Sydney’s Wilton suburb mandates lighter roofs to combat climate change

Dark roofs will be banned and backyards expanded for all new homes built in Sydney’s up-and-coming suburb of Wilton, as part of planning controls being put in place to help lower temperatures in the city.

According to the plans of the Government of New South Wales, the slate gray roofing typical of much Australian housing should be abandoned in favor of lighter, more reflective alternatives that can passively cool a building.

The Wilton Development Control Plan for the suburb in the west of Sydney, residential lots will also have to be large enough for a tree in the garden.

Together with the cool roofs, the hope is that this will help counteract the urban heat island effect, where cities experience higher temperatures than their surroundings due to their dense, dark infrastructure, which absorbs light and releases it as heat.

“Western Sydney is already experiencing blistering temperatures of more than 50 degrees in the summer,” Planning and Public Space Minister Rob Stokes told the Sydney Morning Herald.

“The need to adapt and reduce urban heat is not a future challenge — it’s already with us.”

Cool roofs can lower heat wave temperatures

The news comes after the latest climate report from the IPCC shows that Australia’s average temperature has already risen by 1.4 degrees Celsius since the industrial revolution due to man-made climate change.

This means the country is warming faster than global average temperatures, bringing it close to the critical 1.5 degree threshold set in the Paris climate agreement.

Due to the urban heat island effect, this is felt even more acutely in cities like Sydney. Wilton and other areas to the west of the city are already seeing temperatures above 50 degrees Celsius in the summer, leading experts to predict that they will unlivable in a matter of decades.

More than 9,000 homes planned for Wilton

In an effort to reduce this, the Wilton Development Control Plan hopes to realize more than 9,000 climate-proof homes in the area in the coming years, none of which should have dark roofs because they trap heat and increase the need for air conditioning and the associated CO2 emissions.

“The Covid-corrected forecasts tell us we will settle another 400,000 people in the area by 2030,” said Sebastian Pfautsch, associate professor of urban ecosystem science at Western Sydney University. told ABC Radio Sydney.

“If we do that with black roofs, we’ll just build an oven for all those people. We have to get rid of it.”

Instead, the roofs will be painted in reflective paint, which Pfautsch says can lower a building’s surface temperature by up to 40 degrees.

Applied to scale, studies have shown that cool roofs can reduce the intensity of the urban heat island effect by 23 percent and lower maximum temperatures during a heat wave by two degrees Celsius or more.

This can be achieved by simple white paint, which naturally absorbs less heat than dark materials and has been used in initiatives such as New York’s CoolRoofs program and Ahmedabad’s Heat Action Plan for more than a decade.

Research initiatives have also spawned more advanced technologies, including a fluoropolymer paint developed by architectural firm UNStudio and a barium-based formulation by Purdue University, which has been called “the whitest paint ever” and is capable of reflecting 98 percent of sunlight.

Cities leading the fight against climate change

To enhance the cooling effect of the roofs, the Wilton Development Control Plan also requires residential lots measuring 15 by 18 meters to house a mature tree of at least eight meters in both their front and back gardens.

This will help create a so-called green corridor, which counteracts the urban heat island effect by improving ventilation, absorbing carbon dioxide from the atmosphere and improving local biodiversity.

Medellin, Colombia’s second largest city, adopted a similar strategy and was able to: reduce the average temperature in the area by two degrees Celsius since 2016.

Both initiatives illustrate how cities can often be more agile and do more to tackle climate change than national governments, as Hélène Chartier of C40 Cities argued in an interview with Dezeen.

“Cities have really been leaders, especially when the nations were stuck with Trump,” said Chartier, C40 Cities’ head of zero-carbon development.

“Sometimes urban areas are more progressive, so they feel they have more operational capacity. They get more support from their residents to accelerate the transition and help countries move in the right direction.”

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