Mark XI energy research project, Airtightness and air infiltration measurements.

Reports measurements of air leakage rates in the four energy-conservation research houses using the fan pressurization method. One of the houses is standard for the area and the other three houses have added insulation and vapour barriers. One house has a heat pump and one an air-to-air solar heating system. Air infiltration rates were measured in two of the houses using CO2 as a tracer gas. Discusses results and compares tracer gas with pressurization tests. Finds that air infiltration accounts for about 20% of the total energy purchased for the standard and heat-pump houses in the 1978-79 heating season.