Heriot-Watt University Design and low energy ventilation solutions for atria in the tropics Abdullah

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by  Abd Halid Abdullah

Heriot-Watt University

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Design and low energy ventilation solutions for atria in the

tropics

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Abdullah, AH & Wang, F 2012, 'Design and low energy ventilation solutions for atria in the tropics',

Sustainable Cities and Society, vol. 2, no. 1, pp. 8-28. https://doi.org/10.1016/j.scs.2011.09.002

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10.1016/j.scs.2011.09.002

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SustainableCitiesandSociety2 (2012) 8–28

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Sustainable Cities and Society

journal homepage: www.elsevier.com/locate/scs

Design and low energy ventilation solutions for atria in the tropics

AbdHalidAbdullaha,FanWangb,∗

aFacultyofCivilandEnvironmentalEngineering,UniversitiTunHusseinOnnMalaysia,86400ParitRaja,Johor,Malaysia
bSchoolo ft heBu iltE nvironment,He riot-WattUn iversity,E dinb urghEH 144A S,United Kingdo m

a r t i c l e i n f o a b s t r a c t

Articlehistory: Agenericatriumbuildingwasdesignedtoincorporatelowenergysolutionsandfeaturesofbothvernac-
Receiv ed28July2011 ul arandc ontemp orarySo uth Asianarc hit ecture.Toac hiev elowe nergyan dcom fortwi thi nthe atrium
AReccceepivteedd i2n6 r Seevpis teedm fboermr2 10 1S1eptember 2011 spac e, so me key design variab les we re examined by running a dy namic therm al mod el (DTM ) fo r some
representativecases.ThisDTMmodelwasdevelopedwithmultiplelevelsandzonestosimulatetheheat

andairmovementthroughoutthebuildingandvalidatedwiththedatameasuredinarealbuildingof
Keywords: simi lar form.Them odellingst udy wascarr iedo uttoinve stiga tet heef fectsoftw or oo ffo rmsfort he
Thermalcomfort
atriumandthreelowcostventilationsolutionsonindoorthermalcomfort.Itrevealsthatlowcostven-
Atrium
tilationandacceptablecomfortareachievableinthistraditionalformofarchitectureandlowenergy
Walkway/balcony
Ventilation solutions and careful design can complement well its functional aspects and even enhance its aesthetic
Top-lit/side-litroof andpracticalqualities.
Th esolarh eatgain,airtemperature,andmeanradianttemperatureintheatriumwereusedtoassess

theeffectivenessofclerestorywindowswithopaquerooftop(i.e.side-litmodel)ascomparedtothe

fullytransparentglazedrooftop(i.e.top-litmodel).Dataoncoolingloads,indoorairtemperature,and

meanradianttemperaturewereusedtoevaluatethedesignoptionswithspecialconsiderationonlocal

adaptablethermalcomfortcriteria.Thepossibleeffectsoftheresearchoutcomesontheincorporation

ofatriaarediscussedattheend.

Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved.

1. Introduction Incoldclimatetheenvironmentalbenefitsofsuchvoidspaces

areobviousastheyareusedasasunspaceduringsunnydayand

Atria have become very popular in modern buildings, partic- bufferzonesbetweenharshexternalclimaticconditionsandthe

ularlylargecommercialbuildings,suchashotels,shoppingmalls indoorenvironment(Hawkes&Baker,1983;Nelson,1984).Inhot

andofficeheadquarters(Reidetal.,1994).Oftenrightafterthemain climate,however,theenvironmentaleffectsarenotalwaysdesir-

entranceorastheextensionoftheentrylobby,anatriumprovides able. A typical example of this is that the glazing cover allows

acentralcorecirculationareawithfeelingofspaceandlightaswell deeperpenetrationofhighlevelnaturallighting,amuchwelcome

asatransitionzonebetweentheoutdoorsandtheinteriorforlong featureforaninteriorspace,andstrongsolarradiation,anadverse

stay(Saxon,1994).Moreover,traditionalbalconiesareadoptedas factor to thermal comfort (Douvlou & Pitts, 2001; Edmonds &

walkwaysabovegroundleveltomaximisetheuseoftheatrium Greenup,2002).Inthetropics,solarradiationpenetratingthrough

space.Thisisparticularlytrueinbuildingslikeshoppingmalls,as thelargeglazedenvelopecanseverelyworsenindoorthermalenvi-

a linear atrium create a semi-outdoor environment for the long ronment of a building during the occupied hours, especially the

balconies,thekeycirculationpathsinthesebuildings.Apartfrom radiations from the high altitude of the afternoon sun and high

thismajorattraction,atriahavemanyenvironmentalimplications, temperatureinthehighleveloftheatriumspace(Pan,Li,Huang,

suchasforsolargain,daylightandthermalcomfort.Theyaffectthe &Wu,2010).

