Comparative Whole Building Life Cycle Assessment of Energy Saving and Carbon Reduction Performance of Reinforced Concrete and Timber Stadiums—A Case Study in China PDF Free Download
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Sustainability2020,12,1566;doi:10.3390/su12041566www.mdpi.com/journal/sustainability
Article
ComparativeWholeBuildingLifeCycleAssessment
ofEnergySavingandCarbonReductionPerformance
ofReinforcedConcreteandTimberStadiums—
ACaseStudyinChina
YuDong
1,2
,TongyuQin
1,2
,SiyuanZhou
1,2
,LuHuang
1,2
,RuiBo
1,2
,HaiboGuo
1,2,
*
andXunzhiYin
1,2,
*
1
SchoolofArchitecture,HarbinInstituteofTechnology,Harbin150001,China;
dongyu.sa@hit.edu.cn(Y.D.);18S034015@stu.hit.edu.cn(T.Q.);18S034024@stu.hit.edu.cn(S.Z.);
19S134163@stu.hit.edu.cn(L.H.);bromine@hit.edu.cn(R.B.)
2
KeyLaboratoryofColdRegionUrbanandRuralHumanSettlementEnvironmentScience,
MinistryofIndustryandInformationTechnology,Harbin150001,China
*Correspondence:guohb@hit.edu.cn(H.G.);x.yin@hit.edu.cn(X.Y.)
Received:21January2020;Accepted:17February2020;Published:19February2020
Abstract:ManystadiumswillbebuiltinChinainthenextfewdecadesduetoincreasingpublic
interestinphysicalexerciseandtheincentivepoliciesissuedbythegovernmentunderitsNational
FitnessProgram.Thispaperinvestigatestheenergysavingandcarbonreductionperformanceof
timberstadiumsinChinaincomparisonwithstadiumsconstructedusingconventionalbuilding
materials,basedonbothlifecycleenergyassessment(LCEA)andlifecyclecarbonassessment
(LCCA).TheauthorsselectfiverepresentativecitiesinfiveclimatezonesinChinaasthesimulation
environment,simulateenergyuseintheoperationphaseofstadiumsconstructedfromreinforced
concrete(RC)andtimber,andcomparetheRCandtimberstadiumsintermsoftheirlifecycle
energyconsumptionandcarbonemissions.TheLCEAresultsrevealthattheenergysaving
potentialaffordedbytimberstadiumsis11.05%,12.14%,8.15%,4.61%and4.62%lowerthanthose
ofRCbuildingsin“severelycold,”“cold,”“hotsummer,coldwinter,”“hotsummer,warmwinter,”
and“temperate”regions,respectively.TheLCCAresultsdemonstratethatthecarbonemissionsof
timberstadiumsare15.85%,15.86%,18.88%,19.22%and22.47%lowerthanthoseofRCbuildings
fortheregionsabove,respectively.ThisdemonstratesthatinChina,timberstadiumshavebetter
energyconservationandcarbonreductionpotentialthanRCstadiums,basedonlifecycle
assessment.Thus,policymakersareadvisedtoencouragethepromotionoftimberstadiumsin
Chinatoachievethegoalofsustainableenergydevelopmentforpublicbuildings.
Keywords:reinforcedconcrete;timber;energysaving;carbonreduction
1.Introduction
1.1.EnergyConsumptionandCarbonEmissionsofPublicBuildings
Energyisnecessaryforhumandevelopmentandeconomicgrowth[1].Theworld’spopulation
reached7.69billioninmid‐2019andisexpectedtoexceed9.8billionbymid‐2050[2].Thismassive
populationgrowthhashadahugeimpactontheglobalenvironmentandnaturalresourcesoverthe
lasttwocenturies.Fossilfuels(i.e.,coal,gas,andoil)havebeenthemajorenergysourcesforhuman
activitiessincethe1760s.Burningfossilfuelsforenergyreleasesgreenhousegases(GHGs)intothe
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atmosphere[3].Theuseoffossilfuelspollutestheenvironmentandemitslargeamountsofcarbon
dioxide(CO2)[4].Theuseoffossilfuelsisbelievedtobethemainfactorleadingtoglobalwarming
[5,6].Globalwarmingiswidelyconsideredtocauseglacierretreatandregionalclimatechanges,
speciesextinction,andfurtheruncertainrisks[7,8].
Measuringthe“greenhouseeffect”formitigationpurposeshasbecomeamajorinterest
internationallyinthelastfewdecades.Duringthelast50years,globalwarminghasmainlybeen
causedbyexcessiveGHGemissionsduetohumanactivities[9].InternationalEnergyOutlook(2019)
reportedthatthebuildingsector,oneofthemostimportantareasofhumanactivities,accountedfor
20%oftheworld’sdeliveredenergyconsumptionin2018[10].Thisfigurewillrisetoabout22%by
2050[10].TheBrowntoGreenReport(2019)showedthatcarbonemissionsdirectlyfromthebuilding
sectoraccountedfor9%ofG20energy‐relatedCO2emissionsin2019andthat18%oftheseemissions
arosefromelectricityuseinbuildings[11].
Attheendof2016,theenergyconsumptionofbuildingsinChinawas26billionGJ,accounting
for20.6%ofthecountry’stotalenergyconsumption.Intotal,thebuildingindustryemitted1.96
billiontonsofCO2inthisyear,accountingfor19.4%ofdomesticcarbonemissions[12].Atthe2015
UnitedNationsClimateChangeConference[13],theChinesegovernmentsetthegoalofreducing
carbonemissionsperunitofGDPby60%–65%by2030,relativeto2005levels.Therefore,theannual
averagerateofdeclineincarbonintensitybetween2005and2030wasexpectedtorangefrom3.6%
to4.1%[13].Tomitigatethegreenhouseeffect,itisvitaltoreducetheenergyconsumptionofthe
buildingindustry[14].AccordingtotheResearchReportonBuildingEnergyConsumptioninChina
(2018),publicbuildingsinChinaaccountedfor38.5%oftotalenergyconsumption(Figure1a)and
about41%ofcarbonemissionsin2016(Figure1b)[12].Thereportalsorevealedthatthenational
averagecarbonemissionfactorofbuildingsectorinChinawas2.18kgCO2/kgce.Specifically,the
carbonemissionfiguresofpublicbuildingsandtheurbanresidentialbuildingswas2.15kgCO2/kgce
and2.39kgCO2/kgce.Thereportalsohighlightedthatthecarbonemissionintensityofpublic
buildingswas64.61kgCO2/m2.Thefiguresofnationalaverageandurbanresidentialbuildingswere
30.88kgCO2/m2and29.04kgCO2/m2respectively(Figure2).Thecarbonemissionsintensityofpublic
buildingsinChinawasapproximately200%higherthanthatofthenationalaveragein2016[12].
