Thermal mass: What it is and how it’s used

Thermal Mass Explained

ContentsIntroduction 3

Whatisthermalmass? 4

Thermalmassinsummer–howitworks 5

Thermalmassinwinter–howitworks 6

Designingforyear-rounduseofthermalmasswithpassivesolardesign(PSD) 7

• Southfacingwindows 7

• Thermalmassandinsulation 8

• Internalsurfaces 8

• Internallayout 9

• Nightcooling 9

• Intermittentlyheatedbuildings 9

Measuringandoptimisingthebenefitsofthermalmass

• Whatareadmittancevalues? 10

• Effectiveslabdepthin

commercialbuildings 12

• Whataredecrementfactors

anddecrementdelay? 13

• WhataremassenhancedU-values? 14

PartLoftheBuildingRegulationsandtheCodeforSustainableHomes 14

Summary 14

References 15

2 ThermalMassExplained

Cover images:Front, main picture: St Matthew’s keyworker estate, Brixton. A multi award-winning and highly energy-efficient building that combines high levels of insulation and air tightness with thermal mass and passive design features. Heating and hot water costs are around £98 per year for each flat. Courtesy of Benedict Luxmoore/arcaid.co.uk.

Back cover: Great Bow Yard, Somerset features a sunspace-based passive solar design utilising a high thermal mass solution. Courtesy of Building for Life/Design for Homes. Photography: Richard Mullane.

Admittance

Theadmittanceofamaterialisitsabilitytoexchangeheatwiththe

environmentwhensubjectedtocyclicvariationsintemperature(see

page10).Inpracticalterms,admittancevaluesshowtheextenttowhich

aspecificfloororwallconstructioncanabsorbandreleaseheatinsidea

building,typicallyovera24hourperiod.

Decrementdelay

Thetimelag,measuredinhours,forheattopassthroughamaterial

orconstructionelement(seepage13).Inpracticalterms,itisthedelay

betweenthepeakouterandinnersurfacetemperatureofawallor

rooftypicallyonasummerdayasexternalheatgainspassthroughina

wave-likemotion.

Decrementfactor

Thisistheratiobetweenthecyclictemperaturevariationontheinside

surfaceofawallorroofcomparedtotheoutsidesurface(seepage13).

Inpracticalterms,itbasicallydescribesthestabilityoftheinsidesurface

temperature,typicallyoverthecourseofasummerday.

Diurnaltemperaturevariation

Thedailytemperatureshiftthatoccursfromdaytimetonight-time.

Diurnalheatflow

Theheatthatflowstoandfromabuildingorspaceoverthecourseof24

hours.

MassenhancedU-value

Thisdescribestheability,incertainclimates,forheavyweightconstruction

elements,toachievebetterenergyperformancethansuggestedbytheir

standard(steady-state)U-value.

k-value

k-valueisshortforKappavalue.Itisameasureofthermalcapacityusedin

SAPandSBEM(thecompliancetoolsforPartLoftheBuildingRegulations).

TheunitsarekJ/m2K(seepage10).

Passivesolardesign(PSD)

PSDbasicallyoptimisesabuilding’sform,fabricandorientationto

maximisesolargainfromautumntospring,whilstminimisingitduringthe

warmerpartofthesummer.Atthesametime,daylightingismaximisedat

alltimes.

Thermalmass

Thecapacitytostoreheatwithinamaterial(seepage4).

Glossaryofterms

3ThermalMassExplained

Introduction

Oriel High School, Crawley features an in-situ concrete frame with precast concrete wall panels, insulated and rendered externally. The underside of the floor slabs at both levels, which are exposed concrete cast in situ, provides thermal mass that can be cooled overnight via opening windows to help to moderate internal temperatures when daytime external temperatures are high.

Theenergyusedforspaceheatingaccountsforaround20to50percentof

abuilding’senergyconsumption dependingontype[1],andaroundathird

ofthecarbonemissionsfromallUKbuildings[2].Tolessenthisimpact,

revisionstoPartLoftheBuildingRegulations,alongwiththeintroduction

ofothercodesandstandards,havedonemuchtoreducefabricheatloss

throughrequirementsforgreaterlevelsofinsulationandreducedair

leakage.Theseareveryeffectiveandwellunderstoodmeasures.Something

lesswellknownisthatreducingheatlossfromabuildingalsoenhances

thepassiveperformanceofthermalmass,helpingfurtherreducethe

spaceheatingload.ThisisnowaccountedforintheStandardAssessment

Procedure(SAP)forPartL1oftheBuildingRegulationsandtheFabric

EnergyEfficiencyStandard(FEES)fornewdwellings,bothofwhichtake

someaccountofthermalmassinthecalculationofbuildingperformance.

Withtheadventofawarmingclimate,summertimeperformanceisalso

adriverforthermalmass.Whenitisusedincombinationwithgood

ventilationandshading,ithelpsbuildingsadapttotheeffectsofhotter

weatherbyreducingboththeriskofoverheatingandthecoolingloadinair

conditionedbuildings.

Untilrecently,theuseofthermalmasswasoftendisregardedinfavourof

alargelyservicesbasedsolutiontotheheatingandcoolingofbuildings,

whichisnotsurprisinginanagewhencheapenergywasplentifulandthe

effectsofclimatechangehadyettobefelt.However,thetimehasnow

cometore-evaluatethecontributionitcanmaketotheperformanceof

bothnewandrefurbishedbuildings.Todothis,itisimportanttohavea

basicworkingknowledgeofthermalmassandhowtobestuseit.Thatis

thepurposeofthisguide,whichwehopeyoufinduseful.

Furtherfreedetailedpublicationsonthermalmasscanbedownloadedfrom

TheConcreteCentre-www.concretecentre.com/publications.

BenefitsofdesigningwiththermalmassExploitingthermalmassonayear-roundbasisisnotdifficult,but

doesrequireconsiderationattheoutsetofthedesignprocess

whenrequirementsforthebuildingform,fabricandorientation

arebeingestablished.Providingthisisdonesympathetically,

amorepassiveapproachtodesigncanrealisebenefitswhich

include:

• Enhancedfabricenergyefficiencyandcarbonsavingsoverthe

lifeofthebuilding.

• Improveddaylighting.

• Improvedventilationandairquality.

• Optimaldecrementdelay(timelag)anddecrementfactor

(heatflow)forreducingheatgainsinsummer.

• Goodsummertimecomfortandareducedriskofoverheating.

• Ameasureoffutureproofingagainsttheeffectsofa

warmingclimate.

• Reductionintheneedformoreexpensivelowandzero

carbontechnologiestomeetCO2targets.

• Enhancedpropertyresalevalue.

4 ThermalMassExplained

Whatisthermalmass?Thermalmass,inthemostgeneralsense,describestheabilityofanymaterialtostoreheat.

