Building Services for Historic Buildings

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Guide to buildingservices for historicbuildingsSustainable services fortraditional buildings

CIBSEThe Chartered Institution of Building Services Engineers222 Balham High Road, London S W 2 9BS

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The rights of publication or translation are reserved.No part of this publication may be reproduced, stored in aretrieval system or transmitted in any form or by anymeans without the prior permission of the Institution.

November 2002 The Chartered Institution of BuildingServices Engineers LondonRegistered charity number 278104ISBN 1-903287-30-8This document is based on the best knowledge available a tthe time of publication. However no responsibility of anykind for any injury, death, loss, damage or delay howevercaused resulting from the use of these recommendationscan be accepted by the Chartered Institution of BuildingServices Engineers, the authors or others involved in itspublication. In adopting these recommendations for useeach adopter by doing so agrees to accept fullresponsibility for any personal injury, death, loss, damageor delay arising out of or in connection wi th their use by oron behalf of such adopter irrespective of the cause orreason therefore and agrees to defend, indemnify andhold harmless the Chartered Institution of Building ServicesEngineers, the authors and others involved in theirpublication from any and all liability arising out of or inconnection with such use as aforesaid and irrespective ofany negligence on the part of those indemnified.Typeset by ClBSE Publications Department

Printed in Great Britain by Page Brothers, Norwich.

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AcknowledgmentsThis Guide originated in a proposal to CIBSE by Ma rtin Cook AAD ip MPhil(Cantab) RIBAof the Buildin g Research Establishment. Wit hout M artin's perseverance over a num ber ofyears, it would not have been completed. It has been drafted by Peter Warm CE ng MCIBSEM SL L and R ichard O xley BSc DipBldgCons MRICS IHBC, with funding from the CarbonTr ust unde r th e Action Energy programme. Picture research and case study collation wereundertaken by Catharine Bull. Assistance was provided by Dr W T Bordass. Martin Cookalso drafted one of the case studies. The project was supervised by a ManagementCommittee an d received invaluable advice and support from an Advisory Panel. T han ks arealso due to Noel B urns of BRE for his strategic help.Information for the case studies has been provided by many people, too numerous to listhere. F ull details are available on the C IBSE website www .cibse.org.Photographs have been provided by the following individuals and organisations: RichardOxley, Catharine Bull, Peter Warm, Douglas K ent (SPAB), John P reston (Cambridge CityCouncil), James Th orpe (Klober Ltd), Paul Jennings (Retrotec Europe Ltd), Joh n Young(Bath 8z NE Somerset Council), Martin C ook (BRE), Richard A tkins, Ian M ilford (Atkins),John W inter (John W inter 8z Associates), Th e National T rus t (T he Vyne, p. 42), AnnePhilps (Martin Thomas Associates), James Featherstone (Tuffin Ferraby z Taylor), BobSandford (Julian Harra p Architects), Neil Ha milton (Design Consultancy), David G ibbons(Urban Projects Ltd), Brough Skingley (English Heritage), Laurie Jonas, WarwickSweeney (RICS Awards), Michael Davies (Davies Sutton Architecture), Brian F ord (WSP),Peter CookNiew, Ingval Maxwell (Historic Scotland), Bob Ferris (CIBSE BuildingServices Heritage Group), G lasgow School of Art, Silabhadra Sen (Palace of Westminster,p. 73).Management CommitteeChairman:David Bailey (James Joy - David Bailey Partnership)Members: Ma rtin C ook (BRE), Jonathan David (CIBSE), Derek Lawrence (CIBSE), VerneyRyan (BRE).Advisory PanelRichard Atkins; Douglas Hogg (Cadw); Ingval Maxwell (Historic Scotland); Ian Milford(Atkins); Brough Skingley (English Heritage); Sarah Staniforth (National Trust); TimYates (BRE).CIBSE Publications ManagerJacqueline BalianCIBSE Co ordinating EditorJonathan DavidNote from the publisherThis publication is primarily intended to provide guidance to those responsible for thedesign, installation, commissioning, operation and maintenance of building services inhistoric buildings. It is not intend ed to be exhaustive or definitive and it will be necessaryfor users of the guidance given to exercise their ow n professional judgm ent when decidingwhether to abide by or depart from it.Tha nks are due to the following bodies for their support du ring preparation of thispublication

H I S T O R I C S C O T L A N DR THE NATIONAL TRUSTC A D WWSI PI, nis menc w w r t u z x n

E N G L I S H H E R I T A G E

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ContentsForeword by Simon Thu rleyChief Executive, English Heritage

'v i

Preface v i i1 Principles

1 . 1 General1.2 Scope and definitions1.3 Aim of this Guide1.4 Target audience1 . 5 T he relationship between b uilding services, energy efficiency and

conservation of the existing building stock and the environm ent1.6 Legislation1.7 Building R egulations1.8 Design principles1.9 Summary of design principles appropriate for work in

older buildingsSim ple nonintrus ive ways of impro ving energy efficiency.10 7

2 Building services 72.1 Modern expectations and standards of service 72.2 Increasing sustainability 72.3 T he value of historic building services 102.4 Re-using existing services 112.5 Criteria for th e selection of new building services in 11

historic building s2.6 Installing new building services and upgrading existing ones 11

3 Building fabric 153.1 Moisture m ovement in older buildings 153.2 Adding insulation 173.3 Ventilation, draughtproofing and fan pressurisation testing 183.4 Therm al mass and controls 193.5 Conservation heating 193.6 Initial and ongoing monitoring 20

4 A design approach for historic bui ldings4.1 Introduction4.2 T he project team4.3 An approach4.4 Design principles4.54.6 Commissioning4.7 Into th e future

Th e RIBA Plan of Work

2020212121242626

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5 Case studies5.1 Introduction to case studies5.1 Table of case studies in dicating relevance of eachGlossaryReferencesFurther readingUseful contactsIndex

27272776

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Foreword

Throughout my career, working in historic buildings, I have frequently beenfrustrated by building services engineers who, despite their best intentions, havebeen unsympathetic towards the important structures in which they work. Thislack of sympathy normally arises from a tension between the requirements ofowners and occupiers who wish to benefit from 2lst-c entury technology and t heneeds of the historic building, both in its fabric and in its appearance. Mostengineers do not have th e experience or knowledge to reconcile these competingpriorities adequately.Yes, mod ern technology and old buildings need n ot be enem ies. English H eritagebelieves that it is essential to give Englands historic built environm ent a long-termeconomic future and part of this m ust be fin ding ways to service historic buildingsthat are compatible with conservation and aesthetics. Th is Guide is an importantstep in helping bu ilding services engineers to understand the problems of workingin historic buildings and providing the m w ith an opp ortunity to learn from bestpractice.

Simon ThurleyChief Executive, English HeritageOctober 2002

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Preface

If you are about to install, upgrade or renew the services or make alterations toimprove the en ergy efficiency of an existing building, it is importan t to ask:Is the bu ilding historic orof a traditional construction?If it is, you m ust stop and think before taking any fur ther action. In m ost cases, thebuild ing services in a buildin g last typically 15 to 30 years, a fleeting event in th elife of an histo ric building. F or example, some parish chu rches are over 1000yearsold.Energy-efficient systems and improved thermal performance will save on runn ingcosts, maintain comfort and reduce carbon dioxide emissions. However, anyalterations or changes to the building services in a traditional building requirecareful plann ing to ensu re that the proposed work w ill be effective and beneficial.Whe n plan ning alterations, you need to develop a thorough und erstanding of thetypes of construction, the materials used and the likely impact of any proposedchanges. Modern materials and techniques can often be incompatible withtraditional construction, and careless alterations can cause serious harm to thebuildin g fabric, both directly and indirectly.Acting without thinking can be damaging, for the building and for theenvironment. This Guide will help you to avoid this, so that th e existing buildingstock can be managed and maintained in a more sustainable manner. It alsoillustrates best practice for techniques co mm only used in planning, installing andupgrading building services.When installed in an app ropriate and sympathetic manner, b uilding services canassist the preventive conservation of historic buildings, prolong their lives inbeneficial use, improve the internal environment, and so bring immense culturaland environmental benefits. Building conservation is a sustainable form ofproperty developmentT h e case studies starting on page 27 illustrate many issues that were taken intoaccount in making approproate and efficient alterations; and the often imaginativesolutions tha t results.

Peter Warmand Richard OxleySeptember 2002

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Figure 1 What so often happensThi s chancel screen in a Grade I l isted church was insensit ively punched through with heating pipework. Th escreen is thou ght to have Tud or origins and was untouc hed from t he Jacobean period (1603-1689) until thisrecent act of vandalism. Simply stopping and thinking of more app ropriate and less damaging routes beforework started would have redu ced greatly th e physical damage to irreplacemable hsitoric fabric; and might haveavoided it altogether.

