SOME OUTSTANDING TITLE 24 ISSUES FOR文档格式.docx
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⏹HIGH-RISERESIDENTIALSHGCREQUIREMENTS&
HEATINGENERGY:
The2001StandardsadoptedrelativelylowSHGCsforHigh-RiseResidentialbuildings,evenincoastalclimatezones.AmorerigorousanalysisshouldbeperformedtoseewhethertheselowSHGCsactuallyproducebuildingswithlowerenergyusethanbuildingswithmoremoderateSHGCs,thatwouldreceivemorebeneficialsolarheatgaininwinter(thusloweringheatingenergyuse).
⏹SHGCREQUIREMENTSANDPERFORMANCECOMPLIANCE:
The2001StandardsreducedtheallowedSHGCrequirementsforallbuildingtypes.WhentheprescriptivestandardhasalowSHGCrequirement,asitnowdoes,performancecomplianceneedtoberigorouslytestedtodeterminewhetherthelowSHGCrequirementiscausingthestandardstobeweakenedwhencomplyingundertheperformancemethod.ThiscouldoccurbecausetheStandardBudgetwillassumeabuildingwithlowsolarheatgaininwinter.AproposedbuildingwithhigherSHGCwillhavelowerenergyconsumptioninwinter.
⏹VARYRESIDENTIALSHGCREQUIREMENTS?
:
ConsideradoptingahigherSHGCrequirementformulti-unitresidentialbuildingsthatuseacentralheatingsystemandhavenocoolingsystem.Becauseitisdifficulttoaddmechanicalcoolingtosuchabuildingtypewhenithascentralheating,itisverylikelythathigherSHGCglasswillsavemuchmoreheatingenergythanitwillcauseanincreaseincoolingenergy.
⏹LOW-RISERESIDENTIALFENESTRATIONTHERMALEFFICIENCY:
ReevaluatethefenestrationU-Valuerequirement.NonmetalframesandLowEglasspriceshavegonedownsincethepreviouseconomicevaluationofresidentialfenestrationefficiencyrequirements.
⏹LOW-RISERESIDENTIAL“STANDARD”WATERHEATER:
Considerallowingtanklessgas-firedwaterheaterswithelectronicignitiontomeettherequirementsofa“standard”system.Ifthesesystemsareasenergy-efficientasthemanufacturer’sclaim,Title24shouldnotcreateanimpedimenttotheiruse.Unlessitimposesanenergypenalty,allowanynumberoftanklesssystems(withelectronicignitions)perresidencetomeetthedefinitionof“standard”system(unlessthesystemhasrecirculation).
IntheRFQfortheaconsultantforthe2003/2005Standards,theCECcorrectlypointsoutthathigh-efficiencystoragewaterheaters(40and50gallons)costaboutthesameaslow-efficiencywaterheaters,andthereforeacttoweakentheresidentialstandards.TheRFQsuggestsapossibleremedyofrequiringwaterheatingenergyrequirementstobemetindependentlyofthespaceheatingandcoolingenergybudget.Whilethisremedyisdefinitelyworthconsideration,itwouldnotproduceanincentivetousetanklessgaswaterheaters.CouldtheACMrulesdivorcethewaterheaterenergyfromthespaceconditioningenergywhenastorage-typewaterheaterisused,butcontinuethecurrentpracticeofcombiningallenergywhenatanklesswaterheaterisused?
Orperhapsanothertypeofincentivecouldbeadoptedtoencourageuseoftanklesswaterheaters.
⏹NONRESWATERHEATING:
Regulatenonresidentialservicehotwatersystems.Perhapsanygas-firedsystemshouldbeacceptable.However,ifanelectricsystemisproposed,performancecompliancewouldberequired.TheStandardwaterheaterenergywouldbebasedonagas-firedsystemofthesamecapacity.
⏹HEATRECOVERY(ResandNonres):
Requireventilationairheatrecovery(e.g.air-to-airheatexchanger)inbuildingsorspaceswithhighOSAdesign(e.g.above25%ofHVACsystemcfm),andcertainamountofoperatinghours(e.g.min.of40/week).SomeresidentialbuildingsdohavehighOSArequirements,likeconvalescenthomes.
INITIATIVESTOREDUCEPEAKCOOLINGLOADS:
⏹NONRESWESTGLAZING:
Limitwestfacingglassareato40%ofthewestGrossWallArea(prescriptiveapproach).Currently,thestandardsonlylimitoverallglassareas.Theperformancebudgetwouldbebasedonthesamerequirement.
⏹RESIDENTIALWESTGLAZING:
PrescriptivePackagecompliancedoesnotregulatewestglassarea.Consideralimit(perhaps30or35%oftotalfenestrationarea?
).NotethatunderPerformancecompliance,thereismodestregulationbyorientationinthattheallowedbudgetisbasedonequalareasoffenestrationinallfourcardinaldirections.
⏹RES&
NONRESACEFFICIENCY:
Increaseminimumefficienciesforairconditioningequipment.
NONRESACSIZING:
Mandatemaximumairconditioningsizing,basedonprescribedloadsanalysis,forbothResidentialPrescriptiveandPerformancecompliance,andforNonresidentialPerformancecomplianceapproach(asiscurrentlyrequiredundertheNonresidentialPrescriptiveapproach).
NONRESEVAPORATIVECOOLING:
Developacompliancecredittoencouragetheuseofevaporativecoolersinsteadofconventionalairconditioners.
