1、2010 ASHRAE 437ABSTRACTAir infiltration has a significant impact on the heating andcooling loads of small office and residential buildings. In aradiantly heated and cooled office, air infiltration normallydetermines whether this type of system can operate withoutcondensation on the radiant cooling s
2、urface in summer in mildand humid climatic conditions, because infiltration may bringconsiderable moisture into the space. The office studied expe-riences infiltration that seriously limits the effectiveness of theradiant cooling system and active desiccant dehumidificationsystem. Earlier infiltrati
3、on measurements using the tracer gasprocedure showed infiltration levels of 0.7-1.12 ACH, whileCO2concentration measurements gave values from 0.1-0.2ACH. This paper reports the results of infiltration levels deter-mined from blower door measurements and logged humiditydata from the ventilation unit
4、as well as a reanalysis of the CO2data. There were still significant discrepancies that areresolved by combining the measured results with a calibratedsimulation and additional site measurements. It is found thatinfiltration in the studied office is from two sources: one isoutdoor air; the other is
5、the indoor air from the floor below thestudied office. The total air infiltration for the studied spacemay vary from 0.74 ACH in the summer to 1.5 ACH in thewinter, while the air leaking into the studied office from thespace under the floor may range from 0.46-1.03 ACH.INTRODUCTIONTo provide a healt
6、hy indoor environment for buildingoccupants, an adequate outside air supply is necessary todilute and remove indoor air contaminants. Outside air isnormally provided by mechanical ventilation in commercialbuildings and by natural ventilation in most residentialbuildings. However, the energy required
7、 to condition theoutdoor air in buildings is often a significant portion of thetotal space conditioning load. Large commercial buildingsnormally operate continuously at a slightly pressurized condi-tion in which air infiltration is expected to have less impact onbuilding conditioning load. In most s
8、mall office buildings andresidential buildings, the air infiltration has a significantimpact on the space conditioning load since the buildings arenot pressurized and air conditioning systems operate intermit-tently. In a radiantly heated and cooled office, the infiltrationnot only has an impact on
9、building heating and cooling load;it also strongly affects the indoor humidity level and hence theability to operate the radiant cooling panels without conden-sation. The magnitude of the infiltration into this type of thebuilding must be known in order to size the radiant panels anddehumidification
10、 equipment for this type of system properly.Significant research has been done on building air flowmodels and infiltration measurement procedures. Building airflow models can be classified as single zone models and multi-zone models. A widely used multizone model is COMISwhich was developed by Feust
11、el and Raynor-Hoosen (1990),and improved by Feustel (1999). The single zone LBNLmodel developed by Sherman and Grimsrud (1980) has beenused very widely. Walker and Wilson (1993) also proposed awell recognized enhanced single zone model. For small officebuildings and residential buildings, the single
12、 zone model isapplicable. According to Persily (1986) and Walker andWilson (1998), these models can have an error of 40% orhigher. In order to obtain an applicable yearly infiltrationprofile, these models should be combined with air infiltrationmeasurements. Commonly used infiltration measurementpro
13、cedures include the tracer gas method, CO2concentrationdecay method, blower door test method, etc.Infiltration Investigation of a Radiantly Heated and Cooled OfficeXiangyang Gong David E. Claridge, PhD, PE David H. Archer, PhDFellow ASHRAEXiangyang Gong is a graduate student and David E. Claridge is
14、 the Leland Jordan Professor in the Department of Mechanical Engineeringat Texas A from September to May, the loads shown in the above table are heating loads. There is no overlapbetween heating and cooling.minmoutmgenWinWoutWgenWstorageVsVrVL 2010, American Society of Heating, Refrigerating and Air
15、-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions 2010, Vol. 116, Part 1. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission. 446 ASHRAE TransactionsPro
16、ject Report, Department of Architecture, CarnegieMellon University.Boonyakiat, J. 2003. A model-based approach to ventilationcontrol in buildings. PhD dissertation. Department ofArchitecture, Carnegie Mellon University.Claridge, D.E., N. Bensouda, S.U. Lee, G. Wei, K. Heine-meier, and M. Liu. 2003.
17、Manual of procedures forcalibrating simulations of building systems, LawrenceBerkley National Laboratory, October, 2003.Environment Protection Agency. 2006. Atmosphere changes,accessed in December, 2006. http:/www.epa.gov/climatechange/science/recentac.html.Feustel, H.E. and A. Rayner-Hoosen. 1990.
18、COMIS funda-mentals, LBL-28560. Applied Science Division, Law-rence Berkeley National Laboratory, Berkeley, CA.Feustel, H.E. 1999. COMISAn International multizoneair-flow and contaminant transport model. Energy andBuildings, Vol. 18, pp. 3-18.Gong, X. and D.E. Claridge. 2006. Indoor humidity analysi
19、sof an integrated radiant cooling and desiccant ventila-tion system. Proceedings of International Conferencefor Enhanced Building Operation, Part 1, I-6-1, Nov. 6-9, 2006, Shen Zhen, China.Gong, X. 2007. Investigation of a radiantly heated andcooled office with an integrated desiccant ventilationuni
20、t. PhD Dissertation. Texas A&M University, August2007.Mahdavi, A., R. Ries, and D. Cho. 2000. Infiltration, naturalventilation, and HVAC performance in the IW. ASHRAETransactions 106(1):728-736.Persily, A.K. 1986. Measurement of air infiltration and air-tightness in passive solar homes. In Measured
21、Air Leak-age of Buildings, p. 46. ASTM STP 904. H.R. Trechseland P.L. Lagus, eds.Sherman, M.H. and D.T. Grimsrud. 1980. Infiltration-pres-surization correlation: Simplified physical modeling.ASHRAE Transactions 86(2):778-803.Sherman, M.H. and D.J. Dickerhoff. 1998. Airtightness of U.S.dwellings, ASH
22、RAE Transactions 104(1):1359-1367.Walker, I.S. and D.J. Wilson. 1993. Evaluating models forsuperposition of wind and stack effects in air infiltration.Building and Environment 28(2):201-210, Pergamon Press.Walker, I.S. and D.J. Wilson. 1998. Field validation of equa-tions for stack and wind driven a
23、ir infiltration calcula-tions. International Journal of HVAC&R Research 4(2).APPENDIXDERIVATION OF INDOOR CO2CONCENTRATION DECAY MODELThe indoor CO2level can be calculated as follows. CO2mass balance in the space can be expressed as the followingequation:(A-1)where, = indoor CO2change with time Let
24、Cr= indoor CO2concentration, ppmCo= outdoor CO2concentration, ppm, (A-2)(A-3)(A-4)By substituting Equations (1-2), (1-3), (1-4) into Equa-tion (1-1), the following equation is obtained:(A-5)By assuming the initial indoor CO2concentration is Croppm, the above equation can be solved as (A-6)dmCO2dt- m
25、inmout mgen+=dmCO2dt-mCO2CrVr106=minCoVr106=moutCrVr106=dCrdt- CrComgenVrCO2106-=CrComgenVr106-CroComgenVr106-et+= 2010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions 2010, Vol. 116, Part 1. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.