physicalenvironmentwithinthevoidspaceandeventotheadja- Anexampleofsuchpoorindoorconditionsisbestillustratedby

centspaces.Theseenvironmentalconditionsintheatriadepend SandraDayO’ConnorUnitedStatesCourthouse,aglassboxbuild-

directly on the complex interaction between the buildings’ ele- ing.Itiswellknownthattheairtemperatureinsidetheatriumcan
ments(a nd con struction materials),a rchitectu ralfo rmsandm uch easi ly go bey ond38 ◦C.E ven wi thOveArup’ sinno vati vesolut ion
moret heou tdoorweathe rcondition s(Atif,1992) . theind oo rairtem peratu reris esas high as33◦C onthegrou ndfloor

oftheatriumunderthescorchingArizonaSun(Stephens,2011)

Unfortunately the problem of overheating is not easily seen

untilthebuildingisactuallyoccupiedandthehighbillforcool-

∗ ingisincurred.Apparentlythebenefitfromtheabundantnatural
CE-omrraeislpaodnddreinssg: afaunth.woar.n [email protected]: w+4.a4c 1.u3k1( 4F.5W14a6n3g6);. fax: [phone]. ligh ts often ov ershadows the adverse effec ts o f excessiv e solar

2210-6707/$–seefrontmatter.Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved.

doi:10.1016/j.scs.2011.09.002
A.H.Abdullah,F.Wang/SustainableCitiesandSociety2 (2012) 8–28 9

penetrationonthermalcomfort.Thenegativesidesofsolarpen- stagewastodevelopamulti-levelandmulti-zonemodellingtech-

etration are often neglected in many building projects involving niqueusingadynamicthermalmodelling(DTM)toolandcarrying

atriumforminhotregionsasthefunctionsofatriaaremainlyfor avalidationtest.ThefinalstagewastoapplytheDTMtotherep-

spatialandaestheticreasons,whichareoftenjustifiedbytheabun- resentative models with differing design variables and to carry

dantnaturallightsassociatedwiththeatriumform.Moreoverthere outaparametricstudytoinvestigatequantitativelytheeffectsof

isamisconceptionamongarchitectsthatglasstechnologyisnow selectedparametersthatspecifytheatriumandventilationsolu-

veryadvancedandunshadedglasswouldnotpresentanythermal tions.

problems.Thispracticehasbeenbestsummarisedas“architectural

designersdonotalwaysrecognisethehighprobabilityofthermal 2.1. Thebuilding

discomfortinglassbuildingsinhotclimate”asreportedinASHRAE

(2009),andmoreandmoreglassatriaareappearingatrapidpace.A The generic office building was developed to contain the fol-

recentreviewonsomebuildingswell-acclaimedamongarchitects lowingelementsofthevernaculararchitecturalfeaturesinSouth

andarchitecturalcriticsshowsasignificanttrendofincreaseinthe EastAsia,asidentifiedinapreviousreviewstudy(Abdullah,2007)

useofglazedenvelopeseveninSouthernAsiacountries,wherethe (Figs.2and3):

airishotandsolaraltitudeislow(Welch&Lomholt,2011)(Fig.1).
AS HR AE(2 009) hasalso po inte doutth at glassbox build ingsa re • Three storey building with rectangular plan of 21×30m and

notoriouslyuncomfortableregardlessofaverylarge,sophisticated, elongatedalongEast–Westaxis;
expensivea ndmaintenanc e-intensive sy s tem. • 3.4mfloor toflo orheightfo rallthreestoreys;
Thehea tat thetopoftheatriumca nberemovedbybothwind • Lin ear cent ra l atri um wit h g rou nd fl oor area of 9×21m, four

andstackforcesinanaturallyventilatedbuilding.Winddrivesair storeyhighandsurroundedbyoffice/shopspacesonthreefloors;
mov emen tthrou gh o utthebui ldinginclu dingthea trium well.T his • Longb alcon ies, orwalkway s, of1.5mwid eonfi rst ands econd

forcehoweverisoftenweakforurbanbuildingsduetocanyonshel- floorssurroundingtheatriumwell,servingasmaincirculation

teringeffects(Santamouris,Papanikolaou,Koronakis,Georgakis,& areasaswellasplatformtoenjoythevoidandlandscape;
Assim akopou los,1998).The stackeffectca nbedomin anttodra w • Atrium f orm wi thPlanA spe ctRat ioo f0.3 (or 1:3)toreflectthe

airfromlowerpartofthebuildingandliftitupwardintheatrium smallestlinearform;
and even tually push it out throughr ooft opo p enings.H ea tco llected • TheSect ionalA spectRatioforallthetestedmodelstakinginto

ataglazedrooftop,isbeneficialforenhancingtheairflowbutits accounttheheightoftheatriumwellfromthegroundfloorlevel

radiation also causes discomfort particularly to the users on the tothesecondfloorceilinglevelwasabout1.7(or1:0.6);
higherlev elba lconies . • Th eto talvolu meof thebel owro ofsp acebe yon dt hesecondfloor

