ENGLISHHERITAGEENGLISH HERITAGE PRACTICAL BUILDING CONSERVATION

BUILDING ENVIRONMENT

ENVIRO27JULY2014.inddENVIRO 27 JULY 2014.indd a 29/07/2014 00:00 © English Heritage 2014

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British Library Cataloguing in Publication Data

Practical building conservation. Building environment. 1. Building materials–Environmental aspects. 2. Weathering of buildings. 3. Historic buildings– Conservation and restoration. I. English Heritage. 720‘.288-dc22

Library of Congress Control Number: 2001012345

ISBN-13: 9780754645580

ENVIRO 27 JULY 2014.indd b 06/08/2014 09:51 To the memory of John Ashurst (1937–2008), an inspiration and friend to all the editors, whose encouragement and support was a great motivation for this new series of Practical Building Conservation.

ENVIRO 27 JULY 2014.indd c 29/07/2014 00:16 ENGLISH HERITAGE PRACTICAL BUILDING CONSERVATION

BUILDING ENVIRONMENT

Series Editors: Bill Martin and Chris Wood

Volume Editors: Robyn Pender, Brian Ridout, Tobit Curteis

ENVIRO 27 JULY 2014.indd i 29/07/2014 00:20 NIO2 UY21.ndii ii 2014.indd 2014.indd JULY 27 ENVIRO ii PRACTICAL BUILDING CONSERVATION ocrigeeg s ntehsoi ul environment. built historic the issues in on concentrating use currently energy concerning is he architecture conservation; studied building and in Team, specialising Research before and Conservation Building the 200 in over Conservator to contributed has and operation, in pu buildings historic and existing new, of of series this in volumes B the of many reviewed Warns has he Nicholas Pinchin, Sarah Beckett McCaig, Paul Iain Bordass, Bill Beckett, Paul Contributors: Principal Church the Heritage, Trust. English National to the consultant and a Council is Building He issues monuments. environmental and in buildings specialising historic practice in conservation private a runs wall and of Conservation, conservation the and University Warwick at pa art of history studied problems. who damp Curteis, and Tobit decay timber on worked expert has international who an scientist as building years and many biologist for a Building Heritage's is English He in Team. Conservator Research Architectural and Senior Conservation a also is Ridout Brian Dr Art. of Institute Courtauld the at conservation wall-painting studied she for Commission Fabric Cathedrals the on Englan and serves Conservation and Building Heritage, the English in at Team Conservator Research Architectural Senior a is Pender Robyn Dr Curteis Tobit Ridout, Brian Pender, Robyn Authors: Principal & Editors Volume CONTRIBUTORS & EDITORS VOLUME ON NOTES stone. of Institute Courtauld the he from Art; conservation wall-painting in training postgraduate with ee uly onSeat mnaWie lr ilt,CrsWood Chris Willett, Clara White, Amanda O'Farrell, Stewart, Geraldine John Rumley, More, Peter Andrew Mueller, Edith Marshall, Will Manning, Tracy Stev Paul Contributors: Other have they images and information the for as well for provided. contributors as generously their book, so all this thank with to support opportunity and help this their take to like would editors volume The England. in churches 90 almost for architect inspecting is Buildings, l Bordass ill nig tteCutudIsiueo r,i elwo h nentoa nttt of Institute International the of fellow a is Art, of Institute Courtauld the at intings lctoso nryadbidn performance. building and energy on blications mr,PdoGsa,Spi ofan,Aio er,Atu McCallum, Arthur Henry, Alison Godfraind, Sophie Gaspar, Pedro Emery, e ae,Sao ahr aoieCtii ik uti,J emn,DvdDrewe, David Deeming, Jo Curteis, Vicky Cattini, Caroline Cather, Sharon Baker, ihlsWarns, Nicholas xets nldspeetv osrainadtedtroainof deterioration the and conservation preventive includes expertise r .Apyiitseilsn nmitr rnpr nbidn aeil n systems, and materials building in transport moisture in specialising physicist A d. sabidn cets tdigtetcncladevrnetlperformance environmental and technical the studying scientist building a is sacons a is rainsreo h a okdo itrcbidnso l periods; all of buildings historic on worked has who surveyor ervation omrShlrwt h oit o h rtcino Ancient of Protection the for Society the with Scholar former a anMcCaig Iain cia uligConservation Building actical Pr Sara Pinchin h saSno Architectural Senior a is sa archaeologist an is in-situ building . 90/0400:20 29/07/2014 CONTENTS iii

The Practical Building Conservation Series ...... v About This Book ...... vii Using These Books...... viii

INTRODUCTION...... 1 The Building Environment...... 3 The Building Itself...... 11 The Building Envelope...... 13 Failure of the Envelope...... 14

BUILDING SCIENCE ...... 17 Conservation of Energy ...... 19 Understanding Failures...... 32 Failure Under Load...... 32 Thermal Behaviour...... 35 Moisture in Building Materials ...... 37

INTERACTIONS WITH THE ENVIRONMENT...... 51 The Building Envelope ...... 53 Functions of the Building Envelope...... 54 Interior Parts of the Envelope ...... 99 How the Envelope Modifies the Interior Conditions...... 103 The Effect of Building Occupation ...... 109

CONTROLLING THE INTERIOR ENVIRONMENT ...... 113 Environments for Users ...... 115 Ventilation...... 117 Heating ...... 121 Cooling ...... 128 Lighting ...... 131 Service Supplies...... 139

BUILDING ENVIRONMENT

ENVIRO 27 JULY 2014.indd iii 29/07/2014 00:21 E NIO2 UY21.ndiv 2014.indd JULY 27 ENVIRO NV R 7JL 04id iv 2014.indd JULY 27 IRO iv PRACTICAL BUILDING CONSERVATION ACKN INDEX 601 GLOSSARY...... 503 ...... Performance Carbon & Energy Improving Disasters...... 461 with Dealing 447 Health...... Human & Buildings 445 TOPICS...... SPECIAL 443 Interventions...... Assessing ramn ear...... 350 ...... Repair & Treatment ...... 327 Care Day-to-Day CA 309 DIAGNOSIS...... 256 Investigations...... Specialist Surveys...... 221 Performance Building Research...... 218 Background Assessment...... 213 Environmental ...... 211 ENVIRONMENT BUILDING THE ASSESSING Envelope...... 161 the of Deterioration Materials...... 149 of Deterioration Deterioration Environmental ...... 145 DAMAGE & DETERIORATION E&REPA & RE oiyn h neirEvrnet...... 408 Environment...... Interior the Modifying 362 Envelope...... the on Interventions 354 ...... Interventions Planning Issues...... 351 Persistent with Dealing WEGMNS&PCUECEIS...... 647 CREDITS...... PICTURE & OWLEDGEMENTS ...... R...... 325 IR ...... 147 629 90/0400:21 00:21 29/07/2014 THE PRACTICAL BUILDING CONSERVATION SERIES v

This series of Practical Building Conservation technical handbooks supersedes the original five volumes written by John and Nicola Ashurst, and published in 1988.

The series is aimed primarily at those who look after historic buildings, or who work on them. The ten volumes should be useful to architects, surveyors, engineers, conservators, contractors and conservation officers, but also of interest to owners, curators, students and researchers.

The contents reflect the work of the Building Conservation and Research Team, their colleagues at English Heritage, and their consultants and researchers, who together have many decades of accumulated experience in dealing with deteriorating building materials and systems of all types. The aim has been to provide practical advice by advocating a common approach of firstly understanding the material or building element and why it is deteriorating, and then dealing with the causes. The books do not include detailed specifications for remedial work, neither do they include a comprehensive coverage of each subject. They concentrate on those aspects which are significant in conservation terms, and reflect the requests for information received by English Heritage.

Building conservation draws on evidence and lessons from the past to help understand the building, its deterioration and potential remedies; this encourages a cautious approach. New techniques, materials and treatments often seem promising, but can prove disappointing and sometimes disastrous. It takes many years before there is sufficient experience of their use to be able to promote them confidently. Nonetheless, understanding increases with experience and building conservation is a progressive discipline, to which these books aim to contribute.

The volumes also establish continual care and maintenance as an integral part of any conservation programme. Maintenance of all buildings, even of those that have deteriorated, must be a priority; it is a means of maximising preservation and minimising costs.

Most of the examples shown in the books are from England: however, English Heritage maintains good relations with conservation bodies around the world, and even where materials and techniques differ, the approach is usually consistent. We therefore hope the series will have a wider appeal.

Dr Simon Thurley Chief Executive, English Heritage

BUILDING ENVIRONMENT

ENVIRO 27 JULY 2014.indd v 29/07/2014 00:21 ABOUT THIS BOOK vii

Any book that tries to deal with the vast topic of ‘the building environment’ must necessarily cover a great deal of ground, from the weather, the physics of heat and moisture, and the basics of architecture and engineering, to the building's use and the maintenance and repair of complex materials and systems. Building Environment is the product of the many years spent observing buildings by the volume editors and their contributors: buildings of all kinds, modern as well as traditional in construction, in all uses and under all conditions. It presents a comprehensive overview of building performance, and aims to equip anyone responsible for a building's care with sufficient knowledge to be able to recognise fundamental problems, and to either confidently deal with those that are straightforward themselves or successfully delegate those that are more difficult to specialists.

Many patterns of deterioration appear repeatedly, and familiarity with these patterns makes it possible to recognise and even predict common causes of problems, such as the inevitable blocked gutters and drains. Even so, every building environment is essentially unique, and the underlying causes may not always be as they first seemed. We therefore aim to steer readers away from ‘symptoms-led’ thinking: the same patterns of deterioration can arise from many different problems, and it is important to always approach the situation with an open mind. This is why the book is structured to present a coherent and logical picture of first what the building environment is, then how it works, how it fails, and finally how problems can best be remediated.

After a short Introduction, the Building Science chapter describes the physical processes that explain the many links between the building and its environment. Interactions with the Environment shows how these links affect the way building envelopes are designed to work, and the impact of their surroundings. The role played by the building occupants – particularly when trying to adjust the interior conditions – is covered in Controlling the Interior Environment. Deterioration & Damage looks first at the environmental degradation of individual building materials, before proceeding to consider how the envelope as a whole can fail. Assessing the Building Environment covers the actions needed to understand how a particular building is functioning and how it is failing, including specialist investigations such as environmental monitoring. A short chapter discussing approaches to Diagnosis is followed by Care & Repair, which introduces the various maintenance and remedial works designed to address environmental problems. Finally, the Special Topics at the end of the book address three important issues associated with the building environment: human health; disasters such as floods and fires; and reducing energy use and carbon emissions.

At times the conclusions we have drawn will be familiar to most readers, at others they may be at variance with accepted wisdom; but we have taken the decision to contest familiar notions which we have good reason to believe to be wrong. Too many problems can be traced back to the repetition of misconceived ideas about how building environments operate.

