What levels do I need to achieve to pass my Air Test?

The result of the air leakage test is expressed as a quantity of air leakage (m3 per hour) per square metre of building envelope or m3/hr/m2. The maximum allowable air permeability rate for Building Regulations compliance is 10 m3/h.m2, however it is very common for a dwelling to have a much lower design air permeability rate in order to meet the target CO2 emission rate (see SAP calculations).

In In our experience most new-build dwellings and commercial buildings have a design air permeability rate of around 3 m3/hr/m2 to 5m3/hr/m2. Where mechanical ventilation with heat recovery (MVHR) has been installed to the dwelling the air permeability rate should be no greater than 3 m3/h.m2 for the system to operate effectively.