WeigerFinalReport 45|P a g e

6.0Analysis2:ChilledBeamsCost&ScheduleImpact(MechanicalBreadth)

6.1BackgroundThemechanicalpackagefortheJHHprojectaccountsfor29.1%oftheconstructioncost.TheHVACsystemalonetotals$79,444,970or13.9%oftheconstructioncost.ThecriticalpathoftheprojectlargelyinvolvestheinstallationoftheHVACsystem.

TheJHHcampushasacentralutilityplantthatiscapableofsupplyingtheNCBwithchilledwaterandhighpressuresteam.Therefore,thenewfacilitydoesnotincludeanyboilersorchillers.ThecurrentHVACsystemisavariableairvolume(VAV)withreheatcoilsineachVAVbox.OnaverageeachVAVboxserves3roomsthatareononezone.Thereare19airhandlingunitswithsizesrangingfrom11,000133,000CFM.Theyareprimarilylocatedonthe6thand7thfloor.

WhendesigningaHVACsystemforahealthcarefacility,theengineermustconsiderinfectioncontrol,filtrationrequirements,outdoorairrequirements,recirculatedairrequirements,airchangerates,etc.Hospitalshavemuchstricterdesigncriteriathantypicalbuildings.AVAVsystemisthemostcommonsystemusedininvasiveareasofhealthcarefacilities.However,noninvasiveareassuchasofficespace,waitingrooms,cafeterias,patientrooms,etc.donothaveasstrictofguidelines.Forthisreason,theseareashavethepotentialtouseadifferentHVACsystem,suchaschilledbeamsthatcouldpotentiallysavetimeandmoney.

6.2ProblemStatementAnalysis1showedthatthetoptwogoalsfortheowner,A/E,andcontractoraretodelivertheprojecton/underbudgetandontime.

Currently,the1stpackageofchanges(CCD138)hasbeenevaluatedbyClark/Banksandtheyhavedeterminedthattheschedulewillneedtobeextended7months.ThisisbecausetheHVACsystemwasseverelyimpactedbythechanges.Thecostofacceleratingtheschedulefrom7monthsto3monthsdelaybyworking300mechanicalcraftsmenovertimeis$2million.ThishascausedJHHtonotmeettheirtoptwogoals.

6.3GoalThegoalofthisanalysisistodemonstratethatchilledbeamHVACsystemsinnoninvasivespaceshavethepotentialtolowerthecost(initialandlifecycle)andacceleratetheconstructionschedule.

6.4ResourcesTROXUSAKenLoudermilk TROXUSAChrisLawrenceDADANCOBillRaffertyPierceAssociates,Inc.DanDonaghyClarkConstructionJimSalvino

pdw5000Highlight

pdw5000Highlight

pdw5000Highlight

WeigerFinalReport 46|P a g e

Poole&KentDonaldCampbellUnitedSheetMetalMikeTopperJohnsHopkinsFacilityGroupBobSingerBR+AMarkOcteauSmithGroupDavidVarnerPennStateMosesLing

6.5Analysis

ChilledBeamSystemBackgroundAnemergingtechnologyfromEuropeisthechilledbeamHVACsystem.Theyhavebeensuccessfullyusingchilledbeamsystemsinhealthcarefacilitiesforthepast20years(seeTable4belowforsampleprojects).Withinthepastfewyears,severalprojectshavepoppedupintheUSAwiththesesystemssuchasConstitutionCenterinWashingtonD.C.andtheYaleHospitalExpansionprojectinNewHaven,CT.

Hospital HealthcareTrust #ofChilledBeams Year ConsultingEngineer

RoyalSussex,Brighton

Brighton&SussexUniversityHospitals

450 2003 WhichloeMacfarlane

UCLHLondon UniversityCollegeLondonHospitals

1,100 2005 DSSR

BeatsonOncology GreaterGlasgowHealthBoard

500 2006 DSSR

QMCNottingham NationsHealthcare 200 2007 TB&AACADHospitals,Scotland

GreaterGlasgowHealthBoard

1,000 2007 DSSR

WakefieldHospitals

MidYorkshireHospitals

350 2008 BuroHappold

Barts&RoyalLondon

TheLondon 4,500 20082013 TB&AandDSSR

Table4:HealthcareProjectsinEuropeUsingChilledBeams(Source:FrengerSystems)

