Green roofs are becoming a major urban trend as cities see the benefits of reduced stormwater runoff, lower summer energy bills, and overall reduced ‘heat island’ effect.
Cities offering incentives for green roofing include Toronto, Chicago, Portland, New York, Philadelphia and Washington, and others are expected to follow.
For example, since 2008, building owners in New York City who install green rooftops on at least 50 percent of available rooftop space can apply for a one-year property tax credit of up to $100,000.
“Remember that planning for a green roof must include a structural engineering review of the space to assess weight bearing capacity and drainage issues. Care should also be taken with the choice of green roof landscape firms to avoid wasting money on inappropriate plant choices,” says Barbara Fischer, who runs the Great Forest office in Armonk, NY, and is also a Cornell cooperative extension master gardener, a certified horticultural therapist, and chairperson of the steering committee of the Native Plant Center in Valhalla, NY.
Research has begun to find the most suitable plants for certain climates: the Chicago Botanic Garden has installed an evaluation garden, and the New York Botanical Garden provides information on plant species that are adapted to the Northeast here.
Take a look at this green roof database to see examples around the world.
Another popular rooftop idea to reduce energy? White roofs.
U.S. Energy Secretary Steven Chu has explained that this technique could reduce energy costs by reflecting the sun’s rays rather than absorbing the heat.
“Whitening the world’s roofs and roads would have the same effect on global warming as removing all the world’s cars for 11 years,” Secretary Chu said.