EVIDENCE-BASEDANALYSISREPORT:CLIMATE6A
HardiShah,Student UniversityofPennsylvania,Philadelphia,PAAbstract
Thispapercoverstheworkflows,decision-making,and finalresultsofasimulationstudyperformedona shoeboxmodelofanapartmentwithabedroomand officeprograminAugusta,Maine.Afteranalyzingthe climateandsitetoidentifyenvironmentalproperties affectingthemodel,thebaselinecasewassimulatedand analyzedfordaylightandthermalcomfortconditions. Pointsofimprovementwerethenidentified.Basedon thosepoints,variableswerechosentoiterateand determinetheresultwiththebest-balancedconditions Fromthere,multiplestepsoftheiterativeprocesswere conductedbywayofthesameprocess:identifying concernsfollowedbyiteratingimpactful,relevant variablesandthenselectingtheidealoptionwith balancedresultantdaylightingandthermalcomfort conditions Theconcludedversionoftheshoeboxmodel showsoveralldaylightingandthermalimprovementfrom thebaselineandabenchmarkinganalysisisperformedto depictit Theoverallstudywasconductedusingthe followingprograms:Rhinoceros,Grasshopper,Ladybug, Honeybee,andDesignExplorer.
TheSite-Augusta,Maine
AugustaisthecapitalcityofMaineinthenortheast UnitedStates AccordingtoASHRAE,thecityislocated inclimatezone6A,acold,moistclimate.The DepartmentofEnergy’sTMY3filewaschosenforthe studywithdatacollectedneartheAugustaairport Itis importanttonotethatthelocationofrecordeddataisnot thesameasthelocationofthesiteforthestudywhich wouldresultinsomedifferencesinmicroclimatemaking theresultsnotdirectlyapplicable Thesimulationshould beaddressedsubjectivelytakingthosenuancesin microclimateintoaccountandadjustedperaprojectsite nearAugusta
TheClimate-Zone6A
Themacroclimateanalysisforthisclimatefocusedonthe overalltemperaturerangesintheareathroughoutthe year,therelativehumiditylevels,andthesolarangles
throughouttheyear Thewindwasnotconsideredtoo heavilyduetotheficklenatureofwindbeingsohighly dependentonimmediatesurroundingswhicharevery differentfromanydatathatwouldbecollectedonan airportsite Uponinvestigation,itwasfoundthat64%of hoursareoutsidethecomfortablerelativehumidityrange between40and70percent Alargeportionofthose hoursisover70%humidityasidentifiedonagenerated psychrometricchart.Thedewpointtemperaturewas assumedtobeamoreaccuraterepresentationofthe seasonaltemperaturesduetothepresenceofhigh humidityyear-round Theassumedcomfortable temperaturewasassumedtobeanythingabove18oC takingintoaccountthelikelihoodthatindividualsinthis areawouldhaveahighertolerancetocooler temperaturesthanthetypicallyassumedcomfortable temperaturerangeof22oC-26oC) Thesummershave a fewhoursabove18oCandthetemperaturepeaksat around28oC.Itisacceptabletoassumethatthemajority oftheyearhaslowerthancomfortabletemperaturesand thereforehasahighheatingload Basedontheclimate analysis,94%ofhoursarebelow18oCdewpoint temperature.
