The leakage of air out of and into air handling supply, return and exhaust ducts can have a significant effect on energy usage and greenhouse gas emissions. AS 4254.2 [1] mandates leakage testing of all duct systems, this is contrary to recommendations in earlier editions of the standard. AS 4254.2 is incorporated by reference into the NCC (National Construction Code).

Improved duct sealing and leakage testing has the potential to provide substantial reductions in operating cost and greenhouse gas emission, as well as improving the quality of the service delivered. This TECHnote examines the impact of duct leakage, statutory testing requirements and NATSPEC provisions for leakage testing.