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AIVC#13,671ASHRAE Journal'Ventilation for EnclosedParking GaragesBy Moncef Krartt, Ph.D., P.E., and Arselene Ayarl, Ph.D.Member ASHRAEindication of risks from exposurepen l:!arngs arA and g ncra l l d n t n·foh!c I.typically above-grade \Vith open sidesThi.: ventilation rate re4uireml.'nts rec other codes;ire in lq1endenr of the characteristics ofthe parking g arag e and do not cnnsiderthe \ arinus paramckrs that may affectindoor air gualit.y. sw:h as the ernis iongeneration rate and the acceptable pol l utan t level. A new design method isneeded to dctcm1inc the ventilation rated mechanical ventilation. However, follyommended by ASH RAE andenclosed parking garages arc usually underground and require mechanicalventilation. Indeed. in the absence ofventilation. cndoscJ parking facilitiespresent several indoor air qua I ity problems. The most serious is the emis sion of high levels ofcarbon monoxide ((0) by cars within the parkinggarages. Other concerns related to endoscd gar.iges arc the presence ofoiln.·quired for a wide nmgc ofcndoscd park fumes. and other contaminant-; such as oxides ofnitrogen(NO\ )and 1.rnsolinc-and smoke haze from diesel engines.To d t·t crm i nethe adequate ventilationfor garages, two factors arL' typically.:unsidereJ: the number of car in opera monituring of CO con the moni toring system being interlm:ked with theber of cars in operation depends on theccptahle kvel ufcontaminant rnnccntra garage and may varyconsensus on acceptahlc con taminant levels for enclosed parking ga rages is needed.Un fortunately. Standard 62- l 9X9 doesnot address the issue of \entilation con trol through contaminant monitoring forratetion and the emission quantities. The num type of thl! facility served by the parkingfrom3' ;, (in shop ping an.:as) up to 20' 'o (in sports stadi ums) of the total vchick capacity. Theemission of carbon monox idc depends onindividual cars including factors such asthe age of the car. the engine power. andthe levelof car maintenance.For enclosed parking facilities. ANSI!ASllRAE Standard 62-1989. 1;:111ilutio11/i1r Acceptahle Indoor Air ()uafi i· speci fics a fixed vcntih1tion rate of below 7.62L/s·m' ( 1.5 ct'rn/fl') of gr oss floor area.:Therefore, a ventilation flow of about11.25 air changes per hour is required forgarages with 2 5 m (8 ft) c eil i ng height.However. some of the model code au thorities speei ty an air change rate of fourto six air changes per hour. In addit ion .some of the modi:! code au1horities allowthe ventilation rat.: to \ary and be re duced to sa vc fan energy if CO-demandc on1 ro l l cd ventilation is pertl11mcd. that52ASHAAE Journalis.aing garages. Thi s design md h od slwuldbe llexiblc to accommodate rlllt on!;. thevarious CO cxpo ure lnnih defined by thestar11forJs but also the d1 .Jnging. emissioninventory from motor vehicle. .continuouscentrationsisconducrcJ. withField Testing Resultsmechanical exhaust equipment. The ac tions varies signi tirnntlycode. Afrom codeluenclosed garages. Thus. ASHRAE com missioned a rescard1 projeu (945-RP) toevaluate c ur r ent ventilation standardsand recommend rates appropri:1te to cur rent vehicle cmissions/usagt:.COforhmg-tcm1 CO cxposure would meet al most every co le and standard li ted inutomobile I arkin!!garage· an be partially open or fully enclosed.Partial Itoin parkin g garages. A I imit of 25 ppmAs part of an ASllRAE-sp1insorcdproject (945-RP}, ticld mea urcmcntsthe seven testedparkingforfacilities w.:rcpcrfonned. The air change rates are mea sured using the tracer gas technique. First.t hctr;1cer gas(SF,,l was injected in thebu ildi n g directly or through the supplyfans, Then. the concentration of the tracergas was monitored using a ficld-portabkeb:tron capture gas chromatograph. Fora more detailed description of the fiddmeasurements. sec Rd rcncc 4.About the AuthorsVentilation RegulationTab/ ! I pro\ i lcs a summary of exist ing codes and standard:-. for ventilatingMoncef Krartl, Ph.D., P.E., is anassociate professor in the Civil, Envi ronmental and Architectural Engineer enclosed parking garages in the Unitesing (CEAE) Department at the Univer States. and other selectedsity of Colorado at Boulder. He is ashown in Tahli! I.thew un tr ie s.Asrecommendationsfor the CO exposure limits arc not consis member of TC 6.9, Thermal Storage,and and TC 4.7, Energy Calculation.tent bi.:twccn various regulations withinArselene Ayarl, Ph.D., is a consuJt the United Stares and o t h er countries.Hm,\evcr. the recommendations offer anant engineer in indoor airwww.ashraej o urn al. orgcontrol systems.quality andFebruary 2001