Building material [3] Specific heat capacity (J/kg.K)

Density (kg/m3) Thermal conductivity (W/m.K)

Effective thermal mass

Timber 1600 500 0.13 Low

Steel 450 7800 50.0 Low

Lightweight aggregate block 1000 1400 0.57 Medium-high

Precast and in-situ concrete 1000 2300 1.75 High

Brick 1000 1750 0.77 High

Sandstone 1000 2300 1.8 High

Foramaterialtoprovideausefullevelofthermalmass,acombinationof

threebasicpropertiesisrequired:

1. Ahighspecificheatcapacity;sotheheatsqueezedintoeverykg

ismaximised.

2. Ahighdensity;theheavierthematerial,themoreheatitcanstore.

3. Moderatethermalconductivity–sotherateheatflowsinandout

ofthematerialisroughlyinstepwiththedailyheatingandcooling

cycleofthebuilding.

Heavyweightconstructionmaterialssuchasbrick,stoneandconcrete

allhavetheseproperties.Theycombineahighstoragecapacitywith

moderatethermalconductivity(acombinationofallthepointsabove).

Thismeansthatheatmovesbetweenthematerial’ssurfaceanditsinterior

ataratethatmatchesthedailyheatingandcoolingcycleofbuildings.

Somematerials,likewood,haveahighheatcapacity,buttheirthermal

conductivityisrelativelylow,limitingtherateatwhichheatisabsorbed

duringthedayandreleasedatnight,althoughthiscanbeusefulinother

ways(seepage13).Steelcanalsostoreheat,butincontrasttowood,it

possessesaveryhighrateofthermalconductivity,whichmeansheatis

absorbedandreleasedtoorapidlytobesynchronisedwithabuilding’s

naturalheatflow.

Onwarmsummerdays,wallsandfloorswiththermalmasswillsteadily

absorbheatattheirsurface,conductingitinwardly,andstoringituntil

exposedtocoolerairoftheevening/night.Atthispoint,heatwillbeginto

migratebacktothesurfaceandisreleased.Inthisway,heatmovesina

wave-likemotionalternatelybeingabsorbedandreleasedinresponseto

thechangeindayandnight-timeconditions.

Theabilitytoabsorbandreleaseheatinthiswayenablesbuildingswith

thermalmasstorespondnaturallytochangingconditions,helpingstabilise

theinternaltemperatureandprovidealargelyself-regulatingenvironment.

Whenusedappropriately,thisstabilisingeffecthelpspreventoverheating

problemsduringthesummerandreducestheneedformechanicalcooling.

Similarly,theabilitytoabsorbheatcanhelpreducefuelusageduringthe

heatingseasonbycapturingandlaterreleasingsolargainsandheatfrom

internalappliances(seepages6-7).Theseasonaluseofthermalmassis

explainedinthenextsection.

Figure 1: Stabilising effect of thermal mass on internal temperature.

Table 1: Thermal properties of common construction materials

Peak temperaturedelayed by up tosix hours

Up to 6-8oC differencebetween peak externaland internal temperature

Internal temperaturewith high thermal mass

Internal temperaturewith low thermal mass

Externaltemperature

30oC

15oC

Day DayNight

5ThermalMassExplained

Duringwarmweather,muchoftheheatgaininheavyweightbuildingsis

absorbedbythethermalmassinthefloorsandwalls,helpingpreventan

excessivetemperatureriseandreducingtheriskofoverheating.Thismakes

naturallyventilatedbuildingsmorecomfortableand,inair-conditioned

buildingswiththermalmass,thepeakcoolingloadcanbereducedand

delayed.Thebuildingfabricallowsasignificantamountofheattobe

absorbedwithonlyasmallincreaseinthesurfacetemperature.Thisisan

importantqualityofheavyweightconstructionastherelativelylowsurface

temperatureresultsinabeneficialradiantcoolingeffectfortheoccupants,

allowingaslightlyhigherairtemperaturetobetoleratedthanwould

otherwisebepossible.

Byallowingcoolnight-airtoventilatethebuilding,heatthathasbuiltup

inthefabricduringthedayisremoved.Thisdailyheatingandcoolingcycle

worksrelativelywellintheUKastheairtemperatureatnightistypically

around10degreeslessthanthepeakdaytimetemperature,soitis

aneffectivemediumfordrawingheatoutofthefabric.Thisdiurnal

temperaturevariationisrarelylessthan5degrees,makingnightcooling

reasonablydependableintheUK[4].Astheclimatewarmsoverthe

21stcenturythediurnalvariationispredictedtostaythesameor

increaseslightly[5],howeverthetemperaturerangeinwhichitoccurs

willprogressivelyshiftupwards.So,towardstheendofthecentury,the

effectivenessofnightcoolingislikelytodiminishslightlyasaverage

temperaturesincrease.Despitethis,thecombinationofthermalmassand

nightcoolingis,andwillcontinuetobe,aneffectivemeansofhelping

buildingsadapttotheeffectsofawarmingclimate[6, 7, 8, 9].

Inwarmerpartsoftheworld,suchasnorthernAustralia,thatexperience

asmalldiurnaltemperatureswing,thermalmassofferslittleornobenefit

andthevernaculararchitectureuseslightweightmaterials.

Thermalmassinsummer-howitworksThebenefitofthermalmassinresidentialbuildingsiswellunderstoodinwarmerpartsofEurope,butisalsobecomingincreasinglyrelevanttootherregionswheretheimpactofclimatechangeisleadingtomorefrequentoccurrencesofoverheating.Itsapplicationincommercialbuildingsisalsogrowingduetoitsabilitytosignificantlyreducecoolingloads.

Figure 2: Thermal mass in summer

Summernight

• Windowsareopenedatnighttoventilatethebuilding

andcoolthefabric.

• Ifanotherhotdayisexpected,thewindowsareclosedagain

inthemorningandthecycleisrepeated.

Summerday

• Duringveryhotweather,windowsarekeptshuttokeep

outthewarmair.

• Overhangsonthesouthelevationkeepoutthehighangle

sunduringthehottestpartoftheday.Alternativeformsof

shadingcanalsobeused.

• Radiantandconvectivecoolingisprovidedbythermalmassin

thefloorandwalls,whichabsorbheatandhelpstabilisethe

internaltemperature.

Maximum solar altitudein summer 40 o - 64 o

South

6 ThermalMassExplained

AbenefitofthermalmassthatisperhapslesswellknownintheUKisits

abilitytohelpreducefuelconsumptionduringtheheatingseasonwhen

usedinpassivesolardesign.Thisapproachtodesignseekstomaximise

thebenefitofsolargaininwinter,usingthethermalmasstoabsorb

gainsfromsouthfacingwindows,alongwithheatproducedbycooking,

lighting,peopleandappliances.Thisisthenslowlyreleasedovernightas

thetemperaturedrops,helpingtokeepthebuildingwarmandreducingthe

needforsupplementaryheating.Byapplyingsimplepassivesolardesign

techniques,fuelsavingsofupto10percentcanbemade[10],increasing

toaround30percentwheremoresophisticatedpassivesolartechniques

areadoptedsuchassunspaces[11].

