

2 Department for Education,Building Bulletin 79, PassiveSolar Schools, a design guide,HMSO 1994,ISBN 0 11 270876 5, £19.95.

3 CIBSE Applications ManualWindow Design AM2: SectionB5.2 Useful Heat Gains 1987,ISBN 0 900953 33 0.

Good Practice Guide 16Guide for Installers ofCondensing Boilers inCommercial Buildings EnergyEfficiency Office Best PracticeProgramme, October 1990.

Department of Trade andIndustry, Digest of UK EnergyStatistics.

Energy Efficiency Best PracticePublications:

Introduction to EnergyEfficiency in Sports andRecreation Centres.

Good Practice Guide 129Good housekeeping in drysports centres.

Good Practice Guide 130Good housekeeping inswimming pools a guide forcentre managers.

Good Practice Guide 173Energy efficient design of newbuildings and extensions forschools and colleges, 1997.

For further information contactBRECSU, address given onpage 36.


ReferencesDepartment for Education,Building Bulletin 73, A guide toenergy efficient refurbishment,ISBN 0 11 270772 6, HMSO,1991, £8.50.

BRECSU, Department of theEnvironment, Introduction toEnergy Efficiency, BuildingEnergy Efficiency in Schools, Aguide to a whole schoolapproach, 1996.

Reference should also bemade to the Energy EfficiencyOffice Good Practice Guidesand Energy ConsumptionGuides. These can be obtainedfree of charge from theBuilding ResearchEstablishment ConservationSupport Unit (BRECSU),Building ResearchEstablishment, Garston,Watford, WD2 7JR,Tel: (01923) 664258.

Building ResearchEstablishment, The SchoolToolkit, A guide for reducingcosts and environmentalimpacts, 1996, is available oncomputer disc from theBREEAM Office,Tel: 01923 664462Fax: 01923 664103

Organisations promotingenergy conservation inschoolsBRECSU Department of theEnvironment sponsored adviceon best practice and design(address above).

EST manages energyconservation schemes andgrants,Energy Saving Trust,11-12 Buckingham Gate,London, SW1E 6LB.Tel: 0171 931 8401Fax: 0171 931 85488

CREATE national coordinatingbody for energy education,The Centre for Research,Education and Training inEnergy, Ken ley House,25 Bridgeman Terrace,Wigan, WN1 1TD.Tel: 01942 322271.

36

Energy managementThe management of a building canenhance or nullify the design effortexpended to achieve efficiency and lowfuel consumption. As these guidelinesare intended to aid energy conservation

in existing buildings as well as in new, ashort summary of good managementpractice is appropriate. Staff and pupilsshould be made aware of the issues andencouraged to play their part in energymanagement.

Checklist of energy management measures

1 In the heating season, do not cooloverheated rooms by openingwindows or using extractor fans.Adjust the heating system instead,and where possible set thermostats togive the recommended roomtemperatures. If additional ventilationis still required, open windows theminimum amount or use fans for theminimum period. Excess ventilationcauses over-cooling and an increase inthe heating requirement.

2 Economise on the use of hot water,subject of course to the need forcleanliness and hygiene. The use ofspray taps and/or a decentralizedsystem helps to minimise energy waste.Caretaking and purchasing staffshouldbe given information on cold watercleaning compounds. These caneliminate the need for hot water forcleaning during periods out of normalschool hours.

3 Encourage staff and pupils to wearclothes that are suitable for the requiredtemperatures.

4 If separate zones of a building can beheated independently, allocate roomsfor both daytime and use out ofschoolhours so that the plant is usedeconomically, and heat and light arenot supplied to unused areas.

5 Start heating plant no earlier than isnecessary to achieve normal workingtemperatures by the beginning of theoccupied period. The plant can also beturned off some time before the end ofoccupation. Optimum stop/startcontrols can achieve this. Ifa buildingenergy management system is installeda member of staff should be trained touse it and be responsible for itsoperation.

6 External doors should be kept closedas much as possible in cold weatherand all windows closed overnight.Blinds or curtains drawn at dusk willhelp conserve heat overnight.

7 Equipment with high electrical powerconsumption should not be used attimes during the winter months whenthe total electrical load from othersources is likely to be near the`Maximum Demand' limit. Themaximum demand meter measures theamount ofelectricity being used at anyinstant. The highest reading in anymonth or quarter (depending on thetariff) is often used to calculate thestanding charge. The increase instanding charge caused by exceedingthe limit can increase the cost of theelectricity for the winter quarter by asmuch as three times.

