What is a house’s energy efficiency star rating?
A house’s energy efficiency (star rating) applies to the design of the ‘building shell’—roof, walls, windows and floor. The building shell significantly influences the indoor comfort and energy efficiency performance of the dwelling. The rating is out of 10 stars. It does not include major fixed appliances like air conditioners, hot water systems, lighting and fridges.
How does the 6-star standard apply to houses?
The minimum energy efficiency rating for new houses and townhouses (class 1 buildings) is 6 stars. This standard also applies when undertaking a renovation to an existing house, such as additions, alterations or re-locations.
What are the benefits of a 6-star house?
A 6-star house is not only more comfortable to live in, it will also provide homeowners with ongoing savings on electricity bills because it uses less energy for artificial cooling and heating. This standard can also reduce the need for additional electricity infrastructure caused by peak demand by encouraging more energy efficient building design.
What are the design features of a 6-star home?
Architects and designers are able to use a range of styles and energy efficient features to comply with the 6-star standard. A 6-star house may not look any different from another house, but it can have a better energy performance. Many energy efficient (or ‘passive’) design features can be included at little or no extra cost, such as:
- northern orientation of living areas and good layout of rooms
- minimising the area of east and west facing walls and windows
- wider eaves and window awnings for shading
- well-located and designed windows to capture breezes for ‘natural ventilation’
- insulation under roofs and in walls
- roof ventilation with roof and eave vents
light coloured roof and walls
- treated glazing, particularly for western facing windows
- ceiling fans in living areas and bedrooms.
What compliance methods can be used for the 6-star rating?
A range of compliance options are available to achieve a 6-star house. The assessment methods have been improved over time, including better consideration of shading and ventilation, and lifestyle.
The two typical compliance methods used are:
- software: a house energy assessor uses approved software under the Nationwide House Energy Rating Scheme (NatHERS), these being BERS Pro, AccuRate or FirstRate5, to model the design and produce a star rating certificate, or
- elemental (deemed-to-satisfy [DTS]): an architect or building designer follows the more prescriptive design requirements set out in the National Construction Code (NCC, formerly known as the Building Code of Australia) in Volume Two (section 3.12), noting any state specific variations.
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