WeigerFinalReport 47|P a g e

Chilledbeamunitshavefinnedchilledwaterheatexchangercoolingcoils,capableofproviding1,000BTU/hrofsensiblecoolingperfootofbeam.Theytakeadvantageofthefactthatwatercanmoveenergymoreefficientlythanair.Figure14belowshowsthata1diameterwaterpipecancarrythesamecoolingcapacityasan18x18airduct.Thus,chilledbeamscandramaticallyreduceAHUandductsizes.

Therearetwomaintypesofchilledbeamsactiveandpassive.Passivechilledbeamsusefinnedtubeheatexchangercoiltoprovideconvectivecoolingtothespace.Theydonotusefans,ductwork,oranyothercomponent.Sincetheydonothaveasourceofprovidingprimaryairtothespace,anothersourceofairisrequiredforventilationandhumiditycontrol.

Activechilledbeamsuseaductedprimaryair(conditioned)supplytoinduceroomairacrossthecoolingcoilwhereitmixeswiththeprimaryairanddischargesinthespace.Thechilledbeamprovidesmostofthesensibleloadwhiletheprimaryairprovidestheventilationandlatentcooling.AHygienicActiveChilledBeamistherecommendedsolutionforthisproject(seeAppendixAforproductdatasheets).

Figure15belowshowsacrosssectionthroughanactivechilledbeam.(1)PrimaryairisfedfromacentralAHUthroughaseriesofnozzles(2).Theprimaryaircreatesaninductionofroomair(3)thatpassesthroughacoolingcoil(4).Theprimaryairandroomairarethenmixedanddischargedtothespace(5).

Figure14:CoolingEnergyTransportEconomiesofAirandWater

Figure15:Active ChilledBeamCrossSection

WeigerFinalReport 48|P a g e

Chilledbeamshavemanyadvantagesincludinglowenergyconsumption,spacesavings,improvedcomfort,noregularmaintenance,andeasycommissioning.Thedesignintentofchilledbeamsistosizetheprimaryairtomeetventilationorlatentloadrequirementsandusethebeamstoprovidetherestofthesensiblecoolingload.Itiscommontosee7585%reductionincirculatedairwhenusingchilledbeamscomparedtoallairsystemsaccordingtoDADANCO.Thisreductioninaircanreducetheductwork,fans,AHUs,etc.bythesameproportionedamount.ThedownsizingoffansandAHUsresultsinlessenergyconsumptionbecauseitismuchmoreenergyefficienttomovewaterinsteadofair.Thiscansavesignificantlyonthelifecyclecostofabuilding.

Byreducingtheductworkby7585%itfreesupspaceintheceilingplenum.Therefore,thefloorfloorheightcanbereduced.Thiscansavemoneyonstructureandthefaade.AnotheradvantagecouldbeinareaswithheightrestrictionssuchasWashington,D.C.whereitmaybepossibletoaddanotherfloor.Italsolendsitselfnicelytorenovationprojectswheretheceilingplenumisrestricted.

Theroomcomfortismaintainedbyprovidingexcellentairmovementwithuniformairtemperatures(seeFigure16and17below).Thisreducesunwanteddraftsandhotspacesintheroom.Fullventilationairrequirementsaredeliveredtothespacesatalltimesandloads.Humiditycontrolismetastheconstantvolumeprimaryairisdeliveredwiththepropermoisturecontenttosatisfythelatentloads.

Figure16:AirMovementThroughouttheRoom(Source:DADANCO)

Figure17:UniformTemperatureThroughouttheRoom(Source:DADANCO)

WeigerFinalReport 49|P a g e

Chilledbeamsdonothaveanymovingpartswhichreducesthemaintenancecosts.IntherecommendedHygieneChilledBeamforthisproject,thereisaninbuiltfilterwhichwillcapturealltheairbornebacteriaastheairisrecirculated.Thiswillneedtobereplacedevery6monthswhichisthesameasthecurrentVAVsystem.Figure18belowshowsmaintenancepersonnelcleaningachilledbeam.