42

section Lnergy (carbon aioxicie) rating

Energy (carbon dioxide) rating calculation sheet

Floor area square metres excluding kitchens and swimming pools

Factors for use with Figure 3 in lighting calculationAverage room depth metresWindow : wall ratio percentage glazing on internal elevation of external wall

Occupancy persons

Density of occupancy square metres of gross floor area per person

Design temperature Internal °C

External `C Local 20-year degree day average

Temperature difference °C

Model year factors page 28 W School days in heating season DR RP DI

Losses Area U-value Watts/m2Opaque area page 33(a) Walls

Roof

FloorWindows North

SouthEastWest

Rooflights

Ventilation rate m3/hour/person Ventilation loss page 33(b) Watts/m2

Convert to kWh/m2: (divide by 1000 and multiply by corrected equilvalent hours of operation I kWh /m2

GainsIncidental Installed load (w/m2) Hours of operation kWh/m2

Miscellaneous power page 33(c)Lighting from Figure 3 page 33(d)

Metabollic rate Hours of

(N/Person) occupancy

? Occupancy page 33(e)

Factors for solar gain calculation page 31Transmission of glazing T Utility factor f Shadow factor TsSolar gain factor

Solar gain pages 31 and 33(f) Area Average solar radiation Solar gain kWh/m2

North

South

East

West

Rooflights

Sum of solar gains

Total gains kWh /m2

Heating requirement: losses - gains km/m2Delivered fuel equivalent: (divide by heating system efficiency I kWh/m2Carbon dioxide equivalent: (multiply by carbon dioxide conversion factor ) KgCO2/m2 (i)

Other uses Installed Load (w/m2) Hours of operation kWh/m2

Domestic hot waterDelivered fuel equivalent: (divide by hot water system efficiency )

Carbon dioxide equivalent: (multiply by carbon dioxide conversion factor ) KgCO (ii)

Electrical energy Installed Load (W/m2) Hours of operation kWh/m2

Lighting (Figure 3)

Miscellaneous power

Heating circulators

Total electric kWh /m2

Carbon dioxide equivalent: (multiply by carbon dioxide conversion factor ) KgCO2/m2 (iii)

Total Annual Carbon Dioxide Production Value(heating + hot water + electrical) (i + ii + iii) Kg carbon dioxide per square metre of gross floor area

4 37

section r: tnergy ( carbon aioxiaej rating

Energy (carbon dioxide) rating spreadsheet formula sheet

A 1 6 C D I E I F I G I FI I I

1

2

Floor area exc. kitchens & swimming pools

Factors for use with Figure 3

square metres.

metres

percentage glazing on internal elevation of external wall

persons

square metres of gross floor area per person

4

5

6

7

a

Average room depth

Window: wall ratio

Occupancy

Density of occupation =Cl/C7a

10Model year factors page 28 W 0.8 Days in school heating season 144

Rp 0.7 DI 0.96 I DR =H9/176

1 2_

1 3

14

15

1617

Design temperature Internal degrees Centigrade

degrees Centigrade

degrees Centigrade

Watts/m2

Local 20-year degree day average 1

External

Temperature difference =D12-D13I

Losses Area U-value

I a

19

20

Opaque areas (page 33(a)) Walls

Roof

Floor

=D18 x C18 x $D$14/SC$1

=DI9 x C19 x $D$14/$C$1=D20 x C20 x $D$14/SCS1

21

22

23

24

25

Windows North

South

East

West

Rooflights

=021 x C21 x $D$14 /$C$1

=D22 x C22 x $D$14/SCS1

=023 x C23 x $D$14/SCS1=D24 x C24 x $D$14/$C$1

=D25 x C25 x $D$14/$C$126

27 m3/person/hour litres/second/person Vent loss(page 33(b)11=1827 /m2

Watts/m2

Ventilation rate 1=027/0.2778 x 0.33 x D14/C8) 1Watts

2829 Total losses: (fabric + ventilation losses) I=SUM(E18:E25)+G27 I

3031

a 2

Convert to kWh/m2: (divide by 1000and multiply by corrected equivalent hours of operation kWh/m21=24 0 1114 x1.3 x C9 x HIO x C10 x EIO/D14) I=E29 x (E32/1000( I

3334

35 Gains

3 6 Incidental37

38

Installed

Miscellaneous power page 33(c)Load(W/m2)

I

Hours of operationkWh/m2kWh/m2

kWh/m2

kWh/m2

, 5 1020 =D38 x F38/100039 Lighting page 33(d) =0.8 x F634041

42 Occupancy page 331e)

Metabolic rate(W/person)

1

Hours of occupancy

1 70 I 680 1=(D42 x F42 x $C$7) /(SCS1 x 1000) I434 4 Factors for solar gain calculation page 31