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1

Guide to building services for historic buildings

1 Principles1 I GeneralPut at its simplest, sustainability is about ensuring that theactivities that we have to cany out to meet our range of needscan be continued indefinitely. To do this, we must ensure thatthese activities, whether they are power generation, farming,waste disposal or tourism, do not irreversibly damage theenvironment and its assetsEnglish Heritage, Sustaining the historic environment ()T h i s G u i d e i l l u s t r a t e s h o w o n e c a n p u t s u s t a i n a b l ed e v e l o p m e n t i n t o e v e r y da y p ra c t ic e w h e n u p g r a d i n gb u i l d i n g s e r vi c e s i n t h e e x i s t i n g b u i l d i n g s t o c k . I tpromotes a holistic and interdisciplinary approach basedon an appreciation and understandin g of:( i ) t h e h i g h l y i n d i v i d u a l n a t u r e o f m a n y o l d e rbuildings, reflecting the unique manner in whichthey have developed over time;

the materials and m ethods of construction;the existing and inten ded performance; andthe formal recognition and protection offered bylegislation.

( i i )( i i i)zv)

Many older buildings give a special value and interest toou r cul ture: they are of archi tectural and/or h is tor icali m p o r t a n c e a n d t h e i r m a t e r i a l s a n d m e t h o d s o fconstruction are no longer in common use. Their perfor-mance characteristics are different from those of modernb u i l d i n g s . T h e i r f o r m a l r e c o g n i t i o n b y l e g i s l a t i o n ,Bui ld ing Regula t ions and Br i t i sh S tandards p laces anob l iga tion on those who work w i th o lder bu i ld ings toreflect and take account of these qualities.Older buildings are a nonrenewable resource which needsto be t reated as such. This Guide highlights basic prin-c i pl e s t o c o n si d e r w h e n w o r k i n g w i t h t h e m . T h e i rindividuality prevents it being prescriptive t identifiesissues that should to be taken into account, but each casemust be considered on its own merits.T h e i m p o r t a n t a n d s e n s i ti v e n a t u r e o f m a n y o l d e rbuildings an d their fabric demand s that work on them:( a ) i s car r ied out in an appropr iate and compat iblemanner ;b ) t a k e s p r o p e r a c c o u n t o f t h e w a y t h e y w e r e

constructed an d were intend ed to perform;(c) causes the minim um amount of intervention; and( d ) is reversible wh erever possible.It is recognised as a global priority to continue to use thee x i s t i n g b u i l d i n g s t o ck w h i l e i m p r o v i n g i t s e n e r g y

efficiency.(*) If we are to achieve w orthwhile progress inachieving sustainable development and reducing carbond i o x i d e e m i s s io n s , w e n e e d t o i n c r e a s e t h e e n e r g yefficiency of all the UKs existing buildings, not just the500000 or so that are listed as of architectural or historicinterest. This Guide therefore covers not only historicbuildings but all buildings of traditional construction.

1.2 Scope and def in i t ionsT h i s Guide i s a imed a t bo th historic a n d traditionalbuildings.1.2.1 Histor ic build ing sA p p r o v e d D o c u m e n t s L1 a n d L o f t h e B u i l d i n gregulation^(^) treat the following as special cases whichneed to be considered on their individual m erits:( i ) listed buildings;( i i )( i i i)

buildings situated in conservation areas;b u i l d i n g s o f l oc a l a r c h i t e c t u r a l o r h i s t o r i c a linteres t and w hich are refer red to as a mater ialconsideration in a local authoritys developmentplan; and

( i v ) b u i l d i n g s w i t h i n n a t i o n a l p a r k s , a r e a s o fou t s t and ing na tu ra l beau ty and wor ld her i t agesites.Additional legislation formally protects scheduled ancientm o n u m e n t s , l i s t e d b u i l d i n g s a n d b u i l d i n g s i n c o n -servation areas.Be f o re t h e s t a r t of p l a n n i n g a n d d e s i g n o f b u i l d i n gservices and energy-efficiency measures, all historic andt r ad i t iona l bu i ld ings o t j us t t hose wi th s t a tu to ryprotection eed care and attention to understand whatthey are, how they work and the performance required.Th is background wi l l then dictate the appropr iateness ,compatibil i ty and nature of alteration and improvementthat can be carried out.1.2.2 Tradit ional build ingsF o r t h e p u r p o s e of t h i s G u i d e , t r a d i t i o n a l b u i l d i n g sinclude not only buildings formally recognised for theirarchi tectural or his tor ic interes t , but a l l bui ldings tha tneed to be approached in a manner which ref lects theindividual characteristics of their co nstruction.Tradi t ional ly cons t ructed bui ldings can be of any s ize,s h a p e o r f o r m . C o n s t r u c t i o n m a t e r i a l s a r e d iv e r se ,sometimes even in a single building. W alls are no t only ofs tone an d b r i ck , bu t can be o f ea r th ( cob) o r h i s to r i c

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timber frames (often with thin render or weatherboardcladding, or with infill between the structural timbers).

Most modern buildings are made of hard, strong andimpervious materials. To exclude moisture, they rely onphysica l barrie rs such as dam p-pr oof courses andmembranes, cavity walls and cladding. Historic and

traditional buildings are completely different. Many havesolid walls and most have porous fabric which bothabsorbs and readily allows the evaporation of moisture.This is often known as the ability of the building fabric to'breathe', i.e. to have a low vapour resistance. It is ofteninappropriate to repair such buildings with modernmaterials. For example, if soft sandstone walls arerepointed with hard Portland cement rather than soft limemortar, not only will they look different and lose theirattractive patina of age, but the new pointing may wellcause the sandstone to weather badly, spall and erode while the hard cement remains (see Fig. 20 on page 16).

Traditional buildings account for one-quarter of the UK'sexisting building stock. Making appropriate and efficientalterations to them as opportunities arise will be a positiveand worthwhile contribution to reducing carbon dioxideemissions.

Figure 2 shows the proportion of UK buildings to whichthe principles in this Guide may apply. Although mosthistoric buildings are of traditional construction, somelisted buildings are relatively new, or include highlyinnovative or unusual construction methods, needingspecial consideration. Examples are shown in the casestudies in Section 5 (e.g. case study 7).

1.3 Aim of thisGuide

This Guide aims to make a sustainable approach tohistoric and traditional buildings an everyday activity, notthe exception. Recognition of the special characteristics ofthese buildings and how best to meet their needs will be afundamental step towards the better and more sustainablemanagement of these existing resources. By adopting goodpractice, one can simultaneously achieve social, cultural,economic and environmental benefits.

Within an overall aim to improve both the internalenvironment and energy efficiency, it is important to takeaccount of the particular circumstances of the buildingand to balance all the issues. For example:

Historic

Traditional - 3%

Traditional - 22%

Modern - 75%

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Pr inc ides 3

Aim 4: Specify environmentally conscious materialsAssess the w hole l i fe cos ts of new an d ex is t ingmaterials before mak ing changes.A s s es s t h e i m p a c t o f ne w m a t e r i a l s o n t h eenvironment.Assess the impact of new materials on the hea lth ofboth those who install them and the users of thebuildings.

1.4 Target audienceT h i s Guide will help all tho se who specify, install o r wishto improve the services and energy efficiency of buildingsof t radi t ional cons t ruct ion par t icular ly those formal lyidentified as of architectural or h istoric interest, e.g.

1.5

building services engineersprincipal a nd specialist contractorsmanufacturers and suppliersstructura l engineersarchitectsbuilding surveyorsquantity surveyorsmainten ance a nd facilities managersproject managers and cost consultantsclients uilding owners and usersregistered installers of equip m ent (e.g. FENSA forw i n do w s , O F T E C f o r o i l - f i re d h e a t i n g i n s t -allations an d C ORG I for gas installations)building control officers (and external providers ofbuilding control services)conservation officers (and nominated officers ina r e as w h i c h h a v e n o d e d i c a t e d c o n s e r v a t i o nofficer)historic building inspectorates and th eir advisersfun din g bodies an d their professional advisersconservators and historic building specialists whomay not themselves real ise the extent to whichenergy and bu ilding c onservation objectives can beharmonised.

The relationship betweenbuilding services energyefficiency and Conservation ofthe existing bui lding stock andthe environment

'It is depressing, at a time when highly sophisticated plant isbeing used for environmental control, to realise that throughoutmuch of history, buildings themselves were highly developedexamples of appl ied sc ience , achiev ing high leve ls ofperformance even when designers could not define or quantifjthe factors that they took into account.'Peter Burberry, Deteriorating design 1978)

T h i s Guide illustrates the principal factors which need tobe taken into acco unt to achieve more sustainable ways ofimproving the building services and energy efficiency ofexisting buildings, and to obtain an appropriate balancebetween historic building conservation and energy con-servation.Th ere is a complex relationship between building services,energy e ff ic iency, a i r an d m ois tu re movement a nd theconservation of the ex is t ing bui lding s tock. If only o nepart of this is considered (e.g. building services, historicbuildings or energy efficiency) the oversimplified view canlead to po ten t i a l danger s to the bu i ld ing , the h i s to r i cf abr i c and the env i ronment . Even apparen t ly f ami l i a rthings should not be taken for granted. For example, atBerg Cot t age ( case s tudy 2 ) m a n y p e o p l e w o u l d h a v eexpected the old single-glazed windows to have been themain source of high air infiltration, and have wanted toupgrade or replace them. In fact, most of the excess aircame throu gh the fabric, especially the walls.T h e three pil lars of global sustainabili ty, und erp inni ngthis Guide, are:Environmental: conserving our environm ent; issues such asglobal warming, pollution, biodiversity;Social: ensurin g that hum an needs are met; issues such asemploym ent, self governm ent;Economic: ensu r ing th at resources are avai lable; i s suessuch as funding, comparing schemes, developingself-sufficiency.

