An aerial view of most urban areas shows swathes of asphalt, black tar and gravel-ballasted rooftops. Heat radiates off of the dark roofs, and water rushes over the hard, hopefully impermeable surfaces. Yet, there is a new trend that breaks up the monotony of common roofs: green rooftops. Long popular in Europe, green rooftops have begun to appeal to homeowners, businesses and even cities as an attractive way to promote environmentalism while solving the problems of conventional roofs. Green roofs supplement traditional vegetation without disrupting urban infrastructure -- they take a neglected space and make it useful.
Green roofs last longer than conventional roofs, reduce energy costs with natural insulation, create peaceful retreats for people and animals, and absorb storm water, potentially lessening the need for complex and expensive drainage systems. On a wider scale, green roofs improve air quality and help reduce the Urban Heat Island Effect, a condition in which city and suburban developments absorb and trap heat. Anyone who has walked across a scalding parking lot on a hot, summer day has felt one effect of an Urban Heat Island.