There is a range of energy rating schemes in Australia. The Nationwide House Energy Rating Scheme (NatHERS) is the most common national scheme, Basix is for NSW only, and EER is ACT's rating scheme.
A home energy rating uses software to predict a home's energy efficiency potential (thermal performance). Generally speaking (apart from in the ACT) the assessment of a building's thermal performance occurs at the design stage of a home. An energy rating can be assessed by a building professional but should only be prepared by a trained assessor. To indicate how efficient the design of an existing or yet to be built home is, it is given a star rating between 0 and 10 stars. 10 stars generally indicates that the home should remain comfortable year-round without using a heater or air conditioner. In most states 6 stars is the minimum standard for new housing under NatHERS. Understanding how to read and understand these ratings can help you with your decisions when choosing the most comfortable home.