ThesefindingsdemonstratethatpublicbuildingsinChinacontributesignificantlytoGHGemissions
andthusoffergreatenergysavingpotential.
1.2.DevelopmentTendencyandCurrentSituationofGymnasiuminChina
Inthebuildingindustry,publicandcommercial(P&C)buildingscanbedividedintosixtypes,
namelyofficebuildings,commerciallodgingbuildings,mercantilebuildings,educationalbuildings,
healthcarebuildings,andothers[15].The“others”categorycovered30%ofthetotalP&Cfloorarea
in2016,includinggyms,transportationjunctions,andculturalvenues[15].Gymnasiumsarelong
andbroad,astheyarespeciallydesignedtoaccommodatespecialeventsandlargeaudiences.With
continuouseconomicimprovement,peoplearegraduallybeginningtopaymoreattentiontophysical
health,somoresportsvenuesareneeded.Tomeettheincreasingdemandforsportsfields,for
example,aseriesofregulationsandgovernmentdocumentshavebeenreleasedtopromotethe
developmentofsuchvenues.AccordingtotheOutlineofBuildingaStrongSportsCountry,releasedby
theStateCouncilofChinain2019,theaverageareaofsportsfacilitiesisexpectedtobe2.5m2per
capitainChinaby2035[16].However,ithadonlyreachednearly1.46m2percapitaby2016[17].To
realizethegoal,71.2%moresportsvenuesneedtobebuiltinthenext20yearsinChina[17].
Therefore,gymnasiums,asoneofthemostimportanttypesofsportsfacilities,havegreat
developmentpotential.
TheChinesegovernmenthasintroducedregulationstoincreaselocalresidents’accessto
existingsportsfacilities,eitherfreeofchargeoratlowprices[16,18].GymnasiumsinChinagenerally
openonlyinsportscompetitionseasonsascompetitiongymnasiums.Theregulationswillgradually
transformthecurrentoperationmodeintothenewone,underwhichgymnasiumswillopenforthe
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wholeyear,becomingnationalfitnesscenters.Nationalfitnesscentersareexpectedtoopenforat
least40hoursaweekand330daysayear[18].Thenumberofgymnasiumswillcontinuallygrow,
andtheiropeninghourswillgraduallyincrease.However,thesetrendswillalsoexacerbatethe
existingproblemofhighenergyconsumptionbygymnasiums,increasingtheircontributiontoGHG
emissionsinChina.Therefore,reducingtheenergyconsumptionofgymnasiumswillgreatlyhelpto
mitigatethegreenhouseeffect.
Someresearchershavestudiedtheenergyconsumptionofgymnasiumsintheiroperationphase.
Forexample,Trianti‐Stournaetalfoundthattheenergyconsumptionofoperationalsporthallsin
Greeceisapproximately100kWh/m2peryear,andsoughttoachieveanoptimalbalancebetween
indoorconditionsandenergyuse[19].Nishiokaetalevaluatedtheindoorthermalenvironmentand
energyconsumptionofalargedomedstadium.Theresultsshowedthattheannualcoolingloadof
thewholebuildingwasabout69.1Mcal/m2andtheannualheatingloadwasabout13.2Mcal/m2[20].
LiandLiangstudiedthecooperativeinteractionamongstructure,soilloadsandthickness,and
energyefficiencywhenapplyingtheoverallroofgreeningtoalarge“saddle‐shaped”shell[21].They
foundthatusingoverallroofgreeningcansave25.1%ofannualair‐conditioningenergyconsumption
inGuangzhou,China[21].However,researchonreducingtheenergyconsumptionofgymnasiums
byreplacingtraditionalmaterialswithsustainablematerialsislimited.
(a)(b)
Figure1.(a)DataonnationalbuildingenergyconsumptioninChina.(b)Dataonnationalbuilding
carbonemissionsinChina.Datasource:ResearchReportonBuildingEnergyConsumptioninChina(2018)
[12].
Figure2.CarbonemissionsfactorsandcarbonemissionsintensityofbuildingsectorinChina.Data
source:ResearchReportonBuildingEnergyConsumptioninChina(2018)[12].
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1.3.EnergySavingandCarbonEmissionReductionPotentialofTimberBuildings
Treesandtheirby‐productshavebeenusedworldwideforthousandsofyears[22].Duetothe
gradualexhaustionofforestresources,however,woodhasbeenreplacedbymineralmaterials,such
asconcrete.However,concretecanproducealotofcarbondioxideduringtheproductionprocess
andincreasetheburdenofscarceecologicalresources.Recentlydevelopednationalandinternational
policiesandregulationsareexpectedtoaddressthecarbonimpactandresourcescarcityassociated
withconcrete[23].
Thesustainabilityoftimberprovidesamaterialsolutiontotheproblem[23].Withthe
improvementoftimberplantingtechnology,timbercannowberecycledwithoutahugenegative
impactonnaturalresourcesfromtheplantingstagetotheharvestingstage.Besides,engineered
timberproductsgreatlyimprovetheutilisationefficiencyoftimberthroughtheadvancementof
timberindustrialisation.Atleast52%ofthelogsbroughttowoodproductmanufacturingcentersare
processedintolumber[24].Ofallengineeredtimber,themostwidelyusedproductsincludecross
laminatedtimber(CLT),gluedlaminatedtimber(GLT),andplywoodandorientedstrandboard
(OSB)(Figure3).Engineeredtimberproductshaveseveraladvantages.Forexample,CLTprovides
greatadvantagesintermsofthespeedofconstruction,minimalwaste,andwide‐spanconstruction
[25].Furthermore,CLThasnegativeembodiedcarbon[25].Theseadvantagesmaketimberastrong
alternativetoconcrete[26].Hence,timberhasregaineditsmarketsharefromtraditionalheavyweight
materialsoverthelastdecade[27].
Figure3.(a)Crosslaminatedtimber(CLT)panelconstruction[28].(b).Gluedlaminatedtimber(GLT)
panelconstruction.(c)Plywoodpanel.(d)Orientedstrandboard(OSB)panel.
Existingstudieshaveshownthatusingtimberinbuildingsoffersmorenotablepotential
reductionsinenergyuseandcarbonemissionthanusingconcreteandotherheavyweightmaterials.