NONRES:
ToreducetheincidenceofACsystemoversizing,requirethatthecoolingloadcalculationaccountforstructuralshadingofthefenestration(e.g.overhangs,fixedawnings).
INITIATIVESTOREDUCEBOTHHEATING&
COOLINGLOADS:
⏹RESFENESTRATIONAREA:
Developmethodforreducingtheprescriptivefenestrationareaallowanceforlargerbuildings(single-familyaswellasmulti-family).Underthecurrentfenestrationallowanceapproach,basedsolelyonfloorarea,verysmallbuildingsarepenalized,andlargerbuildingsgetanunduecredit(i.e.theredesignfenestrationareaisusuallylowerthantheprescriptivefenestrationareaallowance).
Onepossibleremedyistorestructurethebasicpackageglazingareaallowancetoreflectacombinationoffloorareaandperimeter.APPENDIXAexplainsaproposalforasingleformulatodetermineallowedfenestrationareaforalllow-riseresidentialbuildingtypes.Thisformularesultsinsimilarglazingallowancesforaveragesizehomesasthecurrentformula,reducestheallowedfenestrationareaofverylargehomes,andbringstheglazingallowanceofmulti-unitbuildingsinlinewithactualdesignpractice,withouthavingtojustifyvariousformulasfordifferentsizesortypesofresidentialbuildings.
⏹RESMULTI-FAMILYPRESCRIPTIVEGLASSAREA:
Shouldarestructuringofthefenestrationallowanceforallresidentialbuildings,assuggestedabove,notbefoundacceptable,considerreducingthefenestrationallowanceforlargermulti-familyresidentialbuildings.Ihavefoundthatlargermulti-familybuildingsoftenhaveglassareasofaround10to13percentoftheC.F.A.ThecurrentStandardsgivemulti-familybuildingsanunwarranted“credit”underperformancecompliance.
Encourageheatandcoolrecoveryfromexhaustairtotemperventilationair(air-to-airheatexchanger).
MISCELLANEOUSNONRESIDENTIALSTANDARDSEFFICIENCYISSUES:
⏹NONRESIDENTIALPERFORMANCEREFERENCEHVACSYSTEM:
TheselectionofthereferenceHVACsystem(usedtodeterminetheStandardBudget)shouldbebasedontheconditionedfloorarea,buildingvolume,oracombinationofoneofthesefactorsandthenumberofstories,insteadofbasingitsolelyonthenumberofstories.Therearemanyverylargethreestorybuildings,whereaVAVreferencesystemwouldbeappropriate;
conversely,somefourstorybuildingsmaybeverysmall,dependingontheirfootprint.OneexampleofaverylargethreestorybuildingistheMosconeCenterAddition.Itisathreestorybuilding,withveryhighfloor-to-ceilingdistances.Theperformancecompliancereferencesystemwasasingle-zoneconstantvolumetype,butthebuildingappropriately(forit'
svolume)usesabuilt-upVAVsystem.TheTitle24StandardBudgetallowedalightingLPDthatismoderatelyhigherthantheprescriptiveLPD.
⏹NONRESIDENTIALSKYLIGHTS:
Revisitcurbmodelingissue.Tosimplifyskylightmodeling,perhapscurbsshouldnotbeincludedineithertheskylightorroofmodeling.Instead,curbscouldeitherhaveamandatoryminimuminsulationrequirement,ortheNonresidentialManualcouldsimplyemphasizethatallcurbsmustbemodeled(theENV-2formcouldhaveacheckboxforcurbs,asareminderthattheyneedtobemodeled–ormeetamandatoryminimuminsulationlevel)
⏹EXTENDNONRESIDENTIALLIGHTINGREQUIREMENTStoFOLLOWINGOCCUPANCIES:
♦RegisteredHistoricbuildings.
♦IOccupancybuildings(excludingsurgeryrooms).
♦Buildingsmaintainedoutsidethehumancomfortrange.
♦Unconditionedbuildings.
⏹EXTENDNONRESIDENTIALENVELOPEREQUIREMENTStoFOLLOWINGOCCUPANCIES:
♦IOccupancybuildings.
⏹NONRESIDENTIALLIGHTING
♦ELIMINATE“RETAIL”OCCUPANCYTYPE:
Eliminate“Retail”fromthelistofbuildingTypeofUsesandPrimaryFunctionAreas.Theuseoftheword“retail”intheStandardscausesmuchcomplianceconfusion,asitisusedtojustifyretaillightingallowancesfornon-retailtenantsinso-called“retailbuildings”.Inplaceof“retail”,defineboth“ShoppingCenterBuilding”and“MerchandiseSales”.ShoppingCenterBuildingwouldbedefinedasabuildingthatcouldbeoccupiedbyoffice-typeoperations,aswellasbytenantsprovidingservices(suchasrealtyandpackaging)andtenantssellingmerchandise.UnleasedspaceinShoppingCenterBuildingswouldreceivethesamelightingpowerallotmentasofficespace.SpaceleasedforthepurposeofMerchandiseSaleswouldgetanappropriatelygreaterallotment.Typically,requiringunleasedspacetocomplyatanofficeleveloflightingisnotahardship,forthefollowingreasons:
A)Manydevelopersof“plainvanilla”retailspaceonlyinstalloffice-typelightinganyway;
B)Retailtenantsthatmoveinto“plain