Green Roofs

..Another factor driving the spread of green roofs is our changing idea of the city. It's no longer wise or practical or, for that matter, ethical, to think of the city as the antithesis of nature. Finding ways to naturalize cities—even as nature itself becomes more urbanized—will make them more livable, and not only for humans....

..Above all, living roofs are habitable. They recapture what is now essentially negative space within the city and turn it into a chain of rooftop islands that connect with the countryside at large...

...A living roof, though, is not just a biological alternative to a dead roof. It requires a different way of thinking altogether. A standardized green roof such as a carpet of sedums is better than a conventional roof, but it's possible to build living roofs that are even more environmentally beneficial—locally grown, so to speak. The goal for some researchers now is to find ways to build living roofs that are ecologically and socially sound in every respect: low in environmental costs and available to as many people as possible.

See pics here .