There is many a personal anecdote told within the built environment surrounding the thermal performance of Australian houses. Foreigners who travel to the land down under are often sweating in the heat or freezing in the winter, despite coming from areas and climates that reach well below zero in the colder months.

Data is able to confirm that these anecdotes hold weight. Records on existing homes shows that , the average Australian home sits between 1.7-2 stars on a scaling system that has a maximum of 10 as per NatHERS, the ratings system used for evaluating the energy efficiency of a home. It paints a pretty stark picture of what is required to improve the thermal efficiency of our existing homes in order to reduce strain on energy grids, which will gradually lower emissions.

A new report from RMIT, titled Enhancing home thermal efficiency, talks about the challenges faced by Australian architects, designers and built environment professionals in improving residential performance. Commissioned by government-funded research centre RACE for 2030, the report recommends several priorities to help Australia reach its goal of net zero by 2050.

Priya Rajagopalan, the report’s Lead Researcher and Director of RMIT’s Sustainable Building Innovation Lab, believes that complacency has resulted in the poor energy efficiency of Australian homes.

I think that there is this perception that our weather is not as severe as some of the European countries, particularly in the cold seasons, that we don’t need to design for severe weather conditions,” she says.

“Our homes are not really designed for thermal efficiency.”

While all homes are different in some capacity, Rajagopalan believes criteria and grading for certain homes would speed up the process.

“The level of efficiency varies from home to home, with some requiring deep retrofitting and others simple, like putting insulation under the ceiling or even sealing gaps around doors and windows. But before all that, a proper assessment of actual performance of each house is required, because benchmarking is really important to be able to compare.

“The business as usual attitude won’t get us to where we need to be. An accelerated scenario where we look to increase the rate of retrofitting homes will be of a massive benefit to our power grids and emissions targets.”

The current requirement for new home builds within the NCC is a minimum of 7 stars on the NatHERS scale. Rajagopalan says that homes can be pushed further up the scale.

“It doesn’t cost as much as people think to increase efficiency from the start. All affordable and low cost housing needs to comply with 7 star minimums as it is. For some of the climate zones it is only slightly more expensive to increase a home’s efficiency to 8 or 9 stars from 7. But we need to make sure what is designed is then actually built.”

As for what comes next, Rajagopalan believes it is simple. It starts on the ground.

“We need to futureproof efficiency in homes. Training needs to be improved for all construction workers that highlights the consequences of poor construction practices, especially if we want to integrate Passive House type stringency into the standards so that the industry is ready to transition,” she says.

“If homeowners can put a dollar on their comfort and health, that's where the change will come. If you’re thinking about how much money can be made in 10 years by having a solar panel or having a double glazed window installed, the transition will never happen. But if homeowners think about how healthy and productive they are, and the difficulty of performing their jobs in homes that are too hot or cold , that’s where the change will come from.”

To read the report, click here.

Jarrod Reedie

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