Roof gardens. Not just for possums now.

I was blown away by some of the figures in this ABC report about mixing rooftop solar with rooftop gardens. Turns out it makes a huge difference. There are two identical buildings in the Barangaroo development in Sydney and they both had solar, so some brainiac science guys tested a hunch that the panels performance might be improved by a bit of greenery.

On top of one of the buildings was a conventional photovoltaic solar system.

On the other, researchers surrounded the solar panels with plants and foliage.

They then compared how much energy the two solar systems produced over an eight-month period.

What they found was that the "green roof" improved performance by as much as 20 per cent at peak times and by 3.6 per cent over the length of the experiment.

One figure that blew me away; the gardens reduced the temp on the roof by up to 20 degrees Celsius at the height of summer. That’s insane! Except its not. Apparently it’s science.

And a thing that science tells us is that solar panel performance is adversely affected by high temperatures. That could be very depressing, given the future, except we now have an alternative future of green cities being literally greened by rooftop gardens and solar.

Of course the government would probably insist on throwing a coal mine up there too.