The audience for this volume of Practical Building Conservation is certain to be diverse: not only architects and surveyors with many years of experience dealing with historic buildings, but also students, building managers and homeowners who wish to keep their houses in the best possible condition. For this reason a good deal of introductory material is included; we hope that this will prove helpful even to experienced readers when they need to explain to their clients and colleagues exactly how building envelopes work.

BUILDING ENVIRONMENT

ENVIRO 27 JULY 2014.indd vii 29/07/2014 00:21 NIO2 UY21.ndviii viii 2014.indd 2014.indd JULY JULY 27 27 ENVIRO viii PRACTICAL BUILDING CONSERVATION et lsayhsas enicue,adti a efudjs eoeteindex. the before just found be can this and included, been also has glossary a text, Although • • • • • • • • hpes eeecst te etoswti h etaegvnin appropriate given the are of end text the the in at within publications given sections are other reading to further References of chapters. lists short references, than rather Fo US Link h etb h eeatvlm ybl hwn htmr nomto ntetpcwill topic • the on information more volume. that that showing in symbol, found volume be relevant the by text the Timber Stone Roofi Mort Metals Glazing & Glass Eart Concrete osrainBasics Conservation cesblt n aeo s,teifraingvni h ethsntbe otoe,and footnoted, been not has text the in given information the use, of ease and accessibility r oohrbosi the in books other to s N HS BOOKS THESE ING ,Bik&Terracotta & Brick h, r,Rnes&Plasters & Renders ars, ng vr tep a enmd oepantrsa hyfis cu nthe in occur first they as terms explain to made been has attempt every oditalics bold . rcia uligConservation Building Practical " " " " " " " " " STONE EART BASICS MORTARS METALS ROOFING TIMBER C GLASS ONCRETE BRICK & H series bold r niae throughout indicated are n eeecst other to references and , 90/0400:21 00:21 29/07/2014 INTRODUCTION

ENVIRO27JULY2014.inddENVIRO 27 JULY 2014.indd 1 29/07/2014 00:17 ENVIRO 27 JULY 2014.indd 4 29/07/2014 00:17 INFLUENCES ON THE BUILDING 5

THE EXTERIOR ENVIRONMENT

The primary influence on a building is always the environment to which it is exposed. This is typically very complex, since it includes not only the weather, but perhaps also pollution, runoff patterns, the water table, ground movements and many other factors of this type. Every building environment will depend to some extent on the local terrain, and crucially on the way the surrounding land is being used.

The exterior environment has no predefined geographical limit, but extends out as far as any factor that might be affecting the building condition. In some circumstances this could be quite considerable distances: for example, winds can carry sea salts far inland, which means that an assessor trying to understand a problem related to chlorides may be forced to take the maritime environment into account, even though the structure may be some way from the coast.

The building itself will alter the exterior environment in its near vicinity, such as windiness or runoff. To try to understand patterns of complex environmental problems (for example, storm damage, pollution, flooding or traffic vibration), the position, construction and even the materials of the building will need to be taken into account.

As a result, the exterior environment of every building will always be unique.

COMPONENTS OF THE EXTERIOR ENVIRONMENT

AIR QUALITY The air may contain gases and particulates – ‘pollutants’ – able to interact adversely with building materials. Pollutants can be in the form of particles, droplets of liquid or gases, and may be ‘primary pollutants’ emitted directly into the air by some process such as volcanic eruption or combustion; or ‘secondary pollutants’, which will form when two or more primary pollutants interact.

WEATHER ‘Weather’ is the term used to describe the state of the local atmosphere: that is, hot or cold, wet or dry, calm or stormy, clear or cloudy (‘climate’ is the term used for the average atmospheric conditions over longer periods of time).

The components of the weather that have the most impact on buildings include rain and snow, the temperature and humidity of the air, the direction, strength and gustiness of the wind, and the patterns of sunlight. These all will vary locally and according to exposure, and may well have different impacts on different parts of the building.

BUILDING ENVIRONMENT INTRODUCTION

ENVIRO 27 JULY 2014.indd 5 29/07/2014 00:17 NIO2 UY21.nd40 40 2014.indd 2014.indd JULY JULY 27 27 ENVIRO 40 PRACTICAL BUILDING CONSERVATION h surface. the down run may water the marble), polished here, as or example, for metal, or (glass permeability low sufficiently of is surface the If water. liquid form to collect may surfaces cold on Condensation surfaces on Condensation oe hti,t eaoae.Haigasraewl as oeo h ae molecules water the of again. evaporate some once to cause surface it will the upon surface condensed of a free Heating ‘evaporate’. break to to is, energy that enough more: gain may it Eventually it. with colliding heat absorb will molecule th water from condensed energy A state. permanent a not is Condensation vapour that at air to exposed to surface used pr a be if can [DPT]; pressure temperature’ vapour ‘dew-point The a pressure). calculate vapour the on surface is, (that the fi temperature cold a and How cause surface. to cool be a they to on time likely have each would more lose is will condensation molecules so vapour it, the with energy collide more the surface, the colder that The water: liquid of film a a in covered near be air ‘condensation’. may of by pressure surface is, vapour the the eventually If high, condense. very to is forced surface are they that energy much so have to said is Th next away the break again longer away no break its can to of which energy little molecule little a A collides. lose too it with will time it left surface, be a may or it eventually air, until the energy, in molecule other some or molecule, water almoIn EVAPORATION & CONDENSATION suedosblwti eprtr,te ae ilbgnt odneot it. onto condense to begin will water then temperature, this below drops essure oewtrmlclsteeaei h i,temr ieyte r oclie losing collide, to are they likely more the air, the in are there molecules water more e teeycliinamlcl fwtrvpu ae,wehrwt another with whether makes, vapour water of molecule a collision every st ufc n rmtear n cainlyfo aormolecules vapour from occasionally and air, the from and surface e mo odnaindpnso h i' bouehumidity absolute air's the on depends condensation of lm ‘condensed’. 90/0400:24 00:24 29/07/2014 SATURATION & RELATIVE HUMIDITY 41 Returning for a moment to the image of an imaginary box of air, it is easy to see that if more water molecules are added to the box, eventually there will come a point where the number of water molecules condensing exactly equals the number of molecules evaporating: beyond this point, adding more water molecules to the air will simply cause the same number of molecules to condense out. The vapour pressure therefore remains steady, and the air is said to be ‘saturated’: that is, it is holding as much moisture as it possibly could at that temperature.

If the number of water molecules in the imaginary box were kept constant, but the air was heated, each molecule would have more energy to lose before it would be forced to condense: in other words, hotter air can hold more water molecules.

If there is a source of liquid water in a sealed container, the air in the container will take up water molecules by evaporation until the air is saturated. This can take some time, depending on the size of the container and the surface area of the source (the greater the surface area, the faster the evaporation).

Free air is rarely saturated, but instead will be holding only a fraction of the water molecules it could potentially hold. The actual extent of saturation is usually expressed as a percentage, and is called the ‘relative humidity’ [RH] (relative to saturation, in other words). By definition, the RH of saturated air is 100 %, so air at 50 % RH is holding half of the number of water molecules it potentially could hold at that temperature. Air with an RH of 50 % at 25˚C will be holding much more moisture (that is, it will have a much higher AH) than air of 50 % RH at 15˚C.

Condensation in voids Because so very few water molecules are needed to saturate air, if the air in a void or hollow exposed to some sink of liquid water is allowed to equilibrate, its relative humidity will reach 100 % no matter how small that sink of moisture may be. In a closed container even a single drop of water will be ample to cause the air within to saturate: the condensation in these bottles shows that each is at 100 % RH, regardless of the quantity of liquid water present. For this reason, measuring the relative humidity in a void in a wall can only show that the wall is dry or that it has some moisture within it: it cannot indicate how much moisture is actually present.

BUILDING ENVIRONMENT BUILDING SCIENCE

ENVIRO 27 JULY 2014.indd 41 29/07/2014 00:25 NIO2 UY21.nd54 54 2014.indd 2014.indd JULY JULY 27 27 ENVIRO 54 PRACTICAL BUILDING CONSERVATION neoescniinadbehaviour. and condition the envelope's on effect significant a have can wallpapers as such elements minor apparently Even plumbing). and partitions interior as (such conditions environmental interior the on strong impact a have still will which but purposes, other serve to intended primarily are which elements and systems), heating other and fireplaces the as (such conditions interior control to intended elements walls), exterior and roof the as (such function weatherproofing a serve to intended deliberately elements of composed be will It unique. is envelope building Every envelope building The fteenvelope. the of purposes, functional interior have and often exterior whic elements the decorative with interacts apparently work ensemble Even they the how how environments. of of components, and its whole, of a each as of together action and purpose the of developed ENVELOPE Tode BUILDING THE OF FUNCTIONS iudwater liquid wate of sources other d an kitchens Bathrooms, ENVELOPE BUILDING THE OF ELEMENTS IMPORTANT n floors and walls below-ground Fo nain and undations utb nesodi ear n leain r o oedne h operation the endanger to not are alterations and repairs if understood be must h aorand vapour r emn o uligevlp ih eoeaig la itr utbe must picture clear a operating, be might envelope building a how termine Plumbing ovre olvn space living to converted spac tisan Attics s nldn those including es, n use and occupation of Patterns te roof other d environments interior different have that building betw especially floors, and walls Partition supplies energy other and lighting Artificial e ra fthe of areas een rudfloors Ground n/rcoigsystems cooling and/or heating the of elements Chimneys of n lmnsthat elements and Roofs hmesaddormers and chimneys irete,sc as such them, pierce et n other and vents , El mnsta irethe pierce that ements xeirwls uhas such walls, exterior window lmnsta shed that elements tigcussand courses string xeirwlsand walls Exterior odmouldings hood ae,sc as such water, n doors and s Rainwater drainage Ground goods 90/0400:26 00:26 29/07/2014 KEEPING THE BUILDING DRY 55 Inany climate that is not extremely arid, the fundamental demand on any building envelope is that it should be able to handle water. This function is critical to the way the building envelope is detailed and constructed. Water meets the envelope in many forms, and from many sources, of which rainfall and groundwater are the most important. Almost all the familiar detailing of buildings stems from the need to move water from these sources safely away from the fabric, and especially to keep it from penetrating to the interior. Water can be taken up by the building fabric in different ways: absorbed as a vapour, drawn up as a liquid into the pores or through fine cracks, joints and interfaces between building elements, condensed from the air onto cold surfaces, or by a combination of any or all of these (see Building Science). It can then travel through the structure, driven a little by gravity and very much by the ambient conditions, especially those causing evaporation. As it moves, it will transfer heat, and it can often transport contaminants as well. The phase in which water is found (liquid, vapour or ice) is critical to its behaviour, and will also affect building materials in different ways. Phases may be very localised, since they will depend on so many factors: not only the temperature, but also (amongst others) the flow of air across the surface, the chemical and physical nature of the material, and the nature and concentration of any contaminants.

