New housing subdivisions, smaller yards and a dependence on air conditioning have resulted in a 30% per cent decline in Australian residential trees over the past decade.  

The dramatic loss of suburban trees has led to hotter neighbourhoods and increased energy costs, according to a new paper by UniSA researchers.  

Qualified architect and UniSA PhD candidate Mina Rouhollahi said the recent study of 90 Australian residential suburbs found tree-inclusive gardens and yards provided up to a 30-metre buffer around each land unit during summer heatwaves.  

“Deciduous trees, in particular, provide summer shade, while their bare branches allow heat to penetrate into the house in winter,” Rouhollahi said.  

“Local government focuses on public parks and urban forests but it’s the residential trees that make a significant difference to home energy costs.” 

Rouhollahi, Professor John Boland and other UniSA researchers have designed an optimal tree strategy for different housing configurations, nominating specific tree types, tree volumes, and correct placement to achieve maximum benefits. 

“We need a more cohesive urban planning approach to compensate for residential tree loss in recent decades and regulate heat as well as curb energy costs,” Professor Boland said.  

Rouhollahi said Australians had the power to influence the design process by requesting tree allocation when building or buying homes. 

“Redesigning our homes with trees in mind will better serve residents, cities, and the environment,” Rouhollahi said. 

“The net result is a more energy-efficient home, lower energy costs, reduced air conditioning, CO2 emissions and less polluted air.” 

The researchers said the strategy aligned with the latest IPCC report, which recommended increased space between houses to allow for more trees, as well as using reflective building materials.  

The IPCC report said taking those steps could significantly decrease urban heat, reduce the reliance on electricity, and thereby cut blackout risks.  

Their strategy was outlined in their new paper published in Energy and Buildings.