Excessivesolargainisnormallytheimmediatecauseofover- ceilinglevelwasalsokeptconstantforbothrepresentativemod-
heating with in th e spa ce and sola r c ontrol beco mes e sse ntial, els,wh ichw asa bout 432 m3 form ode lsw ithwall-to-roo fvoid
suchas shading dev icesor exter nalev aporativ ecooling (Abdullah, and 270m 3for model with outwa ll-to-ro ofvoi d,respective ly;

Wang,Meng,&Zhao,2009;Wang,Huang,&Cao,2009).Theseprob-

lems could be resolved more easily and less costly during early Toexaminetheimpactofsomekeydesignvariablesandsolar

design process than at later stages (EEBPP, 1996). Hence energy controlmeasuresontheatriumindoorthermalenvironment,other

efficiency and environmental strategies are developed in many features were also included in the parametric modelling study.

building projects and considered well starting from the concep- Theyaretworoofforms,side-lit(Fig.2aandc)andtop-lit(Fig.2b

tual design stage. However, a recent study points out that these and d) and their variations. Side-lit form is a local traditional

conceptsarerarelyfullyanalysedusingmethodssuchasquanti- responsetonaturallightingandstrongsolarradiation,whilethe

tativeprediction,assessmentandoptimisation(Pollock,Roderick, top-litformisanimportedsolutionpopularlyemployedbypresent

McEwan, & Wheatley, 2009). Assessing and optimising solutions daydesigners.

needspredictionofthermalperformanceofeachofthoseproposed Thevariationsincludedtheoverhangsfortheside-litroofform,

designsandquantitativeinvestigationduetothecomplexnature extra space beneath atrium roof, and blinds next to the glazing

andintricaterelationshipsamongdesignvariables. panels.Thesewillbediscussedinfulldetailsinthesectiononthe

This paper presents a study comprising the following three parametricstudy.

components: designing two generic atrium forms for the trop-

ics;proposingtwolowenergymechanicalventilationsolutionsto 2.2. Weatherandinternalconditions

improvethermalconditionwithintheatriumwell,anddeveloping

amethodofmodellingatriumthermalbehaviourusingcommer- The1978weatherdatafileforSubang,KualaLumpurwasused

cialsoftwareduringdesignstage.Asthequantitativeanalysiswas as it consisted the representative data generated from those of

carriedoutusingapopularcommercialprogram,theprimaryaim themonthsselectedfromtheindividualyearsbeforeandconcate-

wastodemonstratehowmodellingshouldbeusedatearlydesign natedtoformthistestreferenceyearortypicalmeteorologicalyear

stagetopredicttheeffectsofanumberofdesignoptionsandventi- (TheMalaysianMeteorologicalService,1993).Thefilecontained

lationsolutionsfortheatriumonitsindoorthermalenvironment. themeanhourlyvaluesofalltheweathervariablesincludingthe

Inadditionitwastoshowthatlowenergysolutionsanddesign airtemperature,humidity,totalandscatteredsolarradiations,and

foranatriumcancomplementwellitsfunctionalaspectsandeven windspeedanddirectionforawholeyear(Deosthali,2000).

enhanceitsaestheticandpracticalqualities. Studies have confirmed the trend of intensified urban heat

island due to recent urbanisation particularly in Asia (Hung,

Daisuke,Shiro,&Yoshifumi,2006;Güneralp&Seto,2008;Lietal.,

2. Methods 2009;Juan-juanLi,Wang,Wang,Ma,&Zhang(2009)).Theyalso

reportalesssignificantchangeinthetemperatureinruralandsub-

Thestudywascarriedoutinthreestages.Itbeganwithdevel- urbanareawhileasignificanttemperatureincreaseincitycentres.

oping a representative atrium building that bears features to be Thereforeanupdatedweatherdatawouldbeneededformodelling

examinedwhichincludetworoofformsandkeydesignvariables, prediction.However,thegenericbuildingisalowriseoneandpre-

andalsoidentifyingtwocommonventilationschemesnamelynat- sumably located in a suburban area. Therefore the weather data

uralventilationandpressurisedmechanicalventilation.Thenext wereusedwithoutanymodification.
10 A.H.Abdullah,F.Wang/SustainableCitiesandSociety2 (2012) 8–28

Fig.1. GazetteersofnotableatriumbuildingsinhotclimateAsiancountries.

For simulating the worst case scenario, 21st March (noted as the reported results for the chosen simulation day are reflec-

Day80)waschosenasthedesignday(i.e.thehottestdesignday tive of any thermal mass effects of the structure, all models

of the year) for Kuala Lumpur as suggested by many authorities were ‘pre-conditioned’ for 10 days. Hence the actual modelling

(Koenigsberger, Ingersoll, Mayhew, & Szokolay, 1980; Nieuwolt, was run for 10 days, and the results of the last day were

1977; Takahashi & Arakawa, 1981). In order to ensure that examined.