1.6 LegislationTh is is a brief introduction to a small part of the existingleg i s l a tion . Th e complex i ty o f the l eg i sl a t ion a nd theindividual nature of older buildings make it impossible toprovide detai led guidance here. Each bui lding must beassessed individually. If the re are any doubts or concerns,a d v ic e m u s t b e s o u g h t f ro m t h e l o ca l a u t h o r i t yconservation officer and the building control officer: i tc a n b e h e l p f u l t o h a v e a n e a r l y m e e t i n g w i t h t h e mtogether. Where the building is of special interest (e.g. ascheduled ancient monument or a building with Grade Io r 11 l is t ing) , the His tor ic B ui ldings Inspectorate mayalso need to be consulted.1.6.1 Background nformationBuildings in the U K have three principal forms of statu-tory protection:( a ) scheduled ancient monumentsb ) listed building s

( c ) buildings situated in con servation areas.Th ere are many reasons why older buildings require thisprotection, e.g. type, method of construction, style, specialstructural o r aesthetic features or finishes, and associationswith fam ous people, historic even ts or their designers andbui lders . Each b ui lding has i t s own par t icular qual i t iestha t c on t r ibu te to i t s spec ia l in t e r es t . Th e con t ro l l ingl e g is l at i on d i f fe r s f ro m c o u n t r y t o c o u n t r y a n d a n ya s s es s m e n t o f a p r o t ec t e d b u i l d i n g o r a n y a d v i c e o r

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4 Guide t o b uild ing services for historic building srecommendations made will need to reflect the relevantcontrols in force locally.1.6.2 Scheduled ancient monumentsAncient monum ents are pr imari ly protec ted under th eAncient Monuments and Archaeological Areas Act 1979and are not subject to th e Building Regulations. T hey aremostly structures (e.g. ruins), although a few buildingsor parts or buildings re scheduled. Th e num ber ofscheduled monuments is small, so they will not often beencountered. Note that scheduled monument consent isrequired for almost ANY work to a scheduled monum entncluding repair. If work is contemplated, the HistoricBuild ings Inspectora te must be approached for advicebefore anything at all is done.1.6.3 Listed buildingsIn England and Wales , l is ted bui ld ings are protec tedp r i m a r i ly u n d e r t h e P l a n n i n g ( L i s t e d B u i l d i n g s a n dConservation Areas) Act 1990. The equivalent legislationi n S c o tl a nd i s t h e P l a n n i n g ( L i s t e d B u i l d in g s a n dConservation Areas) (Scotland) Act 1997 and i n Irela nd isthe Planning (NI) Order 1991. Listed buildings are gradedto show their relative architectural or historic interest. InEngland and W ales the grades are:Grade I: buildings of outstanding historic or architecturalinterestGrade II*: particularly important buildingsGrade 11: of special interest, warranting every effort topreserve them.I n Sco t land and Nor the rn I re land , gene ra l ly s imi la rgrades A, B a nd C are used.Works that affect the character of a listed building requirelisted building consent. Consent is not normally requiredfor like-for-like repairs. Listed building controls apply toworks, both externally and internally, that would affect abui ld ings specia l in teres t , whether o r not the fea tureconcerned is specifically men tioned in th e list description.This effectively means that the whole of the building islisted, including existing services, fixtures and finishes.The listing of a building normally covers its curtilage sooutbuildings may also be listed. Any work that affects thecharacter of th e bui ld ing can only be carried out oncelisted building consent has been obtained from the localplanning authority. It is a crimina l offence to carry outworks without such consent.Carrying out works without listed building consent canlead to prosecution under the relevant legislation (seeabove). T h e legislation c onta ins provisions for fines of&20 000 and/or six months imprisonment. However, caselaw records fines of up to &75OO0. 4)Planning Policy Guidance Note 15 PPG 15) 5 ) rovidesd e t a i l e d a d v i c e a n d g u i d a n c e f o r t h o s e m a k i n g o rconsider ing appl ica tions for l is ted bui ld ing consent inEngland. Similar guidance exists for the remainder of theUK. 6-8)

1.6.4 Conservation areasIn conservation areas, there is generally a presumption infavour o f r e ta in ing bu i ld ings wh ich make a pos i t ivecontribution to th e character o r appearance of the area;a n d c o n s e n t i s r e q u i r e d t o t o t al l y o r s u b s t a n t i a l l yd e m o l i s h a n y b u i l d i n g , w h a t e v e r i t s q u a l i ty . M i n o rdevelopments are controlled to ensure that alterations donot detrac t f rom the conservat ion areas appearance:controlled alterations may, depending on the individualconservat ion area , inc lude cer ta in types of c ladding,inserting dormer windows and putting up satellite dishesvisible from the street. Co nservation area status alone doesnot provide the scope for stringent control, particularly incomparison with scheduled monuments and listed build-ings.Fo r dwelling houses in a conservation area, an Article 4Direction can give increased legal protection. This willr emove pe rmi t ted deve lopmen t r igh ts a f fec ting someaspec ts o f the ex te rna l appea rance , typ ica l ly doors ,windows, roofs and frontages. There may also be controlover adding external services such as gas and drain pipes,extract grilles an d boilerherm ina1 flues, especially to partsof the building visible from the street and other publicplaces. Not all conservation areas have Article 4 direct-ions, but where they are in force they influence the extenta n d n a t u r e o f a l t e r a t i o n s t h a t c a n b e m a d e , e v e n t ounlisted buildings.1.6.5 Recommended approach for buildings

protected by legislationDeterm ine whether the bui ld ing is pro tec ted ornot.I f i t i s p ro tec ted , ob ta in a copy of the fo rm a ldescription, e.g. the list description, to determinewhat the special interest is. T he list descriptioncan usually be obtained from th e local authority orthe Historic Buildings Inspectorate.M a k e e a r l y c o n t a ct w i t h t h e l o ca l a u t h o r i t yconservatio n officer to discuss ini tial proposalsan d to identify areas where problems m ay arise.Identify what other legislation will influence theproposed works, e.g. Health & Safety at Work etcAct.For applications where consent is needed, allows u f f ic i e n t t i m e f o r t h i s i n t h e p r o g r a m m e ,including poten tial delays (this m ay add severalmon ths to th e project).Obtain all the necessary consents and approvals inwriting before carrying out any work. Only carryout th e work authorised: if changes or additionalworks a re requ i red , no t i fy the loca l au tho r i tyconservation officer (and the Historic BuildingsInspectorate, if involved) imm ediately nothe ra p p l i c a t i o n f o r c o n s e n t m a y b e n e c e s s a r y .Unauthorised works could constitute a criminalact (see Section 1.6.3).Allow for periodic visits from the local authorityc o n s e r v a t i o n o f f i c e r ( a n d i f a p p r o p r i a t e t h eHistor ic Build ings Inspectora te) to inspect theworks in progress.

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Pr ncipies 51.6.6 VATSome work to listed buildings or scheduled monume ntsm a y b e z e ro - r a t e d fo r V A T . A t t h e t im e o f w r i t i n g ,alterations are zero-rated, but repair and maintenance isnot. Therefore, installing completely new services, e.g. aheating system in a building wh ich had n one before, couldbe eligible, while upgrading an existing system might beconsid ered a repair, at least in part.Only approved work to a listed building or scheduledmonument qualifies for zero-rating, i.e. where the workh a s r e c e i v e d l i s t e d b u i l d i n g c o n s e n t o r i n v o l v e ssubstantial reconstruction (this would normally requirelisted building consent anyway). All appropriate planningand listed building consents must be obtained before anywork is undertaken. HM Customs and Excise wil l notsanction zero-rating for consents granted retrospectively.

1.7 Building R egulatio nsAs the needs of society are constantly changing, it is ab a s i c t e n e t o f l e g i s l a ti o n t h a t i t s h o u l d n o t b eretrospective. It is therefore contradictory to insist onpresent day standards (U-values, double glazing etc.) forhistoric buildings. On the other hand, historic buildingshave to meet mo dern needs if they are to be conserved oradapted.

