4final cw design analysis

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IV.CurtainWallDesignAnalysisIntroductionThebuildingsfaadeisprimarilyaglazedaluminumcurtainwallwiththeexceptionofsomeareas

aroundtheparkinggarage.Thecurtainwalltiesintothecastinplaceconcretestructurethroughsteelanchorplates.Onthewestelevation,thecurtainwallisslopedoutwardat5.63oallthewayfromlobby

flooruptotheroofofthebuilding. TheslopeofthecurtainwallcanbeseeninFigure4.1outlinedby

thearrowinthebox.

Figure4.1:SouthElevation

ProblemStatementThisdesignaddstothecomplexityofconstructingthecurtainwall.Thecomplexitycomesfromhaving

toinstalldifferentshapedpiecesofglassatdifferentangles.Figure4.2showstheslopedwalljoiningthe

verticalwallwhereuniquecurtainwallpanelswillbenecessary.Thedifferentshapedpiecesofglass

necessarywilladdtothecostsincethiseliminatestheopportunitytoorderinamassquantity.Thiscurtainwalldesignalsoeliminatessomefloorareaofthebuildingonthelowerlevels.Iftheslopeis

eliminatedandmoresquarefootageisprovided,theownercouldincreasethecosttoitstenants

becauseheisprovidingmoreleasablearea.

Figure4.2:WestElevation


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AnalysisGoalThegoalofthisanalysisistounderstandwhattheimplicationsareofeliminatingtheslopeinthecurtain

wall.Eliminatingtheslopewillbedonebyextendingtheshorterhorizontaldistancetolineupinthe

sameplaneasthelongerhorizontaldistanceatthetopofthebuilding.ThiscanbeseeninFigure4.3.

Thiswouldprovidemoresquarefootagetothebuildingsleasingarea.Addingmoresquarefootage

requiresaddingmoreconcreteslabareatothefloorplan.Thiswillchangethedemandsofthestructure,

specificallythecolumnslocatednearthecurtainwall.Changingtheslopeofthecurtainwallwillaffect

howthesunshinesthroughtheglazing.Ifthenewsunanglesonthefaadechangesinawaythat

increasessolargainthroughthewindowsignificantly,itcouldheightentheenergydemandsofthe

coolingsystemduringthesummermonths.

Figure4.3:CurtainWallExtension

AnalysisMethodsThefirstsectionofthisanalysiswillconsidertheareagainedwithanexpandedfloorplan.Floorplans

areprovidedtoobtainaclearerpictureoftheadvantageswithextendingthefloorplan.Atableis

includedthatprovidestheamountofextrasquarefootageaddedtothefloorplans.Finally,withthe

additionalfloorarea,theextramoneytheownercanobtainfromthisnewleasableareaissuggested.

Thesecondsectionanalyzesthenewdemandsofthestructuretosupportthecurtainwallverticaltothe

ground.Itwillbenecessarytoaddanycolumns,beamsorjoiststosupporttheadditionalconcreteslab.

Afterthenecessarystructuralelementsareimplemented,theconstructioncostsoftheseitemsare

calculated.

Thethirdsectioninvolvesanalyzingthesolargainthroughthecurtainwall.Thelocationoftheproposedcurtainwallrevisionisonthewestelevation.Thesunanglesduringthelaterportionofthedaywillhave

themostimpactonthecurtainwall.Ifthesolargainisconsiderable,itmightchangetheenergy

demandsofthecoolingsystemduringthesummermonths.


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AdditionalAreaAnalysisByeliminatingtheslopeofthecurtainwallandextendingthewall,thefloorplanincreasesthesquare

footageavailable.Startingwiththeninthfloor,whichisthefirstofficelevel,themostareaisgainedand

theincrementsofareaobtainedslowlydeclinesasthewallextendstotherooflevel.Theareasgainedin

thefloorplanscanbeseeninFigure4.4.Aredboxoutlinesthenewareasobtained.Alsoindicatedin

Figure4.4isaredcircle,whichshowswherethefloorplancannotbeutilizedeffectively.Thetenant

mightfinditdifficulttolocateanofficearoundthecolumnneartheredcircle.Ifthefloorplanis

extended,theareacanbeutilizedmoreefficiently.

