建筑类外文翻译+译文Word文档格式.docx

建筑类外文翻译+译文Word文档格式.docx

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Constructionsystems

Havingconsideredthechallengepresentedbyglobalwarmingandtheopportunitiestogeneratefossil-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.

Framedconstruction

Volumehousebuildersareincreasinglyresortingtotimber-framedconstructionwithabrickouterskin,makingthemappearidenticaltofullmasonryconstruction.Theattractionisthespeedoferectionespeciallywhenelementsarefabricatedoffsite.However,thereisanunfortunatehistorybehindthissystemduetoshortcomingsinqualitycontrol.Thiscanapplytotimberwhichhasnotbeenadequatelycuredorseasoned.Framedbuildingsneedtohaveavapourbarriertowallsaswellasroofs.Withtimberframingitisdifficulttoavoidpiercingthebarrier.Therecanalsobeproblemsachievinginternalfixings.Forthepurist,theultimatecriticismisthatitisillogicaltohaveaframedbuildingcladinmasonrywhenitcriesoutforapanel,boarded,slateortilehungexternalfinish.

Pressedsteelframesforhomesarenowbeingvigorouslypromotedbythesteelindustry.Thesellingpointisagainspeedoferectionbutwiththeaddedbenefitofaguaranteedqualityintermsofstrengthanddurabilityofthematerial.

Fromtheenergypointofview,framedbuildingscanaccommodatehighlevelsofinsulationbuthaverelativelypoorthermalmassunlessthisisprovidedbyfloorsandinternalwalls.

Innovativetechniques

PermanentInsulationFormworkSystems（PIFS）arebeginningtomakeanappearanceinBritain.TheprinciplebehindPIFSistheuseofprecisionmouldedinterlockinghollowblocksmadefromaninsulationmaterial,usuallyexpandedpolystyrene.Theycanberapidlyassembledonsiteandthenfilledwithpumpgradeconcrete.Whentheconcretehassettheresultisahighlyinsulatedwallreadyfortheinstallationofservicesandinternalandexteriorfinishes.TheycanachieveaU-valueaslowas0.11W/m2K.Abovethreestoreystheadditionofsteelreinforcementisnecessary.

Theadvantagesofthissystemare:

●Designflexibility;

almostanyplanshapeispossible.

●Easeandspeedoferection;

skillrequirementsaremodestwhichiswhyithasprovedpopularwiththeself-buildsector.Experiencederectorscanachieve5m2permanhourforerectionandplacementofconcrete.

●Thefinishedproducthashighstructuralstrengthtogetherwithconsiderablethermalmassandhighinsulationvalue.

Solardesign

Passivesolardesign

Sincethesundriveseveryaspectoftheclimateitislogicaltodescribethetechniquesadoptedinbuildingstotakeadvantageofthisfactas‘solardesign’.Themostbasicresponseisreferredtoas‘passivesolardesign’.Inthiscasebuildingsaredesignedtotakefulladvantageofsolargainwithoutanyintermediateoperations.

Accesstosolarradiationisdeterminedbyanumberofconditions:

●thesun’spositionrelativetotheprincipalfacadesofthebuilding（solaraltitudeandazimuth）;

●siteorientationandslope;

●existingobstructionsonthesite;

●potentialforovershadowingfromobstructionsoutsidethesiteboundary.

Oneofthemethodsbywhichsolaraccesscanbeevaluatedistheuseofsomeformofsunchart.Mostoftenusedisthestereographicsunchartinwhichaseriesofradiatinglinesandconcentriccirclesallowthepositionofnearbyobstructionstoinsolation,suchasotherbuildings,tobeplotted.Onthesamechartaseriesofsunpathtrajectoriesarealsodrawn（usuallyonearcforthe21stdayofeachmonth）;

alsomarkedarethetimesoftheday.Theintersectionoftheobstructions’outlinesandthesolartrajectoriesindicatetimesoftransitionbetweensunlightandshade.Normallyadifferentchartisconstructedforuseatdifferentlatitudes（atabouttwodegreeintervals）.

Sunlightandshadepatternscastbytheproposedbuildingitselfshouldalsobeconsidered.Graphicalandcomputerpredictiontechniquesmaybeemployedaswellastechniquessuchasthetestingofphysicalmodelswithaheliodon.

ComputermodellingofshadowscastbythesunfromanypositionisofferedbyIntegratedEnvironmentalSolutions（IES）withits‘Suncast’program.Thisisauser-friendlyprogramwhichshouldbewellwithinnormalundergraduatecompetence.

Thespacingbetweenbuildingsisimportantifovershadingistobeavoidedduringwintermonthswhenthebenefitofsolarheatgainreachesitspeak.Onslopingsitesthereisacriticalrelationshipbetweentheangleofslopeandthelevelofovershading.Forexample,ifovershadingistobeavoidedatalatitudeof50N,rowsofhousesona10north-facingslopemustbemorethantwiceasfarapartthanon

10south-facingslope.

Treescanobviouslyobstructsunlight.However,iftheyaredeciduous,theyperformthedualfunctionofpermittingsolarpenetrationduringthewinterwhilstprovidingadegreeofshadinginthesummer.

Againspacingbetweentreesandbuildingsiscritical.

Passivesolardesigncanbedividedintothreebroadcategories:

●directgain;

●indirectgain;

●attachedsunspaceorconservatory.

Eachofthethreecategoriesreliesinadifferentwayonthe‘greenhouseeffect’asameansofabsorbingandretainingheat.Thegreenhouseeffectinbuildingsisthatprocesswhichismimickedbyglobalenvironmentalwarming.Inbuildings,theincidentsolarradiationistransmittedbyfacadeglazingtotheinteriorwhereitisabsorbedbytheinternalsurfacescausingwarming.However,re-emissionofheatbackthroughtheglazingisblockedbythefactthattheradiationisofamuchlonger

wavelengththantheincomingradiation.Thisisbecausethere-emissionisfromsurfacesatamuchlowertemperatureandtheglazingreflectsbacksuchradiationtotheinterior.

Directgain

Directgainisthedesigntechniqueinwhichoneattemptstoconcentratethemajorityofthebuilding’sglazingonthesun-facingfacade.Solarradiationisadmitteddirectlyintothespaceconcerned.Twoexamples30yearsapartaretheauthor’shouseinSheffield,designedin1967andtheHockertonProjectof1998byRobertandBrendaVale.Themaindesigncharacteristicsare:

●Aperturesthroughwhichsunlightisadmittedshouldbeonthesolarsideofthebuilding,withinabout30ofsouthforthenorthernhemisphere.

●Windowsfacingwestmayposeasummeroverheatingrisk.

●Windowsshouldbeatleastdoubleglazedwithlowemissivityglass（LowE）asnowrequiredbytheUKBuildingRegulations.

●Themainoccupiedlivingspacesshouldbelocatedonthesolarsideofthebuilding.

●Thefloorshouldbeofahighthermalmasstoabsorbtheheatandprovidethermalinertia,whichreducestemperaturefluctuationsinsidethebuilding.

●Asregardsthebenefitsofthermalmass,forthenormaldailycycleofheatabsorptionandemission,itisonlyaboutthefirst100mmofthicknesswhichisinvolvedinthestorageprocess.Thicknessgreaterthanthisprovidesmarginalimprovementsinperformancebutcanbeusefulinsomelonger-termstorageoptions.

●Inthecaseofsolidfloors,insulationshouldbebeneaththe