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ArchitectureinaClimateofChange（H）Page52-Page62LowenergytechniquesforhousingItwouldappearthat,fortheindustrialisedcountries,thebestchanceofrescuelieswiththebuiltenvironmentbecausebuildingsinuseorinthecourseoferectionarethebiggestsingleindirectsourceofcarbonemissionsgeneratedbyburningfossilfuels,accountingforover50percentoftotalemissions.IfyouaddthetransportcostsgeneratedbybuildingstheUKgovernmentestimateis75percent.Itisthebuiltenvironmentwhichisthesectorthatcanmosteasilyaccommodatefairlyrapidchangewithoutpain.Infact,upgradingbuildings,especiallythelowerendofthehousingstock,createsaclusterofinterlockingvirtuouscircles.ConstructionsystemsHavingconsideredthechallengepresentedbyglobalwarmingandtheopportunitiestogeneratefossil-freeenergy,itisnowtimetoconsiderhowthedemandsideoftheenergyequationcanrespondtothatchallenge.Thebuiltenvironmentisthegreatestsectoralconsumerofenergyand,withinthatsector,housingisinpolepositionaccountingfor28percentofallUKcarbondioxide(CO2)emissions.IntheUKhousinghastraditionallybeenofmasonryandsincetheearly1920sthishaslargelybeenofcavityconstruction.Thepurposewastoensurethatasaturatedexternalleafwouldhavenophysicalcontactwiththeinnerleafapartfromwalltiesandthatwaterwouldbedischargedthroughweepholesatthedamp-proofcourselevel.Sincetheintroductionofthermalregulations,initiallydeemednecessarytoconserveenergyratherthantheplanet,ithasbeencommonpracticetointroduceinsulationintothecavity.Foralongtimeitwasmandatorytopreserveaspacewithinthecavityandalongrearguardbattlewasfoughtbythetraditionaliststopreservethis,sacredspace?.DefeatwasfinallyconcededwhensomeextensiveresearchbytheBuildingResearchEstablishmentfoundthattherewasnogreaterriskofdamppenetrationwithfilledcavitiesandinfactdampthroughcondensationwasreduced.SolidmasonrywallswithexternalinsulationarecommonpracticeincontinentalEuropeandarebeginningtomakeanappearanceintheUK.InCornwallthePenwithHousingAssociationhasbuiltapartmentsofthisconstructionontheseafront,perhapsthemostchallengingofsituations.Theadvantagesofmasonryconstructionare:●Itisatriedandtestedtechnologyfamiliartohousebuildingcompaniesofallsizes.●Itisdurableandgenerallyriskfreeasregardscatastrophicfailure–thoughnotentirely.AfewyearsagotheentireouterleafofauniversitybuildinginPlymouthcollapsedduetothefactthatthewalltieshadcorroded.●Exposedbrickworkisalowmaintenancesystem;maintenancedemandsriseconsiderablyifitreceivesarenderedfinish.●Fromtheenergyefficiencypointofview,masonryhomeshavearelativelyhighthermalmasswhichisconsiderablyimprovediftherearehighdensitymasonryinternalwallsandconcretefloors.FramedconstructionVolumehousebuildersareincreasinglyresortingtotimber-framedconstructionwithabrickouterskin,makingthemappearidenticaltofullmasonryconstruction.Theattractionisthespeedoferectionespeciallywhenelementsarefabricatedoffsite.However,thereisanunfortunatehistorybehindthissystemduetoshortcomingsinqualitycontrol.Thiscanapplytotimberwhichhasnotbeenadequatelycuredorseasoned.Framedbuildingsneedtohaveavapourbarriertowallsaswellasroofs.Withtimberframingitisdifficulttoavoidpiercingthebarrier.Therecanalsobeproblemsachievinginternalfixings.Forthepurist,theultimatecriticismisthatitisillogicaltohaveaframedbuildingcladinmasonrywhenitcriesoutforapanel,boarded,slateortilehungexternalfinish.Pressedsteelframesforhomesarenowbeingvigorouslypromotedbythesteelindustry....