Improving the thermal performance of Australian homes should be an urgent priority to ease cost of living pressures, improve wellbeing and reduce energy consumption and emissions.
An RMIT University-led report which examines the challenges related to home thermal efficiency improvements recommends urgent action to help Australia reach its goal of net zero by 2050.
The thermal efficiency or performance of a building refers to how well a dwelling can be both energy efficient and comfortable for occupants during different seasons.
The report recommends improving how new homes are built and prioritising thermal upgrades.
It also recommends making home energy assessment information widely available and focusing on new research to inform and accelerate progress.
Lead researcher and inaugural director of RMIT’s new Post-Carbon Infrastructure and Built Environment Research Centre, Professor Priya Rajagopalan, said the thermal performance of a home is often overlooked, with factors such as cost, design, location and convenience considered more pressing to buyers and builders than its thermal performance.
“A thermally efficient home is also an energy efficient one given that heating and cooling represents up to 50 per cent of energy used," Rajagopalan said.
“A poorly constructed building shell uses more energy to keep people warm or cool, which leads to an increase in carbon emissions and expensive power bills.”
A 2022 study by Sustainability Victoria also indicated thermally comfortable homes can lead to better health outcomes for occupants.
While the introduction of the new seven star energy efficiency building standard is a necessary step to improve new homes, Rajagopalan said more needs to be done during the design and construction stage.
She said involving thermal assessors early in the design process would make a difference as they are usually brought in at the end, which is too late to make cost-effective improvements.
“Designers rely on energy rating tools to help them make sure the designs are thermally efficient and meet minimum standards, but often what is designed in the software doesn’t translate fully in the real setting,” she said.
“Improved training of all trades, highlighting the consequences of poor construction practices, is essential to make sure they are delivering as per the specifications.
“There might also be unexpected air leakage or moisture entry in the physical build that the software is unable to predict.
“So not only do we need to make assumptions in rating tools as close to reality and involve thermal assessors earlier in the design phase we also need to ensure that what is designed is then actually built.”
Rajagopalan said while high-performance windows and insulation were essential to the thermal efficiency of a building, cost remained a barrier for some.
Australia has 10 million existing homes which have poor energy and thermal performance.
Rajagopalan said government assistance was urgently needed in designing and rolling out an affordable thermal performance assessment program necessary to start the retrofitting process of existing homes.
“You can buy more energy efficient lights and appliances for your home, but it’s trickier and more expensive to retrofit a home to be more thermally efficient,” she said.
Rajagopalan said there was already a lot of information about retrofitting homes, but the reliability and accuracy of the information varied.
Victoria has introduced basic standards for rental homes that included window coverings, adequate ventilation and energy efficient heaters.
In the ACT, all rental homes were required to have at least R5 insulation in ceilings, which can help a home retain heat in winter and reduce heat entering in summer.
Rajagopalan said these initiatives need to be spread across the country.
This research was led by RMIT University in collaboration with CSIRO and Climate KIC Australia for RACE 2030.