shout it from the rooftops

There are many good reasons for developing green roofs:

[An] important environmental benefit of green roof systems is their potential to moderate the urban heat island effect... The climactic benefits of green roof systems are not limited to temperature moderation. Urban plantings have also been shown to improve urban air quality, by trapping and absorbing nitrous oxides, volatile organic compounds, and airborne particulate matter.

And another reason, less often mentioned, is the potential for local food production:

The average American meal travels 1500 miles from field to table (Norberg-Hodge et al 2000), using 10 times more energy than the caloric value of the food itself (TFPC 1999). This represents an incredible environmental cost in fossil fuel emissions, pollution associated with extraction, and loss and division of natural habitat by asphalt, to name a few of the more direct costs... Rooftop agriculture is one way in which urban areas could attempt to be more balanced and sustainable in their resource consumption. It is possible to produce a variety of fruit, grain, and vegetable crops on rooftops, either in containers or as field crops (TFPC 1999).

Some roofs growing food across Canada: in Montreal, Toronto, Peterborough, Calgary, and Vancouver.

My previous post on urban farming.

And for all those stormwater managers out there, in 2004 Earth Pledge was commissioned by the New York City Water Board to develop a stormwater simulation model to measure stormwater retention and detention on a specific building or area, specifically to evaluate the impact of green roofs. Micro Model is applied to specific buildings; Macro Model is applied to an area encompassing a network of green roofs. They are now developing Stormwater Model 2.0 based on updated data.