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EinB2017 – 6th InternationalConference“ENERGYinBUILDINGS2017”
HVACSystemsforHyper-EfficientBuildings(a.k.a Passive)basedon
ASHRAEJournalMay2019
AlkisTriantafyllopoulosEmail:[email protected]
MechanicalEngineerASHRAEHellenicChapterV.President 2018-2019
Introduction
• Originatedbackinthe70sfromsuper-insulatedhousemovementinUSandCanada
• Usedmostlyatfirstforsinglefamilyattacheddwellingshasnowmovedtohighriseresidentialbuildingsandsmallcommercialbuildings
• MostknowisPHI(Germany)andPHIUS(US)
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EinB2018 – 7th InternationalConference“ENERGYinBUILDINGS2018”
HyperEfficient
• Becausetherequiredcalculatedsourceenergyuseintensity(EUI),isfarbelowthatofconventionalbuildingsandiscomparabletothenetzeroreadybuildingclassification.
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Introduction
• SuperinsulatedBuildings• Airtight(minimizeinfiltration)• TripleGlazing• AirHandlingUnits/MechanicalVentilation• ZeroThermalBridges
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PHI-PHIUS• 1. The SpaceHeatingEnergyDemand isnottoexceed15kWhpersquaremeterof
netlivingspace(treatedfloorarea)peryearor10Wpersquaremeterpeakdemand.
• Inclimateswhereactivecoolingisneeded,the SpaceCoolingEnergyDemand requirementroughlymatchestheheatdemandrequirementsabove,withanadditionalallowancefordehumidification.
• 2. TheRenewable Renewable PrimaryEnergyDemand(PER,accordingtoPHImethod), thetotalenergytobeusedforalldomesticapplications(heating,hotwateranddomesticelectricity)mustnotexceed60kWhpersquaremeteroftreatedfloorareaperyearforPassiveHouseClassic..
• 3. Intermsof Airtightness,amaximumof0.6airchangesperhourat50Pascalspressure(ACH50),asverifiedwithanonsitepressuretest(inbothpressurizedanddepressurizedstates).
• 4. Thermal comfortmustbemetforalllivingareasduringwinteraswellasinsummer,withnotmorethan10%ofthehoursinagivenyearover25°C.Foracompleteoverviewofgeneralqualityrequirements(softcriteria)
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EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”
Data
• Insulation20cmU<0,15W/m2 K• GlazingtripleU<0,9…0,7W/m2K• MechanicalVentilationwith80-90%HeatRecovery
• AirtightnesswithBlowerdoor (50Pa)
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EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”
Requirements- Limitations
• HRV- ERV• MaxFanEnergyAbsorbed• AnnualHeating+Cooling Demand• Airtightness• AnnualEUIofthebuilding(EnergyUseIntensity)
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Complexity
• Therealityofprovidingcomfortconditioning(ASHRAESTD55)inabuildingwithaveryhighperformanceenvelopeandverylowinternalheatgainsintroducesanewlevelofcomplexitytoHVACsystemdesignfortheproject.
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“Malfunctions”
• LOWventilationRates(Typically0.3ACHwhichisfarlowerthanASHRAEstandard62.1and62.2)
• HVACmightseemonlyasasystemtoaccommodateloadreductions
• AsaresultwehavesignificantproblemswithIndoorAirQuality,HUMIDITYandPart-Loadoperation
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EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”
(notso)EnergyEfficientVentilation
• Whenoutdoorairismoderateanyconditioningsavingsmaybeoutweighedfromthefanenergyfromthepressuredropoftheheatexchanger
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EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”
“Balanced”Ventilation
• ExhaustalwaysonforKitchensandBathrooms
• Makeupairifneeded(fireplaces,dryersetc)
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Example
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DesignCharacteristics
• VeryLowHeating/CoolingLoads• VeryLowuserequipmentpowerdensityduetoEUIlimitations
• VeryLowBalancePointTemperature
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EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”
HRV
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EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”
ERV
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EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”
HumidityControl- Cooling• AdvancedInsulation/Glazing/airtightnessetccanonlyreduceSensibleLoads
• InternalLatentloads+VentilationneedtobetakenintoseriousconsiderationwhichmaybeHIGHERthansensible.