Researchontheenergysavingofwood‐basedbuildingisdiscussedbelow.Chencomparedthe
energyusedforheating,ventilationandairconditioninginconcreteandCLTofficebuildingsand
(a)(b)
(c)(d)
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pointedoutthattheoperatingenergyofCLTbuildingswas10%lowerthanthatofconcretebuildings
[29].HafnerandSchäferassessedtheGHGreductionpotentialofresidentialbuildingsafterreplacing
mineralmaterialswithtimberinbuildingconstruction.Thesubstitutefactor(GHGreduction
potential)oftimberbuildingsfortheconstructionofsingle/two‐familyhousesrangedbetween0.35
and0.56,whichmeansthatthereisapositiveGHGreductionpotentialwhenusingtimber[30].Tettey
etalrevealedthatCLTbuildingsreducedthetotallifecycleprimaryenergyuseby20%–37%,
comparedwiththeconcretealternative,whenspaceheatingcamefromcombinedheatandpower
[31].Khavarietalsimulateda10‐storeymultiunitresidentialCLTbuildingmodelandfoundthata
timberbuildingmodelsignificantlyimprovedheatingenergyefficiencycomparedwithalight‐frame
metalconstructionmodel[32].TheresultsshowedthatusingCLTcansave2090dollarsinutility
costsannually[32].
Therehasalsobeensomeresearchonthecarbonemissionsandenvironmentalbenefitsoftimber
buildings.Chiniforushetalfoundthatadoptingasteelstructurewithsteel‐timbercompositefloors
andshearwallsystemsresultedina107%reductioninembodiedcarbons,comparedwiththesame
buildingdesignedwithaconcretestructure[33].Pierobonetalevaluatedtheembodiedemissions
andenergyassociatedwithbuildingmaterials,manufacturing,andconstructionformidrise
commercialbuildingswithahybridCLTstructure[34].TheyfoundthathybridCLTbuildingscan
save8%ofnon‐renewableenergy(fossil‐based)comparedwithconcretebuildings[34].Pajchrowski
etalconcludedthattheenvironmentalimpactofaconventionalmasonrybuildingis2.7timesgreater
thanthatofaconventionalwoodenbuilding,andtheenvironmentalimpactofapassivemasonry
buildingis1.6timesgreaterthanthatofapassivewoodenbuilding[35].Dongetalfoundthatthe
heatingenergyofCLTofficebuildingsis11.97%lowerthanthatofRCbuildingsinHarbin[36].
BalasbanehandMarsonoalsofoundthattheGHGemissionsassociatedwithusingtimber
prefabricatedwallsinconstructionwereabout7%lowerthanthoseforblockworksystems[37].
Timberisincreasinglyusedasaconstructionmaterialinbuildingsworldwideduetothe
developmentofengineeredtimber.Currentstudieshaveshownthatreplacingconcreteandother
traditionalheavyweightmaterialswithtimberinbuildingshasagreatenergyconservationand
carbonreductionpotential.Withthepromotionofsportsvenues,gymnasiumswillconsumemore
andmoreenergyandcontributetoGHGemissionsenormouslyinthefuture.However,timberhas
notyetbeenwidelyusedingymnasiumsinChina,andstudiesoftheenergysavingandcarbon
reductionpotentialoftimbergymnasiumsarelimitedandunclear.
1.4.StudyObjective
Basedontheabove,theexistingresearchhasdemonstratedthattimberisakindof
environmental‐friendlybuildingmaterialcapableofreducingbuildingenergy.However,limited
researchhasaddressedtheenergysavingandcarbonreductionpotentialoftimbergymnasiumsin
China.Thispaperevaluatesthecarbonreductionandenergysavingeffectsoftimbergymnasiums
throughlifecycleassessmenttodeterminewhethertimberoffersafeasiblenewbuildingmaterialfor
sportsfacilitiesinChinaintermsofenergysustainability.
2.DescriptionofStudiedBuildingsandItsEnvironment
2.1.ClimateZonesinChina
IntheCodeforDesignofCivilBuildings(GB50352‐2005)[38],fivemajorclimatezonesare
distinguishedtoassessthethermal‐technicaldesignsofbuildingsinChina.Theseregionsare
“severelycold,”“cold,”“hotsummer,coldwinter,”“hotsummer,warmwinter,”and“temperate.”
TheclimateconditionsoftheseregionsvarygreatlyduetoChina’svastterritory.Wherenecessary,
eachofthefiveclimatezonescanbefurtherdividedintoA,B,C,andD,giving20sub‐regions.In
thispaper,fivemajorcities,namelyHarbin,Beijing,Shanghai,Guangzhou,andKunming,are
selectedtorepresenteachclimateregion(Figure4).Buildingsineachregionhavetofollowlocal
constructionregulations,whichdefinestructuralcriteria;theinsulationpropertiesofopaquewalls,
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floors,androofs;andthethermalandopticalperformanceofwindowsandskylights.Thermal
insulationdesignisoneofthemostimportantregulatoryareas,andtheseregulationsshouldbe
enforcedparticularlystrictlyintheseverelycoldandcoldregionsduetotheirfrigidclimate.The
basicinformationonthermaldesigninthesefivecitiesispresentedinTable1[38,39].
Figure4.Locationsofthefivecasestudycities.
2.2.DetailsofSimulationBuildings
Inthispaper,inordertoclarifytheenergysavingandcarbonreductionpotentialoftimber
stadiumsincomparisonwithstadiumsusingconventionalbuildingmaterials,arealstadiumlocated
inHarbinisselectedasareferencebuilding.Thisisatypicalcommunity‐scalestadium,whichcan
accommodate3000peopleatmostinresidentialdistricts.Thestadiumisnormallyavailabletolocal
residentsfrom09:00to17:00,threedaysaweek.Thestadiumcanbedividedintofivefunctionalareas
namelysportshall,office,lounge,bathroomandplantrooms.Thebasicarchitecturaldesign
informationistabulatedinTable2.Figure5presentsthefloorplanandsectionsofthestadium.The
roofoftheoriginalstadiumhasaplate‐likespacetrussandtheexternalwallismadeofreinforced
concrete(RC)andsteel.
Table1.FivecasestudycitiesbyclimateregionsinChina.
ClimateRegionTemperatureSub‐regionRepresentative
City
U‐Value(Local
Regulations)
R‐Value(Local
Regulations)
HottestColdest
SeverelyCold≤25℃≤–10℃Ⅰ（B）Harbin
Roof:≤0.28GroundFloor:
≥1.1
Wall:≤0.38
Window:≤1.3
Cold18℃~28℃–10℃~0℃Ⅱ（B）Beijing
Roof:≤0.45GroundFloor:
≥0.6
Wall:≤0.5
Window:≤1.5
HotSummer,
ColdWinter25℃~30℃0℃~10℃Ⅲ（B）ShanghaiRoof:≤0.5—
Wall:≤0.8
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Window:≤1.8
HotSummer,
WarmWinter25℃~29℃＞10℃Ⅳ（B）Guangzhou
Roof:≤0.8
—
Wall:≤1.5
Window:≤2
Temperate18℃~25℃0℃~13℃Ⅴ（B）Kunming
Roof:≤0.8
—
Wall:≤1.5
Window:≤2
DataSource:CodeforDesignofCivilBuildings(GB50352‐2005),DesignStandardforEnergy
EfficiencyofPublicBuildings(GB50189‐2015).
