A comprehensive theory of multi-chamber air infiltration measurement using a single tracer gas is introduced from the general stand point of system identification. The thermal network model can be applied not only to the temperature transfer and diffusion system but also to the tracer gas transfer system. This model is formulated mathematically in a stale equation. The coefficents in the state equation represent airflow rates of infiltration. Two theories for estimating these coefficients are deduced from the least square.
Flow measurements using rracer gas reclmiques were made on tile exterior doorway of a test house for indoor-outdoor temperature differetJces of 0.5-45 K. The time for door opening and closing was constant at 3.75 s, and fully open hold time varied from 0.5 s to 120 s. Predictions of a variable density sready flow model were in good agreement with the measurements when adjustmenrs were made for the time-varying size of the opening and for the effect of cross-stream mixing between the incoming and outgoing air streams.
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