Activity-rates-a

JournalofThermalBiology26(2001)415–418ActivityratesandthermalcomfortofofficeoccupantsinSydneyDavidMalcolmRowe*DepartmentofArchitecturalandDesignScience,WilkinsonBuilding(G04),TheUniversityofSydney,NSW2006,AustraliaAbstractDesignsforairconditioningsystemsarebasedonsteady-stateequilibriumtheoriesofheatexchangean,however,gitudinalfieldstudyofthermalcomfortinanofficebuildinginSydney,weightingswereappliedtoself-reporageratewasnearlyconstantat1.2met,rrandomindividualvariabilitymaybeacauseofsomeofthefrequentcomplaintsaboutthermalcomfortinoffids:Thermalcomfort;Metabolicrate;Airconditioning;Fieldstudies;uctionHumanthermalcomfortdependsonabalancebetweentherateofproductionofmellestablishedthatthebalancedependsonfourphysicalvariables(airtemperature,meanradianttemperature,airvelocityandhumidity)andthreepersonalvariables(insulationprovidedbyclothing,rateofproductionofmetabolicheatandmechanicalworkperformedbythesubject).Mechanicalworkperformedbysedentaryoffioffiofairconditioningsystemsforthemisbasedontheassumptionofsteadystateequilibriumconditionsincludingclothinginsula-tionandmetabolicrateasrecommendedbytherecognisedstandardsISODocument7730ISO(1994)andASHRAEStandard55ASHRAE(1992).Designersaimtoprovidecomfortforthelargestpossiblepropor-tionofoccupantsbymaintenanceofuniformsteadystateconditionsasnearlyaspossiblethroughoutthe*.:+61-2-9351-2490;fax:+61-2-9351-3031.E-mailaddress:***************.().sicalvariablescanbecontrolledbydesignproactivityratetheyrelyonsteadystateaveragesforvarioustypesofactivitythathavebeenidentifiandASHRAEstan-dardsbothsuggestanaveragesteadystatevalueof1.2metforthemetabolicratefortypicaloffiethebesteffortsofsystemdesigners,sanalysisofunsolicitedcomplaintsfrom23,500occupantsin690buildings,Federspiel(1998)foundthat‘‘thermalsensa-tioncomplaints(hotandcold)arethesinglemostcommonkindofunsolicitedcomplaintinbuildingsandtheoverwhelmingmajorityofunsolicitedenvironmentalcomplaints(77%)’’OverthelastdecadeorsoanumberofhighqualityfieldexperimentshavebeenconductedtostudythermalcomfortinoffiesincludeinvestigationsreportedbySchilleretal.(1988)anddeDearetal.(1993).Laboratorygradeinstrumentshavebeenusedtotakeaccuratemeasurementsofthephysicalvariableswhileparticipantspreparedreportsoftheircurrentthermalsensations,togetherwithdetailsofcurrentitemsofforinsulation0306-4565/01/$-:S0306-4565(01)00053-5

/JournalofThermalBiology26(2001)415–418providedbyclothingandactivityrateshavebeenestimatedfromtheinformationprovidedinthesensa-tionreportswithreferencetotablesofratesforindividualgarmenofthesesttyraetal.(1994)haveanalysedanumberofthesestudiesandhaveconcludedthatagoodaveragevalueforthemetabolicrateoftypicaloffiperreportssomeresultsfromalongitudinalfieldstudyconductedoveraperiodoftwoyearsinatypicalofficebuildinginaninnersuburbofSydney,thestudy1627thermaltyrateswereestimatedbyasimilarmethodtothoseusedinthefieldstudiesreferredtoabovewithadhocweightingfactorsdevisedbytoundthatwhiletheaverageforthewholestudyperiodwasingoodagreementwiththestandards,therewasadiscrepancybetweentheactualmeancomfortvoteandthepredictedmeanvote(PMV)screpancysuggeststhattheestimatedactivityratecouldbeabout10%erablediurnalandbetween-subjectvariationwasobservedwhichcouldaccoalsandmethodsParticipantsinthestudywereselectedbyinvitationfromoccupantsoftwotypicalfldyextendedfromJuly1996toweresuspendedforfittoavailability,eachparticipantwasvisitedtwiceoneachvisitday(morningandafternoon)inanattempttocapturetransienteffsoftheircurrentactivitieswerecollectedfromparticipantsonseparatortprottieswerereportedbycheckingboxesundertheheadings‘‘sittingquietly’’(55WmÀ2);‘‘sittingtyping’’(65WmÀ2);‘‘standingstill’’(70WmÀ2);‘‘onyourfeetworking’’(80WmÀ2);‘‘drivingacar’’(90WmÀ2)and‘‘walkingaround’’(100WmÀ2).Ratingswereconvertedtometvaluesattherateof58WmÀ2=eswerelabelled‘‘lasttenminutes’’,‘‘10minutespreceding’’,‘‘tenbeforethat’’and‘‘thehalfanhourbeforethat’’.Thismethodofestimatingactivityrateswasadoptedsothatresultscouldbecomparedwiththoseofothersworkinginthefisreasonabletoexpectthatmorerecentactivitieswouldbemoreinfluentialthanearlieronesonthecurrentratebut,asfarasitisknown,bsenceofsuchinformationadhocfactorswereappliedas50%oftheratingforactivityduringthelasttenminutes,25%forthenext,15%forthelasttenminutesand10%ultingratingsforerealsocheckedtoindicateintakeoffood,hotorcoldbeveragesandsmokingcigarettesandfurtherweightingwasappliedasplus10%forasnackormealandplus5%nformationcollectedoneachvisitincludedcurrentthermalsensationontheASHRAEsevenpointscalefromÀ3(cold)to+3(hot);thermalpreference(wantwarmer,wantnochange,wantcooler)dentsalsotickedboxestoindicategarmentswornthesensationreportwasbeingcompletedateachworkstation,mentsweremountedonatrolleyat1100mmabovethefloorwithasecondairtemperaturepointat100mmabovetheflcludedashieldedplatinumresistanceelementforairtemperature;anomnidirectionaltem-peraturecompensatedconstanttemperatureanem-ometerforairvelocity;achilledmirrordew-pointsensorforrelativehumidity;and1801opposedianttemperaturewascalculatedfromthesixorthogonalreadingsofradianttemperatureandoperativetemperaturetrumentsmetASHRAEandISOspecififorPMVforthewholegroupandsubgroupswerecalculatedfromaveragesoftemperature,meanradianttemperature,airvelocity,relativehumidity,sAtotalof1627activityreportswithconcurrentreportsofclothingwornandmeasurementsofphngedfrom20tomorethan60with50%alf

/JournalofThermalBiology26(2001)415–418417wereprofessionalorsub-professionalscientistsengagedintypicalofficeworksuchasreading,writing,thestudyoperativetemperatureswereobservedintheivityrateforeachparticipantwascalculatedbythemethodoutlinedaboveandroundedtothefiangedfrom1.0metto1.9metwithdistributionasshowninTable1below.532morning/afternoonpairsofreportswerecollectedand78%ofrespondentsreportedadifferentactivityoractivitiesresultinginrateestimatesbeingdiff13percentthediffalchangeinclothinginsulationvaluewasnotedfor38%thmicregressionwasappliedtotestforrelationshipbetweenactivityrateandoutdoorandindoorthermalconditionsandaweakrelationshipwasfoundwithindooroperativetemperature(R2¼0:3).thecourseisrevealsthatmostofthemcouldreportthermalacceptabilitywithinapersonalrangeof4–occasions,however,theyreporteimitationsprecludeafullpresentationoftheresultsbutsomeotherfisionThemethodofestimatingactivityratesbyanalysingtherangeofactivitiesperformedbyeachsubjectandhis/herintakeoffoodorbeveragesoverthepasthourwasadoptedtocorrespondwiththemethodusedbyotherTable1Distributionofestimatedactivityrateobservationsinanofficebuilding,1met=58WmÀ2Activityrate(met)Numberofsubjects%atesthedifferenceissignificantatthe95%confidencelevelWholesampleOperativetemperature(1C)23.6(1.3)0.14(0.07)42(10)Female23.4(1.3)0.13(0.08)S42(10)1.25(0.22)S0.69(0.17)0.17(1.06)À0.1324.2(1.6)0.72(0.21)S0.096(1.045)+0.0824.4(1.7)SMale23.6(1.3)0.14(0.08)S43(10)1.20(0.21)S0.68(0.14)S0.199(1.05)À0.1424.1(1.5)SMorning23.8(1.4)S0.14(0.08)42(10)1.21(0.21)0.69(0.17)0.27(1.06)SÀ0.0724.4(1.5)SAfternoon23.4(1.2)S0.14(0.07)42(10)1.21(0.22)0.69(0.16)0.09(1.06)SÀ0.1824.1(1.5)SAirvelocity(m/s)Relativehumidity(%)Estimatedactivityrate(met)Clothinginsulation(clo)ActualthermalsensationvotePMVStandardeffectivetemperatureSET*(1C)

/JournalofThermalBiology26(2001)415–418recentthermalcementofheartratemighthaveprovidedausefulcheckonthemethodbutwasconsideredtoointrusiimatedaverageactivityrateof1.2metisingoodagreementwiththeresultsofanumberofstudiesreviewedbyBrageretal.(1994)-ever,whenusedwithaveragevaluesofothervariablestocalculatePMVadiscrepancywasfoundbetweentheactualmeancomfortvoteof+0.17andthePMVofÀggestsanerrorintheestimationoftheactivityrate,auseoftheerrorwaslimitedtotheactivityrateestimateitwouldamounttoanunderestimationofabout10%deroferrorisconsideredacceptablehiblygreatersignificanceisiverelationshipbetweenindoortemperatureandactivityratesuggeststhatsomeofthesubjectsmeysandNicol(1998)haveproposedthatalterationofactivityrateisoneamonganumberofbehaviouraladaptivknessoftherelationshipsuggests,however,thatmanyofn-subjectanddiurnalvariationsintheinsulativevalueoationofthePMVrelationshipassetoutinISODocument7730showsthatadifferenceof0.1metcanbeexpectedtoproduceathermalsensationdifferenceequivalenttothatbroughtaboutbyadifferenceintemperatureof11C,suffifferenceof0.4metwillproduceasensationdifferenceequivalenttoa2.5–31Ctemperaturedifference,suffiampleinafairlytypicalsituationwhereairandmeanradianttemperaturesareequalat241C,airvelocityis0.14m/s,relativehumidityis43%andclothinginsulationis0.7cloapersonwithanactivityrateof1.2metactivityrateof1.6,leofvarisisofthecauseofsuchcomplaintwouldbedifficultifnotimpossibggeststhatwhenphysicalmeasurementsfailtoidentifythecauseofcomplaint,tiveactioninatypicalopenplannedofficeenvironmentmaybedifficultbutatleastarationalexplanation,withassurancethatthecomfortsensationwillimprovewithareturntomoreusualpatternsofactivity,ledgementsThisworkwassupportedbyfundsfromtheAus-tralianDepartmentofEducation,Employment,Train-ingandYouthAffhorisgratefultoparticipantswhncesAmericanSocietyofHeatingRefrigerationandAircondition-ingEngineers,,,G.S.,Fountain,M.,Benton,C.C.,Arens,E.A.,Bauman,F.S.,risonofmethodsforassessingthermalsensationandacceptabilityinthefi:Oseland,N.A.,HumphreysM.A.(Eds.),ThermalComfort:,London,pp.17–,R.J.,Fountain,M.E.,Popovic,S.,Watkins,S.,Brager,G.S.,Arens,E.A.,Benton,C.C.,1993.AfieldstudyofoccupantcomfortandoffirieParkResearchLtd.,piel,C.C.,ticalanalyll.14(1),143–eys,M.A.,Nicol,F.,ll.14(1),1–,ationalStandard7730:moderatethermalenvironmentsFdeterminationofthePMVandPPDIndicesandspecifiationalStandardsOrganisation,er,G.E.,Arens,E.A.,Benton,C.C.,Bauman,F.S.,Fountain,M.E.,Doherty,T.J.A.,1988.AfieldstudyofthermalenvironmentsandcomfortinoffiTrans.94(2).