Convention 6.07 - Estimating Local Mechanical Exhaust Rates in Buildings

Where it is not possible to obtain details of the fan performance from the Fan nameplate or BuildingLogbook, Operation & Maintenance manual etc. during the Site Survey, an approximation of the of the airflow rate in I s-1 m-2(often written as I/s/m2in SBEM) can be established by using an appropriate rate fromthe attached table (Local Mechanical Exhaust Rates) and converting this to I s-1 m-2, using the zone height(do not adjust the height measurement used to compensate for an internal ceiling). It is not acceptable to usean arbitrary value such as 5 I s-1 m-2 or a software applied default for extraction rates where the mechanicalextraction rate is unknown.