A p p r o v e d D o c u m e n t s Ll a n d L 2 o f t h e B u i l d i n gRegulations(3) ecognise the special nature of historicbuildings specifically. The precise wording of DocumentL 2 is as follows Approved Document L1 is similar):4.11 The need to conserve the special characteristics of suchhistoric buildings needs to be recognised: see BS 7913. In suchwork the aim should be to improve energy efticiency where andto the extent that it is practically possible, always provided tha tthe work does not prejudice the character of the historic building,or increase the risk o f long-term deterioration to the buildingfabric or fittings. In arriving at an appropriate balance betweenhistoric building conservation and energy conservation, it wouldbe appropriate to take into account the advice of the localplanni ng authoritys conservation ofticer.4.12 Particular issues relating to work in historic buildings tha twarrant sympathetic treatment a nd where advice fro m otherscould therefore be beneficial include:a ) restoring the historic character of a bui lding that had beensubject to previou s inap propriate alteration, e.g. replacementwindows, doors and rooflights;b ) rebuilding a forme r historic build ing e.g. foll owin g a fire orfilling in a gap site in a terrace);c ) making provisions enabling the fabric to breathe to controlmoisture and potential long term decay problems: see SPABInformation Sheet No 4 . 9 )

eed thermal and visuacomfort control of localtask they carry out

from damp and condensation, carin changes in ventilation or heating,use of inappropriate materials,or design conditions for contentswhich dont suit building

Buildingcontents/artifacts

Needs awareness of effect ofemissions from building:coZemissions from fossil fuelOzone depleting substancesLocal:Pollutants from building products 1Pollutants in case of fire

&-- Need strict control over* environmental conditions:

1Figure 3A balancing act.

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6 Guide to buildinq services for historic buildingsThe Regulations highlight some of the principal issuescovered in this Guide. However, there is a danger that theparagraphs above may be in terpre ted as not requir ingANY improvements. This is an oversimplification: thereis no excuse for wasting opp ortunities and doing nothing.Even i n t he m ost difficult cases, there is usually a range ofth ings one can do to improve ene rgy e f f ic iency , seeSection 1.10. Indeed, because the scope for improvingsome aspects (e .g . fabr ic and window ins ula t ion) mayoften be limited, it is particularly important to seize thoseopportunities that do offer themselves, and to make thevery most of them.On the other hand, pressure to im prove energy efficiencycould expose traditional buildings not defined as historicand with no s ta tu tory protec t ion to inappropria te andunnecessary replacements. F or example, the appearance ofwindows and doors is often a very important part of abu i ld ing ' s ( and an a rea 's ) spec ia l cha rac te r . T o lo seserviceable fabric and to replace it with materials with, atbest, dubious environmental credentials is not sustainable.Every effort should be made to retain serviceable fabricsince this will normally be more cost effective and moreenv i ronmen ta l ly e ff ic ien t in the longe r - te rm. S implemeasures such as repairing and upgrading existing fabricand perhaps ins ta l l ing secondary g laz ing can produceresul ts to match those of modern replacements . Suchmodern replacements may both detract from a building'scha rac te r and be incom pa t ib le wi th i t s pe r fo rmance .Wh ere rep lacemen ts a re necessa ry a r t i cu la r ly o fwindows an d doors he materials and design need verycareful thought (l O)

1.8 Design principlesT hi s Sec t ion h igh l igh ts som e o f the p r inc ip le s to bef o ll o w e d d u r i n g w o r k o n h i s t o r ic a n d s t r a d i t i o n a lbuildings. It is expanded in Section 4.4.The principlescan be followed in any work to historic or traditionalbuildings.T he following funda mental principles are adapted fromthe list in The repair of historic buildings: advice on principlesand methods.( ) Th ey are expanded in Section 4.4:( i )( i i ) Minimise intervention.(iii) Avoid unnecessary damage.( i v )

Understand the purpose of repair or alteration.

Se e k r e v e r s i b i l i t y a n d m i n i m i s e i r r e v e r s i b l edamage.Plan ahead: Allow time to liaise with the relevant officialson conservation an d buildin g contro l issues. Allow forp rob lems wh ich a r i se when un fo reseen p rob lems a reexposed du ring w ork on s i te . Ensure effec tive l ia isonbetween all those involved in the project.Do not impose standard solutions: The individual nature of,and value placed on, many older buildings and their fabricmakes it imperative that bespoke solutions are devised tofit the specific circumstances of the individual building.Get the balance right: Balancing the needs of the buildingfabr ic, th e occupants and the contents , while meet ingdesired environmental criteria can be difficult (Figure 3).

In many cases, the robustness of a building is only testedby making alterations, by which tim e it may be too late.Use only materials that are compatible and consistent with theintended performance of the building: I t c a n a l so b ed e t r i m e n t a l t o t h e f a b r i c to i n t r o d u c e i n a p p r o p r i a t esystems and performance regimes. If standard solutionsare applied to highly individ ual buildings, fun dam entalproblems may be ignored or symptoms may be t rea tedrather than causes. The consequence can easily be fasterdeterioration of th e building.T he consequences o f app ly ing inapprop ria te s tand a rds o l u t i o n s t o h i s t o r i c b u i l d i n g s c a n b e s e r io u s . I npa r t i cu la r , the requ i remen ts o f museum exh ib i t s andcollections can be incompatible with those of the buildinghousing them.(12J3)

Summary of design principlesappropriate for work in olderbuildings

U n d e r s t a n d t h e b u i l d i n g b e f or e m a k i n g a n ychanges: its architectural or historical significance,its structural performance and the patterns of airand moisture movement.Do not rely on standard solutions to what will behighly individual circumstances: devise bespokes o l u t i o n s w h i c h s u i t t h e b u i l d i n g ' s s p e c ia lcharacteristics.Determine w hether the building can accommodatethe proposed alterations.Be sure you know what statutory protection thebuild ing has a nd what consents are required tocarry out any proposed work.Only do work that is necessary: historic buildingsand the i r f ab r ic a re a f in i te and i r rep laceab leresource; once lost they can never be replaced.Make a presumption against damage to or loss ofhistoric fabric. Where works are necessary, aim tominimise th e amount of intervention.Design new services which have long lives an d caneasily be maintained and serviced. This will helpto minimise the building's exposure to potentialdisturbance.S e r v i ce s s h o u l d b e i n s t a l l e d w i t h a s l i t t l edisrup tion as possible to the historic fabricNew work should aim to be reversible, allowingt h e f a b r i c t o r e v e r t t o i t s f o r m e r s t a t e w h e r eappropriate.S e r v i ce s s h o u l d b e s y m p a t h e t i c t o t h e i rsurroundings . They should not detrac t from thea p p e a r a n c e o f t h e b u i l d i n g , i t s f a b r i c o r i t scontents.A l t e r a t i o n s s h o u l d b e c o m p a t i b l e w i t h t h ebuilding, rather than working against it.Use existing spaces and voids rather than cuttingi n n e w ( b u t e n s u r e t h a t y o u u n d e r s t a n d t h epurpose of these voids first; for example, they maybe part of the original ventilation system).

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Building services 7

m) In troduce serv ices tha t minimise the impact onthe environment by being energy-efficient, andwhere possib le maximise the use of renewableenergy sources.

1.10 Simple nonintrusive ways o fimproving energy efficiency

Th ere are simple ways of improving the energy efficiencyof nearly all buildings, includin g:

installing better controlsselecting efficient plant, especially boilers

specifying long-life efficient light sourceslim iting excessive air infiltration (but dont overdoit ee Section 3.3).ensu ring better managem ent of existing systemskeeping proper records , readi ly accessib le (butwith safely archived copies)undertaking effective preventive maintenance

Most of these can be applied without adversely affectingfabric and contents, even in buildings which cannot beal tered physica l ly because of the ir s ignif icance , the ircondition or their sensitivity. It is very seldom th at thereis absolutely no thi ng you can do.

2 Building services2.1 Modern expectations and

standards o f servicePeoples expectations of heating, lighting, transportationand electrical services in buildings are much higher nowthan in th e pas t . In t e rms o f amen i ty , wha t was oncecommonplace can also be unacceptable.

Most h is tor ic bui ld ings have changed s ince they werebuil t . A change can trigger vast a lterations in services:lighting, heating, perhaps some airconditioning, cabling,power poin ts , te lephones and data l inks , p lus modernstandards of fire detection and protection. The followingservices are most likely to be expected today. Historicbuildings cannot always accommodate them all:h e a t i n g b o i le r , f u e l s t o r e / s u p p l y w i t h m e t e r sa nd or delivery arrangementschimneys, flues and flue terminalsheating emitters and controls

sanitary accomm odationh o t a n d c o l d w a t e r p r o v i s i o n , s to r a g e, a n ddistribution

electrical circuits for small power and ligh tingpower, data and telephone lin ksfire detection and alarms and emergency escapelighting enerally man datory for peoples safetyand the preservation of the buildingfire protection schemes such as sprinklersmechanical vent i la t ion , som etimes with supplyand extract ductworkdrainage, both rainwater and foult r a n s p o r t a t i o n a n d d i s a b l e d a c c es s i f ts ,escalators, ram pspublic-address and hearing-loop provisionc o o l in g a n d a i r c o n d i t i o n i n g , i n c l u d i n g h e a trejectioncontrol systemssecurity systemslightn ing protection.

Building services are normally designed to suit people andprocesses. In historic buildings, it is very important toconsider the building itself. For example, one may wish toc o n t r o l t h e h e a t i n g t o r e g u l a t e r e l a ti v e h u m i d i t y( c o n s e r v a t i o n h e a t in g , s e e Se c t i o n 3.5 , a n d n o tnecessarily the comfort of the users. Similarly, fire safetysystems may be designed to th e higher property standard,not merely to give adequate time to evacuate people but tohelp protect th e building (see case study 25).A good solution will strike a balance between the needs ofthe building, the occupants and the global environment.Inevitably, some compromises will often have to be made,b u t g r e a t c a re i s n ee d e d t o e n s u r e t h a t t h e s e d o n o td e v a l u e t h e a i m s o f t h e p r o j e c t : m e e t i n g c l i e n trequirements while protecting the fabric and making thebuilding more energy efficient.