Figure4.4OfficeFloorPlans


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OfficeFloor Length Width AdditionalArea

9 12105/8 416 535ft2

10 115 416 475ft2

11 106 416 435ft2

12 88 416 362ft2

14 737/8 416 304ft2

15 5113/8 416 247ft2

16 46 416 190ft2

17 32 416 133ft2

18 19 416 75ft2

Total 2756ft2

Table4.1:AdditionalAreaProvidedperFloor

Eliminatingtheslopeinthecurtainwallandextendingthefloorplanprovidesanadditional2756ft2to

thebuilding.Table4.1showstheadditionalareaprovidedbyeachfloor.Thisallowstheownerto

chargemoretothetenantsforthemtoleasethespace.Byobservingrentcoststhatotherownersare

charging,itcanbeestimatedthattherent/ft2/yearforMain&Gervaisisaround$21.00/ft2/year. At

$21.00/ft2/yeartheownercouldchargeanadditional$57,876.00eachyeartoitstenants.Afterten

years,thatamountwouldreachoverhalfamilliondollars.Thisisaconsiderableamountofmoneyto

convincetheownertoconsidertheoptionofeliminatingtheslope.

(ft2) (rent/ft2/year) (rent/year) (tenyears)

2756 $ 21.00 $ 57,876.00 $ 578,760.00

Table4.2:ProposedRentCosts

StructuralLoadAnalysis(StructuralBreadth)Theproposedmethodofaddingareatothebuildingsfootprintrequiresastructuralanalysisto

determinewhethertheadditionisacceptable.Mostlikely,additionalsupportisnecessarytomaintain

structuralintegrity.Thisisdonebyaddinganadditionalcolumnandjoisttoeachflooroftheoffice

tower.Also,thebeamthatislocatedontheperimeterbetweentheproposedcolumnandexisting

columnneedstoberesized.Thefollowinganalysisprovidesthestructuraladjustmentnecessaryto

allowthecurtainwallextension.

Thefirstsectionofthisanalysisdisplaysthelocationofthenewcolumnsinthebuildingandthe

calculationstoverifytheapplication.Thesecondsectionindicateswhichbeamneedsreplacementto

supporttheadditionalloads.Thethirdsectionprovidestheadditionalcoststhataccompanytheextra

joists,columns,andslabs.

TheprogrampcaColumnwasutilizedforthecolumnanalysis.RAMConceptwasusedtoanalyzethe

beamtoreplacetheexistingbeambecauseeliminatethebeamisposttensioned.Handcalculations

wereperformedwherenecessary.


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ColumnAdditionCalculationThecornerofthebuildingwherethereisoriginallynothingwillnowrequireacolumntosupportthe

additionalloadplacedonthelargerconcreteslabitsupports.Thenewcolumnplacementcanbeseenin

Figure4.5.Thenecessityofthiscolumnisbasedontheassumptionofsymmetry.Atthetopleftofthe

floorplan,thereisacolumnlocatedinthecorner.Thespanisthesameasinthelowerlefthandcorner;

thereforeacolumnisnecessarytomaintainthestructuralintegrityofthebuilding.

Figure4.5:ColumnPlacement

Thisplacementofthecolumniscontinuousonalltheofficefloors.Therearenineofficefloors;

thereforeitisnecessarytoaddninecolumns(oneforeachfloor).Sincethecolumnloadsdecreaseas

thelevelsgethigher,implementingasmallersecondcolumnispossible.Asecondcolumnwithdifferent

propertiesisplacedonfloorsfifteenthrougheighteeninthenorthwestcorner.Thissamedesignisappliedtothesouthwestcorner.Thefirstcolumn(columnA)proposedisacircularcolumn.Itsdiameter

is30andstands13tall.Thereare(16)#9verticalbarswith#[email protected]

upofconcretewithacompressionstrengthof7000psi.Thesecondcolumn(columnB)proposedisa

circularcolumnwiththesamedimensionsbuttheconcretepropertiesarechanged.Thecompression

strengthoftheconcretecansustainareductionto5000psi.


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Severalcalculationsarenecessarytoverifythatthecolumncansupportitsloads.Itisnecessaryto

considerthedeadloadandliveload.Thewindloadisnotconsideredinthesecalculationsasthedead

loadandliveloadarefactoredtocompensate.Theaxialloadiscalculatedafterthefactoredloadsare

determined.EnteringthepropertiesofthecolumnsintopcaColumnprovidethemaxloadsthecolumns

canwithstand.Ifthecalculatedaxialloadsareunderthismax,thenthecolumnisstrongenough.

