“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.
Other cities are trying to catch up with Toronto. New York City is in the midst of its PlaNYC initiative that’s encouraging green roofs, planting trees, and trying to improve the streetscape so to minimize the heat island effect for which the city is notorious: temperatures there can exceed rural areas by seven degrees. The first green roof in New York City, which is at a large post office facility in Midtown, saves its owners $30,000 in electrical bills.
What’s stopping people the world-over from having green roofs? Higher initial cost. Sometimes, higher maintenance cost or roofs unable to handle the weight. But proponents say electrical savings can help in those areas. Also because the roof is covered with waterproofing and a lot of dirt, the roof is preserved and tends to last longer. And more buildings are under construction that have been designed with green roofs in mind, like this refinery office in Rotterdam.
What’s next? Perhaps “blue roofs,” which preserve rainwater for recreation, like at Urbeach. Then, there’s this: what about green floors? Or Depave, a Portland group that rids areas of “unnecessary concrete?” ”