ThecommissioningprocessismucheasierthanVAVsystems.Chilledbeamsonlyrequireadjustmentstothewaterbalancingvalvesandprimaryairbalancingdampersthroughstaticpressurereadings.Theadjustmentscanbemadebyturningregulatingscrewswithanallenkeywiththeunderplateinposition(seeFigure19below).

Figure18:MaintenancePersonnelCleaningaChilledBeam

Figure19:Adjustment forRegulatingAirAmountandSpeed

WeigerFinalReport 50|P a g e

SizingtheChilledBeamSystemForthisanalysis,thecurrentVAVsystemdesignwillbeleftuntouchedfortheinvasivespaces(i.e.operatingrooms,traumarooms,triage,examrooms,etc.).Theremainingnoninvasivespaceswillbeanalyzedtodeterminethecostandscheduleimpactofusingchilledbeams.

ThesheersizeandcomplexityoftheHVACsystemmakesitvirtuallyimpossibletoanalyzeeachaspectoftheHVACsystemforthisthesis.Therefore,representativeandtypicalspaceswillbeanalyzedandtheirresultswillbeextrapolatedtotherestofthespacesinquestion.

Thetwomainspacesthatarerepresentativeofthenoninvasivespacesaretheofficeandpatientrooms.Theseareasmakeupthemajorityofthenoninvasivespaces.Theyalsorepresentthetwoextremesofthedesigncriteriaforthenoninvasivespaces.Theofficespaceshavetheleastamountofdesignrestrictionswhilethepatientroomshavethemost.Analyzingthesetwospaceswillprovideaworkingaveragethatcanbeusedtoanalyzetheentireimpact.

OfficeSpace

Level6wasanalyzedasthetypicalfloorfortheofficespaces.Theentirefloorfunctionsasfacultyoffices,meetingrooms,lounges,andfilingrooms.EachVAVboxservesacertainzonethatrangesfrom19rooms.Thefollowingassumptionswereusedforthecalculation.

ThesupplyCFMshownonthedrawingsforeachcorrespondingVAVboxrepresentsthedesignloadsforthatzone.

Eachroomthatisapartofthezonehassimilarloads. Byexaminingtheentirefloor,includingthenorth,south,east,westandinsideroomsprovide

representativeloadconditions. Thenumberofseatsorareatoaroomwasusedtoestimatethenumberofpeoplethatwould

occupytheroomatmaximumload. Sizingisbasedoncoolingload,notheatingload

o Heatingwillonlyberequiredonperimeterspacesandcanbeaccomplishedbyaddingheatingcoilsinthebeams.

Thefollowingcalculationisanexampleofhowthechilledbeamsandprimaryairsupplyweresized.

VAVBoxS6D1

TotalSupplyforthisVAV=300CFM 6peopleareexpectedtooccupythezoneatmaximumcapacity 1roomisservedbythisVAV Roomtemperaturedesign=70F Supplyprimaryairtemperature=55F

1.TotalSensibleDesignLoad=1.08xTotalSupplyCFMx(RoomTempSupplyTemp)=1.08x300CFMx(70F55F)=4,860BTU/hr

WeigerFinalReport 51|P a g e

2.VentilationairrequiredperASHRAE62.12007is25CFM/personforpatientrooms(seeFigure20below).Officespacesarenotshown.Tobeontheconservativeside,25CFM/personwillbeusedforboththeofficeandpatientrooms.

3.VentilationAirRequired=25CFM/personx6persons=150CFM

4.Assumethatventilationairgovernsprimaryairsupplyrightnowandthenchecktoseeifitisgreaterthanthelatentloadairrequirementlater.

5.SensibleCoolingCapacityofPrimaryAir=1.08xVent.AirCFMx(RoomTempSupplyTemp) =1.08x150CFMx(70F55F) =2,430BTU/hr

6.SensibleCoolingbyChilledBeam=TotalSensibleLoadSensibleCapacityofPrimaryAir =4,860BTU/hr2,430BTU/hr =2,430BTU/hr

7.Latentloadintheroomcanbeapproximatedbythegeneralruleofthumbthateachpersongivesoff20