Solar gains

4 s Transmission of glazing T 0.76 Utility factor f 1 0.65 Shadow factor TS1

0.84 5 Solar gain factor =100*D45*F45*B45*C9*H10*C10*E10/C1474 8 Solar gains pages 31 and 33(f) Area Average Solar radiation on vertical surface49

50

51

s253

54

North

South

East

West

Rooflights

=049*$B$46*E49

kWh/m2

=D50.$8$46'E50=D5158546*E51=D52.58546'1E52=D53*$B$46*E53

Sum of solar gains =SUM(G49+G50+G51+G52+G53)5 5 Total gains =G38+G39+G42+G5456

57 Heating Requirement: Losses - gainskWh/m2KgCO2/m2 (i)

kWh/m2kWh/m2KgCO2/m2 (ii)

=G32-G55

5 a Delivered fuel equivalent: (divide by heating system efficiency ) =G57/E585 a Carbon dioxide equivalent: (multiply by carbon dioxide conversion factor ) =G58 x E596061 Other uses Installed load (W/m2) Hours of operation62 Domestic hot water 1 2 1500 =D62 x F62/100063 Delivered fuel equivalent (divide by hot water system efficiency ) =G62/E6364 Carbon dioxide equivalent: (multiply by carbon dioxide conversion factor ) =G63 x E646566

.Electrical energy Installed load (W/m2) Hours of operation kWh/m2

67 Lighting (Figure 3) 8.8

kWh/m2KgCO2/m2 (iii)

6 a Miscellaneous power 5 1500 =C68 x E68/10006 a Heating circulators 2 1200 =C69 x E69/100070 Total electric =F67+F68+F6971 Carbon dioxide equivalent: (multiply by carbon dioxide conversion factor 1 ) =G70 x E71

72

7374

Total Annual Carbon Dioxide Production Value(heating + hot water + electrical) (i+ii+iii) kg carbon dioxide per square metre of gross floor areaI .G59+G64+G71

4438

The School Premises Regulations summary sheet

Acoustics

Each room or other space in a school building shall have the

acoustic conditions and the insulation against disturbance by noiseappropriate to its normal use.

Lighting

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

(a) shall have lighting appropriate to its normal use; and

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

(2) Subject to paragraph (3), the maintained illuminance of

teaching accommodation shall be not less than 300 lux onthe working plane.

(3) In teaching accommodation where visually demanding tasks

are carried out, provision shall be made for a maintained

illuminance of not less than 500 lux on the working plane.

(4) The glare Index shall be limited to no more than 19.

Heating

(1) Each room or other space in a school building shall have such

system of heating, if any, as is appropriate to its normal use.

(2) Any such heating system shall be capable of maintaining in

the areas set out in column (1) of the Table below the airtemperature set opposite thereto, in column (2) of that Table,at a height of 0.5m above floor level when the external airtemperature is -1°C:

(1)

Area(2)

Temperature

Areas where there is the normal level of

physical activity associated with teaching,

private study or examinations

18°C.

Areas where there is a lower than normal level

of physical activity because of sickness or

physical disability including sick rooms and

isolation rooms but not other sleeping

accommodation

21°C.

Areas where there is a higher than normal

level of physical activity (for example arising

out of physical education) and washrooms,

sleeping accommodation and circulation

spaces.

15°C.

(3) Each room or other space which has a heating system

shall, if the temperature during any period during which it is

occupied would otherwise be below that appropriate to itsnormal use, be heated to a temperature which is soappropriate.

(4) In a special school, nursery school or teaching

accommodation used by a nursery class in a school the

surface temperature of any radiator, including exposedpipework, which is in a position where it may be touched bya pupil shall not exceed 43°C.

Ventilation

(1) All occupied areas in a school building shall have

controllable ventilation at a minimum rate of 3 litres offresh air per second for each of the maximum number ofpersons the area will accommodate.

(2) All teaching accommodation, medical examination or

treatment rooms, sick rooms, isolation rooms, sleepingand living accommodation shall also be capable of beingventilated at a minimum rate of 8 litres of fresh air persecond for each of the usual number of people in thoseareas when such areas are occupied.

(3) All washrooms shall also be capable of being ventilated ata rate of at least six air changes an hour.

(4) Adequate measures shall be taken to prevent condensation

in, and remove noxious fumes from, every kitchen and

other room in which there may be steam or fumes.

Water supplies

(1) A school shall have a wholesome supply of water for

domestic purposes including a supply of drinking water.

(2) Water closets and urinals shall have an adequate supply of

cold water and washbasins, sinks, baths and showers shall

have an adequate supply of hot and cold water.

