House depressurization is a ubiquitous, dangerous problem. As regional mechanical codes move toward consolidation into one International Mechanical Code, now is the time to add a performance testing requirement for house depressurization.

The Centre for Building Performance Research at Victoria University School of Architecture has recently concluded R&D for the Energy Efficiency Clause of the New Zealand Building Code. This report, contributed to the BEPAC Newsletter, discusses some of the issues that arose in the course of the work.

The National Building Code 1985 identified the need to control movement of air through the exterior walls of buildings. The upcoming 1995 National Building Code has now placed recommendations on the amount of allowable leakage.

Building diagnosticians routinely use measurements of differential pressures, building and duct system airtightness, and mechanical system airflow when investigating air quality, comfort, durability, and energy use problems in commercial and residential buildings. Unfortunately, wind and other sources of noise can create large pressure fluctuations which significantly increase the variability of these measurements, often to the point where they can not be relied upon in the diagnosis of performance problems, or as quality control indicators.