Can a home stay comfortable without high energy bills?
Yes, it’s absolutely possible! More and more homes—whether newly built or retrofitted—can stay warm in winter and cool in summer without relying heavily on air conditioners or heaters.
This is achieved by harnessing passive design principles, which considers elements like the home’s orientation, insulation, thermal mass, shading, and ventilation. These factors work together to take advantage of the natural climate, reducing the need for artificial heating and cooling.
There are many ways to upgrade your home’s performance, step by step, without needing a full overhaul.
What is NatHERS and Star Ratings?
The NatHERS (Nationwide House Energy Rating Scheme) provides a star rating to measure how well a home keeps comfortable temperatures without using extra energy. This is calculated using software that models your home’s performance in its local climate.
New homes in Victoria are required to achieve a minimum of 7 Stars. The average existing home is around 1.8 Stars!
The science behind NatHERS can also be used to improve existing homes. Upgrading a home from 1.8 Stars to 7 Stars can reduce heating and cooling energy by up to 80%.
What makes NatHERS especially effective is its climate responsiveness. Australia has 69 defined climate zones based on 25 years of hourly data from the Bureau of Meteorology, which helps make the ratings accurate and relevant for your area.
A Star Rating isn’t just a performance benchmark—it’s increasingly seen as a measure of value, along with other factors like size and location.
Why is thermal performance important?
Your home’s thermal performance directly impacts how comfortable and healthy it feels—and how much energy it uses for heating or cooling.
Heating and cooling are usually the largest contributors to household energy use, and it’s where most energy savings can be made.
That’s why a focus on the building envelope—the floors, walls, ceiling, windows, and doors—is so important. This is the shell that separates the inside of your home from the outside environment. Improving the envelope first reduces the need for costly and energy-hungry heating and cooling systems.
Once the envelope is well designed, you can then focus on improving the efficiency of heating and cooling appliances, hot water systems, lighting, and other equipment. Lastly, you can turn to renewable energy sources to power your home.
What is embodied energy?
Before we even think about how a home operates, there’s the energy it takes to build it. This is called embodied energy—the energy used to produce and transport building materials and construct the home itself.
While it’s easy to focus on the operational energy use (the energy your home uses to stay comfortable), reducing embodied energy is just as important.
Why retrofit and adapt existing homes?
Retrofitting existing homes is one of the most effective ways to reduce energy consumption, lower carbon emissions, and create more comfortable living spaces. Rather than demolishing and rebuilding, adapting what we already have allows us to preserve the character and history of our homes while making them more resilient to the changing climate.
Central Victoria, with its unique climate, presents some challenges for homeowners, but with thoughtful upgrades—whether it’s improving insulation, enhancing thermal performance, or upgrading heating and cooling systems—it’s entirely possible to achieve significant energy savings and comfort improvements.
Retrofitting also helps to reduce waste and the embodied energy associated with new builds. By working with what already exists, we not only make our homes more efficient and sustainable, but we also contribute to a more sustainable future, helping to minimise the environmental impact of the building industry.
