a study by forhighperformanceinsulation.eu/wp-content/...a_guide.pdf · a guide a study by xco2 for...

Insulation forSustainability

A Guide

A study byXCO2 for BING

Global warming is the most immediate threat to globalsustainability, driven primarily by CO2 emissions. Achievingoptimum thermal design of buildings can achieve large cutsin CO2, with numerous other benefits. But at least half ofEurope’s existing buildings are uninsulated, while currentconstruction standards in most of Europe are also still not highenough.

This guide shows in depth Why and How we should designwell-insulated and energy-efficient buildings, and it discussesthe criteria for choosing Which insulation material and designof insulating systems. The guide is extensively illustrated withdiagrams and illustrative energy modelling.

E: [email protected]: www.xco2.com

1-5 Offord StreetLondon N1 1DH, UK

XCO2 conisbee LtdConsulting engineers

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3Insulation for Sustainability - a Guide 2

Satellite imaging shows theconcentrations of energy use in Europe

Aerial thermographic imageshowing heat loss from a city

Thermographic image showingheat loss from typical houses

Energy technology is vital to adynamic society but globalwarming, driven primarily by CO2

emissions, now demands change incurrent patterns of generation anduse.

Half of our energy is used inbuildings, which form an excellentfocus for actions to reduce CO2

emissions, starting with energyefficiency.

In Europe, the largest share ofenergy in buildings is heating.Insulation and thermal design candramatically reduce heat loss andhelp stop global warming.

ExecutiveSummary - 1

This research study is a result of research and analysiscarried out by XCO2 conisbee and sponsored by:

BINGFederation of European Rigid Polyurethane Foam Associations

Fèdération des associations européennes de mousse de polyuréthane rigide Vereinigung der europäischen Polyurethan-Hartschaum-Verbände

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Graph based on analysis showing incrementalreductions in heating demand possible

Diagram showing principles of LowHeat housingto reduce heating energy use by 90-95%

Image shows typical insulation materials

Heating energy demand in existingbuildings can be reduced by 30-50%through retrofit, compared to thecurrent average. In new buildings itcan be reduced by 90-95%, usingwidely available technology anddesign knowledge and atcompetitive costs.

The choice of insulating materialis relatively insignificantcompared to achieving optimumthermal resistance. The mostimportant design issue is toensure longevity of performanceover the lifetime of the material.

Incremental improvement tobuilding codes is not fast enough,and the savings through retrofit arelimited. Large savings can beachieved through programmes ofreplacement new-build to the bestavailable standard.

250

0

40

80

120

160

Incremental improvements to design, summarised below

1 2 3 4 5 6 7 8 9 10 11 120

Heatingenergy use

2kW.h/m .yr

2000 Standard

Highly insulatedmodular constructionpanels

Zero-CO2 option:

Zero-CO2 option:

(Mechanical ventilationwith heat recovery)

Airtight and highlyinsulated housingachieves very lowheating demand.

ExecutiveSummary - 2

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The globalcontext

Humanity currently faces its greatest challenge ever - tosupport continued growth in living standards worldwidewithin diminishing natural resources and saturatedpollution sinks. This challenge is now driving change at alllevels through government, business and civil society.

More and more business and government leaders aregrasping the great opportunity - if we invest in innovativedesign and new technology, and if we only “cease to bestupid”, we can cherish the natural environment alongsidesocial and economic progress.

As we will show later, the biggest environmental problemof all is the atmosphere, where accumulating greenhousegases are causing climate change and sea level rise. Themost recent report of the International Panel on ClimateChange (IPCC) confirms there is now very little doubt thatanthropogenic (man-made) carbon dioxide is the maincause of climate change.

In response to this challenge, we are now entering an ageof great innovation, another Industrial Revolution, whichwill see a tremendous pace of change. This is muchbigger than just technology, requiring a new Renaissancein design, economics and society.

This revolution is driven by a quest to find solutions withoverlapping benefits and positively reinforcing outcomesin many different sectors - where 1+1+1 = 5 - we callthem XCO2 solutions.

One of these solutions is insulation, a key element of theenergy efficiency strategies and technologies that weneed to rely on to achieve this revolution. I hope that thisguide helps to take this message to a wide audiencewithin the construction industry, and to promoteunderstanding and good design. We need to cut fossil fuelenergy use by 60-90%, while supporting social andeconomic development. The means are there, all that werequire is the will.

You see, we should make use of the forces ofnature and should obtain all our power in thisway. Sunshine is a form of energy, wind andsea currents are manifestations of this energy.Do we make use of them? Oh no! We burnforests and coal, like tenants burning downour front door for heating. We live like wildsettlers and not as though these resourcesbelong to us.

Thomas A.Edison, inventor of the tungsten lightbulb, 1916

Greenhouse gases are accumulating in theEarth’s atmosphere as a result of humanactivities, causing surface air temperaturesand subsurface ocean temperatures to rise.Temperatures are, in fact, rising... Human-induced warming and associated sea-levelrises are expected to continue throughout the21st century.

National Academy of Sciences report on global warmingto the Bush Administration, June 2001http://www.national academies.org

Foreword

Robert Webb, XCO2London, February 2002

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Insulation for Sustainability - a Guide 10

Insulation is a product or service which stands up verywell on its own - offering clear and straightforwardenergy efficiency and economic advantages. So whyfocus on it?

Simply, because it can go much further! Insulationmaterials and systems offer many overlapping benefitsto sustainability in society, the economy and theenvironment. Yet many existing buildings in Europeremain uninsulated, and most new buildings are stillinsulated far below optimum levels.

Those are failures to grasp simple opportunities forsustainable development. And they are massive failures.40-50% of all energy in Europe is used in buildings, and40-60% of this is heating energy. Every new buildingwith suboptimal insulation may remain that way for 100years or more.

The purpose of this document is to explore andchampion the opportunities for sustainability which arepresented by insulation technologies, especiallyenvironmental sustainability, and start to explore howthe overlapping benefits can be capitalised on bybusiness and society.

There are a number of factors to be overcome:• Inertia and inefficiency in financial and managementstructures leading to drastic undervaluing of energyefficiency and whole-life costs.

• Resistance to change in the construction industry,leading for example to lobbying from some quarters forslower improvement in thermal standards.

• A misleading emphasis in many ‘green building’publications, leading to a failure to properly weightwhole-life issues.

We cannot tackle all of these problems in one study. Weaim however to put the issues in context by providing asimple Why?, How? and Which? of insulation, a primerand reference guide for all those involved in the builtenvironment.

Introductionto this study

Why?

How?

Which?

Global Local DetailedTo stop globalwarming and

minimise fossil fueldepletion

To achieve maximumperformance and

longevity

In response toindividual choice &project conditions

To achieve highperformance inconjunction withenergy systems

Guidance for designers and specifiers - theaim is to provide clear guidance and specificexamples on each of the points listed above.

To reduce energyuse and contribute

to economy

To maintain goodcomfort

conditions

As required byconstruction

method

As appropriate for localexposure conditions

use insulation

to use insulation

insulation to use

To minimise heatloss in buildings

Diagram of the overall structure of the document;We ask Why?, How? and Which? questions on threescales - Global, Local, and Detailed.

Symbols used to indicate the report structure

Some definitions of standardsIn this study we refer to a number of standards and typesof housing for energy consumption comparisons in theEuropean context. Existing refers to the average of atypical house built before 1970. Refurbished refers to anExisting property which has been upgraded with a rangeof energy-efficiency measures. 2000 Standard is anaverage standard for new buildings in 2000 (whichhappens to be the same as the 2002 UK regulations).LowHeat Standard and NoHeat Standard are XCO2’sproposed specifications for low-energy housing, whichare defined on pages 39, and 50-51.

Envelope of modelling undervarying assumptions for

climate sensitivity

Envelope for the 35 scenariosof the Special Report on

Emissions Scenarios

Each line refers to aspecific model andscenario from the IPCCSpecial Report onEmissions Scenarios(SRES)

Source: Intergovernmental Panel on Climate Change

Isn’t sustainable development toodifficult to achieve? As a starting point we need to reduce our environmentalimpact by very large margins (between 60 and 90%), butwe know we can do this through a combination ofefficiency and technology. And with no sacrifices to qualityof life.

But it’s so complicated, how do we know where tostart?Energy use is the most important issue. This is becausefossil fuel energy use is leading to global warming andsea level rise, raising the very real possibility ofcatastrophic climate change which might destroy life aswe know it. It's also because our current reserves of fossilfuel will not meet growing world demand in the long-term.

So we should invest in renewable energy, right?Yes, but at the same time we have to invest in energyefficiency. A unit of energy saved is as good as a unit ofrenewable energy generated – in fact better, because it’sprobably cheaper and easier.

So where do we start?The single largest energy-consuming sector in developedcountries is buildings (50% of the total), so let's start here.In European buildings, heating energy accounts for 40-60% of their energy use, so let's reduce this first. In newbuildings you can do this through good design, and byspecifying high levels of insulation. Existing buildingsrequire retrofit of insulation and better glazing.Note: reducing cooling energy use is also very importantin Europe, particularly in office buildings and industrialuses - and insulation also plays an important part in this.

So we should prioritize insulation as an importantpart of reducing energy use in buildings?Yes – it is a very important part of good thermal design.

But aren’t national heat loss regulations becomingmore strict anyway?Yes, but only on an incremental basis. Every houseinsulated below the optimum level may stay that way forits entire life – possibly 60-150 years or more ofunnecessary carbon dioxide emissions and unnecessaryfossil fuel depletion. We need more insulation in all newbuildings.

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Residential

IndustryTransport

Non-residential(tertiary)

Buildings

Temperaturecontrol of industrial

buildings

Summary1 - Global

0

500

1000

1500

2000 Existing

LowHeat

MWh ofheating energy

0 100 yrsLife of building

50 yrs

2000Standard

Refurbished

Predicted temperature change as aresult of global warming

Source: DG TREN

50% of energy use in theEU is in buildings

It is possible to reduce housing heating energyuse to 7.5% of the average level through good

design and high levels of insulation

see pp50-51for definitions

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Is it difficult to reduce heating energy use in new andexisting houses?No - the knowledge and the tools are available. Simpleguidelines are presented here to provide some guidance.

How much heating energy do existing houses use?There is huge variation of course, but most existingproperties built before 1990 will use 150-400 kW.h/m2.yr(we have taken the figure of 200 kW.h/m2.yr forcomparisons).

How far can we reduce heating energy use?Modelling shows that new buildings to the ‘2000 Standard’achieve 70% reduction compared to ‘existing’, while newbuildings to our proposed LowHeat Standard can reduceenergy use by 92% or more. In refurbishment of existingbuildings assessment of the situation is more difficult butthe savings possible are in the order of 30-50%.

Should we focus on refurbishment before new-build?We need both. Modern new buildings can easily be builtwith extremely low heat demand, whereas retrofitting iscomplicated and achieves lower savings. It can be shownthat a radically accelerated building replacementprogramme to LowHeat Standard can achieve muchlarger savings in a 10-50 year timescale thanrefurbishment.

How do we choose the best insulation materials?Different materials will achieve the same performance withdifferent thicknesses. What matters most is that thematerial will last a long time at a high level ofperformance.

What about the embodied energy of the materials?Achieving low energy demand in-use is the mostimportant factor. Embodied energy is especiallymisleading for materials and equipment which are criticalto energy efficiency. Ensuring performance over life ismuch more important.

So how do we assess length of life and performancestandards for an insulation material?There is a shortage of concrete knowledge althoughdifferent materials have different types of ‘failure risks’associated with them. More research is urgently neededin this area.

Summary2 - Local/Detailed

Conventional 2000Standard

LowHeatStandard

5040

5040

302020

15-20

Space heating

Hot water

Electricity

150

kW.h/m2.yrdelivered

Sunspace / wintergarden actsas thermal buffer and passive

solar heat store. Exposedthermal mass should be used

to store heat.


