Air exchange rates based upon individual room and single cell measurements.

For more than two years a series of detailed air infiltration measurements have been conducted over the complete yearly weather cycle on two identical side-by-side test houses in Gaithersburg, Maryland, USA. These measurements have been part of a broad study of the interaction of air infiltration , indoor air quality and energy in tightly constructed, well-insulated homes. The standard method of collecting air infiltration data throughout the study has been tracer gas decay. Operation of the duct air circulation fans has transformed each house into a single well-mixed cell . Natural air mixing in the upper and lower floors, with the fan operated occasionally, results in two cell behavior. The present phase of the air infiltration portion of the study has been to use constant concentration tracer gas equipment to study the air infiltration in six individual zones. This has allowed comparisons between the two methods as well as looking at the air infiltration profile in a much more detailed way. For example, the average infiltration rates for the control house using the two measurement methods are quite similar, but detailed information is now available on individual zone air infiltration rates and the effects of mechanical systems and weather influences on the zones. This paper compares the air infiltration measurement method results in the well-documented control house.