Air leakage in a building at low pressures using an alternating pressure source.

Reports low-pressure measurements of the leakage function of a building using an alternating (AC) pressure source with variable frequency and displacement. Synchronous detection of the indoor pressure signal created by the source eliminates the noise dueto fluctuations caused by the wind. Finds good agreement between AC and DC leakage results in pressure regions where the results can be compared. The low-pressure values made with the AC source suggest that the air flow is dominated by orifice flow effects down to pressures less than one Pascal.