Thermalmassinwinter-howitworksThecombinationoftougherperformancerequirementsandrisingfuelcosts,meanthatweneedtomakethemostofpassivetechniquestoheatourhomesandplacesofwork.Thisrequiresawholebuildingapproachtodesign,inwhichtheorientation,glazingandthermalmassworktogethertohelpprovidecomfortable,lowenergysolutions.

Winternight

• Atnight,curtainsaredrawnandwindowskeptshutto

minimiseheatloss.

• Heatcontinuestobereleasedbythethermalmassand

supplementaryheatingisadjustedsoonlytheminimal

amountisused.

• Bymorningthethermalmasswillhavegivenupmostof

itsheatandtheoccupantswilltypicallyhavetorelyon

supplementaryheatinguntillaterintheday.

Figure 3: Thermal mass in winter

RecentdriversforthermalmassThereareanumberofrecentdevelopmentsthatareleadingto

renewedinterestinthermalmassandthecontributionthatitcan

maketolowenergydesign.Theseinclude:

• Theincreasingriskofoverheatinginawarmingclimateandthe

needtomitigatethisthroughadaptivedesignmeasures,which

includetheuseofthermalmass.

• RevisionstotheStandardAssessmentProcedure(SAP)forPart

L1oftheBuildingRegulationsandtheintroductionoftheFabric

EnergyEfficiencyStandard(FEES),bothofwhichtakethermalmass

intoaccount.

• Ongoingimprovementsinglazingandwindowtechnology,which

makespassivesolardesignmoreeffective(lowerheatlossand

improvedsolargain).

• IncreasingenergypricesandchallengingCO2targets,which

haverefocusedgovernmenteffortstoimproveenergyefficiency

inbuildings.

• Developmentofazerocarbonstrategyfornewbuildhomes

(from2016),whichisbasedona‘fabricfirst’approachtodesign.

Winterday

• Duringtheheatingseason,thelowanglesuncanshine

throughsouthfacingwindows,andtheheatisabsorbed

bythermalmassinthefloorandwalls.

• Intheeveningwhenthesungoesdownandthetemperature

drops,theheatflowisreversedandpassesbackintotheroom.

Maximum solar altitudeduring the heating season 17 o - 40 o

South

7ThermalMassExplained

IntheUKclimate,PSDismostlyusedtoreducedomesticheating

requirements,althoughitisincreasinglybeingusedinnon-domestic

buildings,wheretheemphasisisoftenonmaximisingdaylightwithout

undulyincreasingthecoolingload.PSDrequiresawhole-buildingapproach

todesign,inwhichtheenvelope(particularlytheglazing)isdesignedin

unisonwiththestructure’sthermalmasstoensureoptimaladmissionand

absorptionofsolargainsduringtheheatingseason.PSDcanbeappliedwith

varyinglevelsofsophistication,includingtheuseofbothsunspacesand

Trombewalls.Thesesystemsarebeyondthescopeofthisguide,butplentyof

practicalinformationaboutthemcanbefoundonline.Atamorebasiclevel,

thegeneralrequirementsforapplyingPSDinhousingareoutlinedhere.

Figure 5: To maximise solar gain during the heating season, most of a building’s glazing should face south or within 30° of south, with minimal overshadowing from around 9am to 3pm.

Basicrequirements

Thebasicrequirementsforpassivesolardesignare:· Asufficientlyclearviewoftheskyfromthesouth.· Ahighstandardofinsulationandairtightnessthatmeetsor exceedstheFabricEnergyEfficiencyStandard(FEES).· Adequatesouthfacingwindows(orwithin30°ofsouth)tomaximise solargainsduringtheheatingseason.Theoptimalareaofglazingwill bedeterminedbyvariousdesignissuesincludingcost,ventilationrate andlevelofthermalmass,butasaveryroughguideitshouldbeat leasttwicethatofanynorthfacingwindows,butnomorethan around40-50%ofthefacadetoavoidoverheatingproblems.Lowiron glass(clearerthannormalglass)canbeusedtooptimisesolargain.· Minimalnorthfacingwindowstoavoidexcessiveheatloss.Overthe courseoftheyearnorthfacingwindowshaveanetheatlossand shouldbelimitedtoaround15%oftheroom’sfloorarea,whichis sufficienttoprovideadequatedaylighting.· Amediumtohighlevelofthermalmass.TheSAPThermalMass Parameter(TMP)shouldideallybeinexcessof200kJ/m2Kand includeasolidgroundfloorwithafinishthatpartiallyorfullyexposes thefloor’sthermalmass(seepage10forinformationonTMPs).· Anabilitytoadequatelyventilatethebuildingduringthesummer, takingaccountofanysitespecificsecurityand/ornoiseissues.· Adequateshading.Overhangs,balconiesandbrisesoleilsare particularlyeffectiveonsouthfacingwindows,butotherformsof shadingcanbeused.AlthoughnotpopularintheUK,shuttersare highlyeffective,withtheaddedbenefitofofferingameansofsecure ventilationandreducedheatlossinwinter.

Usingthermalmassonayear-roundbasiswithpassivesolardesignPassiveSolarDesign(PSD)basicallyoptimisesabuilding’sform,fabricandorientationtomaximisesolargainfromautumntospring,whilstminimisingitduringthewarmestpartofthesummer.Atthesametime,daylightingismaximisedatalltimes,addingtotheoverallwellbeingandcomfortoftheoccupants.PSDcostsverylittletoimplementandcanmakeausefulcontributiontotheenergyefficiencyofnewbuildand,tosomeextent,refurbishmentprojects.

Tall buildings located to the north of the site

South

30o

Garages, parking, sheds etc. located to the north of dwellings in the shadow zone

Privacy planting or fences located within the shadow zone avoid the need for net curtains without compromising solar access

Non-deciduous trees should have a mature height that remains within the shadow zone

Glazing orientated within approximately 30o of south tomaximise solar access

Figure 4: House spacing to avoid over shadowing [14]

Minimum spacing required between houses of average height:

• Southampton: 20m• Leeds: 25m

• Edinburgh: 30m• Inverness: 35m

30o

N

S

8 ThermalMassExplained

Figure 6: Locating insulation in external walls to maximise thermal mass.

