Valuing air barriers.

Discusses the importance of selling the cost benefit of tight building practices in the absence of national or local codes or regulations to mandate well-sealed apartment buildings. States that studies carried out by the Canada Mortgage and Housing Corporation have found that air leakage in apartment buildings can contribute to as much as 20% of the annual space-heating energy load. It also represents a substantial proportion of the peak space-heating load. Describes a study to gather air leakage data on large buildings in order to establish baselines for air leakage rates and to assess whether there were any relationships between building age, size, wall construction, location, and use on the one hand, and air leakage characteristics on the other. It appeared that a significant variation in air barrier performance occurs over the envelope of a given building. The study showed that most apartment buildings are 30 to 40 times more leaky than the recommended limits. Even advanced energy efficient buildings do not have requirements for the design, specification, testing and certification of air barrier performance. States that there are now many building materials available that can be used in a systematic fashion to create high-quality air barrier systems, and that design details are being developed for all wall types to show how air barrier systems must be integrated with wall construction. States that without tangible evidence of the benefits, air leakage control will continue to be a difficult commodity to sell at the design stage.