Perth has been ranked the least sustainable city in an assessment of the carbon footprint of Australia's 20 largest cities.

The study looked at key indicators including air quality, climate change readiness, public transport and water use.

Darwin was first, Brisbane ranked third, Canberra was fifth, then Hobart, Melbourne, Sydney was 12th and Adelaide was 14th.

Don Henry from the Australian Conservation Foundation says even the most sustainable cities can still do more to reduce their ecological footprint.

"We found Darwin, the Sunshine Coast and Brisbane are up there near the top. We found Perth, Geelong, Newcastle are near the bottom but I think the important point is we're all in a pretty average space and our cities can do a lot better to be more sustainable".

The Sustainable Energy Association's WA chairman Ray Wills says the West Australian Government needs to follow the lead of other cities and introduce renewable energy programs.

"We have Australia's best, in fact the world's best resources in solar, in wind and there's grand opportunities for much of Western Australia's economy to in fact be powered by renewable energy."

The Sustainable Energy Association's WA chairman Ray Wills says Perth needs to step up to avoid lagging any further behind the national average.

"Across Australia the average use of renewable energy is around about 8 per cent, in Western Australia it's about five per cent.

"The state government is certainly taking steps right now to improve that outcome but right now Perth city is lagging behind."

Mr Wills says many years of low electricity prices in WA has slowed Perth's renewable energy uptake.

"The increase in energy tariffs will actually lead to a more attractive uptake of renewable energy, because the price differential between what has been a subsidised fossil fuel price for 15 years is now going to be remedied by power increases."