scope:

The specifications set forth an engineering standard by which to obtain the ventilation rate/specific airflow rate, using a tracer gas in a building space, which is considered to be of a single zone. 1) The measurement method is valid in spaces where the air is well mixed. In particular, there should be no large air flows such as cross-ventilation. 2) The specifications set forth as measurement methods using a tracer gas, three measurement methods: (1) Concentration decay method (2) Continuous dose method and (3) Constant concentration method. Note 1 In spaces where a large amount of ventilation such as cross-ventilation occurs, concentration is not uniformly distributed and large changes of concentration tend to occur over time, so they are not targeted. However, if the direction of flow is evident such as with flow within a duct, the specific airflow rate can be assessed using the continuous dose method. Note 2 The measuring accuracy of the so-called concentration raise method has a relatively poor accuracy and is seldom used, so will not be mentioned here.