Air Permeability Pressure Testing, also known as Airtightness Testing or Air Leakage Testing, is undertaken to measure the air leakage of a dwelling. All testing should be conducted by qualified personnel and the test should be certified by a third-party organization. Clause 1.5.4.3 of TGD L Dwellings 2011 requires outlines that at least one type of every dwelling is required to have a test undertaken. In large developments, one dwelling of the first four types of units should be tested.
The total number of tests required is dependent on the number of units and the number of failed tests carried out prior. Where a number of apartment blocks are constructed on the same site, each block should betreated as a separate development irrespective of the number of blocks on site. In the case of small developments with 3 dwellings or fewer, specific pressure testing of dwellings is not be necessary if, in the previous 12-month period, the builder could provide the test results from the same type of dwelling constructed elsewhere and has met the necessary requirements to pass the Air Pressure Test.
However, if the assumed air change rate in the calculation of the Energy Performance Coefficient (EPC) and Carbon Performance Coefficient (CPC) using the DEAP methodology is less than the reasonable upper limit for air permeability of 7 m^3^/(hr.m^2^), a pressure test to verify this assumed value should be carried out. Single unit developments are included in the same rules as small developments.
Air permeability Pressure Testing is carried out by attaching and sealing a variable speed blower fan to the front door of the dwelling. The ventilation in the dwelling must be positioned in the closed location but must not be sealed over its installed shut position. The fan will pressurize the building by either extracting or inserting air into the dwelling. The airflow through the fan is measured at a range of pressures and the data analyzed by a software program that calculates the air flow rate in m^3^/(h.m^2^) of building envelope area at 50 Pa. The average quantity of air being supplied to or drawn from the building to maintain pressure levels will be approximately equal to the air quantity escaping from the building through unintentional air paths and therefore reflects the air leakage rate.