Fig.2. Schematiccross-sectionsofrepresentativeatriummodels.(a)Side-litmodelwith1.5mhighwall-to-roofvoidand1.5mwideroofoverhangs;(b)top-litmodelwith

2.5mhighwall-to-roofvoid;(c)side-litwithoverhangsnowall-to-roofvoidwan;(d)top-litwithoutwall-to-roofvoid.
A.H.Abdullah,F.Wang/SustainableCitiesandSociety2 (2012) 8–28 11

Fig.3. Typicalfloorplansofthelinearthree-storeyrepresentativeatrium.
12 A.H.Abdullah,F.Wang/SustainableCitiesandSociety2 (2012) 8–28

In order to investigate the effect of solar penetration on the secondfloorswereusedtoassesstheeffectsofthedesignparam-

atriumthermalperformanceduetoseasonalchanges,threesim- eters on the indoor thermal performance. Hence in this study,

ulation days including the 21st June, 21st September and 21st thermalcomfortwasinterpretedwiththefollowingspecialcon-

Decemberwerealsousedformodelling. siderationsforwarm-humidandhotcountries:

2.3. Ventilationschemes
• In tropical climate thermal comfort is set to a range of tem-
pe rature fr om 20.8 to 28.6◦ C along w it h th e r el ative h um idity
Twotypesofventilationstrategies,namelynaturalventilation
between40and80%inair-conditionedbuildings;andawider
and pressurised mechanical ventilation, were considered to exam- rangeof 20. 8–31 .5◦C al ongwithrelativ ehumidity betw e en54
inehowthethermalconditionswithintheatriumandcommunal
and 76% in naturally ventilated building, with the aid of aver-
spacewereaffectedbytheselecteddesignparameters.
ageairmovementof0.15–1.0m/s;accordingtoMalaysiancases

2.3.1. Fullnaturalventilation (AbdulRahman&Kannan,1997;Sabarinah,2002)andThaistud-

To simulate full natural ventilation, the following general ies(Rangsiraksa,2006;Yamtraipat,Khedari,&Hirunlabh,2005).
assum ptionsan dset tingswe reconsidered for thetworo offorms • Ins hortstayspa ces,su chasanatr ium,ane v enwiderra ngeof

andtheirvariations: comfortshouldbeappliedastheatriumspaceisnormallyused

asarelaxingandtransitionalspace,thecomfortrequirementis
• Theinternalconditionswerespecifiedaccordingly. th er eforeless stri ngent.Arece ntsurv ey overnear ly1150peop le
• Mai nentran cesoneithe rside (eastan dwestsides)ofthelinear usingtran sitio nalspace s inthe tropics reve alsthat the neutral
build ingwereco nsi dered asth emain low -leve lopen ing s(g round tempe ratureisbet ween2 6.1 and 27.6◦C ,althou ghth epr eferred

level)forcrossventilationduetoeasterlywind.Itwasassumed temperatureisslightlylower(Jitkhajornwanicha&Pitts,2002).
thatd urin goffi cehoursfro m08 00 to1800 h,the op enin gareaof Afurtherstu dy shows thata 3◦ higherthanthen or malc ooling

bothexternaldoors,westandeastmainentrances,weremain- standard can result in 4.8–8.5% reduction in cooling energy in

tained equal. The total area of each of the external doors was atriaunderBritishsummerconditions(Pitts&Saleh,2007).The
5m2. redu ctionw illbem oresign ificantwh enthe o utdoo rsisho tter
• Th ehigh-level(rooflevel)openingforbothtop-litandside-lit andforal onge rp eriod.

models was considered a half (50%) of the total area of low-

level openings so that all openings would have the same size.
Respe ctively, t he total are a was 85 m2 for clere stor y wind ows 2.5. Modelling tools
and113.64m 2for theg lazed roof .Th eseout lets(cleres torywin-
Thethreemajorapproachescommonlyemployedinpredicting
dowventforside-litmodelandrooftopventfortop-litmodel)
thermalconditionsinsideabuildinginthedesignstagearetheo-
weresettoalwaysopen.
• Thev ents fo rallwin dows,internaldoorsandexternaldoorswere retical calculation, physical simulation (either water tank or wind
tunnel) and computer modelling. Theoretical calculation shows
setto100%openstartingfrom1800to0700hthenextmorning
clearly the quantitative relationships between the key variables
fornightcooling.
suchasventilationrateandotherdesignvariables,suchasopening

