Slides - Week 6 - Lecture 2- Building Performance

BuildingPerformanceLearningOutcomes•KnowledgeofUKregulationsonbuildingperformance•Understandwhysomegreatdesignsdonotperforminpractice•Understandwhatpostoccupancyevaluationmeansforfuturebuildingdesign.TowardsZeroCarbonZeroCarbonHomeExactdefinitionisconstantlybeingupdated.Butcurrently.....Onlyaccountsforregulatedenergyuse:DoesnotaccountforenergyusefromplugsocketsTowardsZeroCarbon1.INSULATIONandAIRTIGHTNESS2.ENERGYEFFICIENTAPPLIANCESPassivedesignfeatures3.LoworZeroCarbontechnologies(onsite)4.Communityenergyschemes5.OffsettingEnergyuse,splitintoheatingandelectricityComparisontopreviousyearsEnergyEfficiencyDisplayEnergyCertificateTypicalforthisbuildingtypeBuildingPerformanceBuildingsadvertisedasbeing“Green”basedondesignpredictionsVeryrarelyaretheseclarifiedpostcompletion.Inrealitytheperformanceisnotaspredicted.AwardwinningbuildingsimpressjudgesnotoccupantsGrowingnumberofinitiativestoimprovethis.Whydon’tbuildingsmatchpredictions•Designbasedonincorrectassumptionsabouthowpeoplewillbehaveinthebuildings•Poorconstruction(notairtight)•Newtechnologiesrequiretimeandexpertisetoensuretheyworkoptimally,oftenthisisnotprovided.•Complicatedsystemsrequirecalibrationandoptimisation,oftenthisisnotdone.Sometimestheyaren’teventurnedon•EachbuildingisaprototypeHeatPumps•Workonarefrigerationcycle(justlikeyourfridge)•Useasmallamountofelectricitytoincreasethelevelofheat•Mostappropriatewhenyouneedalowtemperatureofheating–e.g.Withunderfloorheating.Notradiators!EnergySavingTrust:Heatpumpsfieldtrials:argumentsforheatpumpsusuallystatesystemefficiencyof3.Whyaren’ttheyworkingcorrectly-Poorinstallationand/ormaintenance-inappropriateforthesetting(usedtoprovidewaterat80˚Cinsteadof40or50˚C)HotAirRisesPrevailingwindscausesuctionattopFreshairentersandcrossesoccupiedspacePassivedesignmethods“Stack”ventilationSometimescalled“buoyancydriven”flowHeatingExposedconcretesoffitstostabilisetemperatureGlasssouthfacade–passivelyheatsspaceRadiatorsonupperfloorsUnderfloorheatingonlowerfloorsExposedconcretesoffitstostabilisetemperatureCoolingHot–wasteaircollectsincirculationspaceandventedtothetopAutomaticwindowsopenwideatnighttopromotenightcooling–coolstheconcreteslabsforthemorningInsummerrequireLOWairflowsduringday+nightcooling.OtherwisehotoutsideairwillheatupthespacePerformanceSummer2006:219hoursabove25C3yearaveragegasconsumption~40%greaterthanpredictedConstantunexplainedbackgroundelectricityuseof~6kwHighestelectricityuseongroundfloorGroundfloordoesnotbenefitfromSolarGain.ToomuchairentersatthelowerlevelsVentilationCommonproblemsTheairneedstoescape,andmayreversetheflowacrossthetopfloortodoso.Thetopflooroccupantsgetallthewasteairfrombelow.TheBuildingManagementSystemcontrollingthewindowsneedtobecarefullycalibratedtopreventthis•Lights(notproperlycalibrated)•Radiatorsshouldnothavebeencoveredbutinbuiltfurniturebuiltaroundthem•Notproperlypressuretested(thereforeveryleaky)•Still~6kWconstantlybeingusedbutwedon’tknowwhere.•Differentfloorsresponddifferentlytopassivesolargain–thelowerfloorsdonotbenefitasmuch.•Groundfloorgetsverycold–thereforeelectricheatersoftenusedEnergyUseIttakestimetocalibrateabuildingsoitperformsoptimally.Engineersneedtobeinvolvedforatleastayeartohelpadjustthesystem.VulcanHouseBREAMMExcellentBuilding(BREAMMisanoptionalsystemforachievingcreditsshowingyouareasustainablebuildings)Ref:CIBSEjournal–January2010Cubebuildingtoreduceheatlosses.HighlevelsofinsulationWorkstationsonnorthandeastsides(lesssolargainandthereforelessair–conrequired)VulcanHouseVeryefficientchiller(usesammonia)SolarshadingEngineeronsiteensuringdetailswerebuiltcorrectly.VulcanHouseRef:CIBSEjournal–January2010DesignTargetMeasured2008-2009PreviousBuildings(2007-2008)Electricity102124173150Gas8869197100Units:kWh/m2/yearAswithpreviousexamples,thereislessgasandmoreelectricityusedthanpredicted.JessopWest•Airtight(Openablewindows)•Highthermalmass•DoubleskinnedfacadeLightwellHighthermalmassSBSsymptomsincreaseanddrowsinessetcstarts(Seppanen,Fisketal1999)WindowopenedfullHowdoweachieveLowCarbonBuildings•Thetechnologyisgoodbutthereareissuesoncecommissioned.•Makesureyoubuildright.•Buildingsshouldbeairtight.•Don’treplacepartsaspecialisthasrecommendedwithcheaperversionsifyoudon’tunderstandwhytheywerechosen•Employtheengineerpostcompletiontoensurecalibrationandoptimisationofthebuildingsystems•Ensurecontrolsarestraightforwardtouse•Don’tovercomplicatesystems–ortheywon’tbeusedcorrectly