StructuralLoads

LiveLoad(psf) DeadLoad(psf) Column(lb/ft3)

120 63 150

Table4.3:StructuralLoads

Load Factor FactoredLoad Units

Live 120 1.6 192 psf

Dead 63 1.2 75.6 psf

Column 9572 1.2 11486 pounds

Table4.4:FactoredLoads

Table4.3providesthestructuralloadsandTable4.4showstheseloadsfactoredtocalculatetheaxial

loadingonthecolumn.Thefactoredloadsarecalculatedasfollows.

LiveLoadCalculation:o

100 20 120 DeadLoadCalculation(floorslab):

o 150 9572

ColumnLoadCalculation:o

150

13 9572

Column Floor n At(ft2) TotalLoad(ksf) ColumnLoad(kips) AxialLoad(kips)

A 9 9 225 0.268 11.5 634

B 15 4 225 0.268 11.5 275

Table4.5:AxialLoads


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Table4.5displaystheaxialloadsoncolumnAandcolumnB.ColumnAisthestrongercolumnbecause

itissupportingmoreloadsaboveit.Anyfloorsaboveitwilltakefewerloadsthanthecolumnbelowit;

thereforeitisredundanttocalculatefloorstenthroughfourteen.ColumnBsupportslessthereforeit

usesconcretewithlesscompressivestrength.Theaxialloadsarecalculatedasfollows.

1 ColumnA(floor9):

o 9 225 0.268 9 1 11.5 634

ColumnB(floor15):o 4 225 0.268 4 1 11.5

275

Figure4.6:pcaColumnDiagram(ColumnB) Figure4.7:pcaColumnDiagram(ColumnA)

Figure4.6and4.7arediagramsthatdisplaythegraphsobtainedfrompcaColumn.Thesearejustthe

graphs;thewholesheetsarelocatedinAppendixE.Asseeninthefiguresindicatedbytheredcircle,

thecalculatedaxialloadsfallwellwithintheallowableload.Thelineisextendedtotherightto

determinethemaxmomentthecolumnscanwithstand.Thisshowsthatthecolumnisstrongenoughto

resistthelateralloads(windloads).Thesecolumnsaresufficientenoughtosupportthestructuralloads.


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BeamReplacementCalculationExtendingthefloorplanwillincreasethespandistancebetweenthecolumns.Thisresultrequires

resizingthebeamtosupportthenewloadappliedtotheslab.Thisassumptionisbasedonsymmetry.

Theothersideofthebuilding,ortheothersideofthereddashedlineinFigure4.8,showsthatalarger

beamisnecessarytosupporttheloadgiventhelargerarea. Figure4.8alsodisplayswheretheexisting

beamisandthenewbeamslocationforlevelnine.

Figure4.8:BeamReplacement

Theexistingbeamis23inchesinwidthand21inchesdeepandisoutlinedaboveinreddashmarks.

Thereplacementbeamis36incheswideand21inchesindepth.Thereinforcementforeachofthe

beamschangesaswell.ThesechangesaredisplayedinTable4.6.Theexistingbeamisidentifiedby

WB26,thesecondrow.AndtheproposedbeamisidentifiedbyWB3,locatedinthefirstrow.


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Table4.6:ReinforcementProperties

AllthisinformationpresentedinthefiguresandtablesisnecessarytoutilizeRAMConcept.Thestrip

wizardinRAMConceptissimpleenoughforthisapplication.ThemodeldrawninRAMisshowninFigure4.9.Thebeamintheleftportionofthefigureisthebeamofinterest.Main&Gervaisisapost

tensionedcastinconcretestructure,meaningthatthestructuralintegrityofonebeamisdependenton

thesurroundingstructuralelements.Becauseofthis,thebeamsalongthesamecolumnlinewere

consideredtoo.

Figure4.9:ModelPlanfromRAMConcept

Toestablishthismodel,thefollowingpropertieswereinputtedintotheprogram.Theloadsappliedto

thestructurearethesameaspresentedinTable4.3.Concretepropertiesare5000psifortheslabsand

beamsand6000psiforthecolumns.RebarandposttensioningpropertiesaretakenfromTable4.6.All

otherinputsarelocatedinAppendixF.

