Convention 2.03 - Air Permeability

The SBEM default value of 25 m3/hr m-2 for all existing buildings shall be amended as follows:

• Less than 10 m3/hr m-2 – only with an accredited air pressure test result

• 10 m3/hr m-2 – buildings > 500 m2 built to 2002 Building Regulations (or later)

• 15 m3/hr m-2 – buildings <= 500 m2 built to 2002 Building Regulations (or later)

• 15 m3/hr m-2 – Buildings built to 1995 Building Regulations

• 25 m3/hr m-2 – buildings built to Building Regulations pre 1995 (pre 1994 in Scotland)

• 35 m3/hr m-2 – to be considered where buildings are pre 1995 regulations (pre 1994 in Scotland) andwhere suitable evidence of high permeability exists, e.g. single skin metal clad structure withinPlanning Use Class B2 – B8 with large roller shutter doors and poor constructional details etc

In the case of a building part designed or modified to be used separately the air permeability is determinedby the floor area of the building part, except where multiple parts are primarily accessed via a commonentrance; in which case, it is determined by the total floor area of all the parts sharing the common entrance