Method and apparatus for measuring air infiltration rate into buildings

Abstract

Sources which emit tracer gas at a known constant rate are positioned throughout a building. Samples of air are collected in selected rooms with constant rate adsorbent samplers. Samplers are analyzed in a laboratory to determine the tracer gas concentration during the period sampled, which concentration is compared to the known volume of the building to determine air infiltration rates. The tracer gas emission rate is rendered independent of room temperature by allowing the gas to escape through specially designed orifices which automatically open and close in response to changes in temperature. In one design, an orifice is formed in a material which expands and contracts with variations in temperature surrounded by a second, less elastic material. In another design, the area of an orifice is changed by a needle valve imbedded in a material which expands and contracts with temperature variations to move the needle in and out of the orifice. In another design, a bimetallic coil is positioned in the bottom of a container for adjusting the length of tracer impregnated material projecting out of an opening in the container. In another design, a bimetallic coil slides a valve which opens and closes an orifice in response to temperature changes. In another design, the bimetallic coil in a circular thermometer is connected to a tracer impregnated wire extending through a rim of an enclosure to adjust the length of wire projecting out of the enclosure. An alternative temperature-independent device uses thermostatically controlled enclosures to maintain constant source temperature.