Air leakage measurement of buildings by an infrasonic method. Final report, May 1976--December 1977

Excessive air leakage in buildings wastes heating and cooling energy. As an alternative to the blower method for measuring the composite effective size of all the air-leakage passages of a building or part of a building, the authors used an infrasonic method to yield the same flow-versus-pressure difference information. Sinusoidably varying volumetric flows between 0.05 and 5 Hz are generated by a motor-driven bellows-like source located inside the building under test. The resulting pressure variations are measured using a microphone-like sensor having an electronic signal processor. An important advantage of the infrasonic system is that no through-the-wall vents or pressure taps are required. One house, five apartments, and three interior rooms have been tested to date. Infrasonic and blower test results usually agree within a factor of three, but improved apparatus is expected to improve the agreement in the future.