LowHeatStandard

In-useEmbodied

60%reductionin-use

75%reductionin-use

Energy in-use compared to embodiedenergy in a typical dwelling

Energy-in-use must be optimisedfirst. Embodied impact can then bereduced if it does not compromise

in-use performance

Note: 100-year life assumed

see p 50 for definitions

see p 50 for definitions

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17Insulation for Sustainability - a Guide

Greenhouse gas data: From the IPCCSecond Report. Note SF6 is also ananthropogenic greenhouse gas

16

Sustainability -where do westart?

Our species is enjoying unprecedented success on theplanet we call Earth. Though huge inequalities remain insociety, the last 150 years have seen unprecedentedgrowth in population, life expectancy and education.

The largest single challenge of global sustainability isprobably the reduction of poverty and inequality. Thisdocument contains no solutions to that problem, thoughas a context it should never be forgotten. Our focus hereis however an essential requirement for any continuationof human development and civilisation, as we will show:the preservation of stability in the global environment.

To achieve sustainability we must balance human societywith environment. The construction industry is a very goodplace to start - not only occupied with the creation of ourphysical environment, it is one of the largest sectors of theeconomy.

There are arguably three main threats to environmentalsustainability: global warming (climate change driven byman-made emissions of gases); resource depletion(including depletion of non-renewable resources, anddamage to renewable resources and ecosystems); andpollution including ozone depletion (the last is now largelydealt with under the Montreal Protocol).

The most immediate of these threats is global warming,which threatens catastrophic climate change and sea levelrises whose impact is likely to be greater than all ofhumanity’s wars combined (see following section).

Global warming is driven primarily by carbon dioxideemissions from fossil fuel energy use. Climate scientistsagree that we need to cut carbon dioxide emissions by60-90% to stabilise the climate, and we need to start now.

The extraction and use of fossil fuels is the primarysource of man-made carbon dioxide, also causes themajority of eco-toxic pollution [Ref: 1], and is the primeresource depletion issue as our economies are currentlydependent on fossil fuels. Action to reduce fossil fuel usenot only helps prevent climate change, but also reducesresource depletion and pollution. Reducing CO2 emissionsis therefore by far the most significant issue in buildings.

Buildings Use…40% of total energy use, adding to: local air pollution, acidrain, damming of rivers, nuclear waste, risk of global warming.

40% of raw stone, gravel and sand; comparable share ofother processed materials such as steel, adding to: landscapedestruction, toxic runoff from mines and tailings, deforestation,air and water pollution from processing.

25% of virgin wood is used for constructionadding to: deforestation, flooding, siltation, biological andcultural diversity losses.

16% of total water withdrawals, adding to water pollution;competes with agriculture and ecosystems for water.

Waste amounts produced are comparable in industrialcountries to municipal solid waste generation, adding tolandfill problems, such as leaching of heavy metals and waterpollution.

Poor air quality in 30% of new and renovated buildings,adding to higher incidence of sickness—lost productivity intens of billions annually.

Source: World Watch Institute

The triple bottom line (TBL) focusescorporations not just on the economic valuethey add, but also on the environmental andsocial value they add – and destroy.... theterm is used to capture the whole set ofvalues, issues and processes that companiesmust address in order to minimize any harmresulting from their activities and to createeconomic, social and environmental value.John Elkington, SustainAbility www.sustainability.com

Emissions of CO2 dueto fossil fuel burningare virtually certain tobe the dominantinfluence on thetrends in atmosphericCO2 concentrationsduring the 21stCentury IPCC, ThirdAssessment Report CO

CH

N O

HFC,PFC,SF

2

4

26

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What is the greenhouse effect?The International Panel on Climate Change (IPCC) hasbeen charged with overseeing the development of climatescience and it’s latest report, the Third Assessment reportpublished in July 2001 [Ref: 2], states that there is verylittle doubt that man’s influence on global warming is real.

The introduction to the Summary for Policy-Makersexplains the basic concept and the reasons for anycontroversy:The Greenhouse concept… is simply that the composition of thegases that make up the atmosphere enveloping the earth iscrucial to the existence of life, by acting as an insulator. This isbecause a precise gaseous composition allows heat which isradiated from the sun to be trapped in by the earth. Furthermoreit allows the specific temperature range for life to flourish, as itallows the right amount of heat loss as well as heat retention tokeep the balance of life stable.

Changes in climate occur as a result of both internal variabilityin the climate system, natural change, and also externalinfluence - unnatural or anthropogenic [man-made] change. Thecontentiousness behind ‘Climate Change’ has revolved mostlyon the whether this ‘external‘ anthropogenic influence can beattributed to the absolute changes observed.

Summary of the historical evidenceHere we quote some of the key points arising from theIPCC Third Assessment Report:• Over the 20th Century global average surfacetemperature has increased by 0.6˚C+/-0.2˚C with theperiod 1972-2000 being one of the times that mostwarming occurred.

• Globally, it is very likely that the 1990s was the warmestdecade and 1998 the warmest year in the instrumental(meteorological) record, since 1861.

• The atmospheric concentration of carbon dioxide (CO2)has increased by 31% since 1750. The present CO2concentration has not been exceeded during the past420,000 years and likely not during the past 20,000,000years. The current rate of increase is unprecedentedduring at least the past 20,000 years.

• About 3/4 of CO2 emissions to the atmosphere in thepast 20 years has been due to fossil fuel burning – withthe rest being predominantly due to deforestation.

Variation of the Earth’s Surface temperatureOver the past 1000 years:

Over the past 140 years:

Globalwarming - asummary

Source: IntergovernmentalPanel on Climate Change


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Status and future implications of the climatechange models - from the IPCC 3rd Report• Recent models are producing increasingly accurate

simulations taking into account both natural changesand anthropogenic [man-made] influences. Simulationsof both external and internal influences produce resultswhich are sufficient and convincing in explaining theobserved changes.

• Most of the observed warming over the last 50 years islikely to have been due to the increase in greenhousegas concentrations.

• Emissions of CO2 due to fossil fuel burning are virtuallycertain to be the dominant influence on the trends inatmospheric CO2 concentration during the 21stCentury.

• The globally averaged surface temperature is projectedto increase by 1.4 to 5.8˚C over the period 1990 to2100. These results are for the full range of 35 climatemodelling scenarios, based on a number of climatemodels.

• The projected rate of warming is much larger than theobserved changes during the 20th Century and is verylikely to be without precedent during at least the last10,000 years.

• Global warming is likely to lead to greater extremes ofdrying and heavy rainfall and increase risk of droughtsand floods.

• Northern hemisphere snow cover and sea-ice extentare projected to decrease further… Glaciers and icecaps are projected to continue their retreat.

• Global mean sea level is projected to rise by 0.09 to0.88 metres between 1990 and 2100.

• Surface temperatures will increase, ice caps will retreatand sea levels rise for hundreds of years, even ifgreenhouse gases are stabilised permanently to currentlevels.

Envelope of modelling undervarying assumptions for

climate sensitivity

Envelope of modellingunder varying assumptions

for climate sensitivity

Model outcome includingassumptions for uncertainty

over land-ice interaction


Emissions Scenarios


Emissions Scenarios






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The internationalresponse toglobal warming

Carbon Trading MarketsAn international carbon trading scheme will be set upnow that the Kyoto Protocol has been signed, probablybased in London. In addition national schemes are beingcreated in a number of countries. For example, the UKEmissions Trading Scheme is expected to be fullyoperational by April 2002.

Companies will be eligible to join the scheme if theyagree to a target on greenhouse gas emissionsreductions. If they do better than the target, they willcreate allowances that can be sold, whereas if theyfail to meet their target they will have to buyallowances. For companies joining voluntarily withthe financial incentive, targets will be framed interms of absolute emission reductions (caps).from The Carbon Trust and the Emissions TradingScheme, a leaflet produced by the UK Government

Draft Directive on the Energy Performance ofBuildingsPublished by the European Commission in May 2001,this calls for:• Establishment of a common European methodology

for calculating the integrated energy performance ofbuildings.

• Application of minimum standards across Europe,based on the methodology.

• Certification schemes requiring new and existingbuildings to carry certificates with details of energyperformance.

• Inspection of medium-sized and older boiler andheating/cooling installations.

The Certification Scheme is already coming into use insome countries. For example in the UK’s trial Seller’sPack scheme, energy data about properties must beincluded. This means that potential purchasers ofproperty are given the opportunity to judge value on thebasis of energy running costs as well as other issues.

There are now many factors driving change to fight globalwarming, from public opinion and consumer pressure tochanging global and local legislation. This combination ofpressures is increasing the speed of change - and themost successful innovations provide benefits bymotivating and educating people at the same time asrealising the economic benefits of energy efficiency andcarbon trading.

Global Scale - KyotoThe Kyoto Treaty, signed at Bonn in July 2001 by 186nations, is an unprecedented global agreement settinglegally binding targets for carbon dioxide emissions for the38 industrialised countries which are signitories (the onlysignificant country which did not sign is the United States).The agreed target is a 5.2% reduction on 1990 emissionslevels by 2010. This alone will have little impact on globalwarming; the treaty’s significance is that it sets theframework for further reductions in future.

The agreement also includes the Clean DevelopmentMechanism, a fund for green technology in developingcountries; carbon credits gained through offset activitiessuch as planting forests; and an international market incarbon credits will be established for companies whichinvest in clean technologies in other states.

Local Scale - European changes in building regulationThere is a general move in the EU towards upgradingthermal insulation and energy regulations for buildings inall European states, though as we argue later, this is notfast enough.

In addition, a number of countries are developingapproaches to the assessment of building materials, andthere are currently strong moves towards a harmonisedEuropean approach for environmental labelling ofconstruction products - otherwise known as theEnvironmental Product Declaration, based on an auditedLife Cycle Assessment of the product. This will act as apositive incentive for companies to compete onenvironmental issues as they currently do on quality, costand other issues. However to be truly useful andmeaningful these assessments should be carried out forthe whole building over its life, rather than for an individualmaterial.

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Energy efficiency and renewable energy measures inbuildings - what we refer to as XCO2 strategies - havehuge potential to improve quality of life and increaseproductivity through better working conditions, as well asreducing running costs, and maximising lifetime return oninvestment.

Massive growth in renewable energy is now occurringwhich will reduce our dependence on fossil fuels. But thefirst step in reducing carbon emissions is through energyefficiency. Efficiency measures tend to be cheaper andeasier to realise than renewables, and offer financialsavings and other benefits.

Meanwhile extensive literature and examples have shownthat efficiency improvements of at least factor four (75%reduction) are available in all the principle sectors whichemit CO2: buildings, transport and industry [Ref: 4] Butbuildings are the largest sector, responsible for 40-50% ofthe EU’s CO2 emissions, and therefore presents amassive potential for savings.

The majority of building energy use in Europe is inheating.Up to 60% of total delivered energy use in Europe’sbuildings is in space heating.

Insulation is a central plank of building energyefficiency strategies.Insulation measures to new and existing buildings offerpotentially the single most effective building efficiencystrategy in Europe. In existing buildings alone, a studypublished by EuroACE [Ref: 3] found that a Europeanprogramme of building energy efficiency could bringreductions of between 430 and 452 million tonnes of CO2

per year by 2010, a reduction of 12.5% of current EUemissions - based on conservative assumptions. Thelargest share of this figure is in improvements toinsulation, giving savings of 185 Mt CO2 per annum (20%reduction in heating energy use; amounting to 5% of totalEU emissions).

And this is not including the improvements possible innew buildings, which have the potential of even greaterimpact, as we shall show.

