Urban design turns up the heat

If Paul Osmond had his way, he’d have householders around Australia ripping up their backyard pavers.
Shanghai night field

In their place would be grass, pebbles, mulch and gardens.

And those McMansions? They’d look a bit different too. Namely they’d have green walls and reflective roofs, and a smaller footprint.

Dr Osmond is an expert in sustainable development at the University of New South Wales. He is concerned about the growing problem of urban heat islands in Australia.

“When you increase areas of hard surfaces which absorb long wave radiation you get hotter,” says Osmond. “If you’re absorbing the solar radiation, you’re re-radiating it [and] it gets trapped in the urban jungle.

Osmond’s colleagues have this week released a study that predicts parts of Australian cities, which already struggle to release built-up heat overnight, could hot up by another 3.7 degrees over the next four decades as our cities grow out and up.

Doesn’t sound like much? Rewind to the stifling heatwaves that gripped southern Australia earlier this year and add another 3.7 degrees overnight, when the urban heat island effect is most noticeable. Not exactly comfortable, and for vulnerable people such as the frail elderly, it could pose serious health risks.

The question of what needs to be done in an Australian context to combat the problem of urban heat islands hasn’t fully been answered. Although the problem has been known about since the 1800s when it was first studied in London, it has only been the last few decades that it has been viewed as a serious issue.

Osmond says on an individual scale, householders can increase the permeable surfaces in their own properties, reducing areas that can trap heat. Planting greenery helps too as extra vegetation provides cooling shade, and increases the evaporative cooling effect.

But there’s only so much individuals can achieve. “With the increasing high density living … it does make life a bit more difficult in terms of what the householder can do locally with greening projects,” Osmond says.

Local council greening plans contribute to the solution by bolstering the urban forest.

However, the biggest changes need to occur when urban areas – ranging from individual buildings to complete suburbs – are being planned.

He is hopeful a three-year research collaboration between universities in Sydney, Melbourne and Adelaide will provide some valuable insights to planners.

“It’s not blue sky research by any means. It’s applied research with the intent to make a difference,” Osmond says of the Co-operative Research Centre for Low Carbon Living.

“The first thing is to find out what’s going on, to actually investigate the effects of urban layouts – what we call urban morphology – the shape, design, grid patterns of streets; the size, orientation and so on of the buildings; and the effects of vegetation,” he says.

“We need to get a handle on all of these factors in the three cities and use that to come up with advice to governments as to what they need to do in order to avoid some of the worst problem of urban heat island effects.”

Do you think our cities getting hotter is a serious issue? What can be done about it?

The original release of this article first appeared on the website of Shanghai Night Net.

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