Air Tightness of New Australian Residential Buildings

To achieve the energy efficiency standards in the National Construction Code, houses generally need to use insulation and weather sealing. However, if poorly installed this can lead to houses that have lower energy efficiency performance than expected. There has been little data collected on newly built houses to quantify air-tightness and assess the quality of insulation. This paper reports on a study that investigated new house construction around Australia to gain insight into the quality of house construction with regard to air-tightness and quality of insulation. Twenty houses in each capital city, except Darwin, were recruited for the project. The houses in most cities were up to 3 years old and assumed to be at the 6 star NatHERS standard.Blower door testing was carried out on 125 of the volunteer homes and the resulting air changes per hour at 50 Pascals pressure (ACH@50 Pa) for each house was then determined. In addition, an inspection of each house was undertaken by a qualified energy assessor to assess the quality of the insulation installed. A thermal inspection of the walls and ceiling was undertaken as well as a visual inspection of the ceiling insulation (if accessible). Weather sealing around windows and doors was also inspected for any gaps and damage.A broad range of results was achieved and found that well sealed houses are being constructed, but equally poorly performing houses are also still being built. To maximise value for energy in our houses, it is critical that we determine why these differences occur and how we can consistently build well sealed houses.