Buildings are responsible for50% of EU energy use

Start withefficientbuildings

Residential

IndustryTransport


Buildings


buildings

185

119

87

50

0 50 100 150 200

ThermalInsulation

GlazingStandards

ImproveControls

Improve LightingEfficiency

Potential savings in EU - Mt CO per annum2

Insulation shows the greatest potential savings of CO2

compared to other building efficiency measures

Source: DG TREN

[Ref: 3]

(including industrial buildings)

Note: Reduce cooling energy alsoFor overall building energy efficiency and especially in officebuildings, reducing cooling energy can also achieve massive impact.In most of northern europe, passive design can eliminate or reducethe need for cooling; where this is not possible cooling and airconditioning systems should be designed to optimise efficiency.

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2 Mid-EuropeanCoastal

3 Continental

1 NorthEuropeanCoastal

4 Southern and Mediterranean

A European initiative intended to improve theenergy performance of buildings bypromoting improved Member State thermalinsulation regulations to a level alreadyattained by some Member States could resultin substantial energy savings for the EU as awhole.Draft Directive of the Commission on the EnergyPerformance of Buildings, May 2001

The European climate varies quite widely from the northto the south, though there is also much common groundbetween countries in central Europe. Variations in thermalinsulation standards are to be expected - however theactual variation is much greater than climatic differences,as a result of cultural (and to some extent economic)forces.

For example in Germany, with an average degree-dayheating requirement of 3845, the annual insulationconsumption is 0.35 m3 per capita [Ref: 3]. However in theUK, with a similar degree-day requirement of 3210, theannual insulation consumption is only 0.15 m3 of insulationper year. This difference is not accounted for by rates ofconstruction, though insulation density may be a factor.

PresentThe comparison of standards (see graph) confirms thateven when climatic differences are taken into account,thermal insulation standards vary considerably and thereis much room for improvement. Standards are in factlowest in southern countries, where typical heat loss for ahouse may exceed that in the north of Europe, despite awarmer climate.

FutureAt present many member states are improving theirregulations separately; in 1999 Germany planned toreduce heat loss by 30% and Finland by a further 10%.An integrated calculation approach has already beenapplied in Germany, France, UK, Ireland and Netherlands.

It seems likely that in due course this will lead to astandardised European calculation with variation forclimatic conditions.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

Germany UK France Nordic Countries Other Europe

roofs floors walls

R = m .K/W

Insulation standards by countryMin. thermal resistance for dwellings

2

Nordic Countries

Germany

France

United Kingdom

Rest of Europe mean

m3 per capitaper year

0 0.1 0.2 0.3 0.4 0.5

Annual insulation consumption per capita, m3 - selectedEuropean countries. [Ref: 3]

Varying thermal insulation standards across Europe. [Ref:3]

What aboutclimatedifferences?

3

A National Programme to improve the standard ofhousing and reduce carbon dioxide emissions

As proposed by Professor Peter Smith, ChairmanRIBA Energy & Environment Committee

Existing HousingSAP 20

c 600 kW.h/m2/yr

New & RetrofittedHousingSAP 60

c 230 kW.h/m2/yr

££Investment

JobCreation

ReducedIllness

CO2

reduction

££Saving

>50% cut inCO2 emissionsfrom housing

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ComfortClearly, insulation is one of the key strategies forachieving thermal comfort efficiently in buildings.

Modern lifestyles require high levels of thermal comfort inbuildings - typically 21˚C for the main living spaces and18˚C for other spaces.

Demand for thermal comfort levels also become higher asmore people work from home and spend irregular hours athome. The travel savings achieved by communicationsadvances are then likely to be partially offset by increasesin domestic heating energy... unless thermal insulationstandards are improved.

Fuel PovertyA prime driver for better insulation practice is theeradication of fuel poverty. Though not often recognisedas a distinct issue outside the UK, fuel poverty certainlyexists in many European countries.

Fuel poverty is found in poor areas and in substandardsocial housing, much of which built since 1945 wassystem-built with air-leaky construction and very little ifany insulation. This is particularly applicable in easternEurope.

Retrofit of existing buildings in fuel-poor areas offers greatadvantages to both society and the environment.

"Fuel poverty arises when people have insufficientincome to heat their homes to the standard requiredfor health & comfort. Affordable warmth is defined bythe World Health Organisation as having atemperature of 21°C in the living room & 18°Cthroughout the rest of the home." (Briefing from AgeConcern, UK charity)

The common definition of a fuel poor household is onethat needs to spend in excess of 10% of householdincome in order to maintain a satisfactory heatingregime. “Evidence shows that it is the poorerhouseholds that have the least insulated homes.” [Ref:6]. The number of fuel poor in the UK in 1999 wasaround 4.5 million households.

Comfort andFuel poverty

Professor Peter Smith of UK’s Sheffield Hallam Universityhas shown how the UK target of 20% cut in CO2

emissions on 1990 levels by 2010 is achieveable entirelyby raising the energy standards required of new homesand by instigating a programme of energy efficiencymeasures in existing housing stock. This would create amajor new industry in energy efficiency and reduceenergy use in housing by up to 50%.

8 million households cannot afford basic standardsof warmth, even though energy prices in the UK arerelatively low... Raising thermal efficiency of theirhomes would meet an acute social need whilstgenerating jobs and cutting down on the £1bnannual health bill attributable to poor housing.

We need to refurbish poor-quality homes to anenergy efficiency standard of SAP60 (UK governmentStandard Assessment Procedure). To put this inperspective, new homes have to achieve aroundSAP75 whilst most of the sub-standard homes will beSAP10-20. Professor Peter Smith

In 1996, one out of every twelve EU citizens(about 28 million people) lived in a householdthat was behind schedule with (re)paymentsof utility bills and/or housing costs.From: European social statistics [Ref: 5]


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Lighting20%

Heating 50%

Ventilation/Cooling 30%

Natural ventilation.Thermal mass cooling.Local comfort cooling.In warmer climes, use

efficient air conditioning

Good daylight design.Efficient lighting.

Glazing specification.Insulation and thermal mass.Atrium as thermal buffer.

Wate

Cooki5%

Lightin14%

Cooli4%


LowHeatStandard

5040

5040

302020

15-20

Space heating

Hot water

Electricity

150

kW.h/m2.yrdelivered

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How do wereduce heatingenergy?

SpaceHeating

60%Electricity 10%

Good daylighting.Efficient lighting.

Hot water 23%Solar water heating.

Site CHP system.

Cooking 7%Efficient appliances.

Macro-scale designLandscaping for shelterand solar penetration.Building form.Orientation & Massing.

Micro-scale designGood insulation.Airtightness/ controlled ventilation.Passive solar design.Thermal mass.Sunspaces.Glazing technology.

These standards for housing form the basis for much of the comparativework in this study, and are defined in more detail on pp50-51.

Improvements in electrical energyefficiency through better lighting andappliances are assumed alongsideimprovements to thermalperformance.

In this section we provide a simple guide explaining someof the principles of low-energy design, and showing howgood thermal design and use of insulation can cut heatingenergy use to very low levels - in many cases to zero.

The charts on this page show that domestic buildings -housing - takes the largest share of building energy use,and offers the greatest opportunities for heating energysavings, hence our focus on it in this section.

While thermal design standards are increasing gradually,we believe that a faster improvement could make majorcontributions to greenhouse gas reduction targets. Ourproposed LowHeat standard offers a benchmark for such‘optimum’ design.

It is commonly assumed that very low-energy and zero-heating houses are very difficult to achieve. This is not thecase, especially in new-build; a simple combination ofclear design steps can reduce energy use without largeincreases in capital cost, as we show in this section bothanalytically and graphically as Guidelines for the designer.

There is a complex dynamic between refurbishment andnew-build strategies, where analysis shows that new-buildreplacement programmes perhaps have the best potentialto reduce carbon dioxide emissions from domestic energyuse.

Key design strategies forcommercial buildings

Reducing heating energy use is the first step

Domestic buildings areresponsible for 60% of EU

building energy use, about 40-60% of which is heating energy

Key efficiency designstrategies for housing

Residential

IndustryTransport


Buildings


buildings

Many buildings e.g.deep-plan air-conditionedoffices will have higherventilation/cooling energycompared to heating

[Ref: 7]

[Ref: 7]

Source: DG TREN

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Domestic buildingsDomestic buildings make up 60% of total building energyuse, and about 60% of domestic energy use is in heating.

New buildings can easily reduce this heating energy useto very low levels through good design and sufficientinsulation. This means that new-build replacement toLowHeat standards can potentially achieve greater CO2

emissions abatement than refurbishment (see pp 40-41for full discussion).

Existing buildingsIt is very difficult to assess the total scope for retrofit inEurope, but it is thought that up to 50% of buildings inEurope are uninsulated. For example Germany, Ireland,Italy, Netherlands, Spain and UK together hold 100 milliondwellings of which about 50 million are uninsulated.

Retrofitting insulation and glazing can reduce heatingenergy use by 30-40% in these buildings. This is mostcost-effective when it takes place at the same time asmajor refurbishment.

Higher savings can be achieved where supply-sideimprovements like district heating and combined heat andpower (CHP) are options. For example in Denmark,average space heating reductions of 53% were achievedin the period 1972-2000, through both demand andsupply-side measures on both new and old buildingsincluding better insulation standards and retrofit insulation.[Ref: 10]

However, many existing buildings do present restrictionsto retrofit insulation due to practical and aestheticconstraints, and supply-side options are more applicableto new-build. A more realistic estimate of the potentialreduction is perhaps 30%, achieveable in half the stock.

Commercial buildingsHeating savings arising from insulation are less significantin commercial and office buildings due to greaterventilation and glazing heat loss and other designconstraints. However design for efficiency overall offersgreat scope for energy reductions in commercial buildings,and many of the principles are similar to those in housingdiscussed here.

Which buildingtypes?

Over 50% of total building stock and 85% ofthat pre-1965 is without any wall insulation..approximately 31% of walls are solidmasonry walls of brick, block, or stone...

In total 58% of the domestic building stock isuninsulated… Where appropriate, 28% savingis expected through cavity wall insulationretrofit, and 41% saving is expected throughsolid wall insulation.

From the English House Condition Survey 1991 – Energy Report[Ref: 8], and interpretation in [Ref: 3]

A small programme of new-build LowHeathouses will achieve similar annual savings to a

much larger programme of retrofit.

100 million existingdwelllings

Refurbishroute

New-buildreplacement

route

100base

50 asexisting

50refurbished

84 asexisting

16 new build

1000 TW.h

700 TW.h

1680 TW.h

24TW.h

SAVE296 TW.h

SAVE296 TW.h

100base

Scenario Energy Demand

Annual delivered heating energy demand, assumptions as at left

Note: industrial process applicationsThis is a very important area, though only c.25% of EU energy useis in industrial uses. Large energy savings are achieveable byincreasing pipe insulation standards in industrial processapplications to optimise them for insulation and life-time cost criteria.

Annual delivered heating energy, see pp 40-41 for full modelling

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1990-

0.45

0.25/0.35

0.45

2.8

2002-

0.16-0.2

0.35

0.25

1.9

ventilationalso

legislated0.16

0.2

0.25

1.6

1970-

WindowWall

Floor

Roof

1980-

0.35

0.6 5.4

?Example based on UK Building Regulations

Window heat loss per square metreshown at 1/5 scale of opaque elements

2007-8 2050-

What energystandards shouldwe adopt?

Building insulation standards have increased generallyover the 20th Century as consciousness of energyconservation has increased, and will continue improvingover time - as shown in the diagram.

Since this incremental improvement is so far below thepotential energy and carbon savings possible, we arguefor an immediate jump to better standards in newconstruction wherever possible - in particular ourproposed LowHeat standard.

