Air leakage characteristics, test methods and specifications for large buildings.

A literature survey was conducted to identify measured airtightness values for various types of large buildings including Multi-Unit Residential Buildings (MURBs); offices; schools; commercial, industrial and institutional structures. Data was identified for 192 buildings in Canada, the United States, Great Britain and Sweden. Information was also collected on various quantitative and qualitative airtightness test methods, performance targets, specifications and quality control procedures. The results of the survey showed that virtually all large buildings, including those built within the last few years, are quite leaky and would not meet the current recommendations contained in the Appendices of the 1995 National Building Code of Canada (NBC). Typical leakage rates were found to be 10 to 50 times those referenced in the NBC. Despite this, the technology now exists to design, build and verify large building airtightness. Design details have been developed and are widely available to the architectural and engineering communities, standards have been established which identify how tight the building (or portions of its envelope) should be, quantitative and qualitative testing methods have been prepared and are commercially available in most parts of the country. Finally, quality control systems are available to integrate the theory into the practical realm of the construction site. The results of the literature survey were used to develop recommendations on measures which could be taken to improve the airtightness in large buildings. These included: a) the adoption of quantitative, whole-building airtightness requirements in the NBC and other standards (as opposed to non-mandatory recommendations), b) an investigation of how the current NBC recommendations are being enforced by building officials across Canada, c) establishment of a national database on large building airtightness, d) on-going provision of industry training programs, e) establishment of educational activities for building owners and property managers, and f) other measures which would create a demand for airtight construction.