2.3.2. Pressurisedventilation areasandheightbetweentwosetofopeningsunderalimitedtem-
Th etworepre sentativemodelsweresimulatedwithtwotypes perat ured ifferen cesbetw een the in doorand outdo or air(Ho lford
ofpres suris edventilation: alloccu pied floorspres surise dan dthe &Hunt,2 003).Fora realbuil ding itcan bev eryhard to usethis
gr oundflooron lypressuris ed. Thepress urised ventilation isas im- m ethod duetot hec o mple xityofbu ild ing geo metr yand flo wp aths
pleand econ omic alsolutionp rima rilybecause itusesthe ai r from configur atio n.P hys icalmodell ing isnorm allyveryti mec onsu ming
the surr oundingair conditio nedroom stocool th eatr ium an dno andexpensive ,asitin volvesscal ed modelte sted ina specialised
retu rnairductw ork isneededin thebu ild ing. Itw asprop osed as labo ratoryenvi ron m entwith equipm ents,s uchas bo u ndarylayer
alow-e ne rgyventila tio nschem e toco oltheatr iu msp ace,asitd id windtunn elswhichare norm allybiginsiz e(Sh arp les&Bens alim,
n otexertextr acoolingon thecon tr acoo ling plant. Thisco uld a lso 2001) and a techniq ue of Planar Las er Indu ced Fluor es cence for
save runn ingco stasth eo utdo orwea therin Malay siais gene rally quant itativ e visualisatio no fflow inaw atertank .Hence,itisd iffi-
warm andhu midw it hlo wwindv elocityfo rm ostparts o ftheyear. culttobeap pliedtoeach atr ium de sig n.
To mod elthe press urise dven tilation, the atriu mw as sup plied C om pu termod el lingh asbeen popularrecentlyduetoincrease
witht heaira t23 ◦Cofftheadj acentoffices ,wh ichwer epre ssurised incomputing powerand cod ecap abilitya ndavaila bili ty. Inmany
bysu ppl yin g1 8◦C coo lair duringo fficeho urs.T heam ountofthe pr actices,mod elling has been routinelyc arri edouttotes td esign
sup plyairwa scalc ulate dl ocallyt oeach ofthe offi cezones .E ach options. A mong the se co mpu ter model ling too ls, c om put ational
ofthes ezo nes wasspecifi edwith th eval ues of casual gainso fthe fluid dyn amics ( CFD) g ives more details of a flow field. A recent
low eren dofth ere commend edra nge inCIBS E guides. revie wonmode llingt oolsre veals thatCFD w as afav ourab le choice
Nig htc oo ling wasappliedfo routo fo fficeh ours. formos tst udiesonb uildin gventi lation per form a nce(Chen, 2009).
Par ticula rlyitsh igh resolutio nforflowd omainallows detaile drep-

2.4. Criteriaforassessmentofindoorthermalperformanceand resentationofthegeometryandsecuresaccuratesolutionsofthe

comfort pressure and velocities over large openings, the key concern in

correctlymodellingnaturalventilationinatriumwithlargeopen-

Fanger’stheoryprovidesaverysoundbaseformanythermal ings(Li,Pitts,&Li,2007).Thehighspaceresolutionalsoprovides

comfort standards, including ASHRAE (1992) and CIBSE (2006). accurateaccountforthecontributiontothermalcomfortmadeby

These standards have been challenged by many surveys carried longwaveradiationfromsurroundingsurfaces(Li&Pitts,2006).

outinhotclimates,astheyoftenresultinovercoolingandcaus- However,duetoheavycomputation,itisnormallyusedforsteady-

ingdiscomforttopeople(Tantasavasdi,Srebric,&Chen,2001).A statemodelling.Hencetheresultsarefeaturedwithhighresolution

newconceptwasintroducedbyFergus(2004)asadaptivethermal forspacebutstaticintime.Nevertheless,specifyingtheboundary

comforttoreflectthelocalclimateandpeople’spreference. conditions has to rely on other modelling to provide reasonable

The predicted air, mean radiant temperatures and resultant values,particularlyformodellingnaturalventilationinatria(Tan

temperature on the ground floor, the walkways on the first and &Glicksman,2005).
A.H.Abdullah,F.Wang/SustainableCitiesandSociety2 (2012) 8–28 13

Theothertypeofcomputermodelling,dynamicthermalmod- theclerestoryspacewereofslopingtileroofconstructionwithaU-
elling( DTM) progr am shavebe enroutinely usedto modelsm aller valu eof0.45W /m2K (Fig. 2a andb). The opa quepartsoft hefac a de
spaces regar ded as ‘ro oms’ in co nventiona l bui ldi ngs (Ab dullah, were wi thU- valueof 1.93 W /m2 K, and theinte rnalw a llsh adthe
2007). Basedon am ulti-zon alm odel,theytr eateachro omwithin U-val ueof 2.12W/m 2 K.Gl azingma teria lsfo rextern alwal ls,m ain

a building as a zone, calculate the heat and air flows moving entrance doors, windows, clerestory windows and transparent
a mong the se zo nes th rough ene rgy and m ass bala nce eq uations rooftopw eresin gleclearfl oatglassw ithU-value sof 5.33W/m2K
andpre dictd ynami ctherma lperfor manc eofa building (Megri& forwind ows (includ ingc learst oryw indo ws)and6 .2 3W/m 2Kfor

Haghighat,2007).Thesimulationresultshavelowresolutionfor glazed roof, respectively. For side-lit and top-lit models without

spacebuthighintime,normallyincludinghourlyfiguresthrough- wall-to-roofvoidareaasshowninFig.2(d)and(c),respectively,

outatypicalyear.Hencetheyareoftenusedforoverallassessment theconcrete‘flatroof’constructionsurroundingtheclerestoryand
of t h ermal p erfor mance and en ergy consu mp tion o f a specific tran sparentr ooft opar eashadaU-v alueof0.27W /m 2K.

design (Chen, 2009). Apart from the whole year performance Theatriumwasdividedoverfivelevelsinto35and34zones

assessment,DTMmethodalsoallowstheindoorconditionstobe respectivelyfortheoneswithandwithoutthewall-to-roofvoid,

assessedonhourlybasis.Hencestatisticaldatacanbeobtainedfor sothatthetemperaturevariationoverandairmovementamong

naturalventilationassessmentatthedesignstage,suchastheper- variouspartsoftheatriumspacecouldbecalculatedindividually

centageofoccurrenceofoverheatingorthetemperatureexceeding (Tables1and2).Otherzonesweresimulatedasofficeswithtypical

agiventhresholdinallzonesofthebuilding(Pollock,2011). casualheatgains(AppendixA).