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ASHRAE Journalfoh!e ] summarizes somi:: of th e resultsobtained during the field testing for sewngarages described in Ayari. ct al.TheACH(2000).Yalues present the range of theair changes per hnurmi::asurcd at va riou sFrom the licld study. thefollowing results weretained:ob i.:r exc ee ded 35 ppm even though the(1.5 cfm/ft')NIOSH/OSHA8Ceiling35200-stringent regulations (i.e. 25BOCA--6ACHeragi:: of CO concen1rntion).SBCCI--6-7 ACHgaragi::s were gencrJlly wellNFPA--6ACHACGIH825-Canada8taminan t kvds that are sig n:quiri.:dthan thoseby even the mostppm of8-hour weighted a\· ·2. The a tual ventilationrates supplied lo the tested ybi.:low 7.62Standard 62- I 9H9. The only garagea \ rnti lation rate ckit;e to 7 .62l. s·m: ( I . 5 c fm tF) is Garage E. whichserv .· a large :,hopping mall with hca\ ythat hasusage throughout t he day.It should benoted t h a t all the garages ari.:continuously except G a ra ge B.sensors were usedwntilati.:dwhcri.: COto control theopera-S t an dardbyctin- n: n.62 - I 9 Q ( i .e ,Us·m' [1.53. When it isus.:d. d.: mand .:ontrnlli.:d vi.:ntilationwas ahk Ill ma intain ac u:ptable indoo r air qual itywithin the IL' s ted enclosedparking facilities. .The location of sup plyandexhaust\'Cills. trafficflow pattern, thi.: number ofm o v i ng cars. and traveltime , ·ere important factorsthat affect thi.:effectivenessof the ventilation system inmaintaining acceptable CO(orNO)levels with in en closed ' p ar k ing garages.Any des ign guiddinesshould account forthi.:scl u:tors to determineventilation requirementstheforenclosed parking facilities.cwM:-ITY1nSTU/IHoo·o816rwe500/o RH75 0 2 5 W89J'l!,RHIt is clear from the resultsFinland2.7 Us m:(0.53 ctmift')Ceiling165 Us· car-(0.66 .815 minutes300Korea503.3 Us· m'6 35-7.62 Lis·m1(1 25-1.5 cfmfft")0.91 Us· m2(0.18cfm/ft'-")6-10 ACHTable 1: Summary of U.S. and international stan dards tor ventilation requirements of enclosed park ing garages.vidc th e minimum ventilation mle requiredmaintain contaminant concentrationsin fan energyuse. Guidelines should ac co unt for vari ability in the parking garage traffic flow.car emissions. tra v el time, and number ofmov ing cars.Journal3075-ties without large penaltiesASHRAE815 minutesGermanylevels set by the relevant health authori 54-(350 cfm/car)New design guidelines are needed to pro Based on the results, 1 /13200100within parking facilities at the acceptable53 on Reader S.rvlce Card)25/3020 minutesoutdated for endosed parking garages.Design Approach1Franceof th.: fi eld study that the current ventila tion rate specified i n Standard 62-1989 isto(Circle No.7.6 Us· m'(1.5 cim!W)7.6 Us· m'wntilation rates in all c;iscs is well belowclin:tl') rewrrnrn:ndcd950below lhosi.: rccorrnm:ndedthe 7.62 L 's·m: ( 1.5351200values provide the total ventilation rate.ne\Ventllatlon,niticantly IO\verTI1e maximum and the avernge ('()con centrntions measured d uri ng the day oftesting arc listed in Tl.Ihle] to character ize the indoor quality within the testedpar k i ng facility. As indicated in fohlc ],the CO fcvd w ithin all the parking garngcsPPM8locations of the facility using the t racers·m' (ctinilF)8ASHRAE(hrs)ICBOI. All the tcskd enclo se dparking garages had Clln·gas technique, whik the Lnmetion of thi.: supply fans.metric analyses,' a simple design mi.:thodwas dev eloped lo detcnni n e the entila t io n flow rate required 10 mainta in aeccpt able CO level within endosed parking fa cilities . Ventilation rates fi.ir cndoscd park ing garages can be i.:xprcsscd in terms ofeithe r flow rate per unit floor area (L/s·m:or air volume changes per unittime (ACH). The design ventilation rati.:required for an enclosed parking facilitydepends on four factors:I. Contaminant kvcl acccptahk withinor cfmlff)the parking facility:2. Number of carspeak conditions:of scveral para-www.as h raejo u rna I. o rgin operation du r ing3. Le ngt h oftnwe! and operationFebruarytime2001

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