Figure4.10:StatusPlanfromRAMConcept

AsshowninFigure4.10,thebeamisstructurallystrongenoughtosupporttheloadsappliedtoit.Thisis

justfortowerfloorlevelnine.Thereareeightmorefloorsofofficeabovethisfloorthatrequireresizing

ofthesamebeams.Itisassumedthattheproposedbeamwillsufficeintherestofthefloors.Thisis

becausethescenarioissimilarforeachofthefloors.

JoistAdditionAssumptionItisassumedthatadditionaljoistsarenecessaryfortheproposedfloorplan.ByobservingFigure4.11,it

isshownbysymmetrythatthejoistinthetopleftportionofthefloorplanisnecessaryinthelowerleft

handcornerifthefloorplanisextended. Additionalcalculationsarenotnecessaryasitwillbe

redundantconsideringtheprevioussection,BeamReplacementCalculation.Thissectionconsideredtheloadimplicationsforthefloorareaabovethereplacementbeam,whicharesimilartothatwhichthe

loadsthejoistsaresupporting.Basedonthesymmetryofthedesignandtheverificationfromthe

calculationsintheprevioussection,the14wideand21deepjoistintheupperleftareaissufficientto


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supporttheadditionalfloorarea.Thisassumptionisappliedtoalltheofficelevels.Thisrequiresan

additionalninejoiststobridgethegapbetweenthebeams,oneforeachfloor.

Figure4.11:JoistPlacement

ConstructionCostsTheadditionalcolumns,joists,andslabswillrequireadditionalmaterial.Themainmaterialsrequired

areconcreteandreinforcementbarssinceeachoftheadditionalitemsarecastinplaceconcrete. The

castinplaceconcreteisdesignedforposttensioningexceptforthecolumns.Itisassumedthatthereis

noadditionalformworkcostsbecauseeachoftheitemsexistsonthedrawings.Inthiscase,the

formworkisalreadypurchased.Thedifferenceforconstructioncostsinthereplacementbeamsandthe

existingisminimalandnotconsideredinTable4.7.

Item Description Count Unit Material Labor Equip. Cost/Unit Total

Concrete 5000psi(elevatedslabs) 40 CY $ 109.00 $ 109.00 $ 4,360.00

6000psi(joists) 40 CY $ 124.00 $ 124.00 $ 4,960.00

8000psi(columns) 36 CY $ 203.00 $ 203.00 $ 7,308.00

Rebar Joists,#8to#18 1.89 tons $ 980.00 $ 520.00 $1,500.00 $ 2,835.00


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Columns,#8to#18 0.76 tons $ 980.00 $ 600.00 $1,580.00 $ 1,200.80

ElevatedSlabs,#4to#7 0.86 tons $ 1,020.00 $ 480.00 $1,500.00 $ 1,290.00

Placement Joists,crane&bucket 40 CY $ 52.50 $ 26.50 $ 79.00 $ 3,160.00

Columns," 36 CY $ 23.50 $ 11.90 $ 35.40 $ 1,274.40

ElevatedSlabs," 40 CY $ 21.50 $ 10.80 $ 32.30 $ 1,292.00

Prestressing PT,50'span,300kip 0.84 tons 1820 $ 1,860.00 $ 80.00 $3,760.00 $ 3,147.87

Total $ 30,828.07

Table4.7:ConstructionCosts

AsshowninTable4.7,thetotaladditionalcostofextendingthecurtainwallamountsto$30,828.07.

SolarHeatGainAnalysis(MechanicalBreadth)Theoriginaldesignforthecurtainwallisslopedonthewestfaade.Thewaythesunshinesinonsloped

glazingdiffersfromthewayitshinesinonverticalglazing.Theangleofincidenceofthesunchangesfor

thetiltintheglazing.Therefore,thereflectivityoftheglassisgoingtochangeatadifferentangle.The

followinganalysisobservesthecurrentdesignofthecurtainwallandcomparesittotheproposed

method.

Thefirsttwosectionsprovidecalculationsandtheirrespectiveresultsforthetotalsolarradiationonthe

glazing.ThethirdsectionprovidesameansofmeasuringwindowheatgainforMain&Gervais.Thelast

sectioncomparesthecurrentstateofMain&Gervaisandtheproposeddesignforthecurtainwallon

thewestelevationintermsofenergyexpenses.

