NATHERS provides a framework that allows various computer software tools to rate the potential energy efficiency of Australian homes. NatHERS defines the minimum set of information that must be used by all software tools.
NATHERS facilitates consistent and repeatable ratings irrespective of the commercial software tool selected, and ensures that homes in all regions are treated fairly in their rating. NatHERS enables homes of good practice for each local climate to receive a similar rating, even though each building will be subject to widely different climatic conditions.
NATHERS defines a fair and transparent process for competing software tools to be accredited. Accredited tools are eligible to use the HERS logo in a responsible way, and advertise their association with NatHERS.
NATHERS provides for energy rating assessors to be registered by Assessor Accrediting Organisations.
House Energy Ratings:
House energy rating through the Nationwide House Energy Rating Scheme (NatHERS) uses computer simulations to assess the potential thermal comfort of Australian homes on a scale of zero to 10 stars. The more stars, the less likely the occupants need cooling or heating to stay comfortable.
A dwelling can be rated before or after it is built. The rating depends on:
- the layout of the home
- the construction of its roof, walls, windows and floor
- the orientation of windows and shading to the sun’s path and local breezes
- how well these suit the local climate.
Energy consumption by hot water systems, lights or household appliances is not part of the rating because those fittings are usually replaced several times during the life of the building.
What the stars mean:
- Zero stars means the building shell does practically nothing to reduce the discomfort of hot or cold weather.
- A 5 star rating indicates good, but not outstanding, thermal performance.
- Occupants of a 10 star home are unlikely to need any artificial cooling or heating.
Fun Fact: Houses built in 1990 averaged about 1 star on the NatHERS scale. Before the introduction of national energy efficiency regulations for houses in 2003, less than one per cent of Australian houses achieved 5 stars.