What is the cost impact of this proposal? On a LifetimeCost basis, it is well documented that even more onerousstandards than LowHeat will achieve the same cost over30 years compared to standard housing (see pp40-41).Moreover experience suggests that the LowHeat Standardcan be constructed at or very close to standard capitalbudgets for housing, and with good design and carefulspecification can even be achieved within social housingbudgets (implying a lifetime cost far lower thanconventional)

How to assess investment in thermal standards‘Economic’ levels of insulation are usually judged on simplepayback, which gives a poor indication of the advantages. Ifconsidered instead as Return on Investment, it can be seen that arelatively small capital investment in better insulation levels canproduce a large return on investment by reducing running costs. Asimportant is that the decision must consider the whole buildingsystem: for example main heating systems can be omitted asdesign improves, a saving which will pay for improvements toinsulation and ventilation systems.

Elemental U-values are only one part of low-energy design.Assessment of designs should be made using calculation andmodelling software on the basis of the whole building, and Europeanregulations will increasingly operate in this way. This enablesdesigners to achieve the desired energy use standards through arange of design and technical strategies.

Building insulation standards areimproving over time, but not fast enough!

Heatingenergy use

2kW.h/m .yr

2000Standard

LowHeatStandard

NoHeatStandard

GB2002

F (s)F (n)

IR2002 D

(EnEV) (Passiv HausStandard)

B

Existing

Selected EUregulations

1990 UKRegs

0

40

80

120

160

12 3

45 6 7 8 9

1011

120

Some EU Building Regulations in force 2002,relative to the Standards in this document

Some EU Building Regulations2002 and energy standards

Relative to the modelling on pp 50-51

2000Standard

1990UK Regs

LowHeatStandard

NoHeatStandard

Existing

Example based on England and WalesBuilding Regulations

Window heat loss per square metre shown at1/5 scale of opaque elements

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Increasinginsulation thickness

Cost

Zero-heating transition

> capital costs reducedRunning costs minimal

No heating system required

Total Lifetime Cost

Insulation + heatingsystem capital cost

Running cost

Why focus onLowHeatStandards?

Increasing insulation gradually reduces running costsbut increases capital costs; but once the LowHeat

standard is achieved, lifetime costs jump down as theradiator system is no longer required

The capitalized total costs (investments inthe building including planning and buildingservices plus running costs over a period of30 years) are not higher than for an averagenew building.from CEPHEUS, EU-funded Passiv Haus demonstration project.www.cepheus.de

While many European nations are approaching or havereached the 2000 Standard, on average across Europenew buildings are performing much worse. Buildingregulations are improving incrementally but buildings lastfrom 60 to 150 years or longer, and insulation is notusually replaced or upgraded in that time. Every buildingbuilt to suboptimal standards may continue to emit carbonfor 100 years or more.

However it is possible to build very low-energy houseswith very low or zero heating demand. There areexemplary schemes around the world, most notably theGerman, Austrian and Swiss scheme known as PassivHaus. Many thousands of houses have been built as partof this scheme, showing that low heating levels can beachieved with no limit to living space or design creativity,and at very little or no additional lifetime cost thanks to theomission of a main heating system (and our proposedLowHeat standard is even less onerous than the PassivHaus in order to be achieveable within lower budgets).

The main limit to the implementation of LowHeat housingon a wider scale is a lack of political will - thoughknowledge and understanding barriers also need to beovercome. The savings achieveable relative to theaverage demand level are very large (92.5%). If theconstruction industry works together to encourage andspeed the adoption of these standards, we can cut carbondioxide emissions, minimise running costs and providehigh levels of thermal comfort.

The LowHeat specification includes:EnvelopeWell insulated: U ≤ 0.2 W/m2.KAirtight (<0.6 ac/h @ 50 Pa)Low thermal bridging

GlazingOrientation and area optimized; c 25-30% of floor area.Double glazing with low-e coating and insulated shuttersor blinds, average U ≤ 1.3 W/m2.K

VentilationMechanical winter ventilation with heat recovery 70%efficient. Supplementary heating via booster coil withinair supply.

0

500

1000

1500

2000 Existing

LowHeat

MWh ofheating energy

0 100 yrsLife of building

50 yrs

A LowHeat house uses 7.5% of the heatingenergy of an existing house, saving large

amounts of energy over its life

2000Standard

Refurbished

See pp52-53 fordefinitions

Ref: XCO2 modelling

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2 annual heating energy use + embodiedenergy for the same scenarios

Year of programme1 2 3 4 5 6 7 8 9 100

500

1000

1500

2000

2500

TWh of delivered heatingenergy and embodied

energy per year

1 2 3 4 213

4

Base figure no changeNewbuild to 2000Standard 5% paGradual refurbish 10%Newbuild to LowHeatStandard 5% pa

Newbuild to LowHeatStandard 10% pa

0

20

40

60

80

100

Year of programme1 2 3 4 5 6 7 8 9 100

Millions ofdwellings 10% per year

5% per year

Cumulativetransformation

Assumptions: no of dwellingsrefurbished and newbuild per year

How to reduce heating energyuse in Europe's housing stock

Base current demand

Theoretical futureminimum demand

Year of programme

Gradual refurbish 10% paNewbuild to 2000Standard 5% paNewbuild to LowHeatStandard 5% pa

Newbuild to LowHeatStandard 10% pa

1 annual heating energy use for different scenarios

1 2 3 4 5 6 7 8 9 1000

500

1000

1500

20001 2 3 4

123

4

TWh of deliveredheating energy per year

Replace, LowHeat Standard 10% pa

0 20 40 60 80 100

000 TW.h of total heatingenergy plus embodied

1

2

3

4

Gradual refurbish 10%

Replace, 2000 Standard 5% pa

Replace, LowHeat Standard 5% pa

On previous pages we raised the common question: toreduce domestic energy use, is it better to focus on new-build, or on refurbishment?

Refurbishment appears to require lower embodied energy,but can be complex, can’t be carried out on all dwellingsand will achieve modest savings (our research suggeststhat fabric improvement measure will probably cut heatingenergy use by 30% on average). New-build meanwhilecan achieve cuts of up to 92% of heating energycompared to the current average, if houses are designedand built to the best of current knowledge - though ahigher embodied energy burden is also implied.

The modelling illustrated on this page has been set up tocompare different scenarios for refurbishing or replacingwith newbuild a percentage of the housing stock, on thebasis of annual energy demand, and then includingconsideration of embodied energy. It shows that aprogramme of radically accelerated new-buildreplacement to LowHeat standards can achieve morethan refurbishing even double the number of buildings,even when embodied energy is taken into account.

The peak at the beginning of the lower graph is due to theembodied energy in newbuild: but the annual demand stillfalls sharply, and the cumulative demand after 60 yearsshows a massive advantage to the new-build replacementstrategies.

In reality it is not an either/or situation. A programme ofaccelerated replacement with newbuild to LowHeatstandards where feasible and refurbishment elsewhere isa strategy which could achieve massive energy andcarbon savings in the housing sector.

New buildings vsrefurbishment?

Cumulative total energy after 60 years

[Ref: 10]

AssumptionsBase: 100 million dwellings each with assumed average heating demand 20MW.h/year. Total number of dwellings constant over time. Note: total numberof dwellings in DE, IR, IT, NL, ES + UK is approx 100 million.1 Refurbishment of 10% of stock per year with thermal efficiency measuresachieving reduction to average demand 14 MW.h/yr per house2 Replacement of 5% of stock per year with Newbuild to 2000 Standard, to6 MW.h/yr per house3 Replacement of 5% of stock per year with Newbuild to LowHeat Standard,to 1.5 MW.h/yr per house4 Replacement of 10% of stock per year with Newbuild to LowHeat Standard,to 1.5 MW.h/yr per houseEmbodied energy: total new-build embodied assumed to be 80 MW.h perhouse, and refurbishment embodied assumed to be 12 MW.h per house).

x and brackets to go

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Shelter fromsouth-west

prevailing wind

Shelter fromnorth-east cold

winds

In exposed sites,respond to climateand microclimate

Heat loss 1.71

Heat loss 2.4

Heat loss 0.62

Energy considerations recommendglazing to max 20-30% of floor

area, though this can be increasedwith the use of moveableinsulation and shading.

Airtightness means that colddraughts cannot get in, and warm

air cannot escape (except forventilation air; see also step 5) 0 20 40 60 80 100

Glazing ratio % glazing of wallre

Total energy use

Heatingenergy

Lightingenergy

Lowest totalenergy demand

Sunspace / wintergarden actsas thermal buffer and passive

solar heat store. Exposedthermal mass should be used

to store heat. Sun Rose

N

Percentage of solar energy from differentdirections (45˚ inclined plane) - London

100%

60%

40%

Win

ter

Mid

seas

on

Sum

mer

1 Site, orientation andbuilt formDesign for solar access &wind protection, compactbuilding form.

Compact form has a large impacton heat loss. Daylighting should notbe compromised however - lightpipes are one way to bring daylightinto the centre of the building. Inexposed sites, wind protection canreduce heating demand by up to10%.

2 Optimise insulation (U-value) and airtightnessMinimise heat loss and maximise airtightness

3 Passive Solar designOptimise glazing, orientation and thermal mass strategy

Heat loss tends to be equallydistributed between opaquefabric, glazing and ventilation- all three elements must beconsidered. Once insulationof opaque and glazedelements is improved beyondthe 2000 Standard thenairtightness is also critical.Area of glazing must achievea balance between heat lossand daylighting (typically 25-30% of floor area if noexternal shading).

Passive Solar design aims to usesolar gains to maximum extent inwinter, and most glazing needs to beoriented towards south - thoughexternal shading or overhangsshould be provided to minimisesummer overheating. In a passivesolar design thermal mass locatedcorrectly is essential to store solarand occupant gains for use whenneeded. However as envelopeinsulation and airtightness increases,passive solar is less important.

Detachedhouse

Terracedhouse

Apartment

DesignGuidelines 1

Relative heat loss fordifferent house forms

Typical variation in energyuse with glazing area

Basic principles for low-energy design, newbuild

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Kitchenextract

Bathroomextract

Heatrecovery

system

Extract can bepartly wind-driven

Ventilationheat loss

Airtight housewith MHVR to

achieve 0.5 ac/h,70% eff (LowHeat

Standard)

Typical modernhouse, 1 ac/h atnatural pressure(2000 Standard)

heatreclaimedfromventilation air

Efficient lighting andappliances will reducedemand dramatically

Solar thermal panels canprovide 70% of water

heating demand

Lighting: CarbonIntensity

tungstenfilament

metalhalide

compactflourescent

8.36.7

mg CO2 perlumen output

per hour

50

4 Energy system &appliancesChoose efficient, low carbon heatingsystem, lighting and appliances

5 Ventilation strategyDesign controllable system, consider mechanicalventilation & heat recovery

6 Materials issuesFinal stage. Without compromising energy in-useperformance, aim to reduce embodied impact wherepossible.

Though a small percentage of domesticenergy use is in lighting and appliances,it relies on electricity which is valuableand of relatively high-carbon intensity.Modern lighting systems and appliancesoffer huge efficiency gains overtraditional, and further improvementsare possible. When specifying, energyratings and eco-labels should bereferred to.

Once a highly-insulated and air-tightfabric has been created, control ofventilation heat losses becomesessential. In the winter, ventilationshould be kept to a minimum (thoughsufficient to provide fresh air) and heatrecovery should be considered. Incolder climates whole-housemechanical ventilation with heatrecovery (70-80% of outgoing heatrecovered) should be considered. Inslightly warmer climates humidity-controlled passive stack vents can beused.

Materials’ embodied impact makes up to 10-15% of the building’s totalimpact, and it is more important to minimise energy-in-use. Thismeans that the first materials to focus on are those which have leastimpact on the energy-efficiency strategy. Most buildings last muchlonger than a ‘design life’ of 70 years, and the longer they last, theless important is embodied energy.

Rating of materials on embodied impact alone is not common sense;using a life cycle assessment approach, the whole building systemshould be considered, in particular the energy use of the building overits life.

