Plant my Roof, Stretch my Green

Excerpt taken from CNNMoney.com 4/17/2007

With eye toward environment, longevity, roofing gets back to nature.

With American’s new found concern over global warming, and the age old desire to stretch the dollar as far as it can go, more and more buildings are going green, literally.

The number of buildings with green roofs - rooftops covered in hearty plants like sedum and prairie grass - grew 25 percent last year, according to the industry association Green Roofs for Healthy Cities.

Moreover, building with intensive green roofs, which generally have larger plants or grasses as opposed to the ground cover-like sedum or other succulents, increased by 110 percent.

The numbers are still small. Leslie Hoffman, executive director of the sustainable development organization Earth Pledge, said 300 roofs went green in the U.S. last year, the average of which was 5,000 square feet.

Easing the burden on the environment is partly driving this trend. Experts say a green roof can save up to 10 percent on a building’s energy costs, mostly by keeping it cool during the summer and reducing the burden on air conditioners.

Plant-covered roofs also help absorb carbon dioxide from the atmosphere, reduce the effect of rediant heating from cities, ease the burden on city storm water systems by drastically absorbing rain water runoff, and can boost the efficiency of solar panels by 15 percent.

Cost is a big barrier for many people.

Christian Werthmann, a Harvard landscape architecture professor, said a basic green roof, using just succulents and rocks, can cost as little as $6 a square foot and go up from there.

A big reason landlords decide to green up a rooftop is structural: protective plants and the material they grow in can more than double a roof’s lifetime, Werthmann said at a recent green roofs conference at the New York Botanical Garden.