Engineering and Construction

It will be mandatory for buildings to be designed and constructed so that an air leakage index will not be exceeded. This index will be set at a  specific value of volume of air leakage per hour per square metre of external surface at a pressure difference of 50 pascals.

Present proposals for this air leakage index are as follows:


To achieve the above, care must be taken to specify and effectively construct sealed junctions between elements, thereby minimizing air leakage.

The air leakage index will be quantified by  in situ air pressurization tests, using fans, which must always be used on buildings with a floor area that exceeds 1000m2.

Should the building fail the test, remedial measures must be undertaken, and further tests carried out until the building is deemed to comply to the satisfaction of building control.