Reference Guide states that the most important is to confirm that ventilation air is provided to all occupiable spaces in the building (especially such as circulation, back of house spaces, and active storage rooms). We have a 100% outdoor air system with single AHU supplying fresh air to multiple zones through diffusers. As we are taking OA flow measurements at the AHU only, how can we prove that ventilation air is provided to all spaces?

Thanks!