DEALING WITH RAINWATER Likelight falling on glass, rainwater meeting the envelope can be deflected from it, absorbed and held by it, or transmitted through it, and the ways in which the building does this are a marker of how successful it is at fulfilling this primary role: • Deflection Good envelopes deflect as much rainwater as possible, by using features such as drips and overhangs. Water may be collected and channelled away in gutters and drains. • Absorption Traditional building materials such as brick, stone and lime mortar are permeable, and can absorb rainwater in surface pores, from which it can later evaporate. • Transmission Modern rainscreen building systems allow a degree of transmission, with penetrating water being collected in internal drainage systems, but in both modern and traditional systems transmission of rainwater right through the envelope is a sign of failure. How rainwater interacts with the envelope depends on other environmental factors as well, most notably windiness, air temperature and solar radiation. The risk of failure, and therefore the need for good detailing, increases with exposure to all these factors.

BUILDING ENVIRONMENT INTERACTIONS WITH THE ENVIRONMENT

ENVIRO 27 JULY 2014.indd 55 29/07/2014 00:26 NIO2 UY21.nd88 88 2014.indd JULY 2014.indd JULY 27 27 ENVIRO 88 PRACTICAL BUILDING CONSERVATION oeeffective. more evaporation makes ratio volume area-to- surface greater wall, the thin where a in lower be also will rise Capillary higher. rise water the make will evaporation the reduce to sample the coating partially whilst rise, capillary of height maximum the reduces sample) the across airflow the increasing by example, (for evaporation of rate the Increasing evaporation. of rate the equals uptake of the rate where point the to up will rise water base, its at moisture of source continuous a to exposed is material permeable of sample a If C playrise apillary j aff is po it means which evaporation, the of by governed speed ambien is the process and This wall at material. the the rate the of to the through permeability wall equals up evaporation the drawn by up removed being rise being is will it is it which water base, which its at at rate water the has where materials point permeable of made wall a If Rise Capillary from Protection mosbet aeraitcwlswt signifi with almost walls proved a realistic has as make it such laboratory, to coating impossible the impermeable in an Even given evaporation. prevents been which has render, one wall cement than the higher where except rises never courses, brick almost two a moisture or In example, picture. for different joints, very lime-mortar a present with buildings wall real metres, several rise could water Although surface both of dispose and collect to runoff intended perimeters, building around drains The perforated incorporated they later down; ran it pipe as water the catch to filled hillsides trenches across sloped for simple developed French originally were Henry These engineer land. American which agricultural drain, ‘French’ runoff the stop on or slow based to e ar used be also may drains Ground lomksmitnnedffiut(see difficult maintenance makes also counter-pr specifically installed backfi was for drainage fashion a been has there England, pe In sewer). public a or soakaway private that drains French it ewe aeil en atclryimportant). particularly being materials between oints iee riswt oregae ahrta apn ihca,epcal fthe if especially clay, with capping than rather gravel coarse with drains rimeter oiyo h aeil n h tutr ftewl tetikesadntr fthe of nature and thickness (the wall the of structure the and materials the of rosity ailr rise capillary n etxielnnst tpte itn ptoquickly. too up silting them stop to linings geotextile and s nsample in oad h uligadriwtrfo h onie,aeuulymodifi usually are downpipes, the from rainwater and building the towards fbrick of odtos(h eprtr,hmdt,adepcal h i oeet,the movement), air the especially and humidity, temperature, (the conditions t dcie ic h rvllt ae u nesl,btpeet teaoaig it evaporating; it prevents but easily, in run water lets gravel the since oductive, oetertclmdl aesgetdta natikhmgnoswall homogeneous thick a in that suggested have models theoretical some iettecletdwtrtwrsadshrepit(omnya (commonly point discharge a towards water collected the direct movement oeair more oda ihmitr rbes hs oee,is however, This, problems. moisture with deal to eeirto Damage & Deterioration atrsn damp. rising cant coating surface cossoe pngon.Most ground. open sloped across and ae&Repair & Care ihgae,set gravel, with sl c fbrick of ice thinner ce ythe by ected ed lling ). 90/0400:28 00:28 29/07/2014 Rising damp? 89 The pattern of damage over the length of this run of brick masonry demonstrates why 'rising damp' – capillary rise from the water table – is unlikely to be a cause of serious moisture problems. The classic pattern of decay and salt staining that is often attributed to rising damp is visible only on the exposed section of wall to the right, where it is clear that the true cause is water percolating down from the top of the wall. To the left, where the top of the masonry is protected, only the very base shows any sign of moisture damage, as would One reason for the resistance of real walls to moisture rising from the base is their be expected where the source of inherent inhomogeneity, and particularly the many interfaces between the different moisture is the water table. materials; every joint between mortar and brick will hinder the passage of water Serious problems from groundwater through the wall. Fundamentally, however, capillary rise is limited by evaporation, and seem to have begun when sewers this is far more effective in a real wall than is assumed in most theoretical models. The and mains water supplies were model most often used to calculate potential capillary rise assumes the wall to be like a introduced in the mid-19th century; bundle of fine long straws, each having a single entrance and exit. This is a reasonable this was when the term 'rising analogy for water uptake in a tree, but not for building materials, where the pore damp' was invented and damp- structure is multi-directional and branching, with many links to surface pores through proof coursing introduced. Leaking which moisture can evaporate. In practice, moisture problems from groundwater tend pipes are a much more serious source of persistent water than the to occur when the wall has an impermeable finish such as a cement render that prevents water table, and the problems seem the water from evaporating. to have been exacerbated when Interestingly, there is no evidence of any technology to prevent rising groundwater until cement renders were introduced the late Victorian period. The first ‘damp-proof course’ was a system of interlocking (these prevent evaporation and so vitrified stoneware tiles laid through the depth of the wall a little way above ground level drive moisture further up the wall). to deal with infiltration from poor early sewers, which tended to back up and flood Often the render will have been applied in response to a moisture cellars. This was developed and christened in 1859 by John Taylor; other builders used problem, and thus have made the bituminous materials, but slate quickly became the popular choice. By the late 1870s situation worse rather than better. damp-proof coursing had been incorporated into English building legislation, and Impermeable finishes may also make although sewers and water supply systems are now much less problematic, it is still it difficult to locate the true source required for new build. For existing buildings, alternatives such as injected damp-proofing of the water. are sometimes used, although there is little or no evidence that these are effective (see Deterioration & Damage). The original cause of the problem appears to have been forgotten, and ‘rising damp’ has become a catch-all phrase for all moisture problems in walls, even when the water is percolating down from above.

Although the water table will not in fact be a source of problems for most types of construction, water-sensitive materials such as timber and cob will still need to be protected from ground moisture. The traditional approach has been to construct walls made primarily of these materials onto a masonry plinth made of stone or brick.

BUILDING ENVIRONMENT INTERACTIONS WITH THE ENVIRONMENT

ENVIRO 27 JULY 2014.indd 89 29/07/2014 00:28 NIO2 UY21.nd106 2014.indd JULY 27 ENVIRO 106 PRACTICAL BUILDING CONSERVATION 7JL 04id 106 2014.indd JULY 27 oaheetedsrdtemperatures. desired the achieve used to be must that energy of amount the reduce will buffering or cooled, heated is building a such If inertia. thermal low of components other and by windows up taken area surface of amount small the by enhanced is thermal buffering type, this of building a In exterior. the than less extreme and stable more both be will temperatures interior the words, other In conditions. exterior the coldest than warmer stay also will it maxima, exterior the than cooler be always will interior the day, although the and of part hottest the after well reached be will temperatures interior maximum heated, not is the building If warming. be still will the interior – cool to begun have exterior conditions the when – evening by that so slowly, wall the heat through this transfers air; the and sun the by warmed are surfaces external their day, the During buffers. temperature excellent therefore are and inertia thermal high extremely an have These walls. masonry massive has Sussex, in Hardham at Botolph‘s, St churches, medieval many Like buffering Thermal nomsiewlsadfloswa floors and transfer walls Radiative massive uncommon. into therefore were bridges thermal ther serious of and deal sparingly, great a have construction the and Traditio al.Gasmyas ecvrdwt lsi filter plastic curtain with and covered windows be in also glass may of Glass sheets walls. and single walls replace for to Units] systems Glazing insulation multilayered [Insulated IGUs breaks, thermal increasing as of such ways mass, sophisticated develop thermal to forced been have engineers response, By (p fabric AMBIENT TEMPERA (°C)TURE 12 16 20 24 28 32 36 40 otat aeil ihlwtemlieta r rtclt oenacietr.In architecture. modern to critical are inertias thermal low with materials contrast, JULY 1 0 4 8 a ulig sal rvd odtemlbufferin thermal good provide usually buildings nal nlig aetisadcarpets). and tapestries anelling, XEIRTEMPERATURE EXTERIOR JULY 8 eue ihwl n orcvrnso ibror timber of coverings floor and wall with reduced s 5JULY 15 a as ea n ls eeused were glass and Metal mass. mal ordc aitv uptake. radiative reduce to s NEIRTEMPERATURE INTERIOR 2JULY 22 ,snebt h materials the both since g, 9JULY 29 90/0400:28 29/07/2014 29/07/2014 00:28 BUFFERING THE EXTERIOR HUMIDITY 107 The primary mechanism for humidity buffering is air exchange: buildings that are very ‘leaky’ tend to have internal relative humidities that closely follow those of the exterior air. The secondary mechanism is permeable materials absorbing and releasing water vapour in response to changing relative humidities. If the interior vapour pressure is constant, the fabric and the interior air will be at equilibrium, but if the vapour pressure of the air changes, then hygroscopic materials such as brick, stone, lime plaster and especially timber will respond by either taking up or giving up moisture until a new equilibrium is reached.

Every permeable building material will have its own characteristic hygroscopicity, taking up moisture from the air in a way that depends on (amongst other factors) the structure of its pore system and the presence of contaminants such as salts. Moisture absorption and desorption depends on the ambient conditions: for example, plotting a hygroscopic material's moisture content against changing ambient relative humidity generates a characteristic curve, showing the ‘equilibrium relative humidity’ of the material.

Some degree of existing moisture is important to the material's buffering capacity, since very dry materials absorb moisture much less effectively (just as a sponge will not absorb water when dry, but becomes very absorbent indeed once slightly wetted: the reasons for this are discussed in Building Science). It has been shown experimentally that an oven-dried lime plaster will absorb very little water vapour from the air, but after several months or years of exposure, even plaster in perfect condition will be holding some moisture in its pores, and will therefore be an excellent buffer. Materials such as timber will usually be holding significant amounts of moisture (as much as 15 % by weight for wood in good condition), and this acts as a sink of water when, say, a temperature increase causes the ambient relative humidity to drop. It also helps the wood to take up water vapour when the humidity rises again (that is, when the temperature drops, or wetter air enters the building).