Emissions to Air

Emissions to Water

Emissions to Land Wastes

EnergyResources

MaterialResources

WaterResources

Inputs

Outputs

Productionof Materials

Manufacturing of Products

Construction andRefurbishment

Demolition Use andmaintenance of Buildings

Building production and life time

'Cradle to Grave' timescale

The principles of LCA analysisof building materials

diagram after BRE


LowHeatStandard

In-useEmbodied

60%reductionin-use

75%reductionin-use



in-use performance


DesignGuidelines 2Basic principles for low-energydesign, newbuild, continued

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New-build housing:lightweight orheavyweight?

Two of the key issues affecting choice of energy-efficiencystrategy are wall thickness, which may be an issue inorder to maximise living space in medium- to high-densitydevelopments; and thermal mass, which may conflict withmass-production system-build approaches. The two issuesare related in the debate about thermally massive againstlightweight construction. The dichotomy is in fact slightlyfalse - as we explore here.

The heavyweight approachThe traditional wisdom in many parts of Europe wouldargue that heavyweight construction is required to givethermal mass which offsets temperature fluctuations:specifically to prevent summer overheating, and in winterto capture and store heat arising from occupants and solargain. There are a number of case studies for thisapproach, particularly in the UK (Hockerton; BedZED), butit is not the only approach to zero-energy buildings.Indeed some energy design experts believe that air-tightness is a more important factor than thermal mass.

The lightweight approachLightweight building construction (e.g. modular timberframe) is being increasingly explored in many circlesbecause it offers opportunities for rapid, defect-free andlow-cost construction with maximum opportunity forprefabrication. In the UK, particularly it is seen as part ofthe solution to a shortage of low-cost housing provision.From the macro scale, this approach can be seen to bemore socially sustainable, assisting the construction ofaffordable housing.

The Hybrid approachA realistic approach for the LowHeat standard is a hybridapproach combining the best of both. In circumstanceswhere the lightweight approach proves insufficient to storeincidental or solar gains then there are opportunities forlocalised exposed thermal mass. The key variable here isexposed mass - concrete floors may be rendered uselessby carpet, or walls covered by hanging pictures. The keyto a successful design is to get enough thermal mass inplaces where it does not conflict with useability.

Lightweight• E.g. Timber or steel frame or SIPs (structural insulated panels)

• Fast response heating.• MHVR works well with airtight construction.

- Ideal for sites requiring rapid construction, wherespace/density is at a premium, or ephemeral occupancy- Appropriate where solar gains cannot be optimised.

Hybrid• Combination of precast orinsitu mass components withairtight modular lightweighthighly insulated ‘skin’construction.

- Allows rapid constructionand thin walls with somestorage of solar andincidental gains.

Heavyweight• E.g. Masonry + overcladding.• Solar-oriented design can use thermal mass.• Design for constant temperature.

- More appropriate for orientations where ‘passive solar’can be optimised, and for continuous occupancy.

Lightweight low-energy houses atAltotting, Germany

Heavyweight low-energy houses atHockerton, UK

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Cavity walls - injectwith loose-fill fibre or

in-situ rigid board

Warm roofspace -insulate with rigid board

or spray at rafter level

Solid masonry or concretewalls - externally insulatewith rigid board.

Cold roofspace: loosefill or quilt or rigidboard at joist level

Floor - rigid board underfloating floor

Vapourbarrier may

be req'd

Must be water-resistant andrigid insulation

Must be water-resistantand structurally stronginsulation

Material must be water-resistant to block watertransfer between skins

Raised timber floor - rigidboard or quilt

Must be water-resistantinsulation

Note: radiant barriers can form a usefulstrategy in many applications wherespace is limited. However maintainingsealed air gaps between and aroundall layers is essential for performance.

Option: internallyline with rigid

insulation-backedplasterboard

Note: where rigid board is used, in-situ sprayed cellular plastic is oftenalso an option

The single best means of encouraging investment isto offer specific financial inducements to consumers.These can be by way of cash-back schemes, grants,tax breaks and accelerated capital allowances. Thesetax breaks are directly required in order tocompensate for the substantial numbers of barrierswhich exist in the marketplace currently, which distortoptimum levels of investment.Report of the Working Group on Sustainable Construction,DG Enterprise

DesignGuidelines -retrofit

It is widely perceived [in Germany, Netherlands, andSwitzerland] that work is needed on existing buildingsas a matter of urgency.. The costs of suchimprovements are reasonable, if they are combinedwith major renovation work..David Olivier, low-energy design specialist [Ref: 9]

While potential savings are not as large as in new-build,considerable improvements can be made in existingbuilding stock (30% reductions on average in heatingdemand, 50% possible) and a refurbishment programmewill form an important part of reducing heating energy inEurope while also reducing fuel poverty and increasingcomfort.

Design considerations in retrofit place more limits onpossibilities, and technical issues like condensation needto be carefully considered. The most common debate isabout the best location for insulation, and we summarisesome of the issues here.

There are pros and cons to each material and applicationwhich are not discussed here. There are also longevitycriteria for the insulant, touched on in the appendix on pp70-71.

The principle locations and types of insulation retrofit are:

Cavity wallInjection of loose-fill or insitu-expanding material.Internal lining with rigid insulation-backed plasterboard.Solid masonry wallExternal insulation with rigid board material, which canthen be overclad with a rainscreen or rendered.Internal lining with rigid insulation-backed plasterboard.Roofspace - coldBetween- and over-joist insulation with loose-fill or quiltmaterial.Roofspace - warmBetween or between and under-rafter insulation with rigidboard material.Solid concrete floorRigid board under new screed or floor finishRaised timber floorRigid board or quilt between and under floor joists.

Retrofit is more cost-effective when combined with otherrefurbishment works. In general, insulation levels shouldbe specified to the maximum possible level as it is likelythat further upgrades to the building will prove expensiveand difficult.

In general, external insulation of the fabric is preferable to internalas it makes it easier to avoid cold bridges, which as well as heatloss can sometimes cause damp in a poorly ventilated building.

Where to insulate - retrofit

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0

50

100

150

200

250

0

40

80

120

160

Zero ODP Rigid Urethanelambda = 0.022 W/m.K

Mineral woollambda = 0.037 W/m.K

Fabric Loss

Glazing Loss

Vent Loss

Co

nve

nti

on

al b

uild

ing

as 1

970

UK

reg

s

As

1990

UK

Reg

s. F

abri

c U

= 0

.5,

1 ac

/hr,

sin

gle

gla

zed

fabr

ic U

= 0

.45

glaz

ing

doub

le U

= 2

.9fa

bric

U =

0.4

2000

Sta

nd

ard

: w

all U

= 0

.35,

gla

zin

g U

= 2

.2, r

oo

f U

= 0

.2

airt

ight

ness

impr

oved

to 0

.75

ac/h

r

Wal

l U =

0.3

, roo

f U =

0.2

,gl

azin

g U

= 2

wal

l U =

0.2

5, r

oof U

= 0

.2, g

lazi

ngdo

uble

low

-e +

cur

tain

s gi

ves

U =

1.7

1fa

bric

U =

0.2

gla

zing

dou

ble

low

-e

+ in

sula

ted

shut

ters

U =

1.3

Lo

wH

eat

Sta

nd

ard

MV

HR

70%

eff

Gla

zing

is s

uper

win

dow

s,U

= 0

.75

No

Hea

t S

tan

dar

dF

abri

c U

= 0

.1 M

HV

R 8

0% e

ff

airt

ight

ness

impr

oved

to 0

.5 a

c/h

Incremental improvements to design, summarised below

0

100

200

300

1 2 3 4 5 6 7 8 9 10 11 120

1 2 3 4 5 6 7 8 9 10 11 120

Insulationrequired

in timber frame wall construction

Heat losscomponents

Heatingenergy use

W/K

2kW.h/m .yr

mm

2000 Standard

Design for low heating energy involves optimising thethermal properties of the fabric in three ways: insulation ofopaque fabric; heat transfer properties of glazing; andairtightness and ventilation strategy.

In order to demonstrate the relative contributions of thesethree elements we have used the INDEX computer modelof domestic thermal design [Ref: 11]. Starting with a housebuilt to 1970 UK standards, we have gradually upgradedthe specification of three elements. It’s clear from thismodelling that thermal insulation, glazing and ventilationare all critical aspects of the overall thermal strategy.

This and other modelling has shown that the LowHeatand NoHeat Standards can cut heating energy use by80-96% compared to the 2000 Standard, and by 90-98%compared to the typical existing dwelling.

Twelve stepsto a zero-heating house

Detailedmodellingresults base terraced house

used for analysis

Ventilation isMHVR 70% eff

19901970 2000Standard

Step 4

Increase opaqueinsulation

Step 0 Step 1

Insulation toaverage opaqueU = 0.5 W/m .K

Infiltration = 1 ac/hr

MHVR = 80%efficient

LowHeatStandard

Glazing triple'superwindows'U = 0.75 W/m2.K

Increase fabricinsulationU = 0.1 W/m2.K

50kW.h/yr

104kW.h/yr

161kW.h/yr

(UK regs) (UK regs)NoHeat

StandardStep 12

2 kW.h/yr

Step 10

10kW.h/yr

Ventilation

HeatingEnergy

Insulation

Glazing

Efficiencystrategies

Infiltration reducedto 0.5 ac/h

2

Double glazingU = 2.2 W/m2.K

Fabric insulationU = 0.20 W/m2.KGlazing doublelow-e + shuttersU = 1.3 W/m2.K

U = 0.35 W/m2.KRoof U = 0.2 Wm2.KGround U = 0.25 W/m2.K

Standards and specifications toreduce heating energy use

Fabric thermal specification and resultant heating energy useNote: modelling is dependent on assumptions and these numbers should be taken as typical not absolute

predictions, within correct orders of magnitude and based on this house type on the London climate.Infiltration rates are indicative of standard new construction ventilation + leakage at normal pressure.


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Array of materialsThere is a large array of different insulation materials,from many different sources and with different properties.This is as it should be - construction is complicated,different construction methods have very differentperformance requirements for insulation, and there ismuch scope for individual choice in response to specificproject conditions. This diversity puts considerableresponsibility on the specifier, and it is important tounderstand the process by which different materials arechosen.

Materials selectionIn fact the choice of material per se has very little impacton the total environmental impact of the building, as wewill show. What is most significant is the thermal designand specification: the overall design strategy and theparticular U-value of components, which can be achievedwith a variety of different materials at differentthicknesses.

On the level of the material choice, there are three keypoints for selecting insulation materials:• Choose a material with long life, sufficient durability

and minimum failure risk (to maximise energy andcarbon benefits).

• Choose a material with zero ozone depletion potential(ZODP) (a global pollution issue).

• Where thickness is constrained, choose the bestthermal insulator appropriate to the construction type(to optimise U-value and energy savings).

In this sectionIn this section we discuss the selection of insulationmaterials, and describe the key environmental issues inthe choice of material. We also show how thermalresistance is much more significant than embodiedenergy, and we summarise the issues with respect toblowing agents. We discuss longevity as an essentialenvironmental issue, and we review the ageing and failurerisks in insulants which challenge longevity.

Finally for reference we summarise the key aspects of themost common material types including raw materials,manufacturing and general properties.

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Introductionto insulationmaterialsClassification of Insulation Materials

Mineral

Oil-derived

Plant / animalderived

Fibre Cellular

'Organic synthetic'

'Organic natural'

'Inorganic'

Rock wool

Glass wool Vermiculite

Cellular glass

EPS XPSPhenolic

Rigid polyurethane

Cellulose Wool

CottonCork

Flax

PUR/PIR

Expandedpolystyrene

Extrudedpolystyrene

RW

GW

Mineral wool

Cellulose fibre

Cellular plastic

Note on assumptions1 Thermal conductivity. Assessment methods for lambda values(thermal conductivity) currently vary slightly across Europe (aharmonised approach has been developed and will be in force inMarch 2003). For the sake of comparisons between materials, thisreport uses lambdas based on ‘best available’ values. Lambdas dovary for different manufacturers, and specifiers should always checkthe specific lambda rather than relying on a ‘generic’.