Therearenohardandfastrulesonhowmuchthermalmassisneeded,

butevenamoderateamount,hasbeenshowntoprovideworthwhile

savings[15].Fromanenergyperspective,itwouldbedifficulttohavetoo

much,andgenerallythemorethermalmassthebetter,however,aswith

allaspectsofdesignitisnecessarytoarriveataworkablebalance,taking

otherconsiderationsintoaccount.Asaroughguide,thesurfaceareaof

thefloor/wallsprovidingthemassshouldbeatleastsixtimesthatofthe

glazingintheroom[16],althoughthiswilltosomeextentbeinfluenced

bytheparticularpropertiesofthemassi.e.itsthermalconductivityand

density.So,astheareaofsouthfacingglazingincreases,morethermalmass

isrequiredtomaintainastabletemperatureduringthesummer[17].The

depthofthermalmasswillalsoinfluenceperformance,andthisisdiscussed

laterinthedocument(seepages10-12).

Figure 7: A tiled floor will allow a concrete floor slab’s thermal mass to be fully exploited and is also suited to underfloor heating.

Thermalmassandinsulation

Thermalmassisnotasubstituteforinsulation,andacombinationofthe

twoisneededtooptimisefabricenergyefficency.Thepositionofthe

insulationrelativetothethermalmassisofparticularimportance.The

simpleruleisthatthethermalmassshouldbelocatedinsidetheinsulated

buildingenvelope.Forthisreason,anouterlayerofbrickofferslittlebenefit,

butcanhelpinotherways(seepage13).Inpracticalterms,acavitywall

alreadysatisfiesthebasicrule,astheinsulationislocatedinthecavity,

allowingtheinnerleafofblockworktobeexposedtotheroom.Forsolid

masonrywalls,theinsulationshouldbelocatedontheoutersurface,which

isusualpractice.Theinsulationforsolidgroundfloorsshouldideallybe

locatedundertheslab,althoughscreedplacedontopofinsulationwillalso

providesomeusefulthermalmass.

Internalsurfaces

Typically,thermalmassisprovidedbyconcrete/masonrywallsandfloors,

butotherheavyweightmaterialscanbeequallyeffective.Itisnotessential

forthesuntoshinedirectlyonallinternalsurfacesforheattobeabsorbed,

asconvectionandradiationbetweensurfaceswillhelpdistributewarmth

throughoutthespace.Surfacesdonothavetobeadarkcolour,asany

smallbenefitinheatabsorptionmayimpactondaylighting.However,it

isimportantthatthesurfaceofheavyweightwallsandfloorsremainas

thermallyexposedaspracticable.

Forwalls,thisisbestachievedwithawetplasterfinish,asthiswillconduct

heatrelativelyfreelyandofferstheaddedbenefitofprovidingarobustair

barrierthatwillhelpminimiseairleakage.Dryliningwillreduceheatflow,

butitsimpactwilldependonthethermalmasspotentiallyavailableinthe

wall.Foranaircreteblockinnerleaf(whichhasarelativelylowthermal

conductivity),plasterboardislessofathermalbottle-neckthanforheavier

weightaggregateblockwork,whichhashigherthermalconductivityandis

moresensitivetothechoiceoffinish.Therefore,tofullyexploitthehigh

levelofthermalmassavailableinaggregateblocks,theuseofdryliningis

bestavoided.

Withsomeformsofconcretewallandfloorconstruction,itispossibleto

achieveahighquality,fair-facedfinishwhichrequireslittlemorethana

coatofpaint.Fromathermalmassperspective,thisisparticularlybeneficial

asheatcanpassdirectlybetweentheroomandtheconcrete.Althoughnot

oftenusedinresidentialbuildings,afair-facedfinishismorecommonin

lowenergycommercialofficesorschoolswhereanexposedconcretesoffit

isoftenusedtoprovidethermalmass.

Whereverpracticable,floorsshouldbetiled,andtheuseofcarpetavoided,

asplacingcarpetonaconcretefloorcanreduceitsabilitytoadmitheatby

half[18].Ashinyorglossyfloorfinishwillabsorblessheatthanadullfinish,

however,thismustbeevaluatedalongsidedaylightingrequirementsand

thetendencyofsuchasurfacetoabsorblight.Atiledflooralsoworkswell

withunderfloorheating,whichinturncanbeparticularlyefficientwhen

designedwithahighlevelofthermalmassintheslabandaheatpumpor

condensingboilertoprovideacontinuoussourceoflowgradeheat[11].

Block InsulationBrick

9ThermalMassExplained

Internallayout

Wherepracticable,themostfrequentlyusedroomsshouldbeonthesouth

sideofthedwelling,sothattheyenjoythegreatestbenefittobehadfrom

solargainduringtheheatingseason.Bathrooms,utilityrooms,hallways,

storesetc.shouldbelocatedonthenorthsideofaccommodation[19].The

coolingbenefitsfromthermalmasstendtobeslightlylowerinbedrooms

thanforthegenerallivingspaces.So,insouthernEnglandwheresummer

temperaturesarehighest,theremaybesomebenefitinlocatingbedrooms

onthenorthside.Anotheroptionthatcanhelpistospecifyaconcrete

upperfloor.Providingthemassremainsreasonablyaccessible,thiscan

improveyear-roundthermalperformance.Afurtheroptionistolocate

southfacingbedroomsonthegroundfloor,sotheygetthefullbenefit

ofstackventilationatnight.Thestackeffectusesthedifferenceinair

temperatureathighandlowleveltodrawcoolnightairintogroundfloor

rooms,whereitthentravelsupwardsthroughthebuildingandexitsfrom

windowsontheupperfloor(s),havingabsorbedheatfromthebuilding

fabriconroute.Ahousedesignedtotakeadvantageofstackventilationwill

benefitfrommoreconsistentairflow,particularlyonstillnights.

Nightcooling

Duringthehotsummermonths,thebuildingfabricmustbecooled

duringthenightbyventilationtoremovetheheatthathasbeen

absorbedduringtheday.Withoutadequateventilation,thermalmass

hasthepotentialinsomecircumstancestoincreasediscomfort.Night

ventilationrequirescarefuldesigntoensureadequateairflowcanbe

achieved,andtoaddressanyacoustic,airqualityorsecurityissuesthat

mayarise.MoreinformationonthiscanbefoundinThermal Mass for

HousingwhichisfreetodownloadfromTheConcreteCentrewebsite

www.concretecentre.com/publications.

Intermittentlyheatedbuildings

Olderheavyweightbuildingswithcomparativelylowlevelsofinsulation

andminimalsolargaininwinter,havetraditionallyrequiredalonger

pre-heatperiodthanlightweightbuildings,resultinginslightlyhigherfuel

consumption.However,thegreatlyimprovedstandardofinsulationandair

tightnessinnewconstructionmeansthisisnolongertheproblemitonce

was,asthefabricremainsrelativelywarmwhentheheatingisoff,reducing

theamountofpre-heatneededtogetthebuildingbackuptotemperature.