The envelope will also have its own characteristic ‘hygric mass’: the way it buffers humidity will depend not only on the permeability of single materials, but on the behaviour of complex groups of materials. Discontinuities, interfaces, joints, surface finishes and coatings may all have a significant impact. For example, moisture-resistant coatings such as vinyl paints will hinder evaporation much more than they hinder moisture uptake, so painted plaster may steadily become wetter (see Building Science).

The average absolute humidity in the interior will be steadier, but typically slightly higher, than the exterior.

All parts of the building can contribute to the humidity buffering, including the interior and the contents such as timber furniture. The floor is one of the largest surfaces for moisture exchange; traditional solid floors, which do not incorporate damp-proof membranes but are bedded directly onto the earth or onto a permeable lime-based mortar, can account for more than half the moisture content of the fabric. So long as there is plentiful air movement and air exchange this does not damage the building, and indeed it prevents groundwater being driven up the walls.

BUILDING ENVIRONMENT INTERACTIONS WITH THE ENVIRONMENT

ENVIRO 27 JULY 2014.indd 107 29/07/2014 00:28 NIO2 UY21.nd168 168 2014.indd 2014.indd JULY JULY 27 27 ENVIRO 168 PRACTICAL BUILDING CONSERVATION o deterioration. for reason a as pinpoint unequivocally to hard often is work freeze-thaw at that be can factors many will So that fail. units weaker the is it stones, since or bricks the of quality the in variation the also but exposure, only not reflects deterioration of pattern The water. trap which mortars, cement-based of use the by exacerbated be may Problems masonry. in seen commonly most is but temperatures, low to exposed material permeable wet any in occur can damage Freeze-thaw damage Freeze-thaw nagrntol h ae n utr,btpsesb swell. as passers-by but gutters, that and building dams eaves to ice the risk causing only a eaves, not be the endanger at can which refreeze off, may the slide meltwater exterior, to The the below. snow elements to the ventilated causing well up, very heat not are may ceilings covering is above the roof space If problems. attic other the face and snow insulated thick not in covered periodically are that Roofs valves. expansion as act which the the cisterns since at toilet pipes, includes apart cold-water pipe often than the system failure cold-water split to to prone sufficient front, more is ice are it the pipes eventually Hot-water of until joints. ahead up trapped build ice air will the the pressure forces compresses air instead This so it and pipe. as strong, the water along too the much grow of is to expansion pipe not crystals the the is by damage: it pipe the least, the does at of that case walls freezes this the In on weather. exerted cold force in the pipes may water actually it of understood, bursting well the not to is related damage be freeze-thaw for mechanism precise the Although of cycles repeated thawing. to and subjected freezing if especially may conditions, materials freezing permeable under wet down and break condensation, to lead may cooling example, For th Many of Damage Indirect rbesidrcl asdb eprtr nov t ffc nmoisture. on effect its involve temperature by caused indirectly problems e 90/0400:37 00:37 29/07/2014 IMPACT OF SUNLIGHT 169 As with temperature, sunlight can cause damage both directly and indirectly, although in this case the direct damage is usually confined to superficial changes, and it is the indirect damage – chiefly localised heating – that is able to cause the most severe problems for most building envelopes. Since exposure depends on the building and its surroundings, this can change quite dramatically through the day and the year.

Direct Damage Although the ultraviolet component of sunlight can break down organic materials in building components, this is usually superficial. It is of most importance for decorative surfaces such as wall paintings or wallpapers that incorporate dye pigments, where the appearance can be dramatically altered by fading. Exposed timberwork will change colour, but this will not affect its strength to any significant degree. Sunlight can also break down glues and sealants such as putties and silicones, which can be a serious issue for some modern curtain-wall construction, but the degree of damage will depend on the exposure. "GLASS

Indirect Damage Solar heating can cause materials to expand and contract, and can also act as a catalyst for chemical reactions. Solar heating can cause very high vapour pressures in surface pores and inside hollow-wall construction, and this can force moisture through the wall. Sunlight exposure is also a critical factor governing the growth of plants and microorganisms in and around the building.

Sunlight damage Many plastics are very susceptible to damage from ultraviolet light. In this railway station roof, the transluscent panels have severely discoloured. Even newer replacement panels (such as that at top left) are beginning to show signs of the same deterioration.

BUILDING ENVIRONMENT DETERIORATION & DAMAGE: DETERIORATION OF THE ENVELOPE

ENVIRO 27 JULY 2014.indd 169 29/07/2014 00:37 NIO2 UY21.nd238 238 2014.indd 2014.indd JULY JULY 27 27 ENVIRO 238 PRACTICAL BUILDING CONSERVATION n a eue ohl lnmore investigations. plan exact help to used be can and envelope, building the of behaviour overall the examine to way a handy be still can they interpretation, in weight much too given be should never day single a for readings the and measurements, spot give only will meters hand-held Although pollution. or movement air as such parameters environmental other of readings take to surveyor the allowing probes, interchangeable have may models sophisticated More point. dew and humidity absolute calculate may and temperature, and humidity relative measure will most cost; little at available now are meters electronic Hand-held meter hand-held a with conditions T kn ednso environmental of readings aking urn evcs(uha etn)aeatal en used. the being ways actually the are of heating) picture as a (such construct services current to questioned users building the and recorded, used being is Al building management. the way the a in eq Changes be identified. are can be system) must heating these new of so a or factor, of tiles, critical installation or the or carpets wallpapers, of or addition paints the impermeable example, (for fabric the to changes Recent seals. and flashings the and windows), po the as such clea not th still at is look damage moisture-related of source likely correctly. the operating If are of they signs whether for see only to not but checked problems, be similar impact must other of doors and terms and leaking in Windows considered whole. as a well as envelope as separately, the assessed on be to need will room Each al motn,a r n leain hthv enmd oteenvironmental the to made been have that alterations any are as important, ually xeiroc gi,dul-hcigdtista ol ecuigproblems, causing be could that details double-checking again, once exterior e nig h onsbtenbidn lmns(o xml,around example, (for elements building between joints the inting, vdneo uligsrie,bt l n e,wl edt be to need will new, and old both services, building of evidence l ewe h xeiradinterior. and exterior the between in comp effects potential the at looking when especially comparisons, general making with approached be should gives this meters. hu and temperature of spot measurements take to possible is It moisture. of source hidden a down narrow to help may patterns resulting the accurate, be not will results mo us wa Relati superfi Mo problems. of sources common fi in even or pipes, heating and plumbing in leaks condensation: to or envelope, building the with problem a to due be always not will problems Water enlsae,freape or example; for spaces, ternal n eitneo capacitance or resistance ing iiy sal ihhand-held with usually midity, l a lob ogl mapped roughly be also can lls suemtr,adatog the although and meters, isture tassosfidi sflt map to useful it find assessors st ato,i a eawyof way a be can it caution, rsn ewe diff between arisons emitr n atlvl in levels salt and moisture ve ildcyot elevations. onto decay cial lhuhteinformation the Although ,i a encsayto necessary be may it r, epoeto ytm,are systems, re-protection fheating: of erent 90/0400:48 00:48 29/07/2014 MAKING DETAILED MEASUREMENTS 239 Almost every aspect of the building environment has the potential to merit closer investigation and measurement as part of a building performance survey, from the slope of the surrounding ground to the structural soundness of the building elements.

CHARACTERISING THE GROUND SLOPE If it is suspected that the ground levels are causing runoff problems, or there are subtle issues between interior and exterior ground levels, this can be checked very easily with simple tools (string, a metre rule and a level), though it does require that the surveyor has some assistance. Alternatively, professional surveying equipment can be used.

Determining relative ground levels Top: Interior floor levels, the difference in the interior and exterior ground levels, and the slope of the ground around the building, can all be determined to sufficient accuracy TAKING LEVELS TAKING LEVELS AT A WINDOW for most purposes using the simplest of tools: two straight sticks or metre rulers, a tape measure, string and a builder’s level, or a line level. Level LEVEL Bottom left: Measurements are taken relative to one point, usually inside the building, with L0 L1 L2 the measurement team working outwards from there; each reading becomes the baseline for the next measurement. The results are marked onto a building plan. d1 d2 Bottom right: To connect the internal and external measurements, it is usually easiest to note the height of the same window sill on the interior and exterior.

BUILDING ENVIRONMENT ASSESSINGTHEBUILDINGENVIRONMENT

ENVIRO 27 JULY 2014.indd 239 29/07/2014 00:48 NIO2 UY21.nd298 298 2014.indd 2014.indd JULY JULY 27 27 ENVIRO 298 PRACTICAL BUILDING CONSERVATION cuaeadrpaal readings. repeatable ensures and This accurate probes). T & RH the case of the in screen Stevenson a or filters and thermistors, the the of in case foam green of block (a screens by movement air of effects cooling and drying the from protected are probes All probe. [RH&T] temperature and humidity relative combined a and temperature, surface reading thermistor a includes cluster each Here, possible. as as comparable are sensors the from readings the that means but easier, installation makes only not this ‘clusters‘: into probes group to convenient is It atre.Rpaaiiyo esrmnstknb igesno,o ewe diff between or in sensor, control single a process se by for taken taken measurements readings example) of (for Repeatability as factories. accurate their as understand be environment to building to important need the is investigating rarely it for so taken it, Readings gathering repeatability. sensors and the accuracy as good as only is Data Se rmtemis rfo oa aes(rsm te lentv source). alternative other some (or panels directly solar either from electricity or with mains, supplied can the be than therefore from power must more They require batteries. – by example provided for be sensors, velocity air low). hot-wire is – power probes battery Some when logger the with to along provided transmitted be be can can warnings life data, battery the because but loggers, renewal; stand-alone periodic (like require batteries these by powered generally are probes telemetry radio vari Al sr rudtebidn,i uhmr motn hnaccuracy. than important more much is building, the around nsors lcrncsnosms esple ihpwr u h a nwihti sprovided is this which in way the but power, with supplied be must sensors electronic l etn h orc esr Probes & Sensors Correct the lecting s adie rbsgnrlyda hi oe ietyfo h aaogr but datalogger, the from directly power their draw generally probes Hardwired es. su an temperature exterior of measurement the unit single a in combining tool, useful particularly a is station weather The working. is envelope building othe any than more this as standard, also exte Monitoring temperatures. surface with together often humidity, relative and temperature measure to equipment Mo a response, component response, e fram structural motion, ground monitoring mean can This wind. or temperature as such parameters environmental by ected aff are these not or refl wh check to monitoring environmental of programme a in incorporated Struct dcepo settlement. or creep nd lgt n wind. and nlight, eaiehmdt,rifl intensity, rainfall humidity, relative d te rntaprn weaknesses apparent not or ether c eiu rbes n whether and problems, serious ect tmntrn eiswith begins monitoring st iraditro irciae is microclimates interior and rior oprsnrvashwthe how reveals comparison r rlmntrn a lobe also can monitoring ural erent 90/0401:19 01:19 29/07/2014 299 COMMONELECTRONIC SENSORS USED TO MONITOR THE ENVIRONMENT

