Green Roofs Benefit the Planet
By Wendy Bedwell-Wilson
 Like living walls, extensive and intensive -– or shallow-planted and deep-planted -– green roofs have been around for decades in Europe to help control storm-water runoff by retaining rainwater and slowly releasing it into sewer systems.
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| Green roofs can be deep-planted (shown) or shallow-planted. (Courtesy of Aquascape Inc.) | “It looks like you’re in an alpine meadow,” said Ed Beaulieu, chief sustainability officer for Aquascape Inc., about his company’s green roof, which was installed five years ago when the corporation built its new facilities in St. Charles, Ill.
“Most green roofs have a couple of inches of soil with sedums and low-growing drought-tolerant plantings,” Beaulieu said. “We decided to go with something more intensive, so we ended up with native Illinois prairie on top of the roof. You go up there in the summertime, and it’s loaded with tall grass prairie plants that are growing to 3.5-feet tall with flowers blooming and birds and insects and all types of wildlife up there. It’s really spectacular.”
These eco-friendly rooftop gardens do more than control storm-water runoff, said Dave MacKenzie, chief executive officer and horticulturist at LiveRoof LLC in Spring Lake, Mich. The benefits of a green roof, he said, include
- Better storm-water management: Immediate storm-water runoff can be reduced by 50 to 90 percent, depending on the climate.
- Longer roof life: Plants and soil serve as a protective shield and prevent UV radiation from degrading roof components.
- Energy conservation: By shading and insulating a rooftop, green roofs bring temperatures in line with the ambient air temperature. They reduce indoor temperatures and energy consumption, especially for air conditioning in the summer.
- Interior noise reduction: Green roofs lower indoor sound levels as much as 40 decibels.
- Urban heat island effect mitigation: Plants release oxygen and evaporate water. Green roof soil also evaporates water, which makes a green roof function like an evaporative cooling