What is air leakage?

Air leakage is the uncontrolled flow of air through gaps and cracks in the fabric of a

building (sometimes referred to as infiltration or draughts). This is not to be confused

with ventilation, which is the controlled flow of air into and out of the building through

purpose built ventilators that is required for the comfort and safety of the occupants.

Too much air leakage leads to unnecessary heat loss and discomfort to the

occupants from cold draughts. The increasing need for higher energy efficiency in

buildings and the need in future to demonstrate compliance with more stringent

Building Regulations targets means that airtightness has become a major

performance issue. The aim should be to

‘Build tight – ventilate right’. Taking this

 approach means that buildings cannot be too airtight, however it is essential to

ensure appropriate ventilation rates are achieved through purpose built ventilation

openings.