The purpose of this study is to estimate the accuracy of SRF (Supply Rate Fulfillment) value using tracer gas methods, which are constant concentration method and constant injection method, on the test house. The test house is established in an artificial climatic chamber, its air tightness can be varied and airflow rate can be known by ΔP method which uses the differential of pressure between outside and rooms. Using SRF as a ventilation performance index, properties given by tracer gas are compared to their values given by network model or ΔP method. The following are conclusions on the experiment in nearly steady conditions. 1. The ways to calculate and to treat SRF and other properties are shown. 2. The SRF values, which indicate less than 1.0, are shown by using the tracer gas method. 3. SRF, α and other properties using tracer gas method can be indicated moderate value compare to other method. 4. The tracer gas method is useful to presume SRF value from practical standpoint.