CalculationmethodsandsolardatawereobtainedfromHeating,Ventilating,andAirConditioning,6thEditionbyMcQuiston,Parker,andSpitler.SunangleswereobtainedbySustainablebyDesignatwww.susdesign.com/sunposition.InformationwasobtainedfromtheASHRAEHandbook,2005aswell.SlopedFaadeSolarRadiationCalculationToobtainthesolarradiationforthewestfaade,itisnecessarytocalculatethedirectradiation,diffuse

radiation,andreflectedradiation.Thesummationofthesevalueswillprovidethetotalradiationona

slopedsurface,specificallythewestfaadeofMain&Gervais.Thissectionprovidesthemeansof

obtainingthesevalues.Thefirstsubsectionincludesthecalculationsnecessaryandthenthefollowing

subsectionappliesthesecalculationstoMain&Gervais.

CalculationSteps

Thefollowingstepsincludethecalculationsnecessarytoobtaintheamountoftotalsolarradiationontheslopedcurtainwallfaade.

Step1

Calculatenormaldirectirradiation,GND(btu/hrft2)


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o A=apparentsolarirradiationatairmassequaltozero(btu/hrft2)o B=atmosphericextinctioncoefficiento =solaraltitudeangleo CN=clearnessnumber

Step2

Calculatedirectradiation,GD(btu/hrft2) cos

o GND=normaldirectionirradiationo =angleofincidence

cos cos cos sin sin cos =solaraltitudeangle =surfacesolarazimuth =angleoftiltforanarbitrarysurface( inFigure4.12) Figure4.12displaystheseangles

Figure4.12:SolarAnglesforVerticalandHorizontalSurfaces

Step3

Calculatediffuseirradiation,Gd(btu/hrft2)

o C=dimensionlessfactoro GND=normaldirectionirradiationo Fws=fractionoftheenergythatleavesthesurfaceandstrikestheskydirectly


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Step4

Calculatereflectedirradiation,GR(btu/hrft2) o GtH=rateatwhichthetotalradiation(directplusdiffuse)strikesthehorizontalsurface

orgroundinfrontofthewall(btu/hrft2)

o g=reflectanceofgroundorhorizontalsurfaceo Fwg=configurationoranglefactorfromwalltoground,definedasthefractionofthe

radiationleavingthewallofinterestthatstrikesthehorizontalsurfaceorground

directly

=angleoftiltforanarbitrarysurface

Step5

CalculateGt,totalsolarradiation,bysummingGD(Step2),Gd(Step3),GR(Step4) cos sin

ApplicationtoMain&Gervais

Nowthatthestepstocalculatethetotalsolarradiationonaslopedsurfacehavebeenoutlined,itis

necessarytoapplythemtoMain&Gervaisinitscurrentstate.Theapplicationbelowissetfor3:00pm

onMay21,2009,at34latitude,whichiswhereColumbia,SouthCarolina,islocated.Table4.8provides

theinformationnecessarytocompletethestepslistedintheprevioussection.Thissectionwillprovide

asimpleversionofthecalculation.ThewrittencalculationscanbefoundinAppendixG.

SolarData SolarAngles SurfaceProperties

A=350.6btu/hrft2 =64.12 g=0.32(concrete)

B=0.177 =255

C=0.130 z=64.51

CN=0.94 =40.5

=95.63

Table4.8:InformationforMay21,2009inColumbia,SouthCarolina

. . . 0.94 o 270.71

cos cos 64.12cos 40.5 sin 95.63 sin64.12cos 95.63


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o cos 0.242 .

o 0.451 .

o 0.549 0.242 0.130.451 0.320.549 sin64.120.13270

o 124.22 ThetotalsolarradiationonMain&Gervaisslopedcurtainwallonthewestelevationat3:00pmMay

21,2009,is124.22btu/hrft2.AppendixHprovidesacomprehensivelistofvaluesforthe21stofMay,

June,July,andAugust.Thevalueslistedinthetableareonlyforthetimesinwhichthesunisshining

downonthewestfaade.Allotherpointsofthedayareirrelevantforthisanalysis.

VerticalFaadeSolarRadiationCalculationCalculationSteps

Thefollowingstepsincludethecalculationsnecessarytoobtaintheamounttotalsolarradiationonthe

proposedverticalcurtainwallfaade.