2 Ozone depletion. In this document cellular plastics are assumedto be those versions available using non ozone-depleting blowingagents (as all materials will be after Jan 1 2004, see pp64-65),which have slightly higher lambdas than some of the materialsavailable today.

Inside Outside

Conduction Radiation

Convection

Uninsulated wall

Insulated wall

Inside Outside

Air gaps with reflectiveand low-emissivity

surfaces block radiation

Cellular or fibrousstructure of trapped gaspockets reducesconvection. Low blowingagent conductivityreduces conduction.

Low density material withcomplex solid pathsreduces conduction Cellular

Fibrous

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Overall performance targetsThe most important factor overall in designing insulationsystems is achieving very low U-values to minimiseenergy use and carbon dioxide emissions. This on its owndoes not provide limitation or guidance on one materialover another, except where thickness is constrained.Those issues that are important are summarised belowand expanded on in this section.

Ageing IssuesMost importantly, insulation materials must be durable andmust not ‘age’ from stated thermal conductivity - theyshould provide consistent performance over the life of thebuilding. Thermal performance over time is criticallyimportant to the total energy saving properties of thematerial. Most insulation is installed on the assumptionthat it will last as long as the building itself, but buildingscan last anywhere between 50 and 500 years. Aninformed choice of materials needs to be made on thebasis of an assessment of ageing or failure risk in anyparticular application.

The myth of embodied energyEmbodied energy has often been used by designers as abasis for environmental comparisons between materials.But in the case of energy-efficiency materials likeinsulation, this is extremely misleading, as we will show:the energy saved over the building lifetime is far moresignificant.

Ozone depletionPerhaps the most well-known of environmental issues inrelation to insulation is ozone depletion potential (ODP),though chemicals with ODP are being phased out. Allinsulation materials are now available in zero-ODPversions which should be specified in preference. Weprovide some background to the issues and blowingagents used.

Materials reference informationAnd finally, in order to help design teams make informeddecisions and to start the longevity debate, we include inan appendix some guidance and opinion on the differentproperties of the many common insulation materialsavailable, including their manufacturing process andassociated detailed design issues and longevity issues.

Choosinginsulation forsustainability

Don't substitute a 'green' insulation for a non-green material if the change will hurt energyperformance. With lower R-value [higherlambda] materials, increase thickness....Durability of building materials, includinginsulation, is a very important environmentalconsideration.

Environmental Building News, US publicationwww.buildinggreen.com

Human health issues - summaryFibrous materials: Some materials cause skin irritationand protective gear is advised for installation. Loose-fillfibre installations should not be ventilated to occupiedinternal building spaces. Whilst in the past some fibrousmaterials have been listed by research bodies like theInternational Agency for Research on Cancer as potentialcarcinogens, they are currently listed as not; classifiableas to carcinogenicity in humans;.

Cellular materials: In the past some materials hadoffgassing problems which could cause internal build-upof pollutants (notably Urea-Formaldehyde foam). Thesematerials are no longer used and in general health termsthere are no detectable problems with any of theproducts available today. There are also no specialinstallation requirements or issues.

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Durability andfailure risks ininsulants - 1

Once low U-values have been achieved, the mostimportant issue in choosing insulants is longevity ofthermal performance. Buildings can last between 50 and500 years, and the insulation will most likely not bereplaced for the life of the building - unless it is specificallydesigned to enable replacement. It’s clear however thatmore research in this area is required to determine long-term performance of insulants, as large-scale use ofinsulation is a relatively recent development compared tobuilding lifespans. In future it may be useful to define‘failure risk factors’ for insulation materials, to be used inassessing their long-term performance.

The biggest risk factor is perhaps moisture build-up(whatever the cause), which will increase thermalconductivity - especially in fibrous materials - and may insome cases damage the fabric of the insulant (see p 61).

Other risk factors include settlement - which some fibresmay be susceptible to; air movement at surface, airleakiness, and attack by vermin and/or rot.

WorkmanshipPoor workmanship is a common denominator of failure for allinsulation materials. For example, fibre batts in cavity walls maysuffer from mortar droppings, while cellular plastic boards may beleft with gaps between boards. Whatever the material, goodconstruction management is essential.

Design considerationsWe believe that these issues should be considered alongside moreconventional design issues. But there is in addition a potential‘macro’ approach: one aspect of making buildings future-proof mightbe to design the building to allow for the future upgrade of insulation(the most practical way to do this might be by making the insulationexternal to the structure).

FireBehaviour of materials in fire is not an environmental performanceissue or a longevity criteria as it constitutes a catastrophic failure tothe entire building system, and it’s not covered in any detail here. Ithas little meaning on the level of the insulant itself as it has to bedefined for building components as a whole, relative to the particularfunction (legislative approaches do currently vary across Europe,though harmonisation is in preparation).

Inside Outside

Leakiness - airescape carries

heat away

Condensation: can reducethermal resistance anddamage building fabricVapour

permeabilitypresents risk of

condensationAir movement atsurface: can causeconvection heat loss

Ageing: any degradation tomaterial or to thermalresistance from quoted valuesover the lifetime, includingsettlement or compression

Installation risks: all materials arevulnerable to poor installation leaving gapsor physical deterioration (compression).

Good workmanship is essential.

Challenges toinsulation performance

Insulated wall

Inside Outside

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61Insulation for Sustainability - a Guide

60

Ageing in cellular plasticsBlown cellular plastics are known to age in the firstyears of their life through a process of gas exchangediffusion between CO2 in the cells and the ambientair. This is taken into account in manufacturer’squoted conductivity values which should be declaredaccording to the European Standard (EN 13165 forrigid polyurethane insulation) to represent the aged -i.e. long-term - value. Where a gas-tight facing isused (e.g. aluminium foil), a lower long-termconductivity value can be achieved as a result ofprevention of the gas diffusion process.

0 2 4 6 8 years

Mea

sure

d t

her

mal

con

du

ctiv

ity

EN 13165 requires that the aged lambda value isquoted by manufacturers.

Typical ageing profile for rigid polyurethane

EN 13165 allows a definedincrement to be added to the

initial lamba value to givethe aged lamba value for theproduct. This increment is

product specific andcalculated to mimic the

ageing profile of theproduct.

Quoted lambda value

Initial lambda value

Measured thermalconductivity overtime. The insulationperforms better thanquoted in the first fewyears.

Aged lambda value

The aged value corresponds to the leveling out of theageing profile. EN 13165 allows this to be measured directlyfor boards that have undergone accelerated ageing.

Moisture causes thermal conductivity increaseThe presence of moisture in the insulant (which couldoccur as a result of condensation, rain penetration orplumbing leak) will increase the thermal conductivity bya large factor, especially in fibrous materials. A ventilatedor vapour-permeable construction will potentially allowthe insulant to dry out, but building heat loss will bemuch greater in the meantime.

0 5 10 15 20 25 300.02

0.04

0.06

0.08

0.10

Th

erm

al c

on

du

ctiv

ity

W/m

.K

Mineral wool

Expandedpolystyrene

Polyurethane

Moisture % of volume

Insulation layer = 80 mm

From a study by Weiland Engineering, Reference xxx

Idiosyncratic Norwegian commentator Bjorn Berge, inhis book ‘The Ecology of Building Materials’ pointsout some insulation failure risks in general terms:

Lambda values… give no indication of amaterial’s structure, moisture properties orreaction to draughts…. The thermal insulationvalue of a material is reduced when damp… thisis important in hygroscopic materials… Age canalso affect insulation value. Certain productshave shown a tendency to compress through theabsorption of moisture and/or under their ownweight, while others have shrunk.

Solid boards.. need to be mounted as anunbroken surface on the structure and not withinit.. Loose fill .. can settle over time. Thedisadvantages of hygroscopic materials becomeapparent here because they take up moremoisture and become heavier..

[Ref: 12]

Durability andfailure risks ininsulants - 2

Many aspects of insulation materials’ performance overlong periods are not understood and more research isrequired. Some general points can be made on thesources of failure:

Fibrous materialsIn fibrous materials the greatest ageing risks are probablytemporary or permanent increase of conductivity due towetting. Settlement due to compression or wetting of thematerial will also have ‘catastrophic’ impact on theperformance.

Animal- and plant-based fibres may be more vulnerable tovermin or insect attack, if the pest-resistant chemicals donot work or if they leach out.

Cellular materialsIn some cellular materials ageing will occur through theloss of cell-gas resistance, usually through inwarddiffusion of air into the cells. This process is successfullylimited through the use of gas-tight facings (aluminiumfoil). It is well-understood, and manufacturers state that itis taken into account in the stated insulation value of thematerial.

[Ref: 13]

[Ref: 14]

Based on a study of ageing of rigid polyurethane cellular boards blown with pentane

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How importantis embodiedenergy?

There is a common misconception that the most importantfactor in a material specification is the embodied energy ofthe material. For base construction materials, thereplacement of one material with an equivalent with lowerembodied energy will of course reduce the overall energyimpact. But energy in-use is potentially much moresignificant, and must be optimised first.

Embodied energy can be particularly misleading for energyefficiency materials and systems - where the embodiedenergy will typically be in the order of 1% - 3% of theenergy saved over 100 years (based on calculations for100 m2 of wall insulated to U = 0.2 W/m2.K).

Analysis shows that over a realistic timescale of 100years, the lifetime energy is not sensitive to the choice ofinsulating material - though it is, of course, extremelysensitive to the thermal standards or U-values achieved.

This reiterates very clearly: thermal standards first, andlongevity of performance second, are the two keyenvironmental issues for choosing insulation materials.

0

3654

83

125

193

290

U = 0.35 W/m2.K U = 0.20 W/m2.K U = 0.10 W/m2.K

Based on the insulation to meet the required U-value in 100 m of timberframe wall with timber cladding and brick-block cavity wall (terraced

house London). Whole building heat energy from INDEX model, assumedbaseline embodied of 80 MW.h for each house construction plus calculatedembodied energy for insulation, all other assumptions kept constant.

Rockwool

Rigidpolyurethane

100000

200000

300000

400000

0

52

91 99

165

208

350

100000

200000

300000

400000

Masonry Cavity Wall

Timber Frame Wall

Total energy consumption to achievespecified U-values with different materials

500000

600000

500000

600000

kWhtotal

kWhtotal

U = 0.35 W/m2.K U = 0.20 W/m2.K U = 0.10 W/m2.K

Rockwool

Rigidpolyurethane

Rockwool

Rigidpolyurethane

Rockwool

Rigidpolyurethane

Rockwool

Rigidpolyurethane

Rockwool

Rigidpolyurethane

LowHeatStandard

NoHeatStandard

2000Standard

demand 50 kW.h/m2.yr 15 kW.h/m2.yr 5 kW.h/m2.yr

LowHeatStandard

NoHeatStandard

2000Standard

demand 50 kW.h/m2.yr 15 kW.h/m2.yr 5 kW.h/m2.yr

100 year totalenergy in useand embodiedinsulantthickness mm

2

100 year totalenergy in useand embodiedinsulantthickness mm

= 0.033= 0.022 = 0.033= 0.022 = 0.033= 0.022

= 0.022 = 0.037 = 0.022 = 0.037 = 0.022 = 0.037


LowHeatStandard

In-useEmbodied

60%reductionin-use

75%reductionin-use


in-use performance



Dense concrete block

Insulation system

Embodied inmanufacture

Energy savedin use

Relative share of total energy impacts

For example, a concrete block in the right design will reduce energy use throughstorage of solar radiation for release when required. The energy saved though

will be minimal compared to energy-efficiency products like insulation.

Key

Embodied impact is a poor indicator of anenergy efficiency system’s total contribution

For insulation, material type doesn’tmatter; but performance does:

Energy in-use must be optimised first.

Note: Energy demand assumptions arebased on our modelling on pp 50-51;[see Ref: 10 for a discussion of the

embodied energy assumptions].