Itisalsoworthnotingthatthepre-heatissueonlyappliestointermittently

heatedbuildings,andinrealityalowlevelofcontinuousheatingisnowthe

preferableoptioninmanyrecentheavyweightbuildings.However,insome

typesofintermittentlyoccupiedbuildings,forexampleweekendholiday

cottages,thermallylightweightconstructionwillstillbethebestoption

whereheatingisconcernedasitwillenableamorerapidwarmupperiod.

Theenhancedpassiveheatingperformanceofahighlyinsulatedand

airtightheavyweighthomeoutweighsanyadditionalpreheatenergythat

maystillexist.ThiscanbeconfirmedbySAPcalculationsformasonry

homes,whichshowspaceheatingsavingsofaround15-30percentwhen

comparedtoequivalentlightweighthomes.

“The 21st century will see a transition to a new energy source just as has happened in previous centuries. In the 19th century a transition occurred from wood to coal, the turn of the 20th century saw the transition from coal to oil, and the end of the century saw the rapid growth in the use of natural gas in the building sector.

Which energy source will dominate as we move further in to the 21st century remains to be seen, but what is certain is that it must be a renewable source. And the use of solar energy will surely be a major energy source, particularly in the building sector.”

(InternationalEnergyAgency)

10 ThermalMassExplained

Measuringthermalmass

k-valuesandThermalMassParameter

PartLoftheBuildingRegulationsanditsassociatedcompliancetools(SAP&SBEM)accountforthermalmassusingk-values(kJ/m2K),whichrepresentstheheatcapacitypersquaremeteroffloororwall.Theyaremeasuredfromtheinsidesurfacestoppingatwhicheverofthefollowingconditionsoccurfirst:

- halfwaythroughtheconstructionelement- aninsulatinglayer(thermalconductivitylessthan0.08W/mK)- adepthof100mm

Inadditiontothek-valuesshowninFigure8,genericvaluesfordifferentconstructionelementscanbefoundinSAP2009Table1eandalsoinTheConcreteCentrepublication:Thermal Performance: Part L1A.

SAPcalculatesadwelling’soverallthermalmassbymultiplyingthesurfaceareaforeachconstructionelementbyitsk-valueandaddingtheresults.ThetotalisthendividedbythefloorareaofthedwellingtogivetheThermalMassParameter(TMP)measuredinkJ/m2K,where‘m2’referstothedwelling’sfloorarea.

Admittancevalues

Describingamaterialashavinghigh,mediumorlowthermalmassgivesausefulindicationofitsabilitytostoreheat,asdoesitsk-value,butinordertoknowhoweffectiveachosenmaterialwillbeinpractice,thereareacoupleofotherimportantfactorsthatneedtobetakenintoaccount.Thesearefirstlythelengthoftimeavailabletogetheatinandoutofthematerial,whichistypicallyassumedtobe24hours(i.e.heatingduringthedayandcoolingatnight),andsecondly,theresistancetoheatflowatthesurfaceofthematerial,whichcanbesignificant.Thesefactorsarebothaccountedforinadmittancevalues,alongwiththermalcapacity,conductivityanddensity.Admittancevaluesprovideapracticalmeansofassessingtheapproximatein-useheatabsorptionperformanceofwallsandfloorsetc.

Fromatechnicalperspective,admittancecanbedefinedastheabilityofamaterialorconstructionelementtoexchangeheatwithaspacewhenitissubjecttocyclicvariationsintemperature.AdmittanceismeasuredinW/m2K,asU-values.Howeverthe‘K’representssomethingdifferenti.e.thedifferencebetweenthemeaninternaltemperatureandtheactualtemperatureataspecifictimeofday.Itisthisdynamictemperaturedifferencethatdrivesheatinandoutofthefabric.Incontrast,the‘K’inU-valuesisthedifferencebetweeninternalandexternaltemperature,whichisassumedtobeconstant,whichiswhyU-valuesaresteadystate.Anotherdifferenceisthathighadmittancevaluesaredesirablefromathermalmassperspective,whilstlowU-valueswillminimiseheatloss.

LimitationsofadmittancevaluesAdmittancevaluesallowacomparisontobemadeoftheheatabsorptioncharacteristicsofmaterialsinresponsetoasimpleheatingandcoolingcycle.However,cautionmustbetakenifthisapproachisusedtoassessoverallbuildingperformanceasitcanunderestimatetheactualpeakcoolingcapacityofahighthermalmassstructurebyupto50percentincomparisontomoresophisticatedthermalmodellingtechniquesthatuserealweatherdata[20].Amoredetailedexplanationofthisfollows.

Effectoflongerheating/coolingcycles

Inadditiontoabuilding’sdailyheatingandcoolingcycle,thereisoftena

cyclerelatedtoatypicalUKpeakdesignweatherperiod(usuallythreeto

fivedays)andalsothefiveworkingdaysperweekcycle,fromwhichheat

willreachdifferentdepthswithintheavailablethermalmass.Inthecase

offloorsinanon-airconditionedbuildingforexample,thegreatertheslab

depth,thelongerthetimeperioditrespondsto;thecoreofa300mmthick

concreteslabrespondstothemonthlyaverageconditionanddrawsheatin

deeperoveranextendedperiodofhotweather[20].Forlongertimeperiods

thesefactorsareimportantbecauseitisthelonger-termaverageroom

temperaturesthatdefinethethermalstoragecoretemperatureandhence

thetemperaturegradientthatdrawsheatin.Itisforthisreasonthatonly

adetailedthermalanalysiswillshowtheeffectivenessofmediumandhigh

depthfloorslabsandwallsunderrealconditions.However,togetarough

indicationofperformance,thelengthoftheheatingandcoolingcycleused

tocalculateadmittancevaluescanbeincreasedfromtheusual24hoursto

alongerperiod.ThiscanbeseeninFigure8,whichshowsadmittancevalues

forseveraltypesofexternalwallfortimeperiodsrangingfrom24hoursto

120hours.Unsurprisingly,theresultsshowthatadmittancevaluesdecline

astheperiodincreases,howevertherateofdeclineislessformediumand

heavyweightwallsbecausethermalmassatdepthswhichcannotbefully

exploitedina24hourcyclebecomemoreactiveduringthelongercycle.

In addition to the daily heating and cooling cycle, thermal

mass also responds to longer time periods e.g. the typical UK

peak design weather period (usually three to five days), and

the five working days per week cycle. Longer periods such as

these allow thermal mass to be tapped at depths in excess of

the 100mm associated with a 24-hour cycle.