2.2 Increasing sustainability2.2.1 Reducing annual carbon dioxideemissions

Figure 4 These external toilets to a Grade I1 isted public house areconsidered basic today, and can discourage customers. However, th echaracter and special interest of a building can be threatened by suchdemands for change, which may not always be easy to accommodate.

Building services often use large amounts of fossil fuel tomaintain the conditions required. This has a detrimentalimpact on the a tmosphere , owing to th e re lease of theLi

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8 Guideto building services for historic buildings

greenhouse gas carbon dioxide, acid gases including theoxides of sulphur and nitrogen and other pollutants. i n a n y q u a n t i t y ) c a n b e c o n s i d e r a b l y m o r epolluting than using fossil fuels.Pollution can be reduced by: Renewable energy sources (as used in case studies12 and 13) have close to zero CO, emissions. This

using less fuel; is obvious. for direct generators suLh as w indpower,hydro-electric generation etc. It also applies whenburning biomass such as straw and woodchipapar t f rom any foss i l fuel used in cul t iva t ion ,h a r v es t in g , t r a n s p o r t a n d d r y i n g . T h e c a r b o ndioxide produced by burning the woodchips istaken back up in t he cycle if the coppice sourcingthe woodchips is allowed to re-grow. Effectively,one has net zero CO, emiss ions , where energyf r o m t h e s u n i s c o l l e c t e d a n d h a r v e s t e d a s astorable fuel source with m inim al fossil fuel use.

using cleaner fuels, i.e. those with lower, or evenzero, carbon dioxide em issions;using cleaner an d m ore efficient appliances;reducing the design load, for example by addinginsulation (see Section 3.2); andcontrolling and managing systems effectively.

In older buildings, it is not always easy (and sometimesnot even desirable) to reduce the requirements for heatingenergy by adding insulation and cutting air infiltration (asdiscussed in Section 3). To help make up for this, one can2.2.2 Reducing pol lut ion of the externalenvironment

nearly a lways use the most eff ic ient p lant a nd co ntro lsystems, and maintain and manage them well. Other combustion-related pollutants can also damage theenvironment , the bui ld ing fabr ic and peoples heal th .Figure shows t h e of ca rbon di ox id e Oxides of sulp hur and nitrogen (including acid rain) alsodamage trees, aquatic life, and the fabric of buildings, asemissions associated with 1 kilowatt-hour (kW h) of energy illustrated in F igure 6 .delivered to a building in th e form of different fuels. Th efollowing conclusions can be reached. 2.2.3Gaseous fuels emit less CO, than liquid or solidfuels. T hi s reflects the fuels carbon/hyd rogen r atioImproving health and the internalenvironment

he lighter the fuel, the more hydiogen. Henceless of the energy is locked up in carbon in naturalgas (mostly methane, CH,) than in the liquefiedpetro leum gas propa ne (C,H,), an d so on for theheavier fuels.On average, UK mains electricity produces muchlower CO, emissions per delivered unit now thani t d id in 1990 and be fo re wing to g rea te re f f i c ie n c y , a g r e a t e r p r o p o r t i o n o f g a s - f i r e dgeneration and higher availability of nuclear plant.However , bu rn ing foss il fue l s a t a conve rs ionefficiency of between 30% and 60% still accountsfor about 70 of UK production. Therefore, to useelectricity directly for heating (and for hot water

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - - - - - - _ _ -

enewables

NuclearSolar heat

Wood - sustainableElectricity from wind, waterN atu ra l g a s p

Propane (egDomestic h eating oi l

Heavy oilWood -deforestation

CoalAnthracite

CokeElectricity (UK 1998 average)Electricity (UK 1980 average)Electricity from coal

Fossil based ornon renewables

0 0.5 1kg CO2 per k Wh

Figure 5 Carbon dioxide produced by different energy sources in theUK

Bui ld ing se rv ices a re in tended to improve the indoorenvironment, but they can introduce hazards, directly orindirec t ly . T he effec ts of d ir ty , unhygie nic p lant a ndductwork and of leakage of combustion fumes are nowwell known, and careful design is essential, followed byc a r e f u l m a i n t e n a n c e o f c l e a n l i n e s s , s a f e t y a n dperformance. The combined effects of heating, ventilationand insulation on the environm enta l equi l ibr ium of thebuild ing are a lso important . Damp condit ions can not

Figure 6 A carved figure on a Grade 11* listed church. The deteriorationof this fine-gra ined stone has been accelerated by pollution. Recentresearch(14)has shown that the well know n degradation of limestones bythe oxides of sulphur (mostly emitted to the atmosphere during burningof coal and heavy oil) is much accelerated by the oxides of nitrogen(mostly from traffic but also emitted by boilers); so the expectedreductions in stone decay with falling sulphur dioxide levels have nothappened, particularly in and downw ind of urban areas

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Buildinq services 9only cause building decay but can also affect occupanthealth both directly or by the products of biodeterioration,e.g. fungi which colonise the lungs or moulds with toxicspores. The materials used in the building servicesinstallation itself also need examination. The combinationof new, chemically complex and sometimes unstable,building products with changes in lifestyle (e.g. lessventilation and more time spent indoors) have increasedthe exposure of people to potentially toxic materials orbyproducts. Although the long-term effects of manyproducts are not yet quantified, it is responsible to assessthe potential impact of all products on the health ofoccupants.(15)2.2.4 Using more sustainable materialsMaterials should be selected carefully and specified toensure that they cause as little pollution as possiblethroughout their life: during extraction; in manufacture;during construction or installation; when performingtheir intended use; and when finally removed for re-use,recycling or disposal. Increasingly, the specifier must beaware of the life cost and impact of each material specified.This embraces the environmental and health implicationsthroughout i ts life and use including toxicity and thepresence of dioxins and volatile organic compounds(VOCs). Only if a careful holistic cradle-to- graveapproach to design is adopted will the risks to health andthe envi ronment be reduced and t ruly sustainablesolutions formulated.Views on specific materials can change rapidly. Forexample, many countries are becoming concerned aboutthe use of polyvinylchloride, owing to its perceived threatsto environment and health articularly duringmanufacture and if it is burned at the end of its life cycle.Its use needs to be reassessed in t he light of theseconcerns, and alternatives specified where possible.2.2.5 Efficient plantUpgrading the energy efficiency of the fabric of a historicbuilding can often be difficult, so it becomes particularlyimportant to make the installed plant and systems asefficient as possible, even if they cost more. The mainareas of concern are boiler and aircondi tioning plantefficiency and control, and any electric motors which runfor extended periods.Fossil fuel boilers should be at the top of the availableefficiency range. This will usually mean condensingboilers; and these have been used successfully in many ofthe case studies. However, condensing boilers create amuch larger visible plume of water vapour at the flueterminal or chimney top than do ordinary boilers. Fluesmust therefore discharge away from areas susceptible to abuild up of moisture (as in case study 1).Where this isimpossible (e.g. in a small courtyard), a noncondensingmodel may be necessary. It is also necessary to provide adrain for the products of condensation which can beacidic.It is important to compare boiler efficiency not just at fulloutput but across the likely performing range, e.g at highand low firing. For domestic sized boilers, seasonalefficiency can be checked through the Sedbuk rating (seewww.boi1ers.org.uk). Boilers in category A would be

appropriate, especially in buildings where insulationmeasures are not practicable.Airconditioning plant can have a major physical impactand use a lot of energy. It should only be installed where itis proven to be essential to the operation of the building.Systems which default to on unnecessarily and wastefullyare all-too-common in buildings today, so controls shouldbe designed and commissioned to ensure that plant is onlyoperated when and to the extent it is actually needed.When selecting electric motors, calculate how much theywill run. If this is more than 1500 hours per year, assessthe economics of installing either high-efficiency or DCtypes.Combined heat and power (CHP) is a way of maximisingthe amount of energy from a fuel, so reducing carbondioxide emissions. CHP both produces power (usually aselectricity, but sometimes as mechanical power), andmakes available much of the otherwise wasted heat fromthis process. This can be used to provide heating or hotwater or to run equipment, eg absorption chillers. Takecare that there are sufficient base loads of both heat andpower to make the CHP plant run for enough time toproduce a reasonable economic case for investment(typically at least 3500 hours per year, as often occurs inhospitals and large hotels). The big mistakes often madeare to oversize the plant, or to assume that the heat isfree. CHP is very unlikely to be viable without aguaranteed year-round use for the heat.

