Green roofs for Australian cities would help reduce flooding and save on bills, study shows

By James Hancock

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City councils — including Sydney and Melbourne — have been nurturing the green roof concept for about a decade.

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The University of Melbourne's Dr Claire Farrell said her team found a 10-centimetre-deep substrate could absorb up to 95 per cent of annual rainfall in Melbourne.

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The benefits of capturing run-off also extend to flood prevention.

"As cities become more dense, we're getting more and more rooftops and more impervious surfaces," Dr Farrell said.

"[It] can lead to flash flooding when we have big events in a short period of time."

Associate Professor Nick Williams said green roofs also helped to lower heating and cooling costs.

Modelling for a single-storey brick office with a concrete roof shows potential savings of up to 65 per cent in heating and up to 35 per cent in cooling bills.

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However, an inner-city oasis does not come cheap.

That is why the researchers have recommended government incentives to boost the industry.

They could include fast-tracked building approvals, relaxed height restrictions or financial grants, according to Paolo Bevilacqua from Frasers Property.