Applying Large Datasets to Developing a Better Understanding of Air Leakage Measurement in Homes

TitleApplying Large Datasets to Developing a Better Understanding of Air Leakage Measurement in Homes
Publication TypeJournal Article
Refereed DesignationRefereed
LBNL Report NumberLBNL-1005795
Year of Publication2013
AuthorsWalker, Iain S., Max H. Sherman, Jeffrey Joh, and Wanyu R. Chan
JournalInternational Journal of Ventilation
Start Page323
Pagination 323-338
Date Published03/2013
Keywordsair leakage, air tightness evaluation, error analysis, measurements, pressure testing

Air tightness is an important property of building envelopes. It is a key factor in determining infiltration and related wall-performance properties such as indoor air quality, maintainability and moisture balance. Air leakage in U.S. houses consumes roughly 1/3 of the HVAC energy but provides most of the ventilation used to control IAQ. There are several methods for measuring air tightness that may result in different values and sometimes quite different uncertainties. The two main approaches trade off bias and precision errors and thus result in different outcomes for accuracy and repeatability. To interpret results from the two approaches, various questions need to be addressed, such as the need to measure the flow exponent, the need to make both pressurization and depressurization measurements and the role of wind in determining the accuracy and precision of the results. This article uses two large datasets of blower door measurements to reach the following conclusions. For most tests the pressure exponent should be measured but for wind speeds greater than 6 m/s a fixed pressure exponent reduces experimental error. The variability in reported pressure exponents is mostly due to changes in envelope leakage characteristics. It is preferable to test in both pressurization and depressurization modes due to significant differences between the results in these two modes.

Refereed DesignationRefereed
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