Table2.Stadiuminformation.
ItemsFiguresItemsFigures
TotalFloorArea(m2)5800.00 PlaneSizeofPerformanceStage(m)18.00×12.00
ExternalWallArea(m2)2401.02 PlaneSizeofGameHall(m)24.00×42.00
ExternalOpeningArea(m2)1347.78 AreaIndex(m2/perseat)1.93
TotalVolume(m³)51420.86 SportsHallArea(m2)2844.13
TotalHeight(m)17.60 OfficeArea(m2）947.26
NumberofLayers3.00 LoungeArea(m2）1181.95
NumberofSeats3000.00 BathroomArea(m2）426.46
PlaneSize(m)50.20×58.20PlantRoomArea(m2)400.20
DataSource:Originalconstructiondrawings.
Theprocessofdesigningthesimulationbuildingsisdividedintotwoparts.Thebuilding
materialsandstructuresaredesignedaccordingtothedifferentclimatezones.Inthefirststage,four
similarbuildingslocatedinotherclimateregionsaredesignedonthebasisoftheoriginalstadiumin
Harbin.Thestadium’sexteriorenvelopeconstructionandbuildingmaterialsarethesameasthose
oftheoriginalstadium,butthethicknessoftheenvelopeisadjustedtoreflecttheactualsituationand
meetthelocalbuildingregulationsineachclimateregion.Duringthesecondstage,fivetimber
stadiumsaredesignedinfiveclimateregions,respectively,onthebasisofthereferenceRCstadiums.
Thebasicdimensionsofthetimberbuildings,suchasfloorheight,buildingorientation,groundarea,
andmajorfunctions,arethesameasforthereferenceconcretebuildings.However,theload‐bearing
structureandexternalenvelopearereplacedbytimber.TherelateddesignparametersfortheRC
andtimberstadiumsinthefivestudiedcitiesarepresentedinTables3and4.
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(a)
(b)
(c)
Figure5.(a)Firstfloorplanofthebuilding.(b)1‐1Sectionofthebuilding.(c)2‐2Sectionofthe
building.
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Table3.Externalwallandroofdesignsofthereinforcedconcrete(RC)stadiumsinthefivecities.
CitiesExternalWallandExternalWindowRoofGroundFloor
Harbin
Beijing
Shanghai
Guangzhou
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Kunming
Table4.Externalwallandroofdesignsofthetimberstadiumsinthefivecities.
CitiesExternalWallandExternalWindowRoofGroundFloor
Harbin
Beijing
Shanghai
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Guangzhou
Kunming
3.MethodandData
3.1.FrameworkoftheStudy
LifeCycleEnergyAssessment(LCEA)andLifeCycleCarbonAssessment(LCCA)
Inrelationtobuildinglifecycleassessment(LCA),abuilding’senergyconsumptionandcarbon
emissionsduringitslifespancanbedividedintothreestages,namelymaterialisation,operationand
endoflife.Inthispaper,bothenergyconsumptionandcarbonemissionsduringthebuilding’slife
cyclearetakenintoaccount.Duringtheconstructionphase,energyconsumptionandcarbon
emissionscanbefurtherdividedintobuildingmaterials,transportationandon‐siteerection.During
theproductionprocess,conventionalmaterialssuchasRC,steel,andcementconsumealargeamount
ofenergyandreleasecarbondioxide.Incontrast,duringthefabricationofwoodmaterials,trees
absorbcarbondioxideandconsumeasmallamountofenergy.Theexistingresearchhas
demonstratedthat1cubicmeterofwoodstoresapproximately140–510kgofC(carbon),which
meansthatitcontainsabout513–1870kgofCO2[40].Itiswellacceptedthatbuildingenergy
consumptionandcarbonemissionsarethedominantcomponentsduringtheoperationphase.Inthe
contextofthebuildinglifespan,twothirdsofthetotalbuildingenergyareconsumedduringthis
stage[41–43].Inthisphase,theenergyconsumptionandcarbonemissionsofaresidentialbuilding
canbefurtherdividedintosixcategories,namelylighting,spaceheating,spacecooling,ventilation,
appliances,andwaterheating.Thisstudyalsoconsidersthecarbonationanddurabilityofcement
andRC.Thecarbonationofreinforcedconcreteandcementisoneofthecausesofcorrosion,butitis
alsoawayofsequesteringCO2.Theendoflifephasecomprisestheenergyconsumedandcarbon
emittedduringbuildingdemolition,transportationandmaterialdisposal.Flowchartsdepictingthe
lifecycleenergyassessment(LCEA)andlifecyclecarbonassessment(LCCA)inthisstudyare
presentedinFigure6andFigure7,respectively.
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3.2.EnergyConsumption
3.2.1.ConstructionPhase
Asmentionedabove,thematerializationstagecomprisesmaterialproduction,transportation
andon‐siteerection.SeveralassumptionsaremadewhencarryingouttheLCEAandLCCAinthe
materializationstage.
(1)Theenergyconsumedandcarbonemittedduringthedecorationofconcretebuildingsare
ignored.
(2)Basedonexistingresearch,theon‐siteerectionenergyconsumptionofRCandCLTbuildings
issetat100MJ/m2and20MJ/m2,respectively[44].
(3)Theboundariesofthematerials,includingconcrete,sand,cement,steel,andbrick,startwith
theextractionofrawmaterials,whereastheboundaryforCLTstartswithtreeharvesting.Thetotal
volumeofconsumptionofbuildingmaterialsforRCandtimberstadiumsisshowninTable5.The
inventoryofdatausedtocalculatetheenergyconsumptionofbuildingmaterialproductionis
presentedinTable6.
Figure6.Flowchartofthelifecycleenergyassessment(LCEA).
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Figure7.Flowchartofthelifecyclecarbonassessment(LCCA).
Table5.MassandvolumeofRCandtimberbuildings.