2.2.6 Low water useWhere new water appliances are installed, consider water-efficient types, e.g. low-flush (less than 6 litres) and dual-flush (two-button) WCs, hand basins with automatic spraytaps using less than 2 l/min, low water showers (less than 8l/min), and waterless WCs and urinals. Equipment foundin older buildings can often be very extravagant, but itsperformance can sometimes be improved considerably,e.g. by fitting flow restrictors to taps. New equipmentdesigned to look traditional can also be very wasteful:take care that your choice properly balances therequirements of appearance and water economy.Convoluted hot-water supply and distribution systems canwaste a lot of heat, particularly if uninsulated and in largerbuildings. Seek opportunities to rationalise and improvethem. Sometimes, a decentralised system with local gas oreven electric water heaters will be more economical andenergy efficient.Water leaks are a serious threat, with risks ranging frommajor flooding to slow drips causing staining andeventually perhaps dry rot. Problems can be reduced bycareful routing, good specification using burst-resistantmaterials, good workmanship, inspection and testing, andeffective frost protection. In sensitive situations, one caninstall safety guttering or electronic leak detectionsystems; or or major leaks utomatic alarms andshut-offs. Sometimes, it will be best to keep water out ofan area altogether (e.g. upstairs in case study 8).

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10 Guide to bui ld in g services f o r historic bui ld ings

2.2.5 Temporary servicesT e m p o r a r y s e r v ic e s , p a r t i c u l a r l y t h o s e u se d d u r i n gconstruction work (e.g. transformers, cables, lighting,heaters and dehumidifiers), can create hazards of theirown. People may bring in their normal equipment or useit inappropriately, w ithout th inkin g about th e sensitivityof the building. Risks include not only fire, electric shockand o i l sp i l ls from genera tors , but a lso damage to th eh i s t o r i c f a b r i c b y t o o v i g o r o u s u s e o f h e a t e r s a n ddehumidifiers. Rapid decreases in humidity can causeshrinkage and cracking, particularly in timber products.W here temporary heaters an d dehum idif iers are used ,vulnerable con tents will need to be taken int o safe storage,and vulnerable building elements protected. Alternatively,these temporary systems may need to be operated underthe sup ervision of a conservator.On the other hand, dehumidifiers can often be ineffectivebecause the space to be dried is not properly sealed, withdoors , f lues and holes remaining open. S ince water iscollected, people think that the dehumidifier is do ing itsj o b ; w h e r e a s m o s t o f t h e m o i s t u r e h a s c o m e f r o melsewhere ften directly from t he outdoo r air.

2.3 The valu e of his tor ic bu i ld ingservices

Before any changes to a bui ld i ng are considered , i t isessential to assess the existing services (especially an yoriginal features) and understand how they work and howthe building contributes to knowledge of th e developmentof services through the ages. The arrangements can bevery interesting and sophisticated, as in case studies 26and 27. If a building is listed, remember that the listingprotects everything - ncluding the services nd that itis a criminal act to change anything without permission.T he services may form an important part of th e building'shistory, archaeology, character or appearance, or may beimpor tan t in the i r own r igh t . Be fo re cons ide r ing theremoval of any items, it is essential to confirm whetherapproval is needed. Case study 15 illustrates a case whereEnglish Heritage insisted that a derelict original heatingsystem being restored, while in case studies 16 and 24opportunities were taken to remove inappropriate servicesan d to reinstate original features.

Figure 7 A redundant horticultural boiler, previo usly used to heat a green house, in the garden of a Grade I1 isted building. The boiler house andboiler were not specifically listed but, since they are within the curtilage of a listed build ing, they are equally protected as curtilage structures . Listedbuildin g consen t was required to remove the boiler. Its asbesto s claddin g was breaking down, creating a seriou s health hazard. Before the boil er wasremoved, all the asbestos was carefully stripped by a specialist contractorLi

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Building services 11

2.4 Re-using existing servicesExisting building services plant must be assessed regularlyto determine whether it is working properly, its efficiency,safe ty, l i fe expectancy and any r isk s i t poses . Ideally ,provided that it remains safe and reasonably efficient,building services equipment should remain in active usefor as long as possible. Even when its useful life is over,one may want to retain it in situ for its aesthetic, historic orarchaeological interest ither as a whole or in part asevidence of how th e building was once serviced.Ma ny types of serv ices, par t icular ly heat emit te rs andlighting equipment, are often suitable for re-use and addconsiderably to the character of a building. Too often, thisis only appreciated after they have been taken out Suche q u i p m e n t m u s t b e c h e c k e d f u l ly a n d u p g r a d e d a snecessary. It is often possible to restore old light switchesand luminaires and make them safe. Old radiators willrequire cleaning and pressure-testing, and the joints andvalves should b e checked, eased and renewed as necessary.If pipework is to be re-used, the water should be testedand external and in ternal inspect ions of the p ipeworkshould be carr ied out . Chemical c leaning may a lso berequired. Before it is recommissioned, the entire systems h o u l d b e f u l l y p r e s s u re t e s t e d i n o p e r a t io n , a n dthoroughly checked for leaks and other faults.Assess health risks associated with use of the existingbuilding services equipment to determine how to handlethem and whether th e p lant can be re-used . Dangerousand health-threatening services should not, of course, beretained in use: the health and safety of the occupantsmust have priority. D angerous electrical installations andequipment mu st always be made safe immediately. Fi re isone of the greatest threats to the fabric and c ontents ofhistoric buildings.(16>7TAKE GR EAT CARE: Asbestos was very widely used tolag boi lers and p ipework. I f i t is encountered or eventhought to exist, leave it alone and seek specialist advice(owing to th e severe health risks it is better to be safe thansorry). Licensed contractors must be employed to removean d dispose of any asbestos.

2.5 Criteria for the selection of newbuilding services in historicbuildings

First ask the question: are new building services required atall? Exposing a historic building to unnecessary changeincreases the potential for irreparable damage. If you thendecide to proceed, t he new or upgraded services must be:compatible with the building;compatible w ith th e performance of the fabric (asdiscussed in Section 3); ande f fi c ie n t, t o m i n i m i s e t h e i m p a c t o n t h eenvironment.

W h e r e e x is t i n g b u i l d i n g s e r v ic e s a r e r e ta i n e d , i t i sessential to ensure that the new services are integrateds u c c e s s f u l l y i n a m a n n e r t h a t d o e s n o t c o m p r o m i s einstallation, performance, use, efficiency, maintenance orlife expectancy. For example, old heating systems often

came up to temperature s lowly and the thermal shockfrom th e faster response of modern boiler plant m ight giver i s e t o l e a k s i n e x i s t i n g p i p e w o r k . S i m i l a r l y, m o r ecompac t , h ighe r - re s i s tance modern te rmina l dev icesrequiring high water pressures may not mix on the samecircuit as histo ric radiators designed for gravity flow.

2.6

Finding suita

Installing new building servicesand upgrading existing onesde routes for DiDes. cables and ductwor IA *n e e d s c a r e f u l t h o u g h t a n d i m a g i n a t i o n t o m i n i m i s einterventions, and to avoid other problems for the fabricor , a t wors t , s t ructura l s tabi l i ty . In mod ern bui ld ings ,build ing services are often n ot designed o r specified indetail, much being left to the discretion of the contractor.F o r e x a m p le , t h e c a b l e r u n s b e t w e e n s w i t c h e s a n dlumina i re s a re ve ry se ldom shown . In many h i s to r ic

buildings, such detailed design is essential to improveplanning and appearance, and to minimise unnecessaryphysical intervention. T he extra investigations, drawings,specifications and collaboration on site will inevitably addto the time and costs, as will the necessary consultationand approval processes for statutorily protected buildings.However, th is work is absolutely essential.

2.6.1 Notchin g, cut t in g and chasingWo rk to accom modate services can seriously affect thecondit ion , s t ructura l performance and preservat ion ofo lde r bu i ld ings , a nd sho u ld on ly be ca r r ied ou t a f te rappropria te specia l is t advice has been soug ht . A goodstarti ng poin t is to aim not to notch or cut any timbers,chase an y walls, or make holes in important places.Cu t t ing and chas ing des t roys h i s to r ic f ab r ic , may beunsightly and can seriously weaken floors and old wallsand partitions. Floorboards a nd wall finishes of historic,architectural or archaeological interest could be damagedirreparably or even lost. In the end, som e kin d of physicali n t e r v e n t i o n s w i ll n e a r l y a l w a ys b e n e c e s sa r y , b u tapplication of imagination in seeking to minimise themcan be rewarding, as shown in case stud y 19.W here t he cov er ing surfaces (e .g . f loorbo ards) can beremoved safely and carefully (with the approval of ther e l e v a n t o f f i ci a ls ) , o p e n i n g - u p o f t e n r e ve a ls h i d d e no p p o r t u n i t i e s f o r s e rv i c e r u n s ( a n d s o m e t i m e s e v e nequipment, as in case study 24), together with unexpectedobstacles (as in case study 4).A good set of drawings alsoreveals possibilities for vertical conn ections (as for the liftsin case s tudy 4). Thick walls may a lso conta in usefulvoids, particularly in Victorian and Edwardian buildings,e.g. as part of an earlier ventilation system (see case studies26 and 27).O p e n i n g - u p c a n a l s o r e v e a l h o r r o r s , e . g . d e c a y ,unexpected obstacles and structure irresponsibly cut awayby those installing previous build ing services installations.Strengthening will then be required. Ways to strengthenweakened f loor t imbers , for example by using fo ld ingwedges or iron plates are shown in BS 5268.(18)

