Today we started doing ‘Blower Door Testing’. Basically this involves opening the front door and putting some fabric in a frame in it’s place. The fabric has a hole for a fan which sucks air out of the house, causing the inside of the house to be at a lower pressure than the outside. This means that air comes through any gaps fairly fast, making it easy to find the holes in the fabric of the building – either by just feeling for it with your hand or using a smoke generator.
In addition, the rate of air flowing through the blower door for a given pressure drop provides a standard measure of the air tightness of the house. This, combined with measuring the size of the house, can tell you how often the air will change in the house. Too little and we get mould growing everywhere. Too much and your heating bill will be rather high.
We found the house tested was fairly airtight, though it appears our windows weren’t fitted all that well – there was plenty of air coming through the crack between the window frame and wall – more than through the small air hole provided at the top of the window frame. (The crack where the closed window met the window frame was pretty good).
Anyway, here are some photos from the day.
The blower door being assembled
The blower door in place
The fan
The smoke generator
Smoke being blown by a draught
The blower door in place (from outside)