Materials
RCBuildingsTimberBuildings
Material
Volume(m3)
Material
Mass(Tons)MaterialVolume(m3) MaterialMass(Tons)
Concrete3715.084380.53861.081463.84
Sand584.964787.84420.09672.14
Cement194.99253.48140.03182.04
Steel44.85349.8517.33135.20
EPS(Harbin)752.6418.82752.6418.82
EPS(Beijing)435.8910.90435.8910.90
EPS(Shanghai)328.1968.205328.1968.205
EPS(Guangzhou)96.082.4096.082.40
EPS(Kunming)96.082.4096.082.40
Plasterboard109.9276.94126.5088.55
Timber——3186.431593.21
Table6.Listofmaterialsusedforconstruction.
Material
EnergyConsumptionfor
MaterialProduction
Carbonemissionsduring
MaterialManufactureProcessReferences
UnitValueUnitValue
ConcreteGJ/t0.764 Kg‐CO2/m3352.200[45]
SandGJ/t0.029 ——[44]
CementGJ/t3.186 Kg‐CO2/t860.000[44,46]
SteelGJ/t19.520 ——[47]
EPSInsulationBoardGJ/t94.000 ——[44,48]
PlasterboardGJ/m32.400 Kg‐CO2/t213.862[49]
TimberGJ/m30.545 ——
[44]Transportation(Train)MJ/t∙km0.220——
Transportation(Lorry)MJ/t∙km2.300——
3.2.2.OperationPhase
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Thisstudysimulatesbuildingenergyconsumptionduringtheoperationstageusingthe
commercialsoftwarepackageIntegratedEnvironmentalSolutions–VE(IES‐VE).Thesoftwareis
developedbyIntegratedEnvironmentalSolutionscompany,whichislocatedinGlasgow,UK.Inthe
softwareplatform,RCandtimberstadiumscanbeestablishedassimulationmodels(Figure8).
Energyconsumptionfromlighting,spaceheating,spacecooling,appliances,ventilation,andwater
heatingissimulated.Severalassumptionsaremadeduringthesimulation.
(1)AccordingtothebuildinggradeclassificationinChina,thelifespansofthetwostadiumsare
assumedtobe50years[50].
(2)Theindoortemperatureiscontrolledbetween10℃and26℃.Inthewinter,thetemperature
ofthesportshallissetat18℃whenoccupied.Thetemperatureoftheoffice,loungeandbathroom
areasaresetat20℃.Thecomfortabletemperatureinsummerisexpectedtobenomorethan26℃.
Coolingisimplementedautomaticallywhenthetemperatureexceedsthisrange.Thebasic
parametersofthethermalconditionsareshowninTable7[50].
(3)Bothnaturalandinfiltrateventilationaresimulated.Thebasicparametersofventilationare
showninTable8[50].
(4)Electricityisusedforcooling,waterheating,lighting,appliances,andventilation,whileraw
coalisusedforheating.ThisisthecurrentpracticeinChinaandisdescribedindetaillater.
Figure8.EstablishedmodelintheIntegratedEnvironmentalSolutionssoftwareplatform.
Table7.Basicsimulationparametersofthermalconditions.
RoomOccupiedHeating
TimeHeatingMonthHeating
SetPoint
Cooling
TimeCoolingMonth
Cooling
Set
Point
Sports
hall
Tuesday,
Thursday,
Saturday
everyweek
09:00–17:00
24h
15Octoberto15
April(Harbin)
15Novemberto
15March
(Beijing,
Shanghai)
18℃
(When
occupied)
10℃
When
Occupied
andRoom
Temp＞
26℃
1Juneto31
August(Harbin)
16Marchto14
November
(Beijing,
Shanghai,
Guangzhou)
26℃
Office20℃ 26℃
Lounge20℃26℃
Bathroom20℃26℃
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Noheating
(Guangzhou)
15Decemberto
15February
(Kunming)
16Februaryto14
December
(Kunming)
Plant
Room10℃———
Table8.Basicsimulationparametersofventilation.
RoomInfiltrateVentilationSet
PointandTime
NaturalVentilation
SetPointNaturalVentilationSetTimeAuxiliary
Sports
Hall
0.25ach
24h
——
5.56I/s/person
(When
Occupied)
Office1achWhenoccupiedandRoomTemp
isbetween18℃and26℃
—
Lounge3ach —
Bathroom——3ach(When
Occupied)
Plant
Room———
3.2.3.EndofLife
Duringthisphase,thefollowingassumptionsaremadeforcalculation.
(1)Theenergyconsumptionfordemolitionofabuildingisconsideredtobe90%oftheenergy
consumedduringtheerectionphaseastheexistingresearch[51].ThedemolitionareaofRCandCLT
buildingsissetat90MJ/m2and18MJ/m2,respectively.
(2)Fortheconcretebuildings,weassumethatalloftheconcreteandsteelmaterialswouldgo
intolandfillafterdemolition.ThisisalsothecurrentpracticeinNortheastChina.Duetotherelatively
smallamountofsteelusedinthestadium,theignoranceofsteelrecyclingmaynothavesignificant
effectonthetotalcarbonemissionsofthebuilding.
(3)FortheCLTbuildings,arecyclingrateof60%isassumed,with40%usedforbiomassenergy.
(4)Theenergyconsumedbytransportationisignored.
3.3.CarbonEmissionsandCarbonUptake
3.3.1.CarbonEmissions
Duringtheconstructionstage,electricityisthemainsourceforthebuildingmaterials
manufacture.Duringtheoperationstage,asmentionedabove,rawcoalandelectricityarethetwo
mainsourcesofenergyfortheoperationofstadiums.Electricityisusedforcooling,lighting,water
heatingandappliances,andrawcoalisusedforheating.Duringtheendoflifestage,theenergy
consumptionisassumedtobemainlyfromtheelectricity.Theenergyconsumptioncanbeobtained
fromthesimulationandcalculationdirectly.Inordertogetthecarbonemission,theresultsneedto
beconvertedbyconversionformulas.Thecarbonemissionsforcoalandelectricitycanbeobtained
fromEquations(1)and(2)[52].
Et=∑Qjtηj×
(1)
Et=∑QjtCjηj(2)
whereEtistheestimatedamountofcarbonemissionsofthet‐thstudiedcity;Qjtistheenergy
consumptionfromthecoalandelectricityofthet‐thstudiedcity;Cjistheappropriatecalorificvalue
ofthej‐thenergysource;andηjisthecarbonemissionfactorofthej‐thenergysource.Thevaluesof
CjandηjinthisstudyaresummarizedinTable9[52,53].
