In addition to new dwellings requiring to meet NCC energy efficiency requirements, the code also requires that major modifications, renovations, additions and alterations to residential buildings also meet the energy efficiency requirements and consequently NatHERS ratings are undertaken for this type of work. Existing dwellings are also sometimes rated at the request of the building owner, but there is no mandatory requirement to rate existing buildings in Australia.

Nationwide House Energy Rating Scheme
Supported by data from the Nationwide House Energy Rating Scheme (NatHERS) www.nathers.gov.au