Making Sense of Energy Ratings
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Australia's Net Zero Future
Australia is committed to building a net zero future. A key element of the path to net zero is energy efficiency - in industry, transport, and our homes. In 2024, Building Ministers committed to achieving net zero emissions in the built environment - the everyday places we live and work - by 2050. Improving the energy performance of our buildings will also become increasingly important to support comfortable living year-round, lower heating and cooling bills and deliver better health outcomes. 

The minimum energy rating requirement for new houses and apartments in most jurisdictions in Australia has increased from 6 to 7 stars (out of 10). But what does that mean?

​About NatHERS
The Nationwide House Energy Rating Scheme (NatHERS) rates the energy efficiency of new homes. Driven by CSIRO science, NatHERS offers both a star rating out of ten - based on factors, such as the home’s construction, local climate and orientation on the block - and a score out of 100 - based on entire home energy use, including appliances, solar panels, and batteries. 

Achieving a 7-Star NatHERS rating
Focus on energy efficiency measures, including high-performance windows. 

• Consider the layout and orientation of the home to maximise capture winter sun in living areas.
• Add appropriate shading on the western side of the home.
• Utilise more insulation.
• Install high-performance double-glazed windows and doors with thoughtful orientation and placement.

A home's energy performance score - out of 100 - is  assessed using a "Whole of Home" rating, which considers the home's thermal performance, appliances, solar panels, and batteries. The home energy assessment helps you make decisions on energy efficient appliances suited to your family and local climate.

How Windows Affect NatHERS Ratings:
Thermal Performance: Windows are a major source of heat loss and gain, so their thermal properties are a key consideration in NatHERS assessments. 
Glazing: Double or triple glazing significantly reduces heat transfer, improving energy efficiency. 
Frame Type: The type of window frame (e.g., aluminum, timber, or uPVC) has a strong influence on thermal performance, with uPVC offering 1000 times better insulation than Aluminium. 
Window Sizing and Placement: The size and placement of windows, as well as their orientation, impacts the home's heating and cooling needs. 
Shading: Proper shading (e.g., awnings, overhangs, or blinds) can help to reduce solar heat gain in summer and maximize solar heat gain in winter, further improving energy efficiency.

Key Considerations for Window Selection:
U-Factor: This measures a window's ability to resist heat transfer, with lower U-factors indicating better insulation. 
SHGC (Solar Heat Gain Coefficient): This measures how much solar heat a window allows to pass through, with lower SHGC values indicating better protection from solar heat gain. 
ER (Energy Rating): This is a measure of the overall energy performance of a window, with higher ER values indicating better energy efficiency. 
Climate: Window selection should also consider the local climate. 
Orientation: The orientation of windows (e.g., north, south, east, west) can impact their energy performance, with windows facing north or west potentially requiring more shading. 

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