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Author: Amanda Hoh
Source: ABC News
Date: 23rd March 2017

Did you know planting a small tree in your front lawn has the potential to reduce your electricity bill by $28?

Add a few more and let that tree grow for a few decades, and research has shown the savings could be as much as $400 on your yearly bill.

This concept is part of an initiative that has been trialled in the western Sydney suburb of Blacktown, which has seen residential streets retrofitted with sustainable landscaping designs that help reduce the urban heat island effect.

The heat island effect occurs when vegetation from the landscape is replaced with buildings and other infrastructure developments that heat up and retain that heat during the day, according to Dr Brent Jacobs, research director at the Institute of Sustainable Futures at UTS.

“Climate change only amplifies that urban heat island effect.

“Whenever we change the landscape we’ll get some urban heating going on, but it’s about how we plan those developments … and mitigating the heat before we start.”

Dr Jacobs said temperatures were rising faster in western Sydney than in the east due to climate change and urban development.

This summer the region experienced a record number of days measuring over 40 degrees.

 

Change the streetscape

Last year Blacktown City Council received State Government funding to trial a pilot program that saw more trees planted in Boonderoo Avenue in Glenwood.

The council partnered with the Cool Streets initiative that was developed by landscape architect Dr Libby Gallagher, whose PhD found changes to street design could reduce CO2 emissions, cool neighbourhoods and reduce power bills for residents.

“I found that you could basically achieve much higher levels of reduced energy consumption by planting effective trees on their street,” Dr Gallagher said.

“As the trees grow, the projected outcome for these streets was that when [the trees] were at maturity they could achieve really significant benefits … provide shading, shaving electricity bills by up to $400 per annum.”

After several neighbourhood meetings and events, the Glenwood community decided to plant rows of trees along the road and in front of houses.

Cool Streets used data-modelling software that compared the environmental outcomes with different layouts and tree types.

The variety of species included brush box trees, gums, claret ash and deciduous trees.

Dr Gallagher said research had shown that dense tree coverage could reduce the temperature in a shaded area by up to seven degrees.

To get the most benefits from tree shade, the trees need to be over seven metres, although a five-metre-tall tree could help save up to $100 off an annual electricity bill.

“Being able to empower these communities to have a discussion and a dialogue about the possibilities for their street allowed them to not only improve their environment, reduce their electricity bills, but also enabled them to feel like they could do something about this radically changing climate,” Dr Gallagher said.

 

‘Not enough room’ for trees

Dense housing layouts and smaller front and backyards meant it was critical to have trees lining the street, Dr Gallagher said.

But Blacktown Mayor Stephen Bali said it was difficult to get residents to agree to more foliage.

“Most people don’t want a tree in their front yard,” he said.

“I suppose they’re worried about when it grows up, you think, ‘it’s going to destroy my footpath, curb my guttering, drop leaves’ and all those problems with maintaining it, dropping branches.”

It is a situation observed by these ABC Radio Sydney callers who also criticised local councils for cutting down trees.

“In Emu Plains we had these beautiful gum trees. As soon as one dropped a branch they all got chopped down and they were centuries old. The houses next to Penrith Station in the new developments, there’s no room between the houses to put the trees,” John from Emu Plains said.

“The backyards are literally not big enough [for trees]. The other issue is the developers think that if they whack a park for a kilometre-and-a-half, that’s a green space,” John from Blacktown said.

“The blocks of land now are under 600 square metres and you can only put a house on there. You’ve got no breeze way, you’ve got dark roofs, dark bricks, smaller blocks of land and you couldn’t plant a tree there anywhere or a decent shrub,” Gary from Penrith said.

 

Changing roof tiles

Another way to reduce urban heat was to change the colour of roof tiles, Dr Jacobs said.

He said the current fashion was to have dark tiles which absorbed more heat than lighter colours.

Mr Bali said it was important to incorporate these sustainable designs from the beginning.

“The problem we have is trying to influence developers and consumers in having the right type of roof,” he said.

“At this stage it’s really hard to get through to people. Maybe they’re worried about the roof getting dirty.”

 

Read more at ABC News.