PARAMETER TYPE OF MEASUREMENT SENSORS COMMENTS

AIR TEMPERATURE Direct Thermometers Thermocouples are not reliable when used to Thermocouples measure temperatures close to the ambient Thermistors air temperature Resistance sensors

SURFACE Attached sensors Thermistors Accuracy depends on method of attachment TEMPERATURE Resistance sensors

Remote sensors Infrared thermometers Readings depend on surface emissivity as well Infrared thermography as temperature

AMBIENT HUMIDITY Direct Capacitance sensors Need regular recalibration Dew-point sensors

LIGHT Direct Photodetector Can measure different wavebands

Indirect Photodetector Can measure different wavebands

AIR MOVEMENT Pattern and speed of flow Smoke tests Air movement is very variable, so spot Particle velocimetry measurements can be particularly deceptive

Speed of flow Cup anemometers The presence of probes can cause turbulence Hot-wire anemometers and affect the reading; this is a great problem Ultrasound at low speeds

AIR EXCHANGE Indirect Tracer gas On-off measurement: therefore, conditions under which to monitor must be chosen carefully

Direct Door or window opening Closure of window or door completes circuit May need quite complicated processing to extract both numbers of opening and closing events, and the duration of each separate event

MOISTURE CONTENT Indirect Resistance sensors Best systems based on measuring dielectric change, Embedded capacitance sensors but currently no totally satisfactory method, since Embedded microwave- sensor must be inserted in a drilled hole, and this capacitance sensors changes the characteristics of the material

WATER EVENT Direct Strip with a simple printed Can be used to detect surface condensation or, for electronic circuit; presence of example, blockages in gutters liquid water completes circuit Can be used to trigger an alarm

HEAT LOSS Indirect U-value reading with flux meter U-value is a measurement of conductive heat loss only

AIR POLLUTION Direct Air pumped through Sensor can be chosen to detect a range of analytical device pollutants, or to monitor a single pollutant to a greater accuracy

BUILDING ENVIRONMENT ASSESSINGTHEBUILDINGENVIRONMENT

ENVIRO 27 JULY 2014.indd 299 29/07/2014 01:19 NIO2 UY21.nd316 316 2014.indd 2014.indd JULY JULY 27 27 ENVIRO 316 PRACTICAL BUILDING CONSERVATION ODNAINISD NUAE LZN NT(DUL’O TIL’GLAZING) ‘TRIPLE’ OR (‘DOUBLE’ UNIT GLAZING INSULATED INSIDE CONDENSATION DESCRIPTION AREA CO CO CO OS ACE IHO WALL ON HIGH PATCHES MOIST DNAINO MEMAL SURFACES IMPERMEABLE ON NDENSATION DNAINISD EODR GLAZING SECONDARY INSIDE NDENSATION MNOSRE YPOSO NIOMNA PROBLEMS ENVIRONMENTAL OF SYMPTOMS OBSERVED MMON F‘DAMP‘ OF S POSSIBL ap oeie c lifespan) Sometimes limited a have (these seals Failed problems moisture has wall j window; the below d staining runoff regularly; occurring Significant render) cement a to example, led (for have problems interventions where wrong exacerbated be well May drains or including goods sources, rainwater other blocked from problems moisture Liquid as condensation with problem, water liquid be May runoff) by affected fi damaged be may feels sign touch; wall to conditions; damp certain and cold under metal or glass as Visibl • • Source liquid of water; M • • ihitro uiiy(ope ihcl glass) cold Insufficien with (coupled humidity interior High wi nenlpluat sc sslht eoisfo heating) from deposits sulphate as (such pollutants internal • use fl building in • material organic trapped • Unusuall o e b nso ea windows metal of ints i c d a n prebernestapn moisture trapping renders mpermeable aeto elside-effect real or parent a ftme iladhrzna ebr of members horizontal and cill timber of cay iny ihriwtrpenetration rainwater with himneys psto fcmuto rdcsi fl in products combustion of eposition okdriwtrgoods rainwater locked ehgocpcsls ore include: sources salts; hygroscopic be y os rcroino oiotlmmesand members horizontal of corrosion or dows, fmitr rbes(uha ea o timber for decay as (such problems moisture of s ae edn niprebesrae such surfaces impermeable on beading water e hnmsnywls hle ywind by chilled walls, masonry thin y v t odnaino h nieo h glass, the of inside the on condensation CA E akdglass racked e tlto oetro,epcal where especially exterior, to ntilation USES omncue include: causes common ue ue nishe s or ne htcniin oswtrbaigappear? water-beading does conditions what Under fo Look Seal fo Look Ma occur? condensation does conditions what Under to compare and poss damage, of distribution Map environmental monitor to necessary be May u co Ma L poss li and lzn ntfistoo fits unit glazing • • glas If qualit Assess DIAGNOSIS SUPPORT TO ACTIONS c gis h ls;i h el aefie,ti will this failed, have seals the if pro glass; the against ice atcnet(okfrhgocpcsalts) hygroscopic for (look and content distribution, salt and content moisture determine fsuc sucer aesmlsfo alto wall from samples take unclear, is source If e o s n oeetcue failure causes movement i eilyfrfiecak htcudwc nmoisture in wick could that cracks fine for pecially dtos nldn ufc eprtr,adto and temperature, surface including nditions, kfo ok mpact esadhwtehaigsse sbigrun being is system heating the how derstand encsayt oio niomna conditions environmental monitor to necessary be y itiuino aae n opr to compare and damage, of distribution p v a etse ypaigacpcnann dry containing cup a placing by tested be can s k condensation oke bebidn fl building ible bebidn fl building ible ntels) a rce,lo o source: for look cracked, has s iudmitr rbesi urudn wall surrounding in problems moisture liquid r osbesucso yrsoi salts hygroscopic of sources possible r joists as (such timbers embedded of decay r o y f onigadrne,checking render, and pointing aw aw s s tigh tly in rm,s htthermal that so frame, 90/0401:21 01:21 29/07/2014 317 COMMON OBSERVED SYMPTOMS OF ENVIRONMENTAL PROBLEMS

NON-VISUAL SYMPTOMS

POSSIBLE CAUSES ACTIONS TO SUPPORT DIAGNOSIS

MUSTY OR DAMP SMELL

Timber decay Is the smell present all the time, or only after the room has been shut up? Mould growth Look for sources of water: most commonly liquid water leaks, but condensation can also Most common in areas with limited air circulation be a problem (such as condensation behind impermeable insulation or membranes)

SPACE FEELS ‘STUFFY‘

Insufficient air exchange and/or air movement Is it a problem at most times, or only in certain conditions or times of the year? Sources of ventilation such as windows, chimneys sealed up Is it a problem in all rooms, or only in certain rooms? Central air-conditioning system with inadequate filtering or ventilation Check airflow and air exchange, especially around doors, windows, chimneys

SPACE FEELS DRAUGHTY

Air leakage through windows, doors or chimneys Is it a problem at most times, or only in certain conditions or times of the day or year? Open-plan interior: no ability to isolate spaces Is it a problem in all rooms, or only in certain rooms? Poor control systems: heating causing air currents, or pulling in colder Check condition of windows, doors and so on air; heating using blowers or localised radiators; air conditioning Check airflow and air exchange, especially around doors, windows, chimneys blowing air too strongly Check for hidden major air leaks through fabric Large areas of glass (thermal bridging)

SPACE FEELS TOO COLD

Radiant heat loss to thermal bridges or materials that readily absorb Is it a problem at most times, or only in certain conditions or times of the year? heat from the body, such as: What activities are happening in the room? How are occupants dressed? • large areas of glass What is the heating system? How is it controlled? • thick masonry walls • cold floors Inadequate heating, or heating/cooling system that is badly controlled

SPACE FEELS TOO HOT

Solar gain, especially through large areas of glazing Is it a problem at most times, or only in certain conditions or times of the year? Inadequate ventilation What activities are happening in the room? How are occupants dressed? Extensive heating system and insulation Check air temperature, ventilation and air exchange Inadequate cooling, or heating or cooling that is badly controlled What is the heating/cooling system? How is it controlled? How is the building insulated?

SPACE FEELS HUMID

Condensation problems Are there any building flaws letting in liquid moisture? Insufficient air exchange and/or air movement Is it a problem at most times, or only in certain conditions or times of the year? Incorrect heating system, or control of heating system Is it a problem in all rooms, or only in some parts of the building? Building use involves a great deal of moisture Check airflow and air exchange, especially around doors, windows, chimneys Moisture-resistant materials have been used, such as AVCLs, water- Monitor to determine vapour content of air, and identify sources of vapour resistant insulation, or impermeable wallpapers or paints

BUILDING ENVIRONMENT DIAGNOSIS

ENVIRO 27 JULY 2014.indd 317 29/07/2014 01:21 NIO2 UY21.nd386 386 2014.indd 2014.indd JULY JULY 27 27 ENVIRO 386 PRACTICAL BUILDING CONSERVATION To ahrta eidit. behind than rather geodrain, the over travels walls the down flowing water to that top ensure the at capped be must geodrain. This a use to is approach one water, of penetration lateral prevent thereby and it, abutting ground the eaaea xeirwl from wall exterior an separate addana fail-safe. a as drain land a signifi landscape or building on impinge only is It building. the and of structural po character both the have change may could an that and exercise around implications, invasive excavation archaeological but and dry, costly stay a and is out building dry existing passageways. to perimeter walls or the allows areas approach well This away forming level, dug ground sometimes interior was the use match in to cellars or basements outside ground the Historically, Excavation require supervision. may archaeological the digging possibly If importance, and expert. historic consent, drainage of statutory a surroundings as the well or so as listed and engineer is footings, building structural the a near from excavation advice require need Both probably trench. will ventilated a create to earth the existing the of repair approach or maintenance by managed be cannot drains, that problem a is there If interior. Penetration the Lateral on wet Preventing very be may exterior, the against up build to allowed been underfloo cellars, but masonry, fi waterproof Ground In the from Moisture with Dealing sbeweeecvto ol o nagrtesrcue n hr tde not does it where and structure, the endanger not would excavation where ssible aor al hthv o enrnee ihcmn rgvnsm other some given or cement with rendered been not have that walls masonry rb ntligln risuhl rmtebidn,teeaetoprincipal two are there building, the from uphill drains land installing by or s oadawtrron laye waterproofing a add to es: ih rudae sulkl oaetmr hntefirs the than more affect to unlikely is groundwater nish, od,adtewlso ulig hr h at has earth the where buildings of walls the and voids, r ac.Ecvtossol eeal incorporate generally should Excavations cance. ntebre eto ftewl,o aeback take or wall, the of section buried the on r eal odyol oad h interior. the towards only will it dry wall, to the able to be in get does water if and barrier, the under especially leaking and some through be to likely is There some risk. entail do geodrains as such Barriers fail. to begins it replacedwhen be to need will It entering. wa ri,adb flashe be and the drain, to bottom the at connect to need will This choice. better a be may channels) drainage integral with barrier plastic (a geodrain modern a so and the ground, from salts and water of quantities to exposed and buried when lifespans long have to likely not are flashings Waterproofing Waterproofing e ahn ontewlsfrom walls the down washing ter otnsadmetal and coatings ttetpt prevent to top the at d oreo w of two or course t 90/0401:27 01:27 29/07/2014 Damp Proofing 387 Damp proofing, which was first introduced in the second half of the 19th century to prevent damage from faulty sewers, is now an automatic inclusion in new construction. A damp-proof course [DPC] is a layer of some waterproof material such as sheet lead, slate, bituminous felt or plastic carried through the entire thickness of the wall just above the ground, to cut off water rising from the footings. This may be bedded into the joint between two courses of masonry, or set on the top of the plinth supporting a timber frame or an earthen wall, or some other moisture-sensitive form of construction. A damp-proof membrane [DPM] is usually a thick sheet of polythene, which may be used in various ways: for example, to protect church monuments positioned against exterior walls, or to isolate a concrete floor slab.