Note: Diagram; not based on a specific example

Ozone Global ThermalAgent Depletion Warming Conductivity

Potential Potential (gas)

Phased-out CFC-11 1 3800 0.0074under Montreal CFC-12 1 8100 0.0105(Class 1)

Transitional HCFC-141b 0.11 600 0.0088(Class II) HCFC-142b 0.07 1800 0.0084

HCFC-22 0.055 1500 0.0099

Long-term HFC-134a 0 1300 0.0124Alternatives HFC-245fa 0 820 0.0140

HFC-365-mfc 0 810 0.0100n Pentane 0 11 0.0140CO2 0 1 0.0145

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Properties of foam blowing agents

The most commonly-known environmental issue withrelation to cellular plastic insulating materials is the issueof ozone depletion, perhaps the best-knownenvironmental issue after global warming since it wasrecognised by the British Antartic Survey in the early1980s and generated one of the first examples of rapidtransnational action in response. The Montreal Protocol of1987 (with amendments in 1990 and 1992) has set atimetable for the phasing-out of CFCs, and their lesspolluting cousins HCFCs.

Blowing agents for cellular plastics are chosen on thebasis of two characteristics: thermal conductivity (as thegas will remain in the cells); and processability. CFCswere initially favoured because they give rise to very lowconductivity materials (they were also used widely asrefrigerants). Their Ozone Depletion Potential (ODP) isdefined relative to the effect of CFC-11 which is given avalue of 1.

The use of CFCs in cellular plastics was phased out inthe developed world in 1995 (though they are still used insome parts of the world). In Europe the transitionalHCFCs, which have a much lower ODP, are being phasedout in insulation boards in 2002 - 2004, and in other partsof the world to a 65% reduction by 2010 and totalelimination by 2030.

The preferred gases in view of thermal conductivity areHFCs, which have no effect on stratospheric ozone, butare quite potent greenhouse gases (defined relative toCO2 which is given a value of 1). The impact of thematerial must here be considered in terms of TotalEquivalent Warming Impact over lifetime, as the increasedthermal resistance of the HFC-blown cellular plasticsmight offset the global warming impact of their blowingagents? There has been much debate on this issue.Some studies [Ref: 16] suggest that HFC-blowing agentshave the advantage over others when 80% of the gas isreclaimed at the end of life (though this is not currentlywidely done). This is particularly relevant to high-demandrefrigeration applications.

However, many manufacturers are now switching tohydrocarbons like pentane, and to CO2, whose globalwarming effect is easily outweighed by their addedinsulating value.

Ozone depletionand blowingagents

Note: GWPs are from the IPCC Second Assessment Report and theMontreal Protocol and are 100 year integrated time horizon values.

Thermal conductivity is in W/mK measured at 10˚C. Pentane value isfrom [Ref: 15]

Note on assumptionsAll cellular plastic materials are now available with zeroOzone Depletion Potential (ODP), and total phase-out ofozone depleting substances in thermal insulation isoccuring. We would argue that all materials should bespecified in their zero-ODP form. Specifiers should beaware that ‘CFC-free’ or ‘HCFC-free’ does not meanzero-ODP. In this document, all comparisons are basedon materials with zero-ODP blowing agents and thethermal conductivity values quoted are those for zero-ODP materials.

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Typical indicators for building material Life CycleAssessment (LCA)Category DescriptionDepletion of resources Non-renewable raw

material use - e.g. oil extractionGlobal Warming Potential Greenhouse gas emissions(GWP) - e.g. CO2, CH4, etcOzone Depletion Potential Ozone depleting emissions(ODP) e.g. CFC, HCFCAcidification Potential Emissions to air causing acid(AP) rain - e.g. NOx, SO2, HClNutrification Potential Pollution of surface water and(NP) soil with nutrients - e.g. NitrogenPhotochemical Ozone Creation Emissions leading to ozonePotential (POCP) pollution at ground level (HCs)Human Toxicity Potential (HTP) Human-toxic emissions - e.g.

heavy metals and dioxinsEcotoxicity Potentials Flora- and fauna- toxic

emissions e.g. heavy metals, acids

Use of land and space Type and duration of man-madechange of land use -e.g. mining.

Background to LCALife Cycle Assessment or LCA is the process of evaluatingthe potential effects that a product has on the environmentthroughout its entire life cycle, from cradle-to-grave. In anLCA, the energy and materials used and released backinto the environment during the life cycle of the productare identified and quantified. This allows an assessmentof environmental impact from raw material extraction andprocessing, manufacture, transport and distribution, use,maintenance, re-use and recovery, to final disposal.

The International Standard Organization has developed aseries of international standards (ISO 14040 series) basedon the guidelines of The Society of EnvironmentalChemistry and Toxicology (SETAC) which was a pioneerin LCA methodology development. Regulators andindustry increasingly use LCA because it providesobjective data that help strengthen the communicationbetween all stakeholders. If used properly, LCA can leadto genuine environmental benefits and support thedevelopment of more sustainable production andconsumption patterns.

LimitationsLCA comparisons must be based on elements withfunctional equivalence - i.e. two wall constructions withthe same U-value. However it is the whole-lifeperformance of the whole system which is most significantand an elemental comparison only gives part of thepicture (for example it won’t consider airtightness, a keyfactor in heating energy use). To be meaningful enough tocompare design options, LCA should be carried out for thewhole building for its total life.

It should also be noted that during the building’s life spanit may undergo changes in its function and fabric whichwill have potentially large effects on its environmentalimpact, which will be outside the scope of an LCA.

In this documentThere are currently only a few public LCA schemes andthese tend to include information on a limited range ofmaterials. While these are excellent initiatives, currentdata availability is partial and assumptions vary. As aresult we have chosen not to include current LCA data inthis document.

Sustainability inbuilding materials -detailed assessment

Scope of LCA in buildingsThe SETAC Working Group LCA in Building concludedthat the final building or construction, defined byperformance requirements, is the central subject of anLCA and provides the most accurate subject for anycomparison. In practice, the products or components of abuilding or construction can provide a valid subject forthe application of LCA. However, the context of thecomplete building or construction should be reflected orat least mentioned in comparative LCAs of building orconstruction components and incorporated wheneverappropriate.

Alternatively, integrated building assessment tools likethe British ENVEST and the Dutch EcoQuantum [Ref: 17]can enable the comparison of impacts for differentconstruction and materials options, for the completesystem over the life of the building. These systems arevery much under development, and should be used withcare by qualified experts.

Construction products cannot be assessed ona standalone basis since construction workswith the highest "green credentials" may useproducts which might have relatively highloads but which significantly contribute toreducing a building's impact throughout itslifetime.An Agenda for Sustainable Construction, DG EnterpriseConstruction Unit, Working Group SustainableConstruction, May 2001


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appendixSome key properties of

insulation materials

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appendix


Design issues for longevity

Mineral fibre materials have design issues relating to their openstructure - they are vapour permeable and air permeable.

• Moisture build-up in insulantCaused by condensation, leaking cladding or leaking pipework. Willcause large increases in conductivity.

• CompressionLower-strength products with lower binder content offer compressionrisk - e.g. in flat roof applications. Good specification should avoid thisproblem.

• Air movementThe open structure means that surface air movement and air movingthrough may reduce the insulation value, though some products havefacings used to prevent this.

There are very few detailed design issues related to cellular plastics.

• Gas exchange (in materials with blowing agent)The main known failure risk in cellular plastics relates to increasedthermal conductivity due to gas exchange (esp in materials withoutgas-tight facings). As discussed on pp 60-61, according to theEuropean Standard this is taken into account in the quoted lambdavalue.

• LongevityCellular plastics are not susceptible to rot, are not attractive to verminas food, and are known to be very long-lasting materials.

Note: as discussed poor workmanship is a commonissue to all materials and is not discussed here.

There appears to be greater need for risk awareness when detailingthese materials, though more research is required to confirm longevityissues.

• Rot / VerminThese fibres are naturally susceptible to rot and vermin and need tobe protected with chemical treatment. If the material becomes wetthere is a risk that this treatment may leach out.

• SettlementSettlement may be an issue for loose-fill blown fibres asacknowledged for example in the British Standard on loft insulation.

• CompressionPhysical strength and resistance to compression is very low, creatinggreater risk during installation and in trafficked areas.

Physicaldegradation

Moisture /Condensation

Vapourpermeability

Airmovement

Possible in material; watercauses large deterioration tothermal performance

Permeable

Only likely in cases ofcatastrophic degradation

Possible reduction to thermalperformance through airmovement at surface and throu

Detailed design issues

Fibrous

Low risk

Design issue

Mineral fibre

Cellular plastic

Plant / animal fibre

Physicaldegradation


Vapourpermeability

Airmovement

Possible on surface, only slighteffect on thermal performance.

Very low except at butt jointsif poorly assembled.

Only likely in cases ofcatastrophic degradation.


Low permeability especially ifjoints are taped or interlocking

Cellular

Low risk

Design issue

Physicaldegradation


Vapourpermeability

Airmovement

Possible in material; watercauses deterioration to thermalperformance and fabric.

Permeable, see comment on'breathing wall'. Not suitablefor masonry applications.

Settlement possible;especially if exposed towater or moisture.

Low air permeability in someproducts. If wet-sprayed mayhelp seal gaps.


Fibrous

Low risk

Design issue

Guidelines on key issues toachieve longevity in detailinginsulation materials: the mostsignificant environmental issue.

Wetness may cause degradation ofmaterials

Possible if insufficientlyspecified. Greater strengthboards have higher binder %

urethane.K

K

d=U

W/m .K2

W/m.K

m

Heat loss rate

Lambda, thermalconductivity

thickness ofmaterial

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Mineral fibre

Thickness required to achievespecified U-values in walls

Note: highlyapproximate, issueslike thermal bridgingmust be considered

Cellular plastic

Plant / animal fibre

Lambda values / conductivity

BetterWorse

Rock wool0.033-0.040 W/m.K

Glass wool0.033-0.040 W/m.K

0.05

0.04

0.03

0.02

0.01

0.05

0.30

0.40

0.35

0.10

0.15

0.20

100

λ = 0.034

100

200Glasswool

50

λ = 0.020

Phenolicwith foilfacing

λ = 0.022

Rigidpolyurethane

with foilfacing

λ = 0.028

Extrudedpolystyrene

(XPS) λ = 0.032

Expandedpolystyrene

(EPS) λ = 0.034

Rock woolbatts

0.25

U-value(W/m2.K) 50

200

50

100

200

50

100

200

50

100

200

50

100

200

0.9

0.8

0.7

0.5

0.6

0.4

0.3

0.2

0.1

50

100

200

50

100

200

50

100

200

50

50

100

200

50

100

200

100

200Glasswool

50

100

200Cellulose

fibres

λ = 0.020

Phenolicwith foilfacing

λ = 0.022

Rigidpolyurethane

with foilfacing λ = 0.028

Extrudedpolystyrene

(XPS) λ = 0.032

Expandedpolystyrene

(EPS)λ = 0.034 λ = 0.038

λ = 0.040

U-value(W/m2.K)

Note: assumes studs tosame depth as insulant, withno low-emissivity cavity (i.e.performance of foil-facedproducts is underestimated)

Rock woolbatts

Masonry Cavity wall, partial fill

Timber-frame wall

Look-up charts on typicallambda values and typicalconstruction thicknessesrequired for different U-values

BetterWorse

Flax0.037 W/m.K

Sheep's wool0.040 W/m.K

Compressed straw0.037 W/m.K

Cellulose fibre0.038-0.040 W/m.K

0.05

0.04

0.03

0.02

0.01

ZODP Rigid Polyurethane0.022-0.028 W/m.K

BetterWorse

Phenolic0.020 W/m.K

Extruded Polystyrene(XPS) 0.028 - 0.036 W/m.K

Expanded Polystyrene(EPS) 0.032-0.040 W/m.K

0.05

0.04

0.03

0.02

0.01

The key equation relating U-value(heat loss rate) to lambda (thermalconductivity) and thickness (d)

Note: based on ‘typical’ lambdas; actual values will vary with manufacturer

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Lambda values / conductivity

BetterWorse

Cellular glass0.040-0.050 W/m.K

Lightweight block0.15 W/m.KAircrete block0.11 W/m.K

0.05

0.04

0.03

0.02

0.01

Look-up charts on typicallambda values and typicalconstruction thicknessesrequired for different U-values

BetterWorse

Typical productEffective 0.030 W/m.K(5 reflective layers, 120mmoverall inc airgaps)

0.05

0.04

0.03

0.02

0.01

BetterWorse

Cork0.042-0.050 W/m.K

0.05

0.04

0.03

0.02

0.01

Cellular mineral

Cellular plant derived

Radiant barriers

Note on Radiant BarriersAssessing the overall effective lambda or U-value of radiant barrierinsulation is slightly controversial because some manufacturersmake claims not justified by the theory! (probably due to additionalairtightness benefits when retrofitting historic buildings).