Image 2.2: Psychrometric Chart with Established Comfort Hours Identified
TheBuilding&Unit
Theshoeboxmodelislocatedonthe5 6-storymid-rise,wood-framedresiden fabricofAugusta,Maineislargelylow structureswithinterspersedopenlands tothis,thebuildingissurroundedby2 structures,leavingthe5thfloorunobst elementsineverydirection Thesolar buildingonthesiteisheaviestonthes theeastandwestreceivedabitlessan receivesnone However,evenatthepe onthebuildingisquitelowat25kWh/m2 sowhileit mightnotimpartmuchlongwaveradiationandprovide heat,itwillstillplayabigroleindaylighting.Totake advantageoftheavailableradiation,thebuildingis orientedwithalongersouthfacade
Image 3.1: Building & Site (left)
Theunitonthe5thfloorisa15mx10m,150m2 residentialprogram.Basedonthesiteanalysisthatwas done,theofficeprogramwasplacedontheeastsoit wouldreceivemoredaylightduringoccupiedhoursfor thatprogramtype.Becausetherearefloorsaboveand belowthetestedunit,thefloorandceilingoftheunitare assumedtobeadiabatic Thebaselinewindowwallratios
inthebedroom.UponanalyzingtheUDIdaylightingand thePMVcomfortconditions,thefollowingconclusions weremade:
● TheAverageUDIintheofficeislowerthanin thebedroom Itneedstobeincreasedtoatleast 50%.Duetothenatureoftheprogramandthe occupancybeinglargelybetween8AMand6 PM,improvingusefuldaylightingconditionsin nt
r2000luxis ncethatistoo ce.Infrontof 00lux50%of hichneedstobe mfortable lycool,the 50%ofthe thebaseline nergyusagefor
theunit.Thechartsdepictedthatthelargestloadforthe unitisheatingwhichisaccuratetotheassumption The glareanalysiswasconductedforapersonsittingonthe couchinthebedroomfacingsouthandforaperson sittingatthedeskfacingeastforthebaselinecondition Itwasrevealedthatalargeportionoftheviewsfromthat angleonthecouchanddeskthatwerechosenhavea veryhighchanceofvisualdiscomfort Theglareanalysis forthefinaliterationmustbeconductedforadifferent furniturelayoutoradifferentanglewithrespecttothe southwindow.
TheFirstRoundofIteration
UnitLength,WWR,andWindowU-Value
Theiterationsweregroupedintotworounds:thefirst wouldidentifyacasewithabalancebetweenthermal comfortandproperdaylighting,andthesecondwould focusonreducingtheEnergyUseIntensity.
comfort.ItwasalsonotedthattheU-valueshada negativerelationshipwiththermalcomfortandapositive relationshipwiththeEUIasexpected Thelowerthe U-value,thehigherthethermalcomfortandthelowerthe EUI AnimportantthingtonoteistherangeofEUI increasedfromthebaselinebutbecausethisiteration prioritizedimprovingdaylighting&comfort,theEUIis prioritizedinthesecondroundofiteration
Image 5 4a: Identifying Both Results
Forthe wouldb dayligh Threeb WWRs resultin wallrat dayligh impacti opening radiationlevels.TheU-valuewilldirectlyimpactthermal comfortbyinsulatingthespaceandretaininginternal heatgaininacoldclimate
The81iterationsweredepictedinDesignExplorerand thenfilteredtoidentifythetwobestoptions Forthefirst option,thehighestAverageUDIwasprioritized especiallyintheofficespace Forthesecondoption,the highest%oftimeincomfortintheofficeandbedroom wasprioritized.Uponfurtherinspectionofthefinaltwo options,itwasnoticedthattheWWRcombinationsfor bothwerethesamebuttheunitlengthsweredifferent The20munitlengthresultedinahigherUDIwhilethe 15mlengthoptionresultedinahigher%oftimein
Image 5.4b: Identifying Both Results WindowU-Value
Tomakeamoreinformeddecision,theU-value032and thetworesultantlengthswereiteratedwiththreelower U-values BecauseoftheU-value'srelationshipwith thermalcomfortandEUI,these8iterationswouldhelp establishabestcaseassumingtheUDIvalueswould remainintheacceptablerangeastheU-valuewouldnot impactthedaylighting Oncetheresultswereavailable,
theoptionwiththehighest%oftimecomfortable& PMVcomfortandwinter-timeMeanRadiant Temperaturehasselected:a20munitlengthwitha U-Valueof0.1resultinginalmost20kWh/m2 lessEUI andslightlyhigher%PPDcomfortthantheprevioustwo options Tovisualizethecomfortinthespace(seeImage 5.6intheappendix),thePMVcomfort(anyvalues betweenslightlywarmandslightlycool)wasanalyzed and100%PMVcomfortisachievedinbothspaces
The%oftimecomfortableis6%lowerinthebedroom and2%lowerintheofficethaninthebaselinedespite improvingthewindowU-valueanditerating window-to-wallratiosandbuildingdimensions However,thisnewoptionimprovestheUDIconditions whichareofhighconcerninourprogram.Comparedto thebaseline,theUDIforthebedroomincreasedbyabout 4kWh/m2 whilefortheofficeitincreasedby22kWh/m2 Totrytofindabalancebetweentheimproved daylightingconditionsthatareachievedinthisstepwhile increasingcomfortandreducingEUI,thenextroundof iterationschangesthewallR-value
TheSecondRoundofIteration
WallR-Value
Fromhere,theR-valuesneededtobeassessedfurtherto seeiftheywouldbringdowntheEUI R-valuehasa positiverelationshipwiththeinsulativepropertiesofa structuresoinacold,climateahigherR-valuewould
comfortlevelswouldbebetterthanbefore.Buttherange oftheoutputswasnottoomuchbetterthantheprevious resultintermsofPPD&PMVthermalcomfortandEUI TofurthertrytoreducetheEUIandincreasecomfortand wintertimeMRT,otherfactorssuchasinfiltrationand occupancyschedulesneededtobeadjusted Asaresult, wewilluseR-32forthewallsmovingforward.
