Gardening Articles: Landscaping :: Lawns, Ground Cover, & Wildflowers

Greenroofs

by Kathy Bond Borie

It started out as a normal work day for Linda Velazquez, catching a plane to Stuttgart, Germany, on her shift as a flight attendant for Delta airlines, but it ended with a glimpse of a new career. As the plane was descending, she looked out the window over the rooftops of city buildings and saw green. At first she thought she was seeing the countryside, then she realized that the buildings were blending into the countryside because their roofs were covered in vegetation. Linda was fascinated. When she wasn't flying, she was studying landscape architecture at the University of Georgia and learning how good planning can soothe the boundaries between manmade structures and nature. Now she was being introduced to greenroofs, and they were so remarkable that she had to learn more.

A greenroof is much more involved than a rooftop garden, in which a roof is treated like a patio full of potted plants. Beautiful as they may be, greenroofs are usually built to solve environmental problems -- primarily rainwater runoff from rooftops and the high cost of energy to heat and cool buildings. A greenroof consists of several engineered layers: a water- and root-proof membrane on the bottom, followed by a drainage layer, a filter cloth, and growing medium (lighter than soil) on top.


Researching greenroofs proved to be difficult because although Germany had been building them for about 30 years, the concept hadn't spread to many other countries, and most of the information was in German. Few of Velazquez' professors were aware of modern greenroofs. Never one to turn down a challenge (she was juggling school, her job with Delta, and a busy life as a mother of three children) she pursued a study of greenroofs and has become a leading proponent of them in the U.S. The politics of this role caught her somewhat by surprise. A plant lover at heart, Velazquez says "All I wanted to do at first was plant gardens on rooftops," she says.

Velazquez now runs a greenroof design and consulting firm in Alpharetta, Georgia, and a Web site on greenroof technology. She's still flying for the airlines, but almost as often she's flying around the world to give talks and consult with governments and municipalities to promote greening up the rooftops of urban areas. The greenroof movement is growing with demonstration projects sprouting up such as at the Chicago City Hall, Toronto City Hall, and Hamilton Condo Apartments in Portland, Oregon.

She's especially excited about a current project close to home -- the City Hall Pilot Greenroof Project in Atlanta, still in the planning stages. Atlanta's motivation for installing a greenroof is to alleviate the sweltering summer heat, which is accentuated by the predominance of asphalt roofs. In summer the temperature of a conventional flat roof can reach 140 degrees, compared to a grass rooftop that keeps temperatures closer to 77 degrees. It's the economics -- cutting building cooling costs by 50 percent and heating costs by 25 percent -- that Velazquez believes will drive this technology in the future.

"Over four years have passed since I saw my first greenroof, and my passion and commitment to the many possibilities of greenroofs continues to grow," says Velazquez. "The way I look at life is, you have to concentrate on the areas that you can have some control over, that you can fix."

To learn more about greenroofs, and for links to greenroof projects, visit Greenroofs.com.

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