Australia's Energy-Efficient Homes: 6, 8, or 10 Stars?

What makes a sustainable home? A sustainable home minimises our energy use through a difference in materials and design. It is both more expensive but greener and more cost-efficient. Australia employs the Nationwide House Energy Rating Scheme (NatHERS) to measure the energy-efficiency of our homes; currently, the nation-wide minimum for new homes is set at at 6 stars on this scale, with 10 being the highest.

Yet 6 stars is not really the most socially or financially optimal rating for new homes, at least from an economic perspective. Over the life-cycle of the home, the optimal rating would be between 7.5 to 8.5 stars. Despite that, Australian builders rarely construct homes of that standard. As of 2018, only ACT had raised their average NatHERS rating significantly, from 6.5 in 2016 to 6.9 in 2018. Victoria's remained flat at 6.2 stars in the same period.

For many in the property industry, it just seems like the demand for more sustainable homes is not enough to warrant reaching for a higher rating. The lower demand makes sense; the increased cost of such homes is immediately visible in the selling price, which scares most people off. Conversely, the net savings produced from reduced energy usage is instead invisible and accumulated gradually over the long-term.

However, in recent years, a growing subset of the market is creating a steady uptick in demand for sustainable homes, potentially making them more appealing to mainstream builders. This niche of builders and buyers of sustainable homes is proving its viability through demonstrating that more sustainable homes are not much more difficult or expensive to achieve—just a matter of north-facing windows and choosing the right resources.

The Cape Paterson Home

The Cape at Cape Paterson is about a 30-minute drive from Victoria's Phillip Island. With all 230 units of its homes at at least 7.5 stars, the beachside development boasts the title of "Australia's most sustainable housing development". One house, however, exceeds the rest—the10-star home designed by The Sociable Weaver and Clare Cousins Architects, retailing for $499,000.

This home generated only 'three bags of rubbish' throughout its construction process. It requires no mechanical heating or cooling, yet maintains a comfortable internal temperature range year-round. At 10 stars, this home will not only save greatly on energy use, it will actually export a surplus of clean energy, producing negative carbon emissions.

With no need for internal heating and cooling, the house also has 5kW photovoltaic solar panels on the roof and highly efficient LED lighting throughout—in layperson terms, this 10-star home costs a grand total of $3 per year to run.

It's certainly not an easy process, however. Building a 10-star home requires builders to be much more thoughtful in every stage of the house's construction, from engaging with suppliers to reduce packaging waste to meticulously implementing design principles that maximise energy usage. Clare Cousins emphasises that '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'. (ET)