Describes how a fully furnished two storey test house was used to perform an experimental study of tracer gas dispersion and airborne moisture movement. The test used two multizone models to simulate the experimental data. States that good agreement was obtained in the comparison and with the tracer gas dispersion. Finds that a representation of adsorption by indoor surfaces must be included in order to accurately model the airborne moisture movement. Indicates that it is very important to represent both the two way flow through open doors and the stack effect in a two storey houses, to correctly describe the interzonal airflow.