1. What needs to be tested?
All new buildings of all types. It is possible to avoid testing individual houses and small commercial buildings but it means using a very poor, assumed air permeability value in energy performance calculations which will make it difficult and/or expensive to achieve the overall Energy Performance of the building so this tends not to be practical. On larger residential developments it is possible to test a sample of units rather than every single one but, in practice, a large proportion of the units will still need to be tested as relatively small variations in size, position, openings, etc will be considered a different type plus to use tested results on untested plots you will need to achieve ‘2’ better on the tested units which is difficult and/or expensive to achieve.
ATTMA is the Air Tightness Testing Measurement Association which operates the largest and longest-established approved competent persons scheme for air testers. Air testers must be a member of such a scheme and must hold the appropriate level of registration for the project they are undertaking e.g. Level 1 is only for dwellings and small, single-fan buildings other than dwellings whereas Level 2 is required for the majority of buildings other than dwellings.