Sustainability2020,12,156616of25
Thevaluesofrawcoal’sηjaresupposedtobethesamenationwide,butthevaluesofelectricity’s
ηjarestronglyrelatedtotheenergysourceusedforgenerating.InChina,thenationalpowergridis
madeupofsixsubpowergrids.TheCO2emissionsfactorsarenotthesameineachregionduetothe
energysourceusedforgenerating.Theenergysourcesofnationalpowergridforelectricity
generationincludecoal,nuclearpower,hydro,windandothers.Electricitygeneratedfromclean
energysourcessuchashydroandwindhaslowcarbonemissions.Whileelectricityfromcoalmay
emittremendousCO2.Generallyspeaking,inChina,theelectricityismainlygeneratedfromthecoal
andthermalenergyaccountedfor70.24%ofelectricitygenerationin2019[54].Asaresult,the
averageCO2emissionsfactorismuchhigherthanthatinothercountry.InItaly,CO2emissionsfactor
in2017isapproximately346g/kWh,whiletheCO2emissionsfactorisapproximately870g/kWhin
China[53,55].The5studiedcitiesbysub‐regionsofthenationalgridandtheCO2emissionsfactors
ofthesub‐regionsarepresentedinFigure9.InnorthernpartofChina,wherethecoalisthedominant
resourceusedforgeneratingtheelectricity,theCO2emissionsfactorsismuchhigherthanthatinthe
otherregions.ThefiguresofCO2emissionsfactorsrangefrom0.67–1.14.
Figure9.Sub‐regionsofnationalpowergridandtheCO2emissionsfactors(ηj).
Table9.Cjandηjforcoalandelectricity.
FossilEnergyItemsCjηjStudiedCities
RawCoal20,934kJ/kg26.80(t‐C/TJ)—
Electricity3600kJ/kWh
1.14(t‐CO2/MWh,NortheastChina)Harbin
1.13(t‐CO2/MWh,NorthChina)Beijing
0.78(t‐CO2/MWh,EastChina)Shanghai
0.67(t‐CO2/MWh,SouthernChina)Guangzhou,Kunming
3.3.2.CO2UptakeofConcreteandCementduringtheOperationStage
Inthispaper,thecementismainlyusedastheopponentoftheexternalrenderingandthe
plaster.TheCO2uptakeofconcreteandcementduringtheoperationstagecanbeobtainedbythe
followingsteps.
(1)Depthofcarbonation.Thecarbonationofconcretestartsattheoutersurfaceandmoves
progressivelyinwards.TheprocessiscontrolledbythediffusionofCO2intotheconcrete.Thedepth
ofcarbonationasafunctionoftimecanbedescribedbyEquation3[56,57].Theservicelifeofthe
concreteisestimatedtobe50years(t):
Sustainability2020,12,156617of25
dk𝑡
.(3)
wherekisarateconstant,presentedinTable10;tisthecarbonationtime;anddisthedepthof
carbonation.TheKvaluesinthisstudyareshowninTable10[58].
Table10.K(carbonationrateconstant)values.
ExposureConditionCompressiveStrength
（15Mpa(mm/(year)0.5)23–35Mpa(mm/(year)0.5)
Exposed5.001.50
Indoors15.006.00
(2)Volumeofcarbonatedconcrete.Thevolumeofcarbonatedconcretecanbeobtainedfrom
Equation(4)[57]:
𝐶𝑎𝑟𝑏𝑜𝑛𝑎𝑡𝑖𝑜𝑛 𝐶𝑜𝑛𝑐𝑟𝑒𝑡𝑒/𝐶𝑒𝑚𝑒𝑛𝑡𝑚
∑
𝐴
𝑑
𝐴
𝑑
𝐴
𝑑(4)
whereAisarateconstant,aspresentedinTable11,anddisthedepthofcarbonation,whichcanbe
obtainedfromEquation(3).
(3)AmountofCO2absorbedpervolume.TheamountofCO2absorbedpervolumecanbe
calculatedusingEquation(5)[57]:
Carbon 𝑈𝑝𝑡𝑎𝑘𝑒 𝑘𝑔 𝐶𝑂/ 𝑚 𝑐𝑜𝑛𝑐𝑟𝑒𝑡𝑒/𝑐𝑒𝑚𝑒𝑛𝑡 0.75 𝐶𝐶𝑎𝑂𝑀
𝑀(5)
whereCisthemassofPortlandcementclinkerperm3concrete/cement,assumedtobe1300kgfor
cementand240kgforconcreterespectively[58];CaOistheaverageCaOcontent,whichisassumed
tobe65%[57,59];andMisthemolarmassofCO2andCaO.
(4)AmountofCO2uptake.Finally,thetotalcarbonuptakecanbeobtainedbyEquation(6).
Total Carbon Uptake kgEquation 4 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 5(6)
Table11.Surfacearea(A)forcementandconcrete.
Exposure
Condition
ConcreteCement
RCBuildingTimberBuildingRCBuildingTimberBuilding
AslabsIndoors15,945.45 —— —
AroofIndoors3612.00 —903.00 903.00
Awalls(ExternalSurface)Exposed2401.02 —600.26 600.26
Awalls(InternalSurface)Indoors9189.59 —2297.40 2297.40
AcolumnsandbeamsIndoors4780.02 —1195.01 1195.01
AgroundfloorIndoors2817.50 2817.50——
3.4.QualityofData
Inthispaper,thedatathatusedforassessmentofenergyconsumptionandcarbonemissions
canbesummarizedasthreeaspects.(1)Thesimulationparameters,suchastheheatingandcooling
time,indoortemperaturesettingsandventilationrateallstrictlyfollowthenationalbuilding
standardsthatissuedbytheChinesegovernment.Thedataisreliablesinceitisofficial.(2)The
equations,calculationcoefficients,andsomeparameterssuchastheCjandηjintheequation1and
equation2aresummarizedfromtherelevantscientificresearch.(3)Theparametersofthebuildings,
suchasthefunctions,dimensionsandthermaldesignsofthebuildingsareobtaineddirectlyfrom
constructiondrawings.Thereliabilityofthefiguresisconsideredashigh,sinceitisfromtheoriginal
design.