Step1

Calculatenormaldirectirradiation,GND(btu/hrft2)

o A=apparentsolarirradiationatairmassequaltozero(btu/hrft2)o B=atmosphericextinctioncoefficiento =solaraltitudeangleo CN=clearnessnumber

Step2

Calculatedirectradiation,GD(btu/hrft2)

cos

o GND=normaldirectionirradiationo =angleofincidence

cos cos cos =solaraltitudeangle =surfacesolarazimuth


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Step3

Calculatediffuseirradiation,Gd(btu/hrft2)

o 0.55 0.437 cos 0.313 cos

o C=dimensionlessfactoro GND=normaldirectionirradiation

Step4

Calculatereflectedirradiation,GR(btu/hrft2)

o GtH=rateatwhichthetotalradiation(directplusdiffuse)strikesthehorizontalsurfaceorgroundinfrontofthewall(btu/hrft2)

o g=reflectanceofgroundorhorizontalsurfaceo Fwg=configurationoranglefactorfromwalltoground,definedasthefractionofthe

radiationleavingthewallofinterestthatstrikesthehorizontalsurfaceorground

directly

=angleoftiltforanarbitrarysurface

Step5

CalculateGt,totalsolarradiation,bysummingGD(Step2),Gd(Step3),GR(Step4)

ApplicationtoMain&Gervais

Nowthatthestepstocalculatethetotalsolarradiationonaverticalsurfacehavebeenoutlined,itis

necessarytoapplythemtotheproposedcurtainwalldesignforMain&Gervais.Theapplicationbelow

issetfor3:00pmonMay21,2009,at34latitude.Table4.8providestheinformationnecessaryto

computethecalculations.Thissectionwillprovideasimpleversionofthecalculation.Thewritten

calculationscanbefoundinAppendixG.

. .

.

0.94 o 270.71

cos cos 64.12cos 40.5o cos 0.242


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0.55 0.4370.242 0.3130.242 o 0.73

o 0.5 0.242 0.2420.73 0.320.5 sin64.120.13270

o 154.58 ThetotalsolarradiationonMain&Gervaisverticalcurtainwallonthewestelevationat3:00pmMay

21,2009,is154.58btu/hrft2.AppendixIprovidesalistofvaluesforthe21stofMay,June,July,and

August.Thevalueslistedinthetableareonlyforthetimesinwhichthesunisshiningdownonthewest

faade.Allotherpointsofthedayareirrelevantforthisanalysis.

WindowHeatGainCalculationThetwoprevioussectionsprovidedthetotalsolarradiationonthebuildingataspecifictime.Nowitis

importanttonotehowthatsolarradiationwillimpactthecurtainwall.Thisanalysisfocusesstrictlyon

theofficeportionofthebuilding.ThetypicalglazingfortheofficetowerisSolarscreenRadiantLowE

(VRE)InsulatingGlassVRE146manufacturedbyViracon.

Figure4.12:CurtainWallGlazingProperties

Thesolarfactor(SHGC)forthisproductis0.278.Thisvaluemultipliedbythetotalsolarradiation,whichishighlightedineachofthetwoprevioussections,willobtainthewindowheatgainat3:00pmonMay

21,2009.AppendixIprovidesalistofvaluesforwindowheatgainforthe21stofMay,June,July,and

August.


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124.220.278 34.53

154.580.278 43.06

Theleftcolumndisplaysthecalculationsfortheslopedcurtainwallandtherightcolumndisplaysthe

calculationsfortheverticalcurtainwall.Thereisa25%increaseinheatgainforthisparticularhour.

EnergyLoadComparisonTheprevioussectionsanalyzedoneparticularhourforonedayforthepurposeofunderstandingthe

calculations. Thefollowingtable,Table4.9,providestheincreaseinwindowheatgainoverthecourse

offourmonths:May,June,July,andAugust.Thisprovidesalegitimatemeansofcomparingtheenergy

costsbetweenthetwodifferentdesigns.

Day(btu/ft2/day) Month(btu/ft

2/month)

Month Sloped Vertical qiInc. %Inc. Sloped Vertical qiInc. %Inc.