Bespoke k-values and other thermal mass related information

can be can be calculated using a free Thermal Properties

Calculator developed by Arup, which can be downloaded at:

www.concretecentre.com/publications

Upperlimitofadmittancevalues

Innaturallyventilatedbuildings,theresistancetoheatflowatthesurface

ofthefloorsandwallslimitsadmittancevaluestoamaximumofaround

8W/m2K [22]eveninveryheavyweightconstruction.Thisisbecause

althoughconcreteandotherheavyweightmaterialshavemoderate

thermalconductivity,theyareoftenlimitedbytherateofheattransfer

atthesurfacewhichmayactasabottle-neck.Tosomeextent,thiscanbe

overcomeinmechanicallyventilatedbuildings,asdiscussedinthesection

oneffectiveslabdepthincommercialbuildings(seepage12).

11ThermalMassExplained

External wall

(U-value = 0.25 W/m2K)

Internal finish Decrement delay (hours)

Decrement factor

Admittance value 24 hour cycle(W/m2K)

k-value (kJ/m2K)

Admittance values for longer cycles (W/m2K)

48 hours 72 hours 96 hours

Timber frame (Brick outer leaf)

Plasterboard 7.5 0.56 1.00 9 0.69 0.45 0.38

Wet plaster - - - - - - -

Masonry cavity wall (100mm aircrete block)

Plasterboard 10.65 0.26 1.85 52 1.45 1.17 0.96

Wet plaster 10.2 0.33 2.65 65 1.9 1.44 1.14

Masonry cavity wall (100mm lightweight aggregate block)

Plasterboard 11.21 0.16 2.38 114 2.16 1.93 1.7

Wet plaster 10.51 0.25 4.05 141 3.33 2.7 2.23

Masonry cavity wall (100mm dense aggregate block)

Plasterboard 10.67 0.13 2.65 154 2.49 2.29 2.08

Wet plaster 10.00 0.23 5.04 190 4.28 3.54 2.95

Solid masonry (215mm aircrete block)

Plasterboard 12.11 0.12 1.74 52 1.37 1.21 1.09

Wet plaster 11.72 0.15 2.45 65 1.81 1.53 1.35

Solid masonry (215mm lightweight aggregate block)

Plasterboard 11.79 0.08 2.24 114 2.00 1.9 1.82

Wet plaster 11.6 0.11 3.7 141 3.14 2.87 2.65

Concrete sandwich panel (125mm internal concrete – precast or in-situ)

Plasterboard 9.62 0.11 2.68 176 2.59 2.48 2.35

Wet plaster 9.11 0.21 5.3 218 4.85 4.3 3.78

Figure 8: Admittance, decrement and k-values for some common types of wall construction [21]A more comprehensive table of values, which includes floors, can be found in The Concrete Centre publication: Thermal Performance Part L1A.This can be downloaded at: www.concretecentre.com/publications

12 ThermalMassExplained

Effectiveslabdepthinnon-residentialbuildings

Asthebuildingfabricbecomesanincreasinglyimportantaspectoflow

energydesign,floorslabsareshiftingfrombeingpurelyastructuralelement

tosomethingthatcontributestoarangeofotherdesignissuesincluding

aesthetics,daylighting,acousticsandthermalperformance.Structural

requirementswillofcourselargelydetermineslabdepth,althoughthermal

massmay,tosomeextent,alsobeafactor.Foranonair-conditioned

building,thecoreoftheslabwillrespondtodaily,weeklyandmonthly

averageconditions,drawingheatdeepintotheconcreteandmakinguse

ofmost,ifnotalloftheslab(seepage10).Inair-conditionedbuildings,

plantisgenerallyoperatedona24hourheating/coolingcyclewhichinturn

governsthetimeavailableforgettingheatinandoutoftheslab.However,

itisstillpossibletotakeadvantageofalargeproportionofthethermal

massintheslab.Thisisexplainedbelow.

Usingbothsides

Inofficeswithmechanicalventilation,theairsupplyoftencomesfromfloor

outletslinkedtoanunderfloordistributionsystem,wherethevoidcreated

bytheraisedfloorisusedtochannelairaroundthespace.Inadditionto

reducingtheneedforductwork,thisapproachalsoallowsconvectiveheat

transferbetweentheairandthefloorslab.Thishelpscooltheairsupply

duringthedayandremoveheatfromtheslabatnight.Whenusedin

conjunctionwithanexposedsoffit,heatcanpassthroughboththetopand

bottomsurfacesoftheslab,increasingtheoveralldepthofconcreteinwhich

thethermalmasscanbeaccessed.

Enhancingheatflowatthesurface

Beforeheatcanentertheslabitmustfirstpassthroughitssurface,which

actsasthemainbottle-necktoheatflowduetoafilmofair(boundary

layer)thatclingstoitandhasaninsulatingeffect.Theboundarylayer

providesagreaterresistancetoheatflowthantheconcreteitself.However,

inbuildingswithmechanicalunderfloorventilation,thesystemcanbe

designedtoensuresometurbulenceastheairpassesovertheslab,which

greatlyreducessurfaceresistanceandcanenhanceheattransferbyafactor

ofupto5[23, 24].Thisallowsthermalmasstobeexploitedatgreaterslab

depthsthanwouldotherwisebepossible.Turbulentairisalsoafeature

ofsystemsthatusethecoresinhollowcoreprecastconcretefloorslabs

tochannelthesupplyair(e.gTermodeck®),ensuringgoodheattransfer

particularlyatbendswherethechangeofdirectionincreasesturbulence.

Profiledsoffits

Inadditiontoreducingtheweightoflargerspans,profiledslabsoffits(e.g.

coffered,troughed,waveformetc.)provideanincreaseinsurfacearea

whichimprovesconvectiveheattransferwiththeslab,allowinggreateruse

ofthethermalmass.

Figure 9: Combining an exposed soffit with optimised underfloor ventilation can enable thermal mass to be reached at a total slab depth of around 250mm or more.

Heat can be absorbed to a combined depth of around 250+mm.

Turbulent air

Radi

ant

heat

tra

nsfe

r

Conv

ecti

vehe

at t

rans

fer

Conv

ecti

vehe

at t

rans

fer

13ThermalMassExplained

Whatisdecrement?

LikeU-valuesandadmittance,decrementisatermthatrepresentsa

specificcharacteristicofconstructionmaterials,andisrelatedtothermal

mass.Itdescribesthewayinwhichthedensity,heatcapacityandthermal

conductivityofawallforexample,canslowthepassageofheatfromone

sidetotheother(decrementdelay),andalsoattenuatethosegainsasthey

passthroughit(decrementfactor).

Decrementdelay

Designingforalongdecrementdelayofaround10to12hourswillensure

thatduringthesummer,peakheatgainspassingfromtheoutertoinner

surfacewillnotgetthroughuntillateevening/night,whentheriskof

overheatinghasmoderated,andtherelativelycoolnightaircanoffset

theeffectofawarmersurface.Shorterperiodscanstillbehelpfulbut

effectivenessreduceswithdecreasingdelay,andavalueoflessthanaround

sixhoursisoflimitedbenefit.

