7 Stars Energy Efficiency

7 Star NatHERS & Whole of Home

The Nationwide House Energy Rating Scheme (NatHERS) provides a star rating (from 0 to 10) that indicates how well a home’s design reduces the need for artificial heating and cooling.

For over a decade, the minimum standard for new homes in Australia was 6 Stars. Following the adoption of the National Construction Code (NCC) 2022, this minimum requirement was lifted:

1. The New Minimum Standard

• 6 Star (Old Standard): The home needed to perform well enough to maintain comfortable temperatures with minimal energy use.
• 7 Star (New Standard): The design must now achieve a 7-Star rating or higher. This requires better insulation, smarter window choices, more efficient shading, and overall superior design compared to the 6 Star requirement. This change is designed to make homes cheaper to run and more resilient to climate change.

2. What are the Rating Measures

The NatHERS rating focuses solely on the thermal performance of the building fabric—the roof, walls, windows, and floors.

• It answers this question: How much energy will this home need to use just to heat or cool itself to a comfortable temperature (between 20°C and 25°C)?

Essentially, a 7-Star home uses significantly less energy for heating and cooling than a 6-Star home, which is a major selling point for homeowners looking to save on their energy bills.

What is Whole of Home (WoH)?

While the 7 Star rating focuses on the building envelope (the “shell” of the house), the Whole of Home (WoH) assessment expands the energy efficiency focus to cover the entire operational energy use of the house.

This is a brand new requirement under the NCC 2022 and ensures homes are assessed holistically.

1. Two Key WoH Metrics

The Whole of Home assessment introduces two key performance targets that your home design must meet:

Metric	What It Measures	Why It Matters
Fixed Appliances	Energy use from major installed systems like hot water systems, lighting, and any necessary pool/spa pumps.	It ensures the appliances you install meet minimum efficiency standards, reducing the home’s total energy footprint.
Solar PV Offset	A calculation of how much of the home’s energy use is offset by mandatory on-site renewable energy generation, primarily solar PhotoVoltaic (PV) panels.	It mandates that a new home must be designed to generate a portion of the energy it will consume, making it significantly more sustainable.

Whole of Home completes the picture. It recognizes that even a perfectly insulated house will still use energy for lighting and hot water.

By requiring efficient appliances and solar PV, the WoH assessment ensures that new Australian homes are not only thermally efficient (7 Stars) but also produce some of their own power, leading to substantially lower running costs and reduced carbon emissions.

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In short, when you work with us, we ensure your design meets:

1. 7 Star NatHERS: For a superior, passive design that saves on heating/cooling.
2. Whole of Home: For a complete, high-efficiency system that saves on appliance and lighting costs.

Let me know if you’d like a simplified, shorter version of this explanation, or if you’d like to work on content for another one of your services, like Section J Reports or BASIX Certificates!