What does it take to build a 10-star energy-efficient home?
Building an energy-efficient home isn’t a new concept, but a home that is 10-star energy-rated is still something few have achieved.
The National Construction Code requires all new homes meet a minimum 6-star energy rating. But for a growing number of new homeowners and builders, aspirations lie beyond the 6-star horizon. Many have their sights set on a 10-star energy-rated home and all the benefits that come with it.
To date, Australia boasts 14 accredited 10-star energy-efficient homes. So what exactly does it take to achieve this energy rating on a new home?
Getting the design right
According to the Nationwide House Energy Rating Scheme (NatHERS), the energy rating of a home takes into account hundreds of factors including building construction, location, climate and orientation. Insulation, ventilation and material choices also play a part.
Homes that are 10-star energy rated do not require any heating or cooling. To achieve this outcome in Australia’s harsh climate, architects and builders agree that careful design is vital – from window volume to thermal mass to material choices to orientation.
Award-winning architect, Clare Cousins, says taking a house from 6 stars to 10 stars is absolutely doable, but “you have to commit before you even put pen to paper on the design because aiming for a 10-star rating informs every decision you make about the home.”
“All habitable rooms must include north-facing windows, and factors such as insulation, ventilation and thermal mass need to be carefully considered. Home orientation is critical, too – achieving a 10-star home in an urban context with a small block of land is certainly more challenging.”
While building a 10-star energy-rated home is a complex undertaking, the success stories prove it is possible.
The Cape Paterson House
At The Cape development in Victoria, residents share a commitment to energy-efficient home design. The combined houses in the development are estimated to cost just $300 a year to run, according to modelling by Renew.
One home within this sustainable residential project has been built to an enviable 10-star energy rating standard.
This four-bedroom home’s sustainability credentials were set from day one, with designers and builders aiming for zero waste from construction through to completion.
Just three bags of rubbish were generated during the home’s build, thanks to the use of recycled and repurposed materials and little or no packaging on materials delivered to its construction site.
The Cape Paterson House makes use of cross ventilation and passive solar design. Key features include:
- Solar panels, including a five-kilowatt photovoltaic panel on the roof
- Thermal mass concrete floors
- Highly efficient LED lighting throughout
- Heavy-duty insulation including under-slab insulation and Bio-Phase Change Material (BioPCM) insulation in walls and ceilings
- Double-glazed windows
- Nighttime power shut down switch.
Thanks to its clever design, The Cape Paterson House requires no heating or cooling, yet its internal temperature sits between 18 and 26 degrees Celsius all year round. And by shutting off power to the home each evening (except the fridge), appliances such as computers and TVs aren’t left on standby, which significantly reduces unnecessary energy waste.
Other sustainable home decisions include the use of natural sealants and paints on the floors, walls and ceilings as well as environmentally friendly furniture and décor.
Recognising 10-star challenges
Homeowners, architects and builders are still working out the best ways to construct 10-star energy-rated homes for the mass market.
According to Wodonga-based sustainable home builder, Brendon Collins, most elements of a 10-star home require different construction techniques, such as triple glazing and bespoke wall and roof design. Treading new ground – going where other home builders haven’t gone before and being highly innovative – does require enthusiasm.
In Western Australia, journalist Josh Byrne – well known for his role as a presenter on the ABC’s Gardening Australia – personally took on the challenge of building an energy-efficient home in the Fremantle suburb of Hilton.
Byrne and his team used conventional building materials and construction methods so that the industry and wider community could easily replicate the design.
As the number of 10-star homes in Australia slowly rises, the outlook can only be positive – not just for the environment, but for homeowners themselves. With home heating and cooling making up around 40% of a home’s energy usage, reducing home energy use is never far from most Australians’ minds.