本标准定义了测量机械通风建筑物或空间换气效率的方法。该方法采用空气龄方法来评估换气效率，并采用示踪气体程序来测量空气龄。给定位置的空气年龄是该位置的空气分子进入建筑物后经过的平均时间。换气效率的定义是基于建筑物被占用部分的空气年龄与通风空气完美混合条件下存在的空气年龄的比较。

 This standard defines a method of measuring air-change effectiveness in mechanically ventilated buildings or spaces. The method involves an age-of-air approach to air-change effectiveness and employs tracer gas procedures to measure the age of air. The age of the air at a given location is the average amount of time that has elapsed since the air molecules at that location entered the building. The definition of air-change effectiveness is based on a comparison of the age of air in the occupied portions of the building to the age of air that would exist under conditions of perfect mixing of the ventilation air.