• SoSHR(SensibleHeatRatio)willbeverylowSHR=SensibleCoolingLoad/TotalCoolingLoad
• ResultingUnacceptablyHighIndoorHumidity
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EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”
HumidityControl- Cooling• Exampleanapartment92.9m2 (1000ft2)with2bedrooms,2bathsand1kitchenand3occupants
• PHI- 0,3ACH• ASHRAE62.1requires0.65L/sm2plus2,4L/sperpersonforatotal35.3L/sforthewholeapartment
• BUTwealsorequireEXTRACTION11,8L/sforeachbathroomand23.6L/sforeachkitchenwhichsumsupto47.2L/sor0.7ACH
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EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”
HumidityControl- Cooling• ASHRAE62.2requires0.33L/sm2plus3,6L/sperpersonBUTwealsorequireEXTRACTION9,4L/sforeachbathroomand5ACHforeachkitchenwhichsumsupto50.5L/s
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EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”
SpaceconditionsResultingDifferentVentilationprotocols
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EinB2018 – 7th InternationalConference“ENERGYinBUILDINGS2018”
HumidityControl- Heating• ERV’scangoupto80%humidityrecovery.Inthesecaseswerecoverallthemoisture/watercontentfrominsidethebuildingasalatentloadandprovideittothefreshairmakingithumidagain,resultinganunacceptablyhighrelativehumidityinthespace
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EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”
• Totalinternallatentloadforthespaceis0.44kg/hr from3persons,one15-minuteshowerand0.09kg/hr miscellaneouslatentloads.Thespaceismaintainedat21.1°C.TheERVisassumedtohaveanefficiency of80%.TotalventilationairmeetstheASHRAEStandard62.1exhaustrequirements.
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EinB2018 – 7th InternationalConference“ENERGYinBUILDINGS2018”
TheapartmentwithERV
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EinB2018 – 7th InternationalConference“ENERGYinBUILDINGS2018”
BYPASS?
• Apossiblesolutionmaybetodisabletheenergyrecoveryandworkwithfreecooling(assumingyoucanbypassthat)andtheenergypenaltyfordisablingrecoveryislikelytobeminimal,sincethebalancepointtemperatureofthebuildingissolow.
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EinB2018 – 7th InternationalConference“ENERGYinBUILDINGS2018”
TerminalSizingandLocation
• Indoorunitsusuallytoobig(minimumvrfunitsaround7.000btu)forsowlowdemand
• Inmanycircumstances,consolidatingmultipleroomsintoasinglezonemaynotbeadvisable,duetodifferentloadprofilesforthevariousrooms.
• Locatingthethermostatinoneroommayresultindiscomfortinotherrooms
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EinB2017 – 6th InternationalConference“ENERGYinBUILDINGS2017”
TerminalSizingandLocation
• Usinganoversizedterminalmaynotbeanacceptablealternative,ifconsistentcoolingloadsbelowtheminimumpartloadoftheterminalresultincycling,diminishingtheterminal’sabilitytoprovideadequatedehumidification
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EinB2018 – 7th InternationalConference“ENERGYinBUILDINGS2018”
• Lowconditioningairflowperunitareamaycreatedifficultyinachievinguniformdistributionofventilationairandmaintaininguniformconditionsthroughthespace.
• Inahyper-efficientbuilding,distributionsystemdesigncanbecritical
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PROS
• Terminallocation,however,isnotascriticalasinaconventionalbuildingsincepeakperimeterheatingandcoolingloadsarereducedalot.
• Forcommercialbuildings,reductioninintensityoftheperimeterloadsmayallowsimplificationoftheHVACsystemandcontrols,eliminatingtheneedforsimultaneousheatingandcoolingwithinthesamebuilding.
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EinB2018 – 7th InternationalConference“ENERGYinBUILDINGS2018”
Suggestions
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Summer
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MidSeasonHighDuePoint
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EinB2018 – 7th InternationalConference“ENERGYinBUILDINGS2018”
Conclusions
• ConfigureventilationsystemstobecompliantwiththerelevantversionofASHRAEStandard62.1
• FollowASHRAEThermalcomfortStandard55(dehumidifyetc)
• Useacertifiedenergyrecoveryventilator.• Controltheenergyrecoverydevicetomaximizeenergyefficiencyandindoorcomfort
• Designspacezoningtobeconsistentwithavailableterminalsizes
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EinB2018 – 7th InternationalConference“ENERGYinBUILDINGS2018”
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HVACSystemsforHyper-EfficientBuildings(a.k.a Passive)basedon
ASHRAEJournalMay2019
• AlkisTriantafyllopoulos• Email:[email protected]
• MechanicalEngineer• ASHRAEHellenicChapterV.President 2018-2019
EinB2018– 7th InternationalConference“ENERGYinBUILDINGS2018”