The concept of a "green roof" — a roof partially or fully covered with vegetation — is rapidly gaining popularity among green building experts because of its excellent ability to insulate buildings, increase roof life span, and reduce stormwater runoff. A green roof also improves air quality, provides wildlife habitat, and, in urban areas, helps reduce the heat-island effect.

A green roof usually consists of a layer of three to six inches of soil, with an underlying drainage system and root barrier. The soil can be used to grow grass, flowers, fruit or vegetables.

Research conducted in Canada demonstrated that a typical one-story building with a six-inch thick green roof could reduce heat loss by 26% and reduce heat gain by 95% compared to a traditional roof.

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Green Roofs for Healthy Cities is a trade association of green roof manufacturers and supporters who are dedicated to developing the market for green roof infrastructure products and services in North America.

Photo of the green roof at the Arlington County (VA) Center.