The lambda equivalent depends on the cumulative benefit ofreflective layers of foil and air, and depends on the size of the airgaps, the fixing between layers and the conductivity of the fixings orinterleavings.

Future possibilities: Evacuated panelsEvacuated panels can achieve extremely low lambda values intheory but are difficult in practice to manufacture (a few companiesnow claim to be developing them). The problem is keeping theskins (usually metal) apart with a low-conductivity material whichdoesn’t become too much of a cold bridge. Once these technicalbarriers are overcome, the next problem is manufacturing at lowenough cost. The first products available are likely to be for high-performance applications like refrigeration.

Note on breathing wallsCellulose and natural fibres is commonly used in a ‘breathing wall’construction, with no vapour barrier. It’s not entirely clear what thebenefits of this approach are, even amongst its proponents. Insome respects it is a ‘fail-safe’ system - as there is no vapourbarrier to puncture. There is concern though that moisture in theinsulant may leach out fire retardents and/or cause settlement.

urethane.K

K

d=U

W/m .K2

W/m.K

m

Heat loss rate

Lambda, thermalconductivity

thickness ofmaterial

Note: highlyapproximate, issueslike thermal bridgingmust be considered

The key equation relating U-value(heat loss rate) to lambda (thermalconductivity) and thickness (d)

120 space mm ‘including’


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appendixMineral fibre

Cellular plastic

Plant / animal Fibre

polyester + boron (fire retardant)heat + pressure

raw materials

[fire retardant + pesticide]

Plant/animal fibre products

Waste paperWoolCottonFlaxStraw

Cellulose fibreWool fibreFlexible battsFibreBoards

(e.g. boron)

Manufacturing process

e.g.Siliconoxide

e.g.Metallic

Heat

Phenol Formaldehyde (binder)Mineral oil / siliconeCompounds - for selective properties

Fibreminerals 1600 degrees C

melt & spin

Rock wool, glasswool, slag wool

Mineral fibre products

Add

Polyaddition /polymerisation

Blowing agentCatalystSurfactant

Cellular plastic,PUR/PIR, phenolic,

XPS

monomers

Cellular plastic products

In EPS manufacture, beads of PS are made withdissolved pentane. Steam is blown into the mixture,expanding the pellets and expelling the pentane.

Products include - rock wool, slag wool and glass wool.

• Produced by melting at high temperatures and spinninginto fibre.

• Binder added to give rigidity (quantity depending onapplication).

• Mineral oil or silicone often added for moistureresistance.

• End of life - recycling possible if not contaminated,currently landfilled in most countries.

Products include - rigid polyurethane (PUR/PIR), phenolic,XPS and EPS.

• Produced by polymerisation using a blowing agent,catalyst and surfactant. EPS is slightly different >>.

• Some HCFCs currently still used in rigid polyurethaneand phenolic as blowing agents (small ODP) - due to bephased out by 2004.

• Renewably-sourced monomers can be used inproduction (e.g. plant- or animal-based).

• End of life - incineration for energy recovery preferable,recycling is possible but dependant on stream qualityand quantities.

Products include - cellulose fibre, sheep wool, cotton, flaxand compressed straw.

• Produced by treating plant or animal products, or wastenewspaper, to form fibres, batts or boards.

• Fire retardents and pesticides are added to the rawmaterial.

• End of life - energy recovery or landfill, althoughproducts treated with boron may require disposal tospecified landfill sites. Incineration/energy recoverymay prove difficult due to the addition of fire retardants.

Summary of key productionsteps and issues associatedwith each class of material - 1

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Cellular mineral

Cellular plant derived

Radiant barriers

Manufacturing process

Products include - foamed glass, ‘aerated’ concrete,vermiculite and expanded clay pellets.

• Foamed material is produced by aerating (using airand/or foaming gas) granulated raw product in afurnace, or aerating a concrete slurry.

• Waste glass can be used in foamed glass production.

• Pre-1990 vermiculite (sourced from a particular mine)has been associated with asbestos contamination.

• End of life - glass and concrete products aretheoretically recyclable, especially for aggregate.

Products include - cork.

• Produced by cooking cork granules at high temperatureand pressure to form boards. Rubber/cork compositesare also made with additives and binders.

• Renewable source with virtually no pollutionassociated.

• Large-scale availability not guaranteed and relativelyexpensive.

• End of life - incineration energy recovery or landfill.

Products manufactured from multiple layers of (e.g.) foil-faced polyethylene sheet, foil-faced paperboard andbubble pack, or open-cell flexible foam.

• Produced by creating multiple layers of foil (usuallyaluminium) with air-gaps that are reflective to short-wave thermal radiation.

• Susceptible to loss of performance over time throughbuild-up of dust and dirt and corrosion of foil.

• End of life - theoretically foil layers are recyclable,landfilling.

e.g.Glass(waste)

raw material

Cellular mineral products (e.g. foamed glass)

Crushed, milled, heatedGranulatedglass

Aerated

(air/foaming gase.g. H S)

Gravel, crushedpieces, blocks

2

raw material

Cellular plant derived (cork)

Cork boardsBark(evergreenoak)

granulationCorkgranules

High temperature and pressure

(granules bond with own resin)

components

Radiant barriers

Foilsheets(e.g. Al)

e.g.Paperboard

Multiple layers

combining air gaps

Radiant barriersheets

Summary of key productionsteps and issues associatedwith each class of material - 2


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References

1The World Environment 1972-1992 - Two Decades of Challenge.Tolba, El-Kholy, Holdgate, McMichael (eds), Kluwer AcademicPublishers for United Nations Environment Programme, 1992

2Intergovernmental Panel on Climate Change, Third AssessmentReport: Climate Change 2001. July 2001 www.ipcc.ch

3Based on Assessment of Potential for the Saving of Carbon DioxideEmissions in European Building Stock. Report to EuroACE by CalebManagement Services, May 1998Report is available on www.euroace.org, referred to as CALEB 1.

4Factor Four: Doubling Wealth, Halving Resource Use, by vonWeizsäcker, Lovins, and Lovins, 1997. ISBN 1853834068

5European Social Statistics: Income, poverty and social exclusion.Eurostat, ISBN 92-828-9034-1

6Best available technologies in housing, Case Study UK. A study aspart of MURE II project, an EU SAVE project (Mesures d’UtilisationRationelle de l’Energie) www.mure2.com

7These are based on UK figures, but the EU figures are very similar.

UK Data:Domestic Energy Fact File 1998; BRECSU, LD Shorrock and G AWalters

Energy Use in Offices, ref EGC 019. Published by Energy EfficiencyBest Practice Programme, UK Government. www.energy-efficiency.gov.uk

EU Data: available from DG TREN, or for exmaple in the presentationImproving the Energy Efficiency of Buildings, downloadable from theEuroAce website. www.EuroAce.org

8English House Condition Survey 1991- Energy Report - UKDepartment of the Environment, 1996; and [Ref: 3]

9David Olivier, Energy Efficiency and Renewables: Recent Experienceon Mainland Europe, 1992 • ISBN 0-9518791-0-3

10Authors note: There are a wide variety of embodied energy figuresquoted in different studies. The Buchanan and Honey study (seebelow) quotes figures ranging from 64 – 154 MW.h depending on

construction materials (an average of 109 MW.h). TheNewton/Westaway report quotes figures indicating an embodiedenergy of 21 MW.h/house on average. A BRE study of 1991 quotesfigures of 28-70 MW.h for UK houses (an average of 49 MW.h). Wehave assumed what we consider a ‘safe’ (i.e. high) average of theseand other figures for embodied energy for new-build of 80 MW.h perhouse, with a complete energy refurbishment at 15% of this, 12 MW.hper house.

Importantly the overall trends in the model on pages 40-41 remain thesame within a wide range of values for newbuild embodied energy –the figure has to increase fourfold before any change is reached inthe hierarchy of best overall energy saving.

Buchanan, A.H. and B.G. Honey. 1994. Energy and CarbonDioxide Implications of Building Construction, Energy and Building 20:205-217.

Embodied energy in residential property development - A Guide forRegistered Social Landlords by John Newton and Nigel Westaway.Published by Sustainable Homes, a UK sitewww.sustainablehomes.co.uk

11The INDEX model developed by Simos Yannas and colleagues at theArchitectural Association School of Architecture, London. Calculationsheets are contained in Solar Energy and Housing Design, SimosYannas, 1994, published by Architectural Association publications, 2volumes, ISBN 1 870890 45 0

12The Ecology of Building Materials by Bjorn Berge, Architectural Press,ISBN 0 7506 3394 8

13After a study by Albrecht. Cell-gas composition - an important factor inthe evaluation of long-term thermal conductivity in closed-cell foamedplastics, Cellular Polymers, Vol 19, no 5, 2000

14Building Physics in a Roof with two trapezoidal sheets, H Weiland,Weiland Engineeing AG

15Montreal Protocol on substances that deplete the ozone layer. 1998report of the flexible and rigid foams technical options. UNEP,December 1998

16Thermal insulation and its role in carbon dioxide reduction, a researchreport by Paul Ashworth of CALEB Management Services, ArranCottage, 6 the Row, Aust, Bristol, BS12 3MAY

17EcoQuantum - www.ecoquantum.nlENVEST - www.bre.co.uk/sustainable/envest.html

Insulation for Sustainability - a Guide 82

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83

Bibliography and Selected Resources

Sustainability and BuildingsNatural Capitalism: Creating the Next IndustrialRevolution, by Lovins, Lovins and Hawken. 1999. ISBN0316353000 www.natcap.org, www.rmi.org

Factor Four: Doubling Wealth, Halving Resource Use, byvon Weizsäcker, Lovins, and Lovins. 1997. ISBN1853834068

Solar Energy and Housing Design, Simos Yannas, 1994,published by Architectural Association publications, 2volumes, ISBN 1870890 450

Environmental Design – an Introduction for Architects andEngineers, Ed. Randall Thomas. Spon Press, ISBN 0419237607

EcoHouse – A Design Guide. By Roaf, Fuentes andThomas. Architectural Press, ISBN 0750649046

The Green Guide to Specification Third Edition, byAnderson, Shiers, and Sinclair, January 2002. BlackwellPublishing, ISBN 0632059613

OrganisationsForum for the Future, think tank and research group onsustainable development. www.forumforthefuture.org.uk

Association for Environment Conscious Building, UK,publishers of Building for a Future magazine.www.aecb.net

Green Building News - US publication and website.www.buildinggreen.com

EuroACE, European Alliance of Companies for EnergyEfficiency in BuildingsSome useful studies on the importance of building energyand the savings possible through efficiency.www.EuroAce.org

Climate Care, charity offering personal and corporatecarbon offset through renewable energy and forestry.www.co2.org

www.xco2.com

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