Forbuildingswithalargeandcomplexmulti-levelspacesuch BasicallyusingtheTASweatherdataforKualaLumpurforsim-

asatria,assigningalargesinglezoneoronlydividingeachlevel ulationday80,parametricalstudiestoexaminetheimpactofsome

intoonezonemaynotbesufficienttocorrectlymodelthespace. keydesignvariablesontheatriumindoorthermalperformancedue

Inthisstudy,therefore,theatriumspacewasdividedbothver- tofullnaturalventilationwerecarriedoutasfollows:

tically and horizontally into a group of small zones in order to

improvethespatialresolutionforthesolutions.Theverticaldivi- (i) Varying low- and high-level opening sizes – the representa-

sion is essential for simulating stratification (Voeltzel, Carrie, & tivemodelsweresimulatedtoinvestigatetheeffectofvarying

Guarracino, 2001). In addition, each of the two horizontal direc- low- and high-level opening sizes on atrium indoor thermal
tionsofthes pacew as furtherdi vided in toat leas tinthreese ctions perfo rma nce.Fouro peningsi zes(i .e.0 .5m2,0 .8m2,1 m2 and
tocal cu late them ove mento fheatan dai rfl ows .Su chte chnique 2m2)wereco nsid ered.The hour lyw ind spe ed and d irection
wa s an atte mpt to improve sp atial reso lut ion of DTM prediction w asfi xedat 3m/sand90 ◦res pective ly,wh ilethe othe rweather

sothataDTMmodelcouldcorrectlymodelthestratificationand parametersremainedunchanged.Analysisofwindconditions

otherthermalbehaviourswithinalargemulti-levelspaceofthe forKualaLumpurindicatesthatthewindvelocitythroughout

atrium. The DTM model for this study was developed using TAS theyearisgenerallylowandtheNorth-easterlywindinMarch

(Jones,2000). islessthan3.3m/s(MMS,2004).

(ii) Varying wind speeds – the representative models were also
2.6. Validation simulate dtoi nvestiga te the effectofvaryin gwind speed son

atrium indoor thermal performance due to cross ventilation
TotestwhethertheDTMtechniquewassuitabletoinvestigate of the easterly wind. T hree different win d s peeds were con-
atrium ve ntilation and strat ification, a real building w ith similar sid ere d: 3, 5 a nd 7m /s. Th ese are s ignific antly h igher than
forman dfeatures,a swe llassituatedin a simi larclimat iccon ditions the actu al loc al co n ditio ns in o rder to see the w ind co oling
wasm ode lledand th epre dic tedresu lts w ereco mpareda gainstthe effe cts.For these simulation s,t heare afo rea chof thelo w-level
mea suredone s. opening sw asma intainedat0 .8m 2,wh ile theh ig h-le velopen-
Thesel ectedbuildingsharedfourkeyfeaturesoutlinedasfol- ingwask ept totallyshut .H enc e,th ehou rly windspee dwas
lows: cha nged acco rdingly andt hewin ddi rection wasfi xedat 90◦

• Alinearatriumwithretractablefabricblindsrightunderneath (easterly wind), while the other weather parameters remained
unchanged.
theroofglazing,externalsprayofevaporativecooling;
• Sim ilarh eightof theatriu mspa ce ; (iii) With and without wall-to-roof void area – the representative
• Interna l balcon ie s/w alkway s to each floor between the atrium models with wall-to-roof void (Fig. 2a and b) and without wall-
to-roof void (Fig. 2c and d) were simulated and their results
wellandthestandardair-conditionedrooms;and
• Vent ilati ons chemes:n aturalventilatio n,grou ndflooronlypres- were compared to examine the effectiveness of the wall-to-
roofvoidareainimprovingthermalconditionsparticularlyon
surisedventilation.
occupiedlevels.Forthesesimulations,theconditionandsizeof

Validation conditions included a hot clear day and a cloudy day openingsweresimilartonumber(ii)above.
tocovertw olevelsof solarimp ac tsan dfull occ upan cy ,toinc lude (iv) Withand with outroo fo verhangs ab ovetheclerestoryarea–
hig hind oorc asual gai ns.Ap artfrom the sta ndardair-co nd itioned side-l itm odelswi than dwithout roofo verh angswere simu -
room s, the atrium space was divid ed into 31 z ones in 6 lev- lated an d their pred icted results were compared to ex amine
els (Fig . 4). The me asurem ent was carr ied o ut i n previ ou s s tudy theco ntri bution ofroofo verhang sinm inimising the effectof
(Ab dulla he tal., 2009). sola rradiationon t heth ermalperfo rm ancewithin th eside- lit
atrium .Thede pth of theroof overhangsab ovethe cle restory