Mediumandheavyweightwallsinsulatedtocurrentstandardswillslow

thepassageofheatbyaround9to12hours(seeFigure8),whichprovides

anoptimallevelofdecrementdelay.Lighter-weightconstructiontypically

providesashorterperiodrangingfromjustafewhoursuptoaround7or8

hours(usuallyinwallswithamasonryouterleaf).

Decrementfactors

Aswellasdelayingheatflowonsummerdays,thedynamicthermal

characteristicsofawallorroofconstructionwillalsodeterminetheeffect

heatreachingtheinternalsurfacewillhaveonitstemperaturestability.

Thisisrepresentedbythedecrementfactor,whichisbasicallytheratio

betweenthecyclicaltemperatureontheinsidesurfacecomparedtothe

outsidesurface.Forexample,awallwithadecrementfactorof0.5which

experiencesa20degreedailyvariationintemperatureontheoutside

surface,wouldexperiencea10degreevariationontheinsidesurface.

So,alowdecrementfactorwillensuregreaterstabilityoftheinternal

surfacetemperature,andisanothermeansofhelpingreducetheriskof

overheating.Mediumandheavyweightwallsinsulatedtocurrentstandards

havealowdecrementfactorofaround0.3to0.1(seeFigure8).Usingthe

previousexample,adecrementfactorof0.1wouldcausetheinsidesurface

temperaturetovarybyonlytwodegreesovertheday.Forlightweightwalls,

thedecrementfactorwilltypicallybeintheorderof0.5to0.8,withthe

lowerendofthisrangeoftenfoundinwallswithamasonryouterleaf.

Heatgainsthroughwindowsandfrominternalsources

Inwellinsulatedlightweightconstructiontheriskofoverheatingcanbe

moreacute,sincethebalanceofheatflowsismuchfinerandonlyasmall

excessofheatgainoverlosscancauseoverheating[25].So,thedecrement

factoranddelayareimportant,anditispossibletoenhancethesebyusing

cellulose(wood-based)insulation,whichhasarelativelyhighheatcapacity

anddensitycomparedtomostotherformsofinsulation.However,forall

typesofbuilding,delayingandreducinggainspassingthroughthefabricis

onlypartofthesolution,asinstantaneousheatgainsthroughwindowsand

frominternalsourcesmuststillbemanaged.Inadditiontogoodshading

andventilation,theimpactofthesegainswillbereducedthroughthe

presenceofinternalthermalmasstohelpsoakthemup(seeFigure2and

page5),whichisakeybenefitofmediumandheavyweightconstruction.

Figure 10: On hot days, internally exposed thermal mass helps counter the impact of heat gains from windows and internal sources. At the same time, the overall mass of the wall reduces and slows external heat gains passing through it, helping ensure that any effect they may have on the internal environment does not occur until late evening/night when the risk of overheating has moderated.

Internally exposed thermal mass absorbs heat, reducing the impact of any daytime gains from windows, appliances and people etc.

The combination of insulation and thermal mass (at any point in the wall) minimises the heat passing through and also provides a significant time lag, so the peak internal surface temperature occurs many hours later.

Solar gains result in a peak external surface temperature at around 2.00 - 3.00pm

2pm

12am

14 ThermalMassExplained

WhataremassenhancedU-values?

U-valuesindicatetherateofheatflowthroughaconstructionelement

foragivendifferencebetweeninternalandexternaltemperature,which

isassumedtobeconstant,i.e.steadystate.Generallythiswillgiveagood

indicationoftheinsulatingpropertiesofawall,rooforfloor,butcanbeless

accurateinclimateswheretheoutdoortemperaturemaycycleaboveand

belowtheinternaltemperatureovera24hourperiod.Inthissituation,the

actualheatlossofaheavyweightexternalwallcanbelessthanitsU-value

wouldsuggest.Thereasonforthisisbecausetheheatflowthroughthe

wallisnotconstant(steady-state),norisitonlyinonedirectioni.e.from

insidetooutside.Thedirectionwillinfactchangeeachtimetheexternal

temperaturecyclesaboveorbelowtheinternaltemperature.Inthis

situationtheperformanceofthewallisnolongersimplyaquestionofhow

muchinsulationitcontains,butisalsoinfluencedbyitslevelofthermal

mass;atnight,whenthetemperaturedrops,heatbeginstoflowthrough

thewalltotheoutside.Butthepresenceofthermalmasswillslowthis

process(decrementdelay)and,thefollowingdaywhenthetemperature

outsidebecomesgreaterthanthatinside,thedirectionofheatflowis

reversedallowingsomeoftheheatretainedbythethermalmasstoflow

backintotheroom.

Thismassenhancedeffectisrealandaheavyweightwallcanthermally

outperformalightweightwallwiththesamesteady-stateU-value.

However,theeffectisonlysignificantwhentheoutdoortemperaturecycles

aboveandbelowtheindoortemperatureina24hourperiod[26].

DynamicThermalPropertiesToolWhilstpublishedthermalmassvaluesareavailableforgenericwallsand

floors,thesewon’tnecessarilybevalidforbespokeconstructions.Toaddress

thislimitation,TheConcreteCentrecommissionedAruptoproduceasimple

Excel-basedtooltohelpdesigners.Thethicknessofeachmaterialusedis

specified,alongwithitsthermalconductivity,densityandheatcapacity,all

ofwhichcanbeobtainedifnecessaryfromareferencetableincludedinthe

tool.Havingenteredthedetailsofaconstructionthefollowingresultsare

provided:

- Admittancevalue

- k-value

- Decrementdelay

- Decrementfactor

- SimpleU-value

- Otheradmittancerelatedinformation.

ThemethodologyusedfollowsEuropeanStandardsforcalculating

thermalproprieties,andk-valuesproducedcanbeusedinSAPandSBEM

(thecompliancetoolsforPartLoftheBuildingRegulations).Thetooland

instructionsforitsusecanbedownloadedwithoutchargeat:

www.concretecentre.com/publications

SummaryPerformance requirements for building materials continue to

increase, driven by a need to design for higher levels of energy

efficiency and other factors such as the effects of climate change.

Meeting these challenges requires a whole-building approach

to design in which the materials, structure and systems work in

unison to maximise overall performance. The thermal mass in

concrete and masonry helps to meet this challenge. It can both

improve energy efficiency in summer and winter, whilst also

providing a degree of adaptation to our warming climate.

Realising these benefits is not difficult, but does require a basic

appreciation of how to use thermal mass, and the way it can work

with orientation, solar gain, ventilation and shading to enhance

thermal performance in a passive way.