Injected ‘damp-proofing’ systems are not recommended for building conservation: not only is there no evidence that they work, but the risk from the associated cement renders and the damage from drilling multiple holes into the wall through which large quantities of liquid are introduced make them unacceptable (see Deterioration & Damage: Problems Due to Alterations & Interventions).

It is very rare that a DPC or DPM will be Drying Wet Fabric found to be a desirable option for controlling water: it risks moving the moisture problem elsewhere. To protect a It is rarely necessary to install any special systems to dry walls recovering building with its footing immersed in from moisture problems, except perhaps where the source of the water water, the damp proofing would need to was widespread and prolonged: a flood or fire, for example (see the form an unbroken barrier across the floor Special Topic: Dealing with Disasters). and through the walls, and an internal Drying proceeds in two stages, and it is only the first – Stage I, where perimeter drain would need to be installed there are liquid flow paths from the centre of the material to the surface together with a pump to take the water it – that is able to remove substantial quantities of moisture from bulk collects back to the exterior. Retrofitting material (see Building Science). Where possible, it is desirable to prolong damp-proof coursing into a building which Stage I drying so that more moisture is removed from the walls, so it is was never designed to incorporate one is usually best not to accelerate the process to any great degree: slight airflow and good air exchange can often be helpful, but strong heating extremely invasive: to protect timber cill and too-powerful fans can easily dry the surface pores, moving the beams resting on damp masonry plinths process into Stage II drying (which is very slow). Rapid drying also from decay the frame would have to be increases the risk of material damage. jacked up section by section to insert the DPC; masonry walls would need to be cut Certainly drying should not be accelerated until all leaks have been dealt with: if the moisture sources have not been removed, drying will never be through section-by-section using special effective, whatever the mechanism. Trying to dry fabric wetted continually saws, or long drills and chisels. It is difficult by a high water table, for example, would simply pull more water to imagine any situations where such through the wall, exacerbating deterioration and raising the humidity invasive works would be justifiable. within the room. Proprietary treatments for drying ‘damp walls’, such as electro-osmosis, are generally unnecessary, and may prove counter-productive.

BUILDING ENVIRONMENT CARE & REPAIR

ENVIRO 27 JULY 2014.indd 387 29/07/2014 01:27 NIO2 UY21.nd402 402 2014.indd 2014.indd JULY JULY 27 27 ENVIRO 402 PRACTICAL BUILDING CONSERVATION fteRylSceyfrtePoeto fBrs[SB lohsexcellent has also [RSPB] Birds of Protection the and website for The Society taken. Royal is the action of any before department government relevant th Legisl at found generallicences.aspx#a be can licences must general licence of www.nat individual Details or Defra. specific from under a sought out Licence, be carried General be a cannot of work comply provisions planned to the and the If covered, is conditions. be situation these must the with licence that the ensure of to conditions carefully the checked provisions Licence: the within General be act relevant must must the and they of so Licence, do to General eligible a are manager of they that building authority satisfied a the If under issued. act and routinely to species, be plans would protected a the licence carry of personal that welfare a or activities where for conservation used the only for to are risk need They low the licence. without personal a species for to protected apply people affect allow that Licenses activities General out certain pigeons. carry capture feral or including kill birds, to of permission) species owner's the with acting allow e someon to Government the nest. by the issued ‘a is at are it or Licences near owl, General are barn England, they the In when as such birds the Act, case the disturb the of to In 1 even it. Schedule offence to on an access listed having an are birds that destroy parent or birds the of damage prevent to to offence or an nest, is active It 1981. Act Countryside & Wildlife Al La toie esn’(h we rtnn fteln rpoet,or property, or land the of tenant or owner (the persons’ uthorised idbrs oehrwt hi et n gs r rtce ythe by protected are eggs, and nests their with together birds, wild l id oi sipratta h aetavc ssuh rmthe from sought is advice latest the that important is it so bird, e ealdavc ( advice detailed sPoetn Birds Protecting ws to a hnerpdyacrigt h osrainsau of status conservation the to according rapidly change can ation uralengland.org.uk/ourwork/regulation/wildlife/licences/ www.rspb.org.uk tews,brsi egbuigaeswl ipymv in. move simply will areas neighbouring in birds otherwise, their po that least not drawbacks, certain have fl acti do including these tried, but repellents, been audible have and scarers deterrence bird to approaches different Many differen bu bu on depend wher Wh Birds Managing uain,bti snvreff never is it but pulations, ligcnevto.Ifrainaottecnevto ttsadtecnrlof control the and status conservation the about Information conservation. ilding ni o pce-pcfi.Cu species-specific. not is on te id as eiu rbesdpnsbt ntehbt fteseis n on and species, the of habits the on both depends problems serious cause birds ether h ece,nsso ossaelctdo h ulig ic aydiff many Since building. the on located are roosts or nests perches, the e ). idseiscnb bandfo h oa oit o h rtcino Birds. of Protection the for Society Royal the from obtained be can species bird t lig o etsts tmyb eesr oblnentr osrainand conservation nature balance to necessary be may it sites, nest for ildings cieuls h ouaini eysaladisolated; and small very is population the unless ective ln sotnpooe o otoln pigeon controlling for proposed often is lling th an from advice in seek to wise is it properties, commercial and buildings larger (for longer no use in are they that ensure be to will necessary it removed, be must nests If fitt limit th to season breeding the after be cleaned can these swifts; and sparrows starlings, underth positioned be can boxes off nest sealed damage, be must roof the confl If direct no is there wherever nest Endangered Englan Natural ne are roofi nests during If found nests. remove or access taken block is to action any before fledge be to must allowed Nestlings bird. wild any of nest to Al eedn pcaitognsto uhas such organisation specialist dependent ienCnrlAvsr Service). Advisory Control Pigeon e be also can Shelves parasites. of number e as such birds threatened for eaves e idnssaepoetdb a:i sillegal is it law: by protected are nests bird l tig hudntb itre,and disturbed, be not should stlings netoal itr rdsryteactive the destroy or disturb intentionally dblwtensst ac droppings. catch to nests the below ed pce hudb loe to allowed be should species hudb consulted. be should d gwrs gsand eggs works, ng oprevent to ighawks, ying rn birds erent ict. 90/0401:28 01:28 29/07/2014 Preventing Perching 403 Feral pigeons and other troublesome birds will perch on buildings to overlook regular food sources. If perching is a problem, the most important step is to try to remove the source of food (for example, preventing people feeding pigeons in the area).

Preventing Roosting & Nesting Birds such as pigeons need to be prevented from entering areas where they may roost or nest in numbers, such as courtyards, balconies and windows, or around statuary or pipe work. Roosting sites may also be popular with other more desirable birds; but fortunately pigeons are large, so it is often possible to exclude them and not the smaller songbirds.

The problem will have to be dealt with in the winter, ideally between October and February when birds should have finished nesting. Any holes or gaps giving access to the roof or some other sensitive area of the building will need to be cleaned out and sealed, which should be done mid-morning to minimise the risk of trapping any roosting birds. If there is any doubt as to whether all birds have left, a fine wire mesh can be fixed over the entrance, and checked at intervals to ensure that no birds are trapped; permanent repairs can be made when it is certain that no birds remain.

The access to the site will then need to be repaired, or blocked off with netting or the correct wire or nylon mesh. Monofilament mesh, for example, comes in a range of sizes: 19 mm for birds as small as sparrows, 28 mm for starlings and larger birds, 50 mm for pigeons, and 75 mm for gulls. If well installed, netting can be relatively inconspicuous, and does not noticeably reduce light levels in the building. However, it does tend to trap windblown leaves and rubbish, so maintenance is an important issue.

Netting and mesh Netting can provide some protection from birds for elaborate features on the building façade, but it is not necessarily unobtrusive.

BUILDING ENVIRONMENT CARE & REPAIR

ENVIRO 27 JULY 2014.indd 403 29/07/2014 01:28 NIO2 UY21.nd450 450 2014.indd 2014.indd JULY JULY 27 27 ENVIRO 450 PRACTICAL BUILDING CONSERVATION Legionella as such microorganisms of growth the support can buildings, commercial of rooftops the on found often are which systems, air-conditioning of tanks storage The bacteria. ULIGUSE BUILDING ORGANISMS MATERIALS FURNISHING MICRO- ULIG& BUILDING SOURCE PRINCIPAL CO MNIDO I CONTAMINANTS AIR INDOOR MMON ottcarcleaners air ostatic Elec motors Electric Photocopiers Occupants Furniture cars) example, (for engines Combustion generators Diesel-powered water nt Stag gus nldn hs nlaminated in those including glues, wood ramnssc sbiocides as such Treatments plastics) industrial solvents many and by softeners released the as (such Off-gassing disinfectant Cleansers, apmaterials Damp ansan Paints ground Underlying Furniture Fabric etr unn abnbsdfuels carbon-based burning Heaters tr na d s n solvents and abnmonoxide Carbon Heav Ozone dust dioxide; Carbon soe,mudsoe,bacteria spores, mould spores, sfo such as [VOCs] compounds organic Volatile mtl uha lead as such metals ldehyde Biot sealants) rubber-based some of from types cyanide as of (such degrees and seriousness types various of Toxins mites Fung gasfirs setsfi asbestos fibres, glass ins Dus Dust CONTAMINANTS t ox , rma i y ; particulates rs radon bres, 90/0401:40 01:40 29/07/2014 HEALTH HAZARDS IN BUILDINGS 451 Anassessment of health hazards in a building may be desired for one of two basic reasons: • works are being proposed that could expose the workers or other building users to hazardous materials (such as asbestos, lead or bird droppings) • building users are reporting health problems that could be associated with the building or its contents (such as respiratory problems).

