Australia Weather News

A new approach to providing shade at notoriously hot car parks has been shown to slash surface temperatures by up to half on summer days in Western Sydney. 

Surface temperatures at a busy car park in Merrylands are being reduced by as much as 35 degrees Celsius by vine-covered trellises which were installed and planted two years ago. 

On the hottest days, surface temperatures were shown to drop from 70C to 35C when in shade.

Results from a study by Western Sydney University (WSU) and Cumberland City Council also show a reduction in air temperatures by up to 2.5C under the shading vines.

The trellises are part of what the study described as Australia's first cool car park.

Fast-growing vines grow over the top of metal supporting structures and then spread over a stainless steel mesh roof. 

Cumberland Mayor Ola Hamed said the project was promising for the area where temperatures in summer heatwaves have reached 45C.

"Merrylands and Granville top some of those suburbs as well in terms of urban heat," Ms Hamed said.

"Cooling also means that asphalt itself has a longer life span, which means less money from council's budget."

Ms Hamed said the shading structures at council-run car park Holroyd Gardens did not reduce car parking spaces.

The initiative was funded by a grant from the NSW government to foster green infrastructure.

WSU's Professor Sebastian Pfautsch, who has been studying the vine-covered trellises' impact for the past three years, said the vines were expected to grow completely over the metal wire mesh in two years.

"If we're serious about reducing the urban heat island effect and all its negative impacts on the community, then car parks are a low-hanging fruit," Professor Pfautsch said.

"We demonstrate with our solution that you can do it in a way so that you don't even lose valuable car parking space."

Professor Pfautsch said the trellises were made of a wire mesh that birds could not rest on, so residents did not find their cars defecated on, and used vines that did not grow fruit that could drop on parked vehicles.

A growing problem in a car-dependent region

Professor Pfautsch said more than 6 square kilometres of Western Sydney were dark-surfaced car parks, and only 1 per cent of that was effectively shaded. Cumberland council's area includes 1 square kilometre of uncovered car park. 

He said these car parks could have surface temperatures greater than 70C on a hot day.

"It's always those unshaded car parks that come out as micro heat islands," Professor Pfautsch said.

A WSU report presenting the findings from the car park shades said the issue was pointed in Sydney's west where there was a greater dependence on cars because of a lack of public transport alternatives.

Urban heat islands are particularly harsh in Western Sydney where temperatures can reach above 40 degrees during summer heatwaves.

Extreme heat has killed 300 people and hospitalised more than 7,000 across the country over the past decade, according to the Australian Institute of Health and Welfare. 

Professor Pfautsch said Western Sydney also experienced hotter temperatures in summer due to the geographical bowl that traps heat in, and increased development replacing green environments.

"That bowl means once you have hot air in it, it's very difficult to blow it out," Professor Pfautsch said.

More car park shading possible

Another cool car park structure has been set up at a commuter car park in Wentworthville, also in the Cumberland council area.

Ms Hamed hoped more of them could be set up at car parks in the area, including at public and privately owned car parks.

"We're looking at other places around the LGA where we can replicate this as well," she said.