Sustainability2020,12,156618of25
4.ResultsandAnalysis
Table12,Table13andFigure10presenttheresultsofLCEAandoperationphaseforRCand
timberstadiumsinthefivecitiesunderstudy,whicharelocatedindifferentclimatezones.The
estimatedenergyconsumptioninRCstadiumsishigherthanthatoftimberbuildingsinallstudied
cities.Theresultsdemonstratethattimberisanenergyefficientbuildingmaterialcapableofsaving
energyandasuitablealternativetoconventionalbuildingmaterials.Theenergysavingpotentialof
timberiscloselyrelatedtotheclimateregion.Theenergyconsumptionduringoperationphase
accountsforthemajorityofthetotallifecycleenergyconsumption.Duringoperationphase,energy
consumedforheatingin“severelycold”and“cold”regionsismuchhigherthanthatinotherclimate
regions.Therefore,thetotalenergyconsumptionofthestudiedbuildingsin“severelycold”and
“cold”regions,whereheatingisthedominantenergy‐consumingactivity,issignificantlyhigherthan
thatinotherclimateregions.BuildingenergyconsumptioninHarbinisapproximatelytwotimes
greaterthanthatinKunming.Intermsofoperationstage,theenergyconsumptionofRCbuildings
duringtheoperationphaserangesfrom343.44MJ/m2to779.95MJ/m2perannum,whilethatoftimber
buildingrangesfrom349.49MJ/m2to712.24MJ/m2perannum.Theresultsalsoechothefiguresof
existingreferences.MaetalcountedenergyconsumptionofpublicbuildingsinNorthChinaand
pointedoutthattheaverageenergyconsumptionofoffice,hospitalandschoolbuildingsare678.11
MJ/m2,711.52MJ/m2and371.77MJ/m2perannum,respectively[60].JiangandToveyrevealedthat
commercialbuildingsinBeijingandShanghaiconsumed622.8MJ/m2and475.2MJ/m2perannum
[61].
Table12.EstimatedLCEAresultsforthereferencebuildings(50years).
CitiesBuildingsEnergyConsumed(MJ/m2)
ConstructionOperationEndofLifeTotal
HarbinRCBuilding2388.80 38,997.6490.00 41,476.44
TimberBuilding1262.47 35,611.9718.00 36,892.44
BeijingRCBuilding2260.46 30,923.5590.00 33,274.01
TimberBuilding1134.14 28,081.4218.00 29,233.56
ShanghaiRCBuilding2216.83 25,106.6090.00 27,413.43
TimberBuilding1090.50 24,071.9718.00 25,180.47
GuangzhouRCBuilding2122.78 22,388.9390.00 24,601.71
TimberBuilding996.45 22,453.5418.00 23,467.99
KunmingRCBuilding2122.78 17,171.9690.00 19,384.74
TimberBuilding996.45 17,474.4718.00 18,488.92
Table13.Energyconsumedduringoperationphaseforthereferencebuildings(50years).
CitiesBuildings
EnergyConsumedDuringOperationPhase(MJ/m2)
HeatingCoolingLightingApplianceWater
HeatingTotal
Harbin
RCBuilding20,627.875163.773258.057585.712362.2438,997.64
TimberBuilding17,089.685316.283258.057585.712362.2435,611.97
Beijing
RCBuilding10,584.657132.903258.057585.712362.2430,923.55
TimberBuilding7511.787363.643258.057585.712362.2428,081.42
Shanghai
RCBuilding4452.497448.113258.057585.712362.2425,106.60
TimberBuilding3332.197533.783258.057585.712362.2424,071.97
Guangzhou
RCBuilding0.009182.923258.057585.712362.2422,388.93
TimberBuilding0.009247.533258.057585.712362.2422,453.54
KunmingRCBuilding410.063555.903258.057585.712362.2417,171.96
Sustainability2020,12,156619of25
TimberBuilding253.064015.403258.057585.712362.2417,474.47
Figure10.Estimatedlifecycleenergyassessment(LCEA)resultsforthereferencebuildings(50years).
Table14,Table15andFigure11presenttheestimatedresultsofLCCAandoperationphasefor
RCandtimberstadiumsinthefivecitiesunderstudy,whicharelocatedindifferentclimatezones.
SimilartotheLCEA,buildingCO2emissionsarehigherin“severelycold”and“cold”regionsthan
inotherregions.ThecarbonemissionvaluesofRCstadiumsduringtheoperationstagerangefrom
156.88kg/m2inHarbinto63.20kg/m2inKunmingperannum.Incontrast,thecarbonemissionsof
timberstadiumsduringtheoperationstagerangefrom156.50kg/m2inHarbinto64.60kg/m2in
Kunmingperannum.Thecalculationresultsalsoechotheoutcomesoftheexistingscientificresearch.
JiangandToveyrevealedthatacommercialbuildinginBeijingandShanghaiemitted178kgCO2/m2
and119kgCO2/m2perannum[61].Jingetalevaluated30officebuildingsinHongkong,andpointed
outthattheofficebuildingemitted190kgCO2/m2perannumonaverage[62].Gargetalcalculated
thecarbonemissionsof197commercialbuildingsinGujarat,India.Theresultsshowedthatcarbon
emissionsofcommercialbuildingsrangedfrom96kgCO2/m2to177kgCO2/m2perannum[63].The
carbonreductioneffectsoftimberbuildingsduringtheoperationstagearenotableincomparison
withthoseofRCstadiumsin“cold,”“severelycold,”and“hotsummer,coldwinter”regions.
However,in“hotsummer,warmwinter”regionsand“temperate”regions,thecarbonreduction
effectsoftimberbuildingsduringtheoperationstagearelessnotable.
Table14.Carbonemissionsanduptakeofthereferencebuildings(50years).
CitiesBuildings
CarbonEmissions(kg/m2)CarbonStorageandUptake(kg/m2)
ConstructionOperationEndof
LifeTimberConcreteCement
HarbinRC1380.381380.3828.50 — 24.34 8.37
Timber7844.137844.135.70 263.70 1.86 8.37
BeijingRC 482.33482.3328.25 —24.34 8.37
Timber7824.817824.815.65 263.70 1.86 8.37
ShanghaiRC1333.461333.4619.50 —24.34 8.37
Timber7424.277424.273.90 263.70 1.86 8.37
GuangzhouRC438.54438.5416.75 —24.34 8.37
Timber7194.747194.743.35 263.70 1.86 8.37
KunmingRC1104.241104.2416.75 —24.34 8.37
Timber4912.594912.593.35 263.70 1.86 8.37
Sustainability2020,12,156620of25
Table15.Carbonemissionsduringoperationphaseforthereferencebuildings(50years).
CitiesBuildingsCarbonEmissionsDuringOperationPhase(kg/m2)
HeatingCoolingLightingApplianceWaterHeatingTotal
HarbinRCBuilding2027.03 1635.19 1031.72 2402.14 748.04 7844.13
TimberBuilding1679.35 1683.49 1031.72 2402.14 748.04 7544.74
BeijingRCBuilding1040.12 2238.94 1022.67 2381.07 741.48 7424.27
TimberBuilding738.16 2311.36 1022.67 2381.07 741.48 7194.74
ShanghaiRCBuilding437.53 1613.76 705.91 1643.57 511.82 4912.59
TimberBuilding327.44 1632.32 705.91 1643.57 511.82 4821.06
GuangzhouRCBuilding0.00 1709.04 606.36 1411.79 439.64 4166.83
TimberBuilding0.00 1721.07 606.36 1411.79 439.64 4178.85
KunmingRCBuilding40.30 661.79 606.36 1411.79 439.64 3159.87
TimberBuilding24.87 747.31 606.35 1411.79 439.64 3229.95
Figure11.Estimatedlifecyclecarbonassessment(LCCA)resultsforthereferencebuildings(50
years).
