At Chiltern Dynamics, we will endeavour to help you identify the probable air leakage/infiltration paths.

There are number of methods we employ to do this of increasing complexity:

• Depressurise the building – we tend to pressurise the building under testing which forces air out, by reversing the fans and depressurising the building air is drawn in and normally can be felt or even seen as ‘draughts’
• Smoke testing – if the air paths are less direct it may be necessary to use smoke puffers and/or fill the building with smoke and pressurise/depressurise again. Points of air ingress and egress should be identifiable.
• Thermography – if it is still not apparent where air is escaping, infra-red cameras can be used to identify hot spots and cold spots on the internal and external surfaces of the building. This requires a temperature difference between inside and outside and usually done at night.

In the vast majority of cases the first method is sufficient to identify air leakage paths. These can be temporarily or permanently sealed and the test repeated to quantify the effect of addressing these areas.

The building will need to be re-tested, sometimes on the same day but usually at a later date.

For buildings other than dwellings, the same unit is tested and must achieve the air permeability require to achieve the Target Emission Rate or for buildings less than 1000m², until October 2007, a significant improvement.

For dwellings, the same unit should be tested, plus another example of the same dwelling type (assuming one exists).

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