Canada and the USA: differences in the energy efficient housing scene.

Describes elements of the 'Building America' initiative, a federally sponsored initiative that has as its goal to persuade production builders (100 plus homes a year) to build more energy efficient and durable homes. Some 'volume builders' in America build more than 20,000 homes a year. It is difficult to persuade buyers to invest in energy efficient homes. Many mechanical contractors fit two furnaces in unconditioned space, because duct runs are easier to install. The more efficient way would be to install a single furnace and to upgrade the thermal performance of the building shell and ensure that ductwork is thoroughly sealed. Standard home airtightness does not approach the 3-4 ACH@50 Pa seen in the average Canadian home. States that the infrequent use of polyethylene as an air or vapour barrier could account for the leakiness. Poly is not advised for warmer climates, and drywall is used as the air barrier, with careful attention to draught-stopping. A blower door test result of 4.0 ACH@50 Pa is viewed as good.