Although health problems reported by occupants can arise from any combination of contaminants, the underlying causes are often linked to environmental issues such as inappropriate temperatures and humidities, or insufficient intake of outdoor air. In cities particularly, commercial buildings are often airtight and use central air plants deliberately designed to limit air exchange with the exterior. This makes it easier and cheaper to condition the building air, and reduces the need to precondition incoming air to bring it to the right temperature or to filter it to remove pollutants, but its unfortunate side-effects cannot be denied. In poor air-conditioning systems, the building air is run through the ceiling and underfloor spaces, which are usually very dirty; even ducts and filters may only rarely be cleaned.

ASSESSING HEALTH HAZARDS Assessments of hazards during building works in the UK are covered by the Health and Safety Executive. The latest regulations and practice recommendations should always be consulted and followed (www.hse.gov.uk). It is harder to assess health problems associated with use of the building, because potential causes are many, and active factors are challenging to isolate. Not only all information about symptoms, but the nature of the building itself, will need to be taken into account. For example, if the building was constructed in the 20th century, or has major 20th-century renovations, asbestos may be a risk. An assessment survey should be made to investigate all possible causes of discomfort, including the lighting and heating, the fabric and furnishings, and the air plant. Forced ventilation should be checked to determine the mix of outdoor and indoor air, the air distribution, and the nature and state of the ducting and the filtration systems. All possible issues, from mould growth to ozone-generating equipment or sources of standing water, will need to be mapped and compared to patterns of occupancy and illness. In some cases it will prove necessary to call in experts to analyse samples of the air and from building surfaces, or to monitor pollutants, or to study airflow. Further information about general environmental monitoring can be found in Assessing the Environment: Specialist Investigations.

BUILDING ENVIRONMENT SPECIAL TOPIC: Buildings & Human Health

ENVIRO 27 JULY 2014.indd 451 29/07/2014 01:43 NIO2 UY21.nd468 468 2014.indd 2014.indd JULY JULY 27 27 ENVIRO 468 PRACTICAL BUILDING CONSERVATION ihnn tie n earthquakes. and strikes lightning worthw • • signifi at th buildings for considered be only would most eff Meas FLOODS GROUND TO RESISTANCE IMPROVING by damage limit to wise be also may rear it internal flooding, ground repeated to prone buildings th from away fl an Fl ALTERATIONS FLOOD-PROTECTION n fcus h xoueo h ulig o xml,absmn a nact a be may city a in flat basement fl a from example, For risk building. received, sufficient the be at of to likely exposure is the warning course much of how and occur, may floods such often likely how duration), the against intervention of cost the benefi up weighing when considered be to Factors • that envelope fl building from the damage on reduce interventions or of number prevent a are there disaster, of risk Asid ENVELOPE BUILDING THE TO ALTERATIONS Mo Likely Less Flooding Making • • archaeology. buried no or are gardens, there Th or and landscapes ground, historic surrounding to the related to issues access insurmountable be have can owners that building actions the of if number taken a are there but organisations, government associated oig ieiefl riverine ooding, oodproofing work work work memal ufcswt aeil htalwtewtrt okit h ground. the into soak to water replace the to allow and that building, materials the with from surfaces away impermeable water surface redirect to re-landscape install to or condition, good in is drainage systems building drainage and improved land existing any that ensure to e groups: ree te nenlsucso ae.Frgon od,weetesucsaecoastal are sources the where floods, ground For water. of sources internal other d cieesadivsvns;n igeslto srgtfreeybidn,adindeed and building, every for right is solution single no invasiveness; and ectiveness otipratare: important most e tdsrc odpeeto work prevention flood district st rmtemn asv n aaeilatosta a etknt euethe reduce to taken be can that actions managerial and passive many the from e rst rvn rlmttedmg rmgon od aywdl ncost, in widely vary floods ground from damage the limit or prevent to ures nld h ye ffloigta r ieyt eecutrd(ohsucsand sources (both encountered be to likely are that flooding of types the include t otebidn oso floodwa stop to building the to s fl make to surroundings the to s otebidn orsrc h muto aaei floodwa if damage of amount the restrict to building the to s iet ntl oefr fpraetlwbrira h aeo h door. the of base the at barrier low permanent of form some install to hile rangements. ulig rt tpi to rfrbybfr trahdteevlp.For envelope. the reached it before preferably or at it stop to or building, e a aemn om,icuigmtclu aneac fplumbing of maintenance meticulous including forms, many take can oigo flas or ooding s uo od,wtrmi usso lce eest aeit make to sewers blocked or water-main bursts floods, runoff ash odn,teotosaetyn odvr h water the divert to trying are options the flooding, h o n fi and ood stepoic fteEvrnetAec and Agency Environment the of province the is oigls likely less ooding esentering ters e n escmo iatr uhas such disasters common less and re, atrs.Modifi risk. cant esd enter. do ters ain alinto fall cations 90/0401:44 01:44 29/07/2014 Preventing Water Entering the Building 469 Floodwater can enter the building through: • floors and exterior walls (especially through cracks and joints) • windows and doors • other apertures in the envelope, such as vents, air bricks, pipe ducts, and gaps around piping and cabling • partition walls from neighbouring properties • back-flowing plumbing systems and sewers.

The first step is therefore to find some way of permanently or temporarily sealing any flaws or apertures. Permanent actions include repairing faulty pointing, replacing cracked cement renders, and sealing gaps around piping and cabling that passes through the exterior walls. For apertures that have important uses, such as doors and drainage holes, sealing methods will need to be demountable. This stops them acting if the flood arrives without warning, so it may be necessary to consider hybrid systems if the risk of flash flooding is very high.

There are a number of systems designed to be applied to the building perimeter to stop floodwaters entering. Most will only hold the water back for a short time, but this may be long enough to prevent damage from flash floods, or (for floods of longer duration) to allow the building contents to be moved or otherwise made safe. Structural engineers do generally advise, however, that no more than one metre or so of floodwater should be held back at the building envelope, since the pressure exerted on the exterior walls by more water than this could cause structural damage.

Buildings may have little protection against runoff floods, which can result from burst water mains and sewers, as well as from heavy rainfall.

BUILDING ENVIRONMENT SPECIAL TOPIC: Dealing with Disasters

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Regardless to time take will this but generation, electricity national h uniyo abndoierlae nrlto oteaon feeg rdcd(xrse sklgaso CO of kilograms as (expressed produced energy Th of electricity. amount or the to relation in [kgCO kilowatt-hour released per dioxide carbon of quantity The th burnt, When To Us Energy ewe 05ad21,atpclcro atr(h msinrt e nto nrya h on fue o electricity for use) of UK point the the In at use. energy of of point unit the per at rate electricity emission as (the fuel factor kgCO the carbon 0.53 in was typical contained a energy 2010, the and of 2005 third between a roughly deliver stations power otoln h neirEnvironment Interior the Controlling eusee ytegot fnwcos notntl,sm ifesrqiehg nuso oslfest produce, to fuels fossil of inputs high require unsustainably. biofuels provided some be Unfortunately, may crops. others new and of growth the by sequestered Bi account. into taken properly Biofuels be to need cold distribution a and of production because stress under is grid Burnin electricity the if time increase fuels the can Lower-carbon at use inefficient Energy is straightforward. pump entirely heat be a spell. not winter or may available, systems) not [CHP] is Power CHP and a Heat Combined in fuels fossil capacity, of terms in Th supply national the for factors. central carbon Redu implications on that has as means This well which time. as to intermittent, efficiency, time be and from may management upon power) water called or be wind may (solar, supplies generation renewable local from Power Avoided hieo nryspl o uligwl aemn fet ttentoa level: national the at effects many have will building a for supply energy of choice e eueeisos h pin r osv nry eueeetiiyueadsic olwcro nrysupplies. energy low-carbon to switch and use electricity reduce energy, save to are options the emissions, reduce fesms essanbypoue,s ihpooto ftecro eesdwe hyaebrtcnbe can burnt are they when released carbon the of proportion high a so produced, sustainably be must ofuels eeiso mrvdefcec ttelclo omnt ee freape sn lcrct nha up,or pumps, heat in electricity using example, (for level community or local the at efficiency improved of benefits e attocnuis h muto nrycnue omk n prt ulig a increased has buildings operate and make to consumed energy of amount the centuries, two past e sy h nutilRvlto eiduo h xliaino oslfes trigwt ol oe energy Lower coal. with starting fuels, fossil of exploitation the upon relied Revolution Industrial The usly. e requirements ced a rdcsls abnprkhta unn ihrolo ol u h soitdmtaelasfrom leaks methane associated the but coal, or oil either burning than kWh per carbon less produces gas g requirements 2 abnadhdoe nfsi ul obn ihoye opoueha,cro ixd n water. and dioxide carbon heat, produce to oxygen with combine fuels fossil in hydrogen and carbon e /kWh ecnaeo msin trbtbet sn lcrct svr ih eas naeaeU thermal UK average on because high, very is electricity using to attributable emissions of percentage e abnEmissions Carbon & e hl htfrgsws015kgCO 0.185 was gas for that while , 2 kh)depend /kWh]) ntefe ore n h effici the and source, fuel the on s ntemi eto hsvolume this of text main the in , 2 kh Kgvrmn oiyi ordc h abncnetof content carbon the reduce to is policy government UK /kWh. nyo h ytmue ocneti oheat to it convert to used system the of ency ). 2 90/0401:45 01:45 29/07/2014 ENERGY & CARBON IN THE BUILT ENVIRONMENT 509 Given a particular site and context, the three most important influences on a building’s energy use in operation are: Fabric The principal factor to be considered is how effective the building envelope is in providing a suitable indoor environment passively (including buffering of heat, humidity, and solar gain; providing natural ventilation and lighting via daylight). Equipment The equipment is the actual user of energy. This includes both the fixed building services (principally heating, cooling, ventilation, hot water, and lighting), and the other energy-consuming equipment (for example, the computers and appliances used for business, cooking, or entertainment). People Factors to consider include how the occupants maintain their buildings; the standards they consider appropriate for the internal environment; the technical services and equipment they bring in; and how they occupy the spaces.

