Slash your energy bills: Suburbs with the most energy-efficient houses
By Jim Malo
Houses in city fringe suburbs have better energy efficiency ratings than those in the inner city, a report shows, but experts say poor construction practices could still leave owners with high bills and uncomfortable homes.
The CoreLogic Amped Up report released on Tuesday found Australian homes built after 2010 had a median NatHERS rating of 5.9 stars, while homes built before then had a median rating of 2.8 stars.
CoreLogic research director Tim Lawless said outer suburbs had higher median ratings because they had more houses built since 2011, when the National Construction Code was introduced, and with it a minimum NatHERS rating of six stars.
“This highlights the importance of the NCC in setting minimum standards of energy efficiency in homes,” he said.
New Energy Thinking efficiency consultant Richard Keech agreed the research showed the efficacy of mandating energy efficiency requirements when building new homes, but results differed in practice.
“Improved stringency gets better outcomes,” he said. “But I would layer that with the understanding that houses never reach their ratings because of common poor practices which are highly detrimental to achieving the intended design rating. It’s heartbreaking.”
Melbourne had high median star ratings for both new and old homes. There, the median new home had a rating of six stars and the median older home had a rating of 3.1 stars. The best-rated suburbs were Clyde, Clyde North and Cobblebank near Melton. All had median ratings of six stars.
Sydney’s houses were rated worse. The median for new homes was 5.3 – the worst in the country. The median for old homes was 2.4 stars. The best-rated suburbs were Appin, Austral and Marsden Park, all with a median rating of 5.4 stars.
Perth and Brisbane had mixed results. Perth’s new homes had a median rating of six stars, but older homes were rated at 2.4 stars. In Brisbane, new homes had a median rating of 5.7 stars and older homes had a rating of 3.1.
The ratings were decided using CSIRO’s RapidRate AI model, which considers the type of property, the floor area, the amount of wall and window space, which direction the house or townhouse faces, insulation and the materials used to construct the building.
Lawless said residential homes used 24 per cent of Australia’s electricity and contributed 10 per cent of the country’s total carbon emissions, and increasing the energy efficiency of homes would ease the burden of high energy costs and be necessary to meet emission reduction targets.
“There’s quite a bit of [star rating] variability across the board, and as we move towards the future you will find there will be a bit more focus on the energy efficiency of homes,” he said. “Partially because of the decreased running costs, but also moving towards our Paris targets in 2050, a big part of that is increasing our energy efficiency in the housing sector.”
Associate professor in architecture at the University of South Australia Lyrian Daniel said inner suburbs would have lower ratings because of their older homes.
“Older stock is performing poorly and some of it might have undergone a renovation, but they may not be to improve performance,” she said. “In the inner-city areas a lot of the housing stock could be in good condition but performing poorly.”
Daniel said living in an energy-efficient home was a benefit to the occupant’s health and wallet and would become more important as the climate changed.
She echoed Keech’s concerns and said more research would be needed to understand if new homes were performing as well as star ratings stated.
Keech said homes that checked boxes on paper didn’t always live up to the star rating. Some new homes might have incorrectly installed insulation or other quality control issues.
He used the example of a recent client’s home in Melton; among other issues, the air-conditioning unit was placed in an inefficient spot on the wall, which meant hot air in the home didn’t mix with cool air correctly, which led to the occupant constantly running the heater to warm the home. When Keech contacted the builder about the issue, he was told it was standard practice.
“This house would have, on paper, been a six-star house. It was probably performing at two or three. These examples of bad practice make a huge practical difference in people’s outcomes,” Keech said.