6. What if I fail to achieve the required air permeability?
The easiest and most common way to identify air leakage paths is to feel them during or after the test. By depressurising the building/unit (i.e. drawing air out using the fan(s)), the air paths should be identifiable as draughts. Where it isn’t easy to feel or pinpoint the draughts, smoke can be used to make the leakage paths visible. In many cases, it can be relatively easy to address the issue permanently in a few minutes and repeat the test. Where the failure is more significant or difficult to access, a further visit may need to be scheduled. If the result is close to achieving the target or design air permeability, it is worth checking with your energy assessor as to whether the performance is good enough to achieve the overall energy targets.