Blower door testing is the process we use to test the air tightness of a building envelope. We will always undertake a Blower Door Test on all our full builds and offer this testing service to other builders or homeowners who wish to undertake it.
It is basically a powerful fan which mounts into the frame of an exterior door. The fan has sensors that can accurately measure the amount of air it takes to maintain a constant pressure of 50 pascals (a fresh breeze). The test includes pressurising the building and depressurising the building and the result is an average of both readings. If significant air leakages are present, they can be detected by several methods.
The testing of a new building is normally carried out twice, once after an airtight seal has been installed (i.e Intello wrap) and once at build completion. It is important to do the first test after the fabric of the building is complete and the windows are fitted as it is still possible to find any breaches and fix them.
In a certified passive house air tightness must be less than 0.6 air changes an hour. Minimum code-built homes average 4 to 10 ac/hr.