This simple guide touches on the basic principles of designing

with thermal mass, and explains its dynamic properties, which in

addition to absorbing internal heat gains, also delays and reduces

the effect of external gains as they pass through the building fabric.

The challenging performance targets for new buildings are more

easily and cost effectively met with materials that perform

multiple functions. In this respect, concrete and masonry have a

good deal to offer as they can help meet requirements for acoustic

separation, fire resistance, flood resilience, durability and of course,

enhanced thermal performance.

15ThermalMassExplained

References1. Part L Review 2010: IAG briefing note,November2008

2. INGENIA,Issue31,BuildingResearchEstablishment,June2007

3. CIBSE Guide A, EnvironmentalDesign,2006 (Sourceofdatafordensity,conductivityandspecificheatcapacity)

4. MartinA.,FletcherJ.,Night Cooling Control Strategies, Technical Appraisal TA14/96, BSRIA,1996

5. Understanding and Adapting Buildings for Climate Change, CIBSE SeminaratCaféRoyal,London,6July2004

6. Climate Change and the Indoor Environment: Impacts and Adaptation, TM36, CIBSE,2005

7. Thermal Comfort in a 21st Century Climate, CIBSEBriefingNote10

8. Adapting to Climate Change: a case study companion to the checklist for development, LondonClimateChangePartnership,April2007

9. UK Housing and Climate Change - Heavyweight versus Lightweight Construction, ArupResearch+Development,BillDunsterArchitects, October2004

10. Climate Neutral Development , A Good Practice Guide - Site Layout and Building Design, WokingBoroughCouncil (seewww.woking.gov.uk)

11. Thermal Mass for Housing, TheConcreteCentre,2006 (seewww.concretecentre.com/publications)

12. Planning for Passive Solar Design, CarbonTrust,1998 (seewww.carbontrust.co.uk)

13. Site Layout and Building Design – a Good Practice Guide, WokingBoroughCouncil(seewww.woking.gov.uk)

14. EdwardsB., Rough Guide to Sustainability, RIBA,2005

15. HackerJ.etal,Embodied and Operational Carbon dioxide Emissions from Housing: A Case Study on the Effects of Thermal Mass and Climate Change, EnergyandBuildings40,2008

16. Passive Solar Design, TEK 6-5A, NationalConcreteandMasonry Association,USA,2006

17. NGS Green Spec – Low Carbon House – Thermal Mass (seewww.greenspec.co.uk)

18. NelsonG.,The Architecture of Building Services, 1995

19. Passive Solar Design Guidance,StrathclydeUniversity (seewww.esru.strath.ac.uk)

20. Mixed Mode Ventilation, Applications Manual AM13, CharteredInstituteofBuildingServicesEngineers(CIBSE),2000

21. ValuescalculatedusingmethodologysetoutinENISO13786:2000.

22. BRECSU,Avoiding or Minimising the Use of Air-Conditioning, Report31,HMSO,1995

23. Modelling the Performance of Thermal Mass, Information Paper IP6/01,BuildingResearchEstablishment,2001

24. Barnard.N.,Thermal Mass and Night Ventilation - Utilising “Hidden” Thermal Mass,CIBSE/ASHRAEConference,2003

25. OrmeM.PlamerJ.,Control of Overheating in Future Housing - Design Guidance for Low Energy Strategies,FaberMaunsell (DTIPartnersinInnovationProgramme),2003

26. Thermal Mass and R-value: Making Sense of a Confusing Issue, EnvironmentalBuildingNews,April1998

UtilisationofThermalMassinNon-ResidentialBuildingsThis guide provides detailed guidance on the use of thermal mass as a sustainable method of cooling which avoids or reduces the need for air conditioning. This publica-tion will assist designers wishing to exploit thermal mass and includes chapters on con-crete floor options, integration of services, acoustic considerations and surface finish options. The guide also includes a number of case studies.

n Publication date: 2007

n Ref: CCIP-020

n Price: £45

ThermalPerformance:PartL1AThis guide focuses on concrete and masonry housing, and presents a range of fabric and services solutions for meeting current and anticipated requirements for Part L1A of the Building Regulations.The second half of the document contains information on a range of general Part L/SAP design issues, with a particular emphasis on the use of concrete and masonry.

n Publication date: 2010

n Ref: TCC/05/22

n Free – PDF download available

ThermalMassforHousingThisguideprovidesinformationonthesimple,passivedesigntechniquesthatcanbeappliedinmasonryandconcretedwellingstotakeadvantageoftheirinherentthermalmassonayear-roundbasis.Readingthisdocument,itwillquicklybecomeapparentthatthedesignofatypicalhouseneedsverylittlealterationtoreapthisbenefit,andthattherearenegligiblecapitalcostimplications.

n Publication date: 2006

n Ref: TCC/04/05

n Free – PDF download available

Thermal Mass for Housing

CONCRETE SOLUTIONS FOR THE CHANGING CLIMATE

Thermal Mass

A CONCRETE SOLUTION FOR THE CHANGING CLIMATE

ThermalMassOurclimateisalreadychangingandwillcontinuetochangesignificantlywithinthelifetimeofbuildingsdesignedtoday.Thispublicationprovidesageneralguidetounderstandingthermalmassandfabricenergystorage(FES).ItoutlinestheapplicationofFEStechniquesusingcastin-situandprecastconcretefloorslabsinnon-domesticbuildingsandgivesreadersfullreferencestofacilitatefurtherreading.

n Publication date: 2005

n Ref: TCC/05/05

n Free – PDF download available

Listed below are other publications on this topic, available from The Concrete Centre. For more information visit www.concretecentre.com/publications.

All advice or information from MPA -The Concrete Centre is intended only for use in the UK by those who will evaluate the significance and limitations of its contents and take responsibility for its use and application. No liability (including that for negligence) for any loss resulting from such advice or information is accepted by Mineral Products Association or its subcontractors, suppliers or advisors. Readers should note that the publications from MPA - The Concrete Centre are subject to revision from time to time and should therefore ensure that they are in possession of the latest version.

Printed onto 9Lives silk comprising 55% recycled fibre with 45% ECF virgin fibre. Certified by the Forest Stewardship Council.

The Concrete Centre,

Riverside House,

4 Meadows Business Park,

Station Approach, Blackwater,

Camberley, Surrey GU17 9AB

Ref. TCC/05/11

ISBN 978-1-904818-71-7

First published 2009, reprinted

with amendments, January 2012

© MPA - The Concrete Centre 2012

Written by Tom de Saulles,

BEng CEng MCIBSE MIMechE

The Concrete Centre is part of the Mineral

Products Association, the trade association for the

aggregates, asphalt, cement, concrete, lime, mortar

and silica sand industries.

www.mineralproducts.org

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