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12 Guide to building services fo r historic buildingsCentre of Centre ofbealing bearingSpan

II I-1- -1-I IDepth of notch Ino t greater I

IIII

I Depth Dt IU II

Notches shouldbe in this zone IIII I-1 -

I-Span 5 .- Holes should ..:be located in jthis zone, and

drilled at theneutral axis I

Maximum Not less than Idiameter three diameters jof holes apart (centre= D/4 to centre)

Folding wedgesFigure 8 Advice on maxim um dim ensions and position s for holes ands grooves in joints, and on restoring compressive strength to timb ers weakenedby ins erting central h eating o r other service pipes(19)2.6.2 Install ing service runsTh e f i r st s tage is to minimise th e am ount of pipework,c a b l i n g a n d d u c t i n g ne e d e d, t o g e t h e r w i t h a n yi n t e r v e n t i o n t o t h e e x i s t i n g f a br ic . C a s e s t u d y 2 4i l lus trates why fan-coi l a i r cond i t ioning was chosen inpreference to an al l -ai r sys tem at th e Royal Society ofChemis t ry . T he bu i ld ing s e rv ices eng ineer m us t w orkc l o se l y w i t h t h e a r c h i t e c t o r s u rv e y o r ( a n d t h e n t h ebuilder) to m inimise, and where possible avoid, situationsthat cause physical damage, surface damage or removal ofany part of the structure and fabric. Even after a carefulsurvey, specification and drawings, it is good practice toagree and mark out on site exactly where everything is to

Figure 9 Exposed pipework in a cellar of a Grade I1 isted building. Thepipework runs rou nd a principal structural floor beam rather th ancutting through the timber, i l lustrating the fundamen tal principle thatthe services should be adapted to suit the building and not vice-versa.Th is arrangement has minimised the disturbance to th e historic fabric,prevented any stru ctural damage, provided flexibility for futu re work andreduced time spent cutting through timbers

go; and also to confirm the types of holes that are to bem a d e a n d t h e f i x i n g s a n d b r a c k e ts t o b e u s e d . A n yalterations to the drawn and agreed scheme should also beconfirmed o n site before any physical work commences.2.6.3 Exposed servicesUse of exposed pipes, cableways and sometimes ducts canminim ise the am ou nt of physical damage and interventionto historic fabric. However, appearance is often param ounthat will the services look like, and do they suit ther o o m i n q u e s t i o n ? I n a f o r m a l ro o m w i t h v e r y f i n edetailing, exposed runs are unlikely to be appropriate asthey would detract from the original attention to detailand geometryUnoccupied areas, att ic spaces, cellars , roof spaces andoth er areas where appearance or presentation is less of anissue create good oppo rtunities for exposed service runsand for less concern about thei r appearance, though aclean, tidy professional job is t he min imu m accep tab lestandard anywhere. Exposing services can also be morereversible and improve access for inspection, alterationand main tenan ce nd eventual removal and renewal.Exposed pipework and ductwork may, of course, need tobe insulated, an d frost-protection strategies must be takenvery seriously. For example, what should be the designstrategy for a building which could be empty and difficultto reach du ring a long cold period, as in case stud y 13.Wh ere cab les a re ru n exposed , they mus t be ca re fu llyp o s i t io n e d , s p e c i f i e d o r p r o t e c t e d t o m i n i m i s e t h e i rvu lnerab i l i ty to phys ica l damage . Cab l ing in h i s to r i cb u i l d i n g s m a y a l so n e e d t o e x ce e d m i n i m u m r e -qu i r ement s , i n o rder to r educe f i r e r isks ; and minera linsulated cables (MIC) o r othe r specialist cable types maybe appropriate. Although specialist cabling can be more

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Build ing services 13expensive, it has th e benefit of minim ising the use of poly-vinylchloride (see Section 2.2.4), can last longer and mayneed fewer fixings and supports.Where installation of cable runs is likely to be extremelydifficult or damaging, radio and signal receptive systemscan be considered ee case studies 19 and 25. Theselook promising , but the ir long-term performance andtheir potential influence on health are currently unknown.Remember that radio devices in inaccess ib le locat ionswithout mains supplies still need regular access to changethe batteries ypically every few years, but sometimesmore frequently.2.6.4 Concealed pipeworkOlder buildin gs often have voids and other spaces that canbe used to conceal pipework and oth er services and tolimit any damage to the historic fabric. Th ese include:

behin d panelling;

und er floors and between joists;in ceiling an d roof void spaces;

in th e voids inside stud walls;u p r e d u n d a n t c h i m n e y s a n d v e n t i l a t i o n f l ue s(these ventilation flues may also prove useful fortheir or ig inal purpose , perhaps with some fan-assistance);along the tops of wide cornices;along redund ant service routes; andopportunity for concealment.w h e r e r e p a i r s o r a l t e r a t i o n s p r o v i d e a n

Pulsed radar and other techniques may be used to locatevoids in solid walls and floors nondestructively.Concealed routes have some limitations:

Not a l l of them (e .g . ch imneys and vent i la t ionflues) are accessible for inspection.Hidden leaks can go unnoticed for long periods,and could trigger serious decay.Fabric can be damaged by opening-up to find theconcealed voids, or if invisible leakage causes asubsequent damp or decay problem.

It is essential tha t any services concealed be hin d fabric befully recorded and tested before they are enclosed and thedecorative finishes applied, particularly pipework thatdistributes water. Testing will provide some confidencethat there are no leaks that might cause decay and requireopening-up later. Similarly, frost protection systems thatcover a l l the bui ld ing are essent ial where p iped waterservices are present.2.6.5 Integration of pipework in timber

floorsLif t ing and protecting historic timber floors: T he g rea tes topportun ity to improve services arises when m ajor repairs,refurbishment, alterations, extensions or changes in useare taking place. However, the floorboards in many olderbuildings are of historic interest and it is undesirable to

renew them. It is sometimes wise to avoid even liftingfloor boards, particularly old wide boards that have notbeen disturbed before.(*O)SPAB Information Sheet I ? *) gives guidance on handlingf l o o r b o a r d s . T o r e d u c e a v o i d a b le a n d u n n e c e s s a r ydamage:

Ident ify and label a l l f loorboards indiv idual lybefore any work starts.D r a w a p l a n s h o w i n g t h e p o s i t i o n s o f a l l t h eboards.Lift the floorboards carefully.Make su re that all lifted boards are stored safely ina n a r e a w i t h a p p r o p r i a t e e n v i r o n m e n t a lconditions.P r o v i d e p r o t e c t i o n t o t h e e x p o s e d a r e a s t opreventing people or tools from falling throughand causing injury or damaging historic ceilingsand finishes.P r o v i d e s af e w o r k a n d s t o r a g e a r ea s w i t htemporary boarding.When the installation work is complete, re-fix thef loorboards in the ir or ig inal posi t ions . Do notreplace any boards unless repair is impossible.When re-fixing, take great care not to punctureunderlyin g cables or pipework w ith secur ing nails.

W h e n i t i s e s s e n t i a l t o l i f t f lo o rs , d o n o t m i s s t h eo p p o r t u n i t y t o r a t i o n a l i s e t h e s e rv i ce s , t o p r o v i d ec o m p r e h e n s i v e i n s t a l l a t i o n d e t a i l s a n d t o p r o v i d eadditional conduit runs to facilitate future installation andupgrading. T o minim ise fu ture d is turbance , i t is goodp r a c t i c e t o p r o v i d e a c c e s s c o v e r s f o r i n s p e c t i o n ,maintenance and future upgrading. T hey should normallybe screw-fixed for ease of access and to prevent damage tothe covers or the services undern eath when re-fixing. T helocation of access points should be noted on drawings forfuture identification.Planning ahead will reduce the levels of disturbance andintervention and be cost-effective in the long term. Care-

* .Figure 10 A redundant flue being used as a pipe route. New timberwainscoting hides electrical wiring

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14 Guide to bu ildi ng services for historic buildingsf u l p l a n n i n g a n d p r o g r a m m i n g w i ll m a x i m i s e t h epotent ia l of any opportuni t ies crea ted . T he ear l ier tha tconsu ltants and the workforce are aware of what is needed,the more likely it is that they will be able to allow for it inthe pre-contract documentation. For example, specificat-i o n o f r e p a i r w o r k s w i l l n e e d a n a l l o w a n ce f o r t h eprincipal contractor to be in attendance on the buildingservices contractor ho may be a subcontractor on theproject. T he cost and pro gramm ing implications for theprincipal contractor would need to be taken into accounta t the t ende r ing s tage . Th e c l ien t wi ll no t app rec ia teaddition al costs that could easily have been foreseen. If thework is carefully planned, many of the services routes canbe pre-assigned and the necessary holes made carefully inadvance.Assessment of exposed fabric: Once floorboards etc. havebeen lifted and the structure, voids and existing servicerun s a re exposed , make a fu l l and de ta i led su rvey . Ifnecessary, re-assess the design proposals in light of thisnew information, and decide whether any major changesare required. Always keep an open mind about what willbe found, and allow enough time to resolve the problemsand exploit opportunities.

