Flat empty rooftops are one of the last urban frontiers, and with newgreen roof technology they can be turned into a force for cleaner air,cleaner water, and cooler and healthier cities. Great Lakes RadioConsortium commentator Suzanne Elston says that thanks to this newtechnology, things are beginning to look up in Toronto:
Transcript
Flat empty rooftops are one of the last urban frontiers. And with new
green roof technology they can be turned into a force for cleaner
air, cleaner water, and cooler and healthier cities. Great Lakes
Radio Consortium commentator Suzanne Elston says that thanks to this
new technology, things are beginning to look up in Toronto.
Chicago was first. Last year a 38,000 square foot garden was planted
on the roof of Chicago’s City Hall. And now Toronto, Canada’s largest
city, is going even further to promote the idea. Besides greening
City Hall’s rooftop, city officials have formed an interesting
partnership with industry and environmental groups. The goal is to
not only plant rooftop gardens, but to make those gardens accessible
to the public and to promote the idea in the marketplace. So that
when builders are planning new projects or renovating old ones, green
rooftops become the preferred option.
And they should be – for a whole pile of reasons. Take urban sprawl.
In the city of Toronto, for example, the rooftops on large buildings
comprise more than 6% of the total land area. With green roof
technology that wasted space could be transformed into opportunities
to reduce energy consumption and cool the air.
This is how they work: According to Environment Canada, on a hot
summer day, the temperature of traditional flat rooftops can soar to
140 degrees Fahrenheit. That’s hot enough to fry an egg. By
contrast, a living, grassed rooftop won’t get any hotter than about
77 degrees and that means cooler buildings and less heat radiated
into the city. With enough green roofs, the entire temperature of a
city can be brought down. A 3 to 6 degree reduction in temperature,
could translates into a 10% reduction in energy use for all
buildings. Again, according research done by Environment Canada, the
shading effect of a green roof alone can cuts cooling costs by 20 to
30% for a one-story structure.
And that’s just the tip of the green iceberg. These living rooftops
temporarily hold as much as 50 to 70% of the storm water that falls
on them. The plants and the growing medium filter out pollutants like
lead and cadmium from the water before sending it on its way. This
reduces storm water contamination – a major source of water pollution
in the Great Lakes. The plants also filter out air borne pollutants
like nitrous oxides and volatile organic compounds.
Another benefit is that green roofs protect the underlying structure
of the roof itself, so it tends to last two to three times longer.
And finally, in my view they’re just plain nicer than flat old black
rooftops. Green rooftops can transform largely wasted rooftop spaces
into beautiful urban gardens for employees, day care centers and
recreational spaces for the public. They can even be used to grow
food. Talk about a win-win idea.
So I think it’s high time we followed in Toronto and Chicago’s
footsteps and started looking up to a great, green idea.