Up in the Air

Turning rooftops as green as possible only makes good environmental sense, says David Yocca, landscape architect and planning director of the Conservation Design Forum in Elmhurst, Ill., a firm that designs ecoroofs. The ecoroofs are lined with special materials, topped with a lightweight blend of soil, compost and perlite, and planted with anything from small grasses to eight-foot conifers. Irrigation systems on timers dispense water on a regular basis.

"It's good from an ecological and human health standpoint," Yocca says. "It's a way to manage [runoff] in a positive way and it minimizes chemicals."

Plus, plants evapotranspire, Yocca explains, and that "creates natural air conditioning, so you don't have an urban heat island. An ecoroof protects the building against heat loss in winter and heat gain in summer." Since plants convert carbon dioxide into oxygen, ecoroofs also improve air quality. In several cities, ecoroof advocates like Yocca are working to have green roofs become common practice. In Europe, they're already fairly common; in Switzerland new buildings are required to have on their roofs the same amount of vegetation they replaced. Get more information on ecoroofs.