Aerial photo exposes 'serious problem' with new Aussie homes branded 'slums of the future'

Dark roofs and other surfaces are contributing to the urban heat problem, experts say.

New housing developments on the outskirts of major Australian cities are the "slums of the future" according to built environment expert Paul Osmond who says urban heat in emerging areas is a "serious problem" that needs addressing now before it's too late.

The abundance of dark surfaces like concrete, asphalt and roofing, with a lack of trees and open spaces, is contributing to record-high temperatures in already-scorching suburbs, including parts of western Sydney which has previously been the hottest place on earth in the midst of a summer heatwave in 2020. Alarmingly, new housing in areas like these is being designed to retain heat, rather than stay cool.

It's now becoming "unsustainable" and is a matter of "human health," the UNSW professor told Yahoo News Australia saying "we don't have time to play around". Hotter temperatures due to poor planning will soon enough have a detrimental impact on lives — and darker roofs, often seen on new homes and chosen for their aesthetic appeal, are partly to blame, he warned.

Left: An aerial photo of a housing development at Manor Lakes, Melbourne showing black roofs. Right: Established housing in the suburb of Blackburn showing plenty of trees.
New housing development in Manor Lakes, Melbourne shows a sea of black roofs compared to the established suburb of Blackburn. Source: Reddit

Dark roofs 'absorb' heat, making suburbs hotter

Aerial photos shared online recently show a housing development in Manor Lakes, west of Melbourne — a sprawling new suburb now home to 9,500 residents. Almost every house features a black or dark-coloured roof, which according to Osmond, is now a common sight sweeping new-build areas.

Lighter colours "reflect the heat back to space" whereas black or darker colours "absorb" it. "It's not a theory, it's just physics," he explained. "It contributes to what's known as the urban heat island effect".

In built-up urban areas that contain dark materials, and other built materials, like concrete, which absorb heat, Osmond said "there's less evaporation, less transpiration from plants – both of which cool an environment".

"All of these things coming together are creating a hotter environment in those new developments".

Additionally, the trend we're seeing "says monotony and boringness," the professor admitted. "Variety is demonstrably something which adds to the attraction of good urban design in our cities. "

New housing development in Marsden Park, Sydney
In suburbs like Marsden Park, Sydney, houses are built right to the boundary line. Source: Samuel Austin

'You cannot live in an environment like this'

Osmond, who's been engaged in sustainable development since the 1980s, said "it's not just the dark roofs, but it's the closeness of the buildings, the lack of green open space, the lack of trees" which combined contribute to what he calls "the slums of the future" where soon enough, "no one will want to live".

"[My colleague] routinely finds temperatures of 49, 50.5 degrees celsius in Western Sydney areas during the peak of heat waves. That is not sustainable," he said. "You cannot live in an environment like this, particularly with increased duration, increased frequency and increased intensity of heatwaves, which is what we're going to be seeing with climate change".

"People will be stuck indoors. They'll be using air conditioners if they can afford to pay for it. But they will pump indoor heat back outdoors and that can increase the heat by one and a half to two degrees if everybody's got an air conditioner."

Goal to reduce temp in Aussie suburbs by two degrees

The ultimate goal is to reduce the overall temperature by up to two degrees. And while he admits it doesn't sound like a lot, he says "a two-and-a-half-degree drop in temperature is actually pretty significant".

"That can be the difference between people, elderly folk, being taken off to hospital with heat stroke or the very young or the disabled who are equally vulnerable, being quite comfortable in their houses and outside enjoying the greenery," he explained.

"When you think of it from the perspective of human health, which is what is really the issue here, and the increased danger of heatwaves on top of climate change, which is already raising temperatures, it's actually pretty significant."

Aussies housing examples leading the way

The Nightingale project in Melbourne — medium-density flats with green roofs, green walls, reflective surfaces and good insulation — is a good example of how we should be tackling housing in Australia. Another is the Christie Walk development in Adelaide, "which has been there for over 20 years and embodies a lot of these characteristics with solar panels being part of this."

All of these components will "without a doubt" help to reduce the temperature in these suburbs by about two degrees.

Aerial view of a Queensland housing estate.
Previously, lighter-coloured roofs were more prominent but have been replaced by black or darker colours. Source: Getty Images.

Dark roofs banned in Sydney suburb

Meanwhile, in Wilton, an emerging western Sydney suburb, it was announced in 2021 that dark roofs would be banned and backyards expanded for all new houses to help lower temperatures in the city. Under plans set out by the NSW government, the darker option was ditched in favour of lighter, more reflective alternatives — a plan Osmond said "100 per cent, totally, absolutely" should be implemented across all new housing estates going forward.

The plan was initiated by former planning minister Rob Stokes, The Guardian reported. He said the policy would help NSW achieve its goal of net zero emissions by 2050. However, the plan was scrapped by his successor Anthony Roberts the following year.

"Local governments should be looking at ways to address urban overheating, whether it's around water, around trees, around materials or around cool roofs," Osmond told Yahoo. "It's exactly what we should be doing and where we should be going.

"Sometimes it can be three steps forward and two steps back [when it comes to planning provisions]. Unfortunately, the issue is not about the science, it's about the policies and sadly the politics."

The professor believes a "conservative" construction and building industry is to blame for "these things taking so long" to change, and suggests our only hope is to better educate future generations about the problem

"We cannot keep going on the trajectory we have been going, which is simply dumping a whole lot of housing developments in the outer suburbs of Sydney," he said.

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