These factors are highly interdependent: for example, the effectiveness of a building envelope will critically depend on how well it is maintained, and the control, maintenance and operation of the technical systems will affect fabric, people and the amount of energy EQUIPMENT used. The complex system of fabric, equipment and people must be looked at holistically if the use of energy in the building is to be understood and reduced. FABRIC

PEOPLE

BUILDING ENVIRONMENT SPECIAL TOPIC: Improving Energy & Carbon Performance

ENVIRO27JULY2014.indd509ENVIRO 27 JULY 2014.indd 509 29/07/2014 01:45 EENVIRO VR 7JL 04id 528 2014.indd JULY 27 NVIRO 2 UY21.nd528 2014.indd JULY 27 528 PRACTICAL BUILDING CONSERVATION a efudi h antx ( text main the in found be can requ to as critical so when be asked being questions the Th to answer the will rarely assessment. Only advanced time-consuming). and disruptive possibly and esrmnscnb aea he ees ai tpclyso hcsmd ihrltvl ayt-s qimn) intermediat equipment); easy-to-use relatively with made checks spot (typically basic levels: (r three at made be can Measurements greater or surfaces). put triggered window are therefore cold many and tall, leaks; from discomfort, air downdraughts of from or originate source necessarily major be not a also do be may they can but Expertise ex draughts systems, interpretation. conditioning example, expert the for on some critical: demands demand are occupant all factors though which challenging, judge to technically are needed few used; be can equipment fullTo Performance Thermal Measuring qiigmr ieo rprto,o oeeaoaeeupet;o dacd(fe n (often advanced or equipment); elaborate more or preparation, or time more equiring an fl between the walls, meet frames door and window where cracks, holes and via but windows, and Occurs no INFILTRATION AIR n oa radiation solar wind and moisture, with vary will ar U-values February to November typically cold weather, in practicable only are Test TH TRANSFER HEAT COMMENTS GENERAL AS ME naro ilb tthe temperature at same be will room a in no because measur to be difficult can occupants from energy Th RA crae ylclhaigo oln cl i eunn vrteflo orpeihtehtarrsn rmardao rconvector, or radiator a from rising air hot the replenish to floor the over returning air (cold cooling or heating local by acerbated al eo umrsssm ftemi ehd sdt esr i infi air measure to used methods main the of some summarises below table e oso ano radiant of gain or loss e fe eidskirtings behind often d IN ETEXCHANGE HEAT DIANT eecnb sfl but useful, be can here s nesadhwtebidn neoei efrig esrmn ilsmtmsb edd ait ftcnqe and techniques of variety A needed. be sometimes will measurement performing, is envelope building the how understand y sesn h hra efrac fteevlp o neeg seset oedtiso esrmn n monitoring and measurement of details more assessment; energy an for envelope the of performance thermal the assessing uttruhdoors through just t RMN TECHNIQUES UREMENT o osat but constant, not e l h surfaces the all t oorboards accurately, e OG H FABRIC THE ROUGH BASIC ecntanso sn hs nsome in interiors these historic using on may constraints there be that note puffers; chemical smoke or sticks smoke Hand-held ae seilywe okn tglass metal at and looking when especially care, needs and challenging is Interpretation excessive of loss heat areas to attention which draw camera, can infrared be an can with envelope made thermal the of Checks Dr Empirica Assessin ice y snaino etloss) heat of (sensation l h uligEnvironment Building the g INTERMEDIATE nrrdcameras Infrared eann ore fleakage of any sources identify remaining to and standards establish to quality work, the alteration in of valuable course also is testing Pressure buildings hours, large few on a even within tests can make specialists usually set; be to improvement an the rate quantify infiltration can testing pressure Fan nassmn ftemltransfer thermal of for assessment enough an steady become for to weeks readings several take usually Will measured be also must interior temperatures and exterior U-values, to calculate movement; points, heat typical monitor at to fabric the of surface sensor Heat-flux ). tahdt the to attached s lo agt for targets allow d tain ettransfer heat ltration, eigseils qimn n expertis and equipment specialist eeding ADVANCED epsil nsniiehsoi interiors historic sensitive in not may possible tests be smoke so and surfaces, Al alerted) authorities be fire to and neighbours switched and be off, to will detectors smoke (latter require circulation air rates of find to routes and tests smoke or gases Tracer antb sdi h uligfbi or fabric building co the if used be Cannot occupied) be building cannot the which several (during takes weeks process for the as suited best research, are 25°C, building a typically at keep to used energy the measure which tests, Co-heating loac o i movement) air for with allowance temperature, radiant mean temperature and air of average (weighted temperature’ ‘operative to the used determine readings and point, a at particular temperature’ radiant ‘mean the lc-lb hroee omeasure to thermometer Black-globe mk eeaoslaedpst on deposits leave generators smoke l tnsaesensitive are ntents n ain etexchange heat radiant and ire e e, 90/0401:47 01:47 29/07/2014 REVIEWING ENERGY USE & ENERGY-CONSUMING SYSTEMS 529 The review of the energy use and equipment should include: • annual energy consumption, by fuel and preferably by end-use • a summary of how the building is managed and maintained, and of how the services and equipment are operated and controlled (both centrally and locally) • an assessment of each item of energy-consuming equipment: what is there, its size and condition, its appropriateness to the building and the building's uses, and how it is being operated • a summary of how committed the building occupants and managers are to reducing energy use • a summary of any opportunities for making improvements, and of possible risks and constraints.

Determining how and where energy is being used will not only make it clear what actions would be likely to reduce consumption most effectively, but could also draw the attention of occupants to wasteful practices and habits, obtain their detailed feedback, and trigger simple and effective behavioural improvements.

Limitations on thermal imaging Imaging glass is particularly difficult: glass is opaque to infrared, and it is also highly reflective. It is perilously easy to over-interpret thermal images of façades: here, the same windows imaged twice in quick succession on the same camera show a wide variation in ‘surface temperature’ readings, due almost entirely to reflectivity. Inaccuracies must be minimised as far as possible by controlling how and when the image is taken, by processing the images with care, and finally by interpreting the results in the light of a good understanding of how building systems behave.

BUILDING ENVIRONMENT SPECIAL TOPIC: Improving Energy & Carbon Performance

ENVIRO 27 JULY 2014.indd 529 29/07/2014 02:35 NIO2 UY21.nd584 584 2014.indd 2014.indd JULY JULY 27 27 ENVIRO 584 PRACTICAL BUILDING CONSERVATION hyaevr elestablished. well very are they until problems water of signs hide may and wall, the from evaporation reduce also will insulation the since concern great of is This window here). the of corner the at stain water the (note pipework and around cills, and eaves at occur may leaks and ingress, water to lead can mouldings drip as such details water-shedding of loss The installed. and designed well meticulously be must so and risk, technical high a carries insulation External restoration. or improvement of programme sensitive a into measure the incorporate to possible be sometimes may it condition poor in is façade a if though appearance, building’s a on impact serious a have will insulation wall External RENDERS) PERMEABLE TO REPOINTING (INCLUDING REPAIR ACTIONS SIMPLE ACTION CH RENDERING ACTIONS INTERMEDIATE PLASTERING RPANELLING OR I TRO HANGINGS NTERIOR CLS:ICESN H HRA EITNEO WALLS OF RESISTANCE THERMAL THE INCREASING ECKLIST: REPAIRS & EEA COMMENTS GENERAL aeil oue nti eisgv nomto bu h repair the types about various information of the give walls heat); series of less this much in transfer volumes will materials wall dry (a penetration Appropriat Applyin r al aemc oetemlresistance thermal more much have walls Dry Render walls cavity pligaprebepatrcnbnfi ohsldand solid both benefit can plaster permeable a Applying iigth Lining atndoftewl,wl mrv hra epneadreduce and response thermal improve will wall, the off battened walls cavity ain etloss heat radiant ilctarifitainadwtrpenetration water and infiltration air cut will s emal edrcnbnfi ohsldand solid both benefit can render permeable a g neirwt hnihset fprebematerial, permeable of sheets thinnish with interior e ear ilipoearihns n water and airtightness improve will repairs e TE CONSIDERATIONS OTHER osdrrpaeeto memal edr n mortars and practicable renders where impermeable of used replacement be lime Consider as always such should materials renders and permeable but mortars and wall; materials the the of on construction depends intervention correct The diie uha epcnices nuaigcapacity insulating increase can mortars; hemp lime-based as as such such additives materials permeable only Use ayodrbidnswr edrdi h at oteemybe may there so records past, historic the in in precedent rendered a were building buildings the older of Many appearance the alter will Rendering diie uha epcnices nuaigcapacity insulating increase can hemp as such Additives Us ti iet einpnligt eesl pnbet chec to openable behind easily wall be the to of panelling condition design to detail wise to is It de difficult as be such may in features panelling reduction original room; some around the and of area appearance, on usable the impact an be will There nyprebemtrassc slm-ae mortars lime-based as such materials permeable only e oaiecornices corative the k 90/0401:57 01:57 29/07/2014 CHECKLIST: INCREASING THE THERMAL RESISTANCE OF WALLS 585

ACTION GENERAL COMMENTS OTHER CONSIDERATIONS

CHALLENGING ACTIONS

INSULATION Demands careful design, correct choice of materials, good detailing and extremely high standards of workmanship Methods and materials will vary according to type of wall, and whether it is being insulated externally, internally or by filling a cavity Great care must be taken to eliminate all possible moisture sources from the wall before works begin Internal and external wall insulation will hide the condition of the wall beneath, so it is wise to consider installing time-of-wetness sensors or other moisture monitoring to reveal problems should they occur

INTERNAL WALL INSULATION

Permeable, hygroscopic insulation would normally be preferable To limit thermal bridging, partial insulation may be necessary to Thickness may need to be limited to reduce condensation risk upper floors, partitions and party walls where these meet the insulated wall Significantly reduces interior floor space, which can be problematic in small rooms Internal services, including electrical wiring and heating pipework, may need to be rerouted Installation requires the occupants to vacate the building Tends to cause problems of thermal bridging

EXTERNAL WALL INSULATION

Where space is available, exterior wall insulation can safely be Carries a significant risk of inducing or exacerbating liquid- made much thicker than interior wall insulation moisture problems Advantage can be taken of the thermal mass of the wall to help External pipes, gutters and other services will usually need to be buffer temperature fluctuations and reduce risks of summer removed and altered before replacement overheating if night ventilation is adequate Detailing (especially around openings, and at cornices and eaves) Can be installed while the building remains in occupation must be meticulous, since any water entering from leaks or Presents fewer problems with thermal bridges than internal condensation will be trapped behind the insulation; problems wall insulation may go unnoticed until they become very serious Insulation must be protected from the weather by a render, or some other protection such as cladding, or hanging tiles or slates

CAVITY WALL INSULATION

Increases the thermal resistance of the wall, but does not affect Carries a significant risk of inducing liquid-moisture problems its appearance If the cavities open into the roof space, they must be closed Least risky in dry, sheltered areas; caution is needed in sites Borescope investigations should be made to locate moisture prone to driving rain sources, and thermal and moisture bridges; these must be dealt Loose fill materials should be used rather than foam to give some with before insulation potential for extraction (which is still extremely difficult) Not suitable for cavity walls bonded with bricks Cavity walls can also be insulated internally or externally Always use reputable contractors, and obtain appropriate insurance-backed warranties

INSULATION OF FRAMED CONSTRUCTION

Sometimes possible when cladding or interior finishes are If insulation is entirely within the framing, the frames will act removed for maintenance as thermal bridges; it is therefore best to combine insulation Options are similar to those for insulating roofs at rafter level between the framing with a complete skin of render or insulation (preferably on the exterior)

BUILDING ENVIRONMENT SPECIAL TOPIC: Improving Energy & Carbon Performance

EENVIRONVIRO 27 JULY 2014.indd 585 29/07/2014 01:57

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