An APZ or Asset Protection Zone is one of several other elements that make up what are called BPMs – Bushfire Protection Measures. These measures are in place to assist in the survival of a building in the event of a bushfire event, to ultimately preserve life.
Extract from Planning for Bushfire Protection, 2019
Prior to 2001 APZs were really afterthoughts in the building process, hence many homes built prior to then are extremely close to bushland with little to no gap, however since the implementation of the Planning for Bushfire Protection in 2006, APZs are now part of the building process with strict guidelines.
Strictly speaking the APZ is the responsibility of the landowner and is essentially the buffer between your home and the bushfire threat.
Descriptively the APZ is the area around the home or building that is maintained to keep potential fuel loads to a minimum, thus giving a potential bushfire less ability to access the property and to minimise the effects of radiant heat, burning embers and smoke. The parameters of an APZ vary, as it depends on the vegetation, slope and construction level of the building.