A UniSA researcher has called for a change in Australia’s building codes following the release of a study that shows new homes could be less resistant to heat than older, double-brick houses.
In a study of typical, single-storey brick veneer homes in Adelaide and Sydney during a heatwave, UniSA researchers found newer homes with 6-star energy ratings used the same amount of energy to cool the interior as older, double-brick homes rated just 2.6 stars.
UniSA research associate Dr Gertrud Hatvani-Kovacs said the study showed Australia needs to change its approach when it comes to cooling homes in summer.
“The newer homes can be more prone to overheating in summer because of the high levels of insulation and air tightness coupled with a lack of shading and natural ventilation. We need housing designs which are both energy efficient and heat stress resistant,” she said.
“Over the course of a year, some newer homes can perform better than older ones only because they are more energy efficient in winter, but the reverse applies in summer.”
Dr Hatvani-Kovacs said Australians were becoming too reliant on air conditioning.
“Air conditioning changes our behaviour. It can have a reverse adaptation effect where people become acclimatised to it and therefore demand lower temperatures in summer to achieve comfort.
“By setting our systems at cooler temperatures we are dumping waste heat to the streets generated by the air conditioners, placing extra demand on the grid, forcing prices upwards and causing more blackouts. If a power cut does occur, it places people’s health at risk because their body is used to cool temperatures and they forget how to adapt to even moderate levels of heat,” she said.
Dr Hatvani-Kovacs said Australian building codes should be changed to mandate the incorporation of a range of measures in new homes to deflect heat and lessen the reliance on air conditioning. These measures should include appropriate orientation, lighter and reflective roof colours, and reflective foils installed in roof cavities.
Other measures, such as planting deciduous trees for natural shading, installing outdoor blinds to block the heat and opening windows at night when the temperatures were lower outdoors than indoors, would minimise the need for air conditioning.
The paper, Heat stress-resistant building design in the Australian context, is published in Energy and Buildings, an international journal focused on energy use and efficiency in buildings.