Green roofs serve three major benefits to the city, said David Reynolds, first deputy commissioner for Chicago's Department of Environment. They help manage storm water by soaking up rain that would otherwise go into the sewer system. They absorb carbon from the air, and they reduce the urban heat island effect.

Green-roof technology refers to a complex system of root-repellant and waterproof membranes, lightweight growing media, drainage layers and plants which rest directly on the rooftops. It does not include potted plants. The benefits include savings on energy for heating and cooling, decreased roof maintenance, sound insulation and aesthetic appeal. These benefits are greatest in the summer and most cost-effective in buildings with high air-conditioning costs.

Although considered a new concept in Canada, green roofs have been used extensively in Europe for more than a decade. More than 10 percent of flat roofs in Germany contain green-roof infrastructure.

Living on the edge of a marshland with plants sprouting from his roof, Maarten Regenboog could well be considered a guinea pig in yet another Dutch social experiment. Instead he sees himself as a happy resident of a community of the future. …

Truly 'Green' Roof

The sod roof took some getting used to, he admits, but helps keep the top floor warm in winter and cool under the summer sun. It looks kind of hairy, with the sod bearing short, thick-leaf plants.