IWARNING: Consultants and contractors tendering forwork in older and more complex buildings must remem-ber that complications will often be exposed by opening-up work.O n c e t h e fl o o r h a s b e e n o p e n e d u p , t h e s t r u c t u r a lcondition of the timbers and exposed walls needs to bed e t e rm i n e d . S t r e n g t h e n i n g m a y b e r e q u i re d . W h e r eproblems of decay or deta i l ing br ing in to quest ion th es t ruc tu ra l capab i l i t i e s o f the f loo r t imbers and the i rbearings with the walls, the advice should be sought of as tructura l engineer conversant with h is tor ic bui ld ings .The structural engineer (and where appropriate the buil-ding archaeologist and the historic buildings consultant)should also be asked to comment on the appropriatenessand compa t ib i l i ty o f any p roposed a l te ra t ions . I f anytimbers are to be notched, it is important to assess notonly their stren gth but also the part they play in the widerstructural system, especially in framed structures wherethere is an inter-relationship between individual timbersso that to weaken on e timber can pass loads onto another.

Figure 1 Opening-up work will also reveal former building servicesroutes, and som etim es several previous generati ons of systems. Th isphotograph shows an old lead pipe (which may or m ay not still be i n use)and a redu ndant copper one which had been cu t off many years earlier

Figure 12 In this photograph, floorboards have been lifted to expose therema ins of another, older floor below. Th is is itself of historic int erestand w ill add to the difficulty and cost of the work

Figure 13 Th e parapet of this Grade I listed church had been repairedcarefully, removing inappropriate cement m ortars and using lime-basedmortars and renders. The repairs had been specified carefully to slowdown th e rate of deterioration of the exposed stone. Once this w ork wascomplete and the m ortars and renders had set, a new lig htning cond uctorwas installed by a specialist compan y under a separate contract. Althoughthe com pany had extensive experience of work i n chu rches and otherlisted buildings, the li ghtning condu ctor was secured to the stonework(the most vulnerable part of the parapet wall and the most difficult torepair) and so increased the risk of accelerated d eterioration. Thi sdamaging work was not in t he spirit of the careful repairs previouslycarried out, an d could easily have been avoided. It would have beenbetter to secure the conductor to the m ortar, which by its nature isrepairab le and replaceable. Th e lesson is that, however experienced thecontractor, it is important to agree with them on site exactly how th einstallation is to be carried out, even down to th e last fixingLi

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Building fabric 1 52 6 6 FixingsMortar and masonry: Provided tha t the m or ta r i s s t rongenough, it is generally better to secure fixings in mortarthan into masonry. It provides a degree of reversibilityand prevents damage to masonry, which is more difficultand expensive to replace.Timbers an d plaster: Where a large number of securingpoin ts is required, a separate fixing plate will provide asuitable surface and reduce t he nu mb er of fixings to th ehistoric fabric.

Figure 14 A Grade 11*buildi ng was fitted with Christm as lights, fixedstraight into the br ickwork

Figure 15 Another view of the b uilding in Figure 14 showing the lightsfixed directly to the lead roof. The lead has been holed and is at risk ofleaking and the brickw ork has been dam aged: it would have been betterto fix the cable in the mo rtar

3 ding fabricIn new buildings, insulation a nd draughtproofing are usedroutinely to reduce heating an d ventilation loads. Greatcare is required, however, when doing the same thing intraditional and historic buildings. Th is Section explainswhy, and what can be done.

3.1 Moisture movement in older buildingsTraditional buildings, including most historic buildings,tend to be of a solid-wall construction, buil t prim arilywith porous fabric that absorbs moisture, but also allows itto evaporate readily. T hi s is often called th e ability of thebui ld ing fabr ic to 'breath e' .e. it has a low vapo urresistance. In contrast, modern buildings are usually madeof harder, strong er an d less pervious materials. T o excludemoisture, this co nstruction relies on physical barriers suchas damp-proof courses and membranes, wall cavities andimpervious cladding.F ig u re s 16 to 18 i l l u s t r a t e t h e d i f fe r e n c e s. A n o ld e rbuilding uses evaporation and ventilation to reduce themoisture in the walls to an acceptable level, i.e. one thatd o e s n o t c a u s e d e c a y, m o u l d g r o w t h , o r d a m a g e t od e c o r a t i o n s . I n c o n t r a s t , m a n y m o d e r n i n s u l a t i o ntechniques in c lude imperv ious vapour con t ro l layers ,des igned to s top mois tu re f rom indoors d i f fus ing ou tt h r o u g h t h e i n s u l a t i o n a n d l e a d i n g t o i n t e r s t i t i a lcondensation. However, if these same impervious layersa r e u se d in a t r a d i t i o n a l b u i ld in g , t h e y c a n t r a p th emois tu re a l ready in the wal l and s top i t evapora t ing ,making t he wall damper a nd more prone to decay.

Ventilation throughgaps where tile(or slate) bedsWind b lownrain and snow

Open firesdrawinglargequantitiesof aira --I enetrationby drivingrain

\, D a r n p r is in gthrough f loorDamp risingthroughfoundationsFigure 16 A section of an old building showing how m oisture movesthrough the structure and the air(22)

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16 Guide to building services for historic buildings

Household

Figure 17 Moisture control in older buildings. The re is a dynam icequilibrium between absorption and evaporation.To keep the fabricreasonably dry and the internal en vironm ent healthy, extra indoorventilation is required to remove the moisture that evaporates. Fu rthe rmoisture is driven off when the building is heated, so any extra heatingmay also require more ventilation

;Isorption ~

Groundmoisture

Heating does notCavity drive off significantamount of moisture.Dam p only appearswhere bui ldingdefect occursPCt DPM/i IFigure 8 Moisture control in m odern buildin gs. Cavities andimpervious layers act as barriers to moisture. D ampness appears onlywhere there is a defect. Apart from during the initial drying-out periodto remove construction moisture, additional ventilation to keep thefabric dry is not norm ally requiredAnother example of the danger s of inappropr iate , lesspermeable modern materials is where a hard imperviouscement mortar is used to re-point soft masonry (brick orstonework). As shown in Figure 19, the h ard m ortar trapsmois ture and reduces the rate of evaporat ion f rom theoutside of the wall, so leading to accelerated decay of themasonry, as in Figu re 20.The fundamental differences in moisture performance oftraditional and modern buildings make it imperative that,before making an y de ta i l ed p roposal s , t he mate r i a l s ,m e t h o d s o f c o n s t r u c t i o n a n d t h e p a s t a n d p r o p o s e dp e r f or m a n c e a r e a l l id e n t i f i e d a n d u n d e r s t o o d . A n yprogramme of repair and alteration needs to take this intoaccoun t and to r edres s any imbalances in th e in t ende dperformance of the building. For good results, addres thecauses of the problems, a nd not just th e symptoms.For example, in Figure 20, the fundamental problem isn o t t h a t t h e s t o n e i s de c a y in g b u t t h a t a n u n s u i t a b l ec e m e n t p o i n t i n g w a s u se d . A l l r e p a i r s n e e d t o u s ematerials an d methods that are appropriate and consistentwi th the t radi t ional per formance, e .g . us ing l ime-basedmortars to repoint th is wall. It would be futile to repair orr e p la c e a n y o f t h e s t o n e u n t i l a f te r t h e h a r d c e m e n tpoin ting had been carefully removed. Similarly, if a dam pp a t c h i s f o u n d , d o n o t c o v e r i t u p , b u t g a i n a nunder s t and ing o f why i t i s t he re and what needs to bedone to m ake it go away.

Wall buil t of poro us materia ls Effect of impervious po in t ingR a $ ptrong cementRay>v

point ing

Deposit ion of b I Deposit ion ofL L II \ -Interstitialcondensation Interstitialcondensation(water vapour)

b F 1 I ising dampUsual pattern of decay when m ortarused for pointing i s softer and m oreporous than wal l ing mater ialFigure 9 How hard m ortar can damage masonry(9)

Usual decay pattern whenwall materials are mo reporous than point ing

3.1 I Differences between tradit ional andmodern materials

Tradi t ional mater ials are of ten relat ively porous , as inmany stone, brick, earth and tim ber buildings w ith earth-and/or l ime-based m ortars a nd renders. T hese materials ,used both externally and internally, enable the fabric oft h e w h o l e b u i l d i n g t o b r e a th e , w i t h t h e l e v el s o fd a m p n e s s i n t h e f a b r i c b e i n g c o n t r o l l e d b y a l l o w i n gmoisture to evaporate readily.Where moisture can evaporate freely and the traditionalb rea th ing per fo rmance i s no t impai r ed , the wal l s o fhistoric buildings often remain relatively dry. Traditionall ime p las t e r s wi th b rea thab le pa in t fin i shes, su ch aslimewash, play an important part in this mechanism, bynot only releasing structural moisture but also absorbingexcess moisture generated internally and dispersing anyp e n e t r a t i n g a n d c a p i l la r y m o i s t u r e o v e r a w i d e a r ea .E x t e r n a l ly , t h e p o r o u s m a t e r i a l s of t r a d i t i o n a l l yconstruct

Building Services for Historic Buildings

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