26 October 2011 – From The Atlantic: Toronto has been aggressive about it: they have a new, comprehensive green roof law, the first one in North America.

Like all laws, it’s complicated, but new building permit applications for residential, commercial, and institutional developments must now have green roofs. New industrial developments (as of April 30, 2012) will soon have to be green, also.

The law states a minimum roof size, so it doesn’t apply to gardening sheds. And the larger the roof, the greater the percentage of it will have to be green. People can opt out, but they have to pay toward a fund.

Efforts are already paying off: Green Roofs for Healthy Cities is reporting that the law has resulted in more than 1.2 million square feet of new green space planned on new commercial, institutional, and multi-unit residential developments. It will also keep enough rainwater runoff out of the lakes and rivers to fill fifty Olympic sized swimming pools. It’s reduced the heat island effect and led to an annual energy savings of over 1.5 million KWH for building owners.

And there are still other benefits: opportunities for parks and recreational areas. Birds and bees do well with these changes. To get an idea of what these roofs can look like, here’s a collection of still images of green roofs around the world.

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