(3) The temperature of hot water supplies to baths andshowers shall not exceed 43°C.

Drainage

(1) A school shall be provided with an adequate drainage

system for hygienic purposes and the general disposal ofwaste water and surface water.

4 5

39

Recommended constructional standards summary sheet

Acoustics

Values for maximum permissible background noise level and minimum

sound insulation between rooms are given in Tables la and lb and

values for reverberation times are given in Table 2 in Section A.

Lighting

Priority should be given to daylight as the main source of light in

working areas, except in special circumstances. Wherever possible

a daylit space should have an average daylight factor of 4-5%.

The uniformity ratio (minimum/average maintained illuminance) ofthe electric lighting in teaching areas should be not less than 0.8

over the task area.

Teaching spaces should have views out except in special

circumstances. A minimum glazed area of 20% of the internal

elevation of the exterior wall is recommended 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 the range 175 250 lux on the appropriate plane.

The type of luminaires should be chosen to give an average initial

circuit luminous efficacy of 65 lumens/circuit watt for the fixedlighting equipment within the building, excluding track-mounted

luminaires and emergency lighting.

Heating

The heating system should be capable of maintaining the minimum air

temperatures quoted in the School Premises Regulations. The heating

system should be provided with frost protection.

During the summer, when the heating system is not in operation, the

recommended design temperature for all spaces should be 23°C with a

swing of not more than +/- 4°C. It is undesirable for peak air

temperatures to exceed 28°C during normal working hours but a higher

temperature on 10 days during the summer term is considered a

reasonable predictive risk.

The air supply to and discharge of products of combustion from heat

producing appliances and the protection of the building from the

appliances and their flue pipes and chimneys should comply with

Building Regulations, Part J, 1990.

Thermal performance

The recommended maximum values of average thermal transmittance

coefficients (calculated using the 'Proportional Area Method' used in the

Building Regulations, PartL, 1994) are:

W/m2°C

Walls 0.4

Roof 0.3

Roof with a loft space 0.25

Floor 0.4

Doors, windows and rooflights 2.8

Vertical glazed areas (including clerestory or monitor lights) should not

normally exceed an average of 40% of the internal elevation of the

external wall. However, where a passive solar or daylight design

strategy has been adopted the percentage glazing may well exceed

40%. Also in areas prone to breakages due to vandalism the

replacement cost may justify the use of single glazing instead of

double glazing. In these cases the insulation of the rest of the building

fabric should be increased to compensate for the increased heat loss

through the glazing.

Horizontal or near horizontal glazing should not normally exceed 20%

of the roof area.

Ventilation

The heating system should be capable of maintaining the required

room air temperatures with the minimum average background

ventilation of 3 litres per second of fresh air per person.

Spaces where noxious fumes or dust are generated may need

additional ventilation. Laboratories may require the use of fume

cupboards, which should be designed in accordance with DfEE Design

Note 29. Design technology areas may require local exhaust

ventilation.

All washrooms in which at least 6 air changes per hour cannot be

achieved on average by natural means should be mechanically

ventilated and the air expelled from the building.

Hot and cold water

Cold water storage capacity in day schools should not exceed 25

litres per occupant.

All water fittings should be of a type approved by the WRC (Water

Research Centre), and all installations should comply with the Water

Supplies Bye laws (to be replaced by the Water Regulations).

Where a temperature regime is used to reduce the risk of

legionellosis, hot water storage temperatures should not be lower

than 60°C. However for occupant safety, to reduce the risk of

scalding, The School Premises Regulations require that the

temperature at point of use should not be above 43°C for baths and

showers and where occupants are severely disabled. This may be

achieved by thermostatic mixing at the point of use. It is also

recommended that hot water supplies to washbasins in nursery and

primary schools are limited to 43°C.

Particular attention should be given to the provision of facilities to

ensure the effective maintenance of systems.

Unvented hot water storage systems should comply with Building

Regulations, Part G3, 1992.

Energy (carbon dioxide) rating

In the design of a new building the calculated Annual CO2 Production

Value should be below the top of band D shown in Figure 1 or 2 (on

page 27), when the environmental standards in Sections B and C have

been achieved.

46

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This building bullet n provides environ-mental guidelines for architects andbuilding services engineers involved inthe design of school buildings.

t covers acoustics[lighting, heating andthermal performance, ventilation, watersupplies and energy consumption. Targetbands are given for energy consumptionn terms of the carbon dioxide produced.

9

ISBN 0- -271013-

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47p. · For ease of reference, the relevant minimum standards and the constructional standards are reproduced in boxes at the beginning of each section and are summarised on pages