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Building Efficiency TAC

BETAC Projects

Multi-Unit Residential Buildings – Air Leakage Testing

August 14, 2015

The research project described in this report was carried out to explore some of the unique problems associated with performing airtightness tests on occupied Multi-Unit Residential Buildings (MURBs).


Current airtightness testing methods and standards are predicated on the assumption that the testing agency has complete control over the building and its operation during the test period.

With unoccupied buildings, this is seldom a problem. However, if the building is an occupied MURB, then major issues arise. Occupant access has to be limited during certain critical portions of the testing, interior doors must be kept open and suite windows have to be kept closed. These last two issues (interior door and suite window positions) were the main focus of this project.

Our Research

Using two unoccupied and four occupied MURB’s, ranging in size from 8 to 124 units, a series of airtightness tests were conducted to determine if reliable results could be obtained with interior suite doors closed and a limited number of windows partially open.


  • The results of this work indicated that conducting an airtightness test with occupied suites and closed doors is indeed possible by applying a correction factor; however all windows must be kept closed during testing.
  • It was found that building owner cooperation and participation during the test is essential.

See the final project report

Large Building Airtightness Testing

June 14, 2015

There is a growing recognition of the need to establish performance targets for the airtightness of buildings either through regulations or voluntary programs. Before this occurs, further research is required to establish baseline air leakage rates and appropriate building airtightness targets (and, for specific building types/uses such as schools).

Our Research

Between 2012 and 2014, with the support of the Natural Sciences and Engineering Research Council and Manitoba Hydro, a total of 26 commercial buildings in Manitoba were tested.

Overall, they represented a fairly diverse sample of Manitoba’s commercial construction:

  • 18 (69%) were situated in the City of Winnipeg
  • They ranged in age from one to over 100 years
  • Floor areas varied from 150 m2to 19,788 m2 (1,615 ft2 to 212,918 ft2)
  • Building heights ranged from one to 16 stories

Five of the structures were owned by Manitoba Hydro who also provided financial and in-kind support for the project. The rest were occupied by a variety of private and public owners. An effort was also made to include a few buildings that were undergoing, or had recently completed, a major building envelope retrofit.


  • While RRC’s work in this area has greatly expanded the knowledge in this area, the number of large buildings tested is still quite small especially when compared to low-rise residential dwellings.
  • The following three projects illustrate RRC’s ongoing efforts in this area through BETAC: See the final project report