Measurement Methods to Determine Air Leakage Between Adjacent Zones

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Air leakage between adjacent zones of a building can lead to indoor air quality and energy efficiency concerns, however there is no existing standard for measuring inter-zonal leakage.In this study, synthesized data and field measurements are analyzed in order to explore the uncertainty associated with different methods for collecting and analyzing fan pressurization measurements to calculate inter­ zone leakage. The best of the measurement and analysis methods was a method that uses two blower doors simultaneously based on the methods of Herrlin and Modera (1988) to determine the inter-zone leakage to within 16% of the inter-zone leakage flow at 4Pa, over the range of expected conditions for a house and attached garage. Methods were also identified that use a single blower door to determine the inter-zone leakage to within 30% of its value. The test configuration selected can have a large impact on the uncertainty of the results and there are testing configurations and methods that should definitely be avoided. The most rigorous calculation method identified assumes a fixed value for the pressure exponent for the interface between the two zones (rather than determining the interface pressure exponent from the measured data) and then uses an optimization routine to fit a single set of air leakage coefficients and pressure exponents for each of three wall interfaces using both pressurization and depressurization data. Multiple pressure station tests have much less uncertainty than single pressure station approaches. Analyses of field data sets confirm a similar level of variation between test methods as was expected from the analysis of synthesized data sets and confirm the selection of specific test methods to reduce experimental uncertainty.

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