Why do we measure the airtightness of a building?

New Buildings
A building that complies with recommended levels of air leakage has a guaranteed performance.

An air leakage test is carried out after the external fabric has been completed to confirm (or otherwise) that the building achieves the minimum air leakage standards set by the buildings designers.

The continuity of the air barrier is fully tested and any areas of failure can be identified. This allows any remedial work necessary to be carried out before retest.

Air leakage measurement on a new building is really the end of the process in ensuring a high performance low leakage envelope.

It follows work at the design stage to ensure continuity of the air barrier around openings and at all joints in the building fabric.

During construction, quality control must be maintained so that the design details are reproduced on site.

Finally the building is tested to confirm that the specified standards have been achieved.