May 279 333 54.29 19% 8364 9993 1628 19%June 281 337 55.92 20% 8437 10115 1677 20%

July 273 327 54.53 20% 8189 9825 1636 20%

August 244 292 48.90 20% 7322 8789 1466 20%

Table4.9:EnergyComparison

AsshowninTable4.9,theenergydemandincreasesby20%.Thiswillincreasetheenergybilleach

monthfortheownerofthebuilding.TheaverageutilityrateduringNovember2008forcommercial

buildingsinSouthCarolinais8.76cents/kwh.ThisvaluewasobtainedfromtheEnergyInformation

Administration.Table4.10providestheconvertednumberstobecapableofcalculatingtheenergy

costs.Table4.11providestheenergycostsfortheselectmonthsandtheincreaseincostforthechange

indesign.

(btu/ft2/hr) (btu/hr) (kwh)

Month Sloped Vertical Sloped Vertical Sloped Vertical

May 39.83 47.58 52692 62953 15.44 18.45

June 40.18 48.17 53156 63725 15.57 18.67

July 39.00 46.79 51593 61899 15.12 18.14

August 34.87 41.85 46130 55371 13.52 16.22

Table4.10:EnergyUnitConversion

($/day) ($/month) $Inc. %Inc.

Month Sloped Vertical Sloped Vertical Sloped Vertical

May $324.58 $ 387.79 $ 9,737.39 $11,633.73 $ 1,896.34 19%

June $327.44 $ 392.54 $ 9,823.14 $11,776.29 $ 1,953.15 20%

July $317.81 $ 381.30 $ 9,534.31 $11,438.95 $ 1,904.64 20%

August $284.16 $ 341.09 $ 8,524.81 $10,232.61 $ 1,707.80 20%

Table4.11:EnergyCosts


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Theenergyconsumptioninbtu/hriscalculatedinTable4.10giventhattheareaofcurtainwallunder

considerationis4,536ft2.AsseeninTable4.11,thepriceforenergycostsincreasesby20%.The

amountexpressedunder($/day)isbasedonsevenhoursofthedaythattheenergyistransmitting

throughthewindow.Thesemonthsunderconsiderationareassumedtobewhentheairconditioning

systemwillberunning.Thetotalincreaseinpriceduringthistimeperiodis$7,461.94.Thisamountis

minimalconsideringthisportionisafractionofthetotalfootprintofthebuilding.

ConclusionTheimplementationofthenewcurtainwalldesignrequiresseveralconsiderations.These

considerationsincludeexaminingthebenefitsofthenewcurtainwalldesign,inputtingnewstructural

elementsandverifyingtheintegrity,andcalculatingtheincreasesinenergydemandduetowindow

heatgain.Thefollowingconclusionscanbeobtainedfromthisanalysis.

AdditionalArea

Extendingthecurtainwallprovidesadditionalareatothefloorplanforeachlevelofofficespace.This

extraareaamountsto2756ft2.Theownercancharge$21.00/ft2/yearforthisspace,whichwillamount

toanadditional$57,876.00.

StructuralLoadAnalysis

Addingextrafloorareawillrequireadditionalcolumns,joists,andbeamstosupporttheextendedslab.

Theconstructioncostsforaddingtheseelementswillcost$30,828.07.

SolarHeatGainAnalysis

Changingtheslopeofthecurtainwallwillchangetheamountofsolarenergythattransmitsthrough.

Theamountofwindowheatgainincreasesby20%withtheproposeddesign.Thiswillresultinan

additional$7,461.94fortheenergybilleachyear.

FinalComments

Implementingthenewdesignwillputmoremoneyintheownerspocketovertime.Thereisanupfront

costof$30,828.07forconstructionofthenewstructuralelements.Also,eachyeartheownerwill

expectanincreaseintheenergybudgetof$7,461.94toruntheairconditioningunitstocompensatefor

thewindowheatgain.Thefirstyear,theownercanexpectanadditional$19,585.99inrevenue.Years

following,theownercanexpecttobringanadditional$50,414.06.ThiscanbeseeninTable4.12.

ConstructionCost EnergyCost RentIncome Difference

Year1 $ 30,828.07 $ 7,461.94 $ 57,876.00 $ 19,585.99

Year2 $ $ 7,461.94 $ 57,876.00 $ 50,414.06

Year3 $ $ 7,461.94 $ 57,876.00 $ 50,414.06

Table4.12:Profit

4final cw design analysis

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