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Gardens in the Sky

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Green roofs reclaim the footprints of buildings, re-creating indigenous habitats, purifying water and cooling off our city

Rooftops alive with native grasses? Urban dwellers picking sage atop their high-rises? Most of us have heard of green roofs only in the past few years—such as the first municipal green roof in the United States, built on Chicago’s City Hall in 2001. Now, the pace of the movement is accelerating: 41 townhouses in Richmond, Virginia; 700 condos in Scottsdale; a new visitor center at the Brooklyn Botanic Gardens—all with landscaped rooftops.

Green roofs are well-established in northern Europe, especially Germany. As a market develops in North America, services are slowly following.

San Diegans Rosalind Haselbeck and Rich Alianelli are tailoring their expertise to launch a green-roof business, an idea that weaves together their strengths and environmental concerns.

Haselbeck is a biologist with a Ph.D. from UC Irvine. She’s an organic gardener, and in her spare time (she and her husband, Bob, also a biologist, have three children), she works as a conservation volunteer in Allied Gardens’ Navajo Canyon.

She and Alianelli, a contractor who’s run his own business for seven years, met when he built an addition and a garage for her home in the College area.

“Everything came together,” Haselbeck says, “the combination of conservation work, the landscape-design work with Rich. When I heard about green roofs, it was perfect. Rich and I have similar goals—to design, to create a business and to serve the larger community.”

A green roof basically comprises a waterproof membrane, a drainage layer and a growth medium. There are two types: intensive and extensive. Intensive green roofs —most often found on commercial or municipal build- ings—require a minimum of 1 foot of soil depth for a more traditional garden, with large trees, shrubs, pavers, ponds or benches. In contrast, extensive green roofs have as little as 1 to 5 inches of soil depth.

For their first collaboration, Haselbeck and Alianelli installed extensive green roofs on detached structures at their homes—one on her garage, the other on his workshop. Bruce Hanson, a habitat-restoration biologist at Recon Native Plants, assisted with native-plant and habitat research.

Green roofs have indisputable environmental benefits. They improve air quality and serve as an insulator, conserving energy while lowering electric bills. They also double the longevity of a roof. And rooftop plants reflect heat and release water vapor through their leaves, cooling the air.

“With enough green roofs,” Haselbeck says, “you get a reduction in the urban heat-island effect, where average daily temperatures are higher in our cities.”

A rooftop garden also absorbs and uses rainwater. “It can retain 75 percent of an inch of rainfall before there is storm-water runoff into sewers,” Haselbeck says. “At the same time, less watering is needed, and excess fertilizer doesn’t contaminate storm water that runs off into the San Diego River and the Pacific Ocean.” Both Haselbeck and Alianelli love to surf, and they’ve seen what ends up in the ocean after a good storm.

“I grew up in Fletcher Hills,” says Alianelli, who’s raising two boys with his wife, Kristin. They live in Del Cerro, where she teaches school. “What we’re doing helps the whole cause; we can have a better place to live.”

His know-how will turn their ideas into physical reality.

In her canyon work, Rosalind has immersed herself in the study of native plants. She’s excited about the potential of green roofs to restore native habitat, with appropriate plants that support native fauna—butterflies, birds, insects and reptiles.

“For example, we’ve planted the native bunchgrass Nussella pulchra,” she says. Purple needlegrass, as it’s known, provides a habitat for ground-dwelling birds as well as material for nest-building, and it discourages rodents, who prefer the higher seed density of nonnative grasses.

“It’s about passing on the planet to your children,” Alianelli says. “This is something we can do—take a problem and make it less of a problem.”

For more information, visit the partners’ Web site, buildinggreenfutures.com, or call 619-300-7114.

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