2.7. Themodelandparametricstudy areaswas1.5m,whichwascalculatedtobesufficienttoblock

directsunlightfromenteringthroughclerestorywindows(less
IntheDTMmodels,thebuildingelementssuchasfloor,roof, than2 .75mhe ight) duetot helowes tsolaralti tudeof6 3◦ in

wall and glazing constructions were all specified from the TAS equatorialregionsinJanuary(Ahmad&Rasdi,2000);forthese

ConstructionDatabasewithreferencetocommonMalaysianprac- simulations,theweatherconditionsandthesizeofopenings

tice (Abdullah, 2007). The ground floor was simulated as being were similar to that of number (iii) above. Apart from simu-

constructed on grade without a false floor, and it U-value was lationforday21stMarch,themodelswerealsosimulatedfor
0.29W/m2K .In termed iatefloor s hadU -value of0 .95 W/m2K .The 21stJu ne, 21st Sept embera nd2 1stDec embe r.The sesimulat ion

hipped roofs surrounding the wall-to-roof void areas and above dayswereparticularlyconsideredtoexaminetheeffectofSun’s
14 A.H.Abdullah,F.Wang/SustainableCitiesandSociety2 (2012) 8–28

Fig.4. TheTASmodelcreatedtorepresentthevalidationbuilding.(a)Themeasured/predictedairtemperaturesaveragedovereachlevelforhotandovercastday(26thof

July).(b)Themeasured/predictedairtemperaturesaveragedovereachfloorforhotandclearday(27thofJuly).(c)Themeasured/predictedresultanttemperaturesandroof

blindssurfacetemperaturesforhotandclearday(simulationday208).(d)Themeasured/predictedairandmeanradianttemperaturesaveragedovereachlevelat1400h

duringtheclearday.

altitudeandsolarradiationintensityduetoseasonalchanges clerestoryfacade.Thesenewbuildingelementswerespecifi-

ontheatriumthermalperformance. callyputintothesubstitutebuildingelementandsubstitution

(v) With and without internal solar blinds – the representative schedule columns of the original building elements for both

models(withoutinternalsolarblinds)andmodelswithinternal atriumroofglassandclearglasswindow.

solarblindsweresimulatedandtheirresultswerecomparedto

examinetheeffectivenessofthesolarblindsinimprovingthe 3. Resultsanddiscussion

atrium’sthermalconditionsparticularlyonoccupiedlevels.The

sameweatherconditionsandsizeofopeningsasthatofnum- 3.1. Resultofvalidation

ber(iii)and(iv)wereusedforthesesimulations.Inorderto

simulatetheatriumthermalconditionswhentheblindswere Fig.5(a)and(b)showsthatthesimulationresultstendtobe

extendedfrom0900to1800h,thenewsubstitutebuildingele- overestimatedforbothfirstandsecondfloors.Inadditiontothe

ments were created to represent both the atrium roof glass dissimilarityinweatherconditions,thediscrepanciesbetweenthe

withblindsandclearglasswindows/wallswithblindsatthe measuredandpredictedresultsmightalsobeduetothefollowings:
A.H.Abdullah,F.Wang/SustainableCitiesandSociety2 (2012) 8–28 15

• Asaresultofuncertaintiesaboutthethermalpropertiesofthe that of the model; thus, resulting in higher prediction of the

existingconstructionmaterials,thethermalpropertiesofbuild- indoornetheatgaininthemodel.
ingelem entsincludin gtheglaz edo penings ofthemo de lwere • In the real buil ding , th ere were numerous infiltration airflow

estimatedandspecifiedusingtheconstructiondetailsprogram- pathswhichallowedtheindoorheattobedissipated.However,

merinbuildingdataeditor.Inaccuratespecificationsofthermal inthemodeltheinfiltrationrateswerefixedandthevaluescould

propertydata,particularlyfortheglazedroofandwalls,hadledto bemuchlowerthanthatoftherealbuilding.Hence,lessheatdis-

higherpredictionofsolarpenetrationinthemodel,whereasin sipationinthemodelledtohigherpredictionoftheindoorheat

therealbuildingsolarpenetrationcouldbemuchsmallerthan gain.

Fig.5. Comparisonbetweenthepredictedandmeasureddataofthevalidationcase.
16 A.H.Abdullah,F.Wang/SustainableCitiesandSociety2 (2012) 8–28

Fig.5. (continued).