5.Discussion
(1)EnergyConsumptionandCarbonEmissionsinDifferentClimaticRegions
ThesimulationresultsdemonstratethattimberisamoresustainablebuildingmaterialthanRC
inallclimateregions.AsshowninTable16,theenergysavingandcarbonreductionpotentialis
greatestin“cold”regions,followedby“severelycold,”“hotsummer,coldwinter,”“hotsummer,
warmwinter”and“temperate”regions.However,asabuildingmaterial,timberlackseffectiveness
inregionswithoutconsiderablespaceheatinginthewinter.AlthoughCLTasasustainablematerial
canbedevelopednationwideinChina,itwouldbebesttodevelopitin“severelycold”and“cold”
regionsfirstduetolimitationsontimberproduction.Thus,policymakersareadvisedtopromotethe
constructionoftimberpublicbuildingsinnorthernChinaasaneffectivewaytoreduceenergy
consumptionandcarbonemissions.
Table16.EnergysavingandcarbonreductionpotentialoftimberandRCbuildings.
CitiesEnergySavingPotential CarbonReductionPotential
LCEAOperationPhaseLCCAOperationPhase
Harbin11.05%8.68%15.85%3.82%
Beijing12.14%9.19%15.86%3.09%
Shanghai8.15%4.12%18.88%1.86%
Guangzhou4.61%–0.29%19.22%–0.29%
Kunming4.62%–1.76%22.47%–2.22%
Sustainability2020,12,156621of25
(2)StadiumOperationMode
Theresultsindicatethatenergyconsumptionandcarbonemissionsduringtheoperationphase
aredominantthroughoutthebuildinglifespan.Theoperationmodeofpublicbuildingshasa
significantinfluenceontheirenergyconsumptionandcarbonemissions.Stadiumsoperateforeight
hoursperday,threedaysaweek.TakingthestadiumsinHarbinasanexample,energyconsumption
andcarbonemissionsseemtovarywiththeoperationaltime(Figure12).Althoughthetotaloperation
timeremainsthesame,thecurrentoperationmodemayresultinenergysavingsof3.90%and5.55%,
respectively,incomparisonwiththeoperationalmodeoffourdaysaweekandsixdaysaweekfor
concrete.Thus,thereasonablearrangementofoperationtimeoffersaneffectivewaytoreducethe
energyofastadium.
Figure12.EnergyconsumptionbyoperationmodeinHarbin.
(3)CO2UptakeofConcreteandCement
Inthisstudy,theCO2uptakeofconcreteandcementistakenintoconsideration.Thecarbonation
ofcementandRCisoneofthecausesofcorrosion,butitisalsoaneffectivewaytosequesterCO2.
Thecalculationresultsindicatethatonecubicmeterofcementmayabsorb497.95kgofcarbon
dioxideduringthecarbonationprocess,andtheequivalentfigurefortheconcreteis91.93kg.
Meanwhile,onecubicmeteroftimbermayabsorb800kgCO2duringitsgrowth[40].Whenthe
amountofcementintheconcreteincreases,boththecarbonationdepthandtheamountofCO2
absorbeddecrease,primarilyduetothedecreaseinporosity.AlthoughthetotalCO2uptakefrom
concreteandcementismuchlessthanthatoftimber,duetothelimitedvolumeofcarbonation,the
carbonationprocessandabilitytosequesterCO2ofcementandconcreteshouldnotbeneglected.
6.Conclusions
Thispapercomparestheenergyconsumptionandcarbonemissionsofreinforcedconcreteand
timberstadiumsinfiveclimateregionsofChina.Themainfindingsfortimberasasustainable
materialaresummarizedbelow.
(1)TheestimatedenergyconsumptionandcarbonemissionsofCLTbuildingsaremuchlower
thanthoseofRCbuildingsinallofthestudiedcities,whichindicatesthatCLTsystemshavegreater
potentialthanRCsystemstoreducecarbonemissionsandenergyconsumption.
(2)TheenergyconsumptionandcarbonemissionsofbothconcreteandCLTbuildingsare
closelyrelatedtotheclimatezones.Buildingsin“severelycold”and“cold”regionsofChina,in
Sustainability2020,12,156622of25
whichheatingisresponsibleforthemajorityofenergyconsumption,consumethemostenergyand
releasethemostcarbon,followedby“hotsummer,coldwinter”regions,“hotsummer,warmwinter”
regions,and“temperate”regions.Therefore,timberisbestsuitedtoregionswithconsiderablespace
heatinginthewinter.AlthoughCLTasasustainablematerialcanbedevelopednationwideinChina,
itisbettertodevelopitinseverelycoldandcoldregionsfirstduetolimitationsontimberproduction.
(3)Differentbuildingoperationmodeshaveagreatimpactonenergyconsumptionandcarbon
emissions.Thereasonablearrangementofoperationtimeisaneffectivewaytoreducetheenergy
consumedbystadiums.
(4)Althoughthetotalcarbonuptakeofconcreteandcementismuchlessthanthatoftimber,the
carbonationprocessandabilitytosequesterCO2ofcementandconcreteshouldnotbeneglected.
AuthorContributions:Conceptualization,H.G.andX.Y.;methodology,H.G.;software,T.Q.andR.B.;
validation,T.Q.andS.Z.;formalanalysis,S.Z.;investigation,T.Q.andY.D.;resources,Y.D.;datacuration,T.Q.;
writing—originaldraftpreparation,H.G.andY.D.;writing—reviewandediting,H.G.andX.Y.;visualization,
L.H.;supervision,H.G.andX.Y.;projectadministration,H.G.andX.Y.;fundingacquisition,H.G.Allauthors
havereadandagreedtothepublishedversionofthemanuscript.
Funding:ThisresearchisfundedbyNationalNaturalScienceFoundationofChina,grantnumber51608144;
andHeilongjiangProvincialNaturalScienceFoundationofChina,grantnumberLH2019E110.
Acknowledgments:Weappreciatedtheanonymousreviewersfortheirthoughtfulsuggestionsandcareful
workthathavehelpedimprovethispapersubstantially.
ConflictsofInterest:Theauthorsdeclarenoconflictofinterest.
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