Flow paths in a swedish single family house.

The traditional description of a flow system with a multicell model, Vc(t)=Qc(t)+p(t), may sometimes be to restrictive. The multicell theory require measurements, or reconstruo tion, of the tracer concentrations in a number of perfect and immediate mixed cells. Often, using of mixing fans and closing doors between cells are necessary to comply with the theory. Another, very usefil and more general description of a flow system is through the weightingfinction. Unlike the multicell model this is not an internal model, but only an input- output model and it is thus less informative. Still, knowing the weighting knction is sufficient to determine the flows rates, the active volumes, the mean ages of exhaust air and of room air and the air exchange efficiencies. Typically, these parameters are determined for each fIaw path fiom an input, often a supply air, to an output, often an exhaust air. Contrary to common air exchange efficiency measurements, resulting in one ore a few figures, the determination of the weighting finction results in a complete model which is also suitable for simulations. In this paper, the theory is only surveyed and no derivations are given. A single family house with exhaust ventilation is used to demonstrate the method.