• Inthemodel,thefixedinternalconditionswerespecifiedbased resultsshowareasonablygoodagreementwiththemeasureddata

on general assumptions and estimations. There is a tendency asrevealedbyFig.5(b).Similartotheresultsforhotandovercast

fortheheatgainsfromoccupants,lightingandequipmenttobe day,thediscrepanciesbetweenthemeasuredandpredictedresults

overestimatedinthemodelsincetheoccupancypatternandthe generallyoccurfromearlymorningtoaboutnoon.Anexplanation

useoflightingandequipmentintherealconditionsweresome- forthiscouldbeduetothelargethermalstorageeffectcalculated

whatirregular.Moreover,thereisalsoagreatpossibilitythatthe byTAS,whichwascarriedontothesimulationday,as10-daypre-

infiltration rates and conditioned air supply rates were under- conditioningperiodwasconsideredforthesemodellings.Therefore

estimatedduetotheuncertaintiesoftheactualflowratesand thehighairtemperatureduetothermalstorageeffectofthestruc-

uncontrolledactionsoftheusersintherealbuilding.Allthese ture calculated by TAS a few days prior to the simulation day

wouldresultinhigherpredictionoftheindoorheatgaininthe affected the air temperature of the simulation particularly from

model. earlymorningtoaboutnoon.However,astheSun’saltitudegets

higher,andsincesolarradiationisthedominantfactoraffecting

However,bothgraphsaboveshowsimilartrendwhichindicates thermalconditionwithinabuildingwithlargeglazedenclosures,

thatthetemperaturestratificationwouldoccurathighlevelinside acorrectsolarpredictioncouldcoverallsmallerrorswhichsubse-

theatriumwheretheindoorairtemperatureonthesecondflooris quentlyledtomorereasonableoverallresultsparticularlyonthe

wellabovetheoutdoorairtemperature.Forovercastdaythedif- secondfloor.

ferenceinairtemperaturebetweenthefirstandsecondfloorsat In general for both simulation days, the predicted and mea-

1500h(thehottesthouroftheday)was9.3Kformeasuredand8K sured air temperatures on the second floor agree considerably

forTASpredictionresultsrespectively.Forclearday(day208),on wellparticularlyfromnoontomidnight.However,fromlatenight

theotherhand,theairtemperaturedifferenceat1400h(thehottest to around noon the predicted results were generally overesti-

hour of the day) was 11K and 9.9K for measured and predicted mated, and particularly between 0800 and 1100h the predicted

resultsrespectively.Theseresultsrevealedthatduringthehottest and measured air temperature show considerably large differ-

hourofthedaythemeasuredconditionsrecordedslightlyhigher ences. On the contrary, predicted air temperatures on the first

airtemperaturedifferencebetweenthefirstandsecondfloorscom- floor are slightly underestimated from 1900h to about mid-

pared to that predicted by TAS. In general for both overcast and night.

cleardaysthepredictedairtemperaturesonthefirstfloorinthe Thereasonforthelargediscrepanciesbetweenmeasuredand

afternoonwascomparativelyhigherthanthemeasuredconditions. predictedairtemperaturesonthesecondfloorisapparentlydue

Thedifferenceinairtemperatureonthefirstfloorintheafternoon to the large overestimation of internal surfaces temperatures by

betweenmeasuredconditionandTASpredictionwasintherange TAS(asdepictedbyhigherpredictionofbothresultanttempera-

of0.7–1.5Kforovercastdayand0.2–1.3Kforcleardayrespectively. tureandblindsurfacetemperatureinFig.5(c).Therefore,atnight

Basicallythehigherairtemperatureonthesecondfloorwasdueto whentheexternalairtemperaturedrops,TAStookintoaccountthe

thefactthattherewasnoprovisionofrooftopventtoexhaustthe heatreleasedbythehotinternalsurfaces,whichledtotherisein

stratifiedhotairathigherleveloutofthebuilding. airtemperaturewithintheatriumparticularlyonhigherlevel.The

ItwasfoundinFig.5(a)thatforhotandovercastday,itwas samesituationappliestothefirstfloorlevelwherethepredicted

noteasytoestimateandmodifytheamountofsolarradiationand air temperature is generally greater than the measured air tem-

cloudinesscomparedtothatofthehotandclearday,astherewas perature.However,whenthesolarblindswerefullyretractedat

considerable discrepancies between predicted and measured air 1800h,thepredictedairtemperaturesfellbelowthemeasuredair

temperatureonthesecondfloorparticularlyfromearlymorningto temperaturesstartingfromabout1900htomidnightastheeffect

1200hwherethedifferencesrangedfrom1.5to4.3K.Ontheother ofblind’ssurfacetemperaturewasnotconsidered.

hand,thepredictedresultsonthefirstflooragreereasonablywell ItcanbeclearlyseenfromFig.5(c)and(d)thateventhough

withthemeasuredairtemperatureseventhoughTAScalculations themeasuredandpredictedairtemperaturesonthesecondfloor

tendtobeoverestimated. differslightly,theTASpredictionofresultant/meanradianttem-

However,duringhotandcleardaywhenthewaterspraywas peratureswasrelativelyhigherthanthemeasurement.Thereason

turnedoffandthesolarblindswereextended,theTASprediction wasthatintheDTMmodel,theblindswereassumedtocoverthe