InfiltrationRate
ThenextsteptoreducetheEUIandincreasethermal comfortwastoassignalowinfiltrationratetosignifya tightbuildingandassignoccupancyschedulesspecificto thetwoprograms Torecounttheestablishedparameters thatimpactthermalcomfort:thewallR-valueishighat R-32andthewindowU-valueislowat0.1.Theunit dimensionsandWWRswereestablishedthroughthe previousiterationoftheprocesstoimprovetheUDIand DAvalues.Thesebuildingmetricsthatwereconcluded werethentestedwiththreeinfiltrationratestoreducethe EUIandincreasecomfort
Image 6 1: Second Round of Iteration - R-Value
AccordingtothetypicalrelationshipbetweenR-value andthermalcomfort,itwasexpectedthattheEUIand
Theinfiltrationrateshadapositiverelationshipwiththe EUI Thelowertheinfiltration,thelowertheEUI The bestinfiltrationratewasfoundtobe0.0001m3/s-m2 signifyingatightbuildingenvelope.Theoccupancy schedulesindicatedthehoursofoccupancyforthespace informingthesimulationofwhenthespacewouldlikely beusedduringthecourseoftheday,resultinginmore accuratevaluesofenergyloads TheresultingtotalEUI isthelowestithasbeensofarat19604kWh/m2 witha lowinfiltrationrate.TheheatingEUIhascomedownby almost50kWh/m2 However,thecoolingEUIhas increasedbyabout20kWh/m2 Theheatingloadsthat werecreatedbyinfiltrationarenowreducedinthenew unit.Basedonthebalancechart,thesolargaininthe summermonthsiscreatingtheneedformechanical cooling
TheFinalRoundofIteration Shading
Afteranalyzingdaylightingmetricsandthebalancechart fortheresultingoption,aneedtoimproveusefulUDI andreducecoolingend-useloadwasidentified Tomore selectivelyimprovetheUDIandcoolingend-useload,
shadingcouldbeappliedatvaryingdepthstocutoff specificsunanglesinthesummerandspring Because theexcessiveUDIvalues(above2000lux)wereallright infrontofthewindow,itisdeducedthatsteepsunangles inthesummermonthscontributegreatly Tocombatthis, threedepthsforshadingonallfacadesweretested:03m, 0.6m,and1m. The0.6mdeepshadingprovidedthe lowestEUIofthethreeoptions Metricsarecomparedto thepreviousunshadedoptionbelow e months,thelargesolargainand l inlowerheatingloads Inthe s , r,thoseparametersresultina highercoolingload.Becausetheclimateislargely dependentonheatingratherthancoolingformoretime intheyear,thereductioninheatingloadisprioritized Introducingnaturalventilationinthesummermonths wouldfurtherreducethecoolingloadandthereforethe totalEUI Thesolargainintheoptionwithshadesis lowerresultinginalowercoolingEUI.Overalladding shadinghelpedreducetheEUIslightlybutitalsoresults inamorebalancedUDIdaylightinginbothrooms
Image 7 2a: Final Iteration UDI within range
Image 7 2b: Final Iteration UDI above 2000 lux
Image 7.2c: Final Iteration - Thermal Comfort
Theglarewasabigissueinthebaselinecasewithmost ofthepointsintimethatwereanalyzedbeingvery visuallyuncomfortablewithhighglare Inthefinal iteration,theinteriorwasarrangedandtheviewwas rotatedtobeperpendiculartotheincomingsourceof light Withthelargestsourceoflightbeingfromthe southinthebedroom,thecouchisfacedwest Inthe office,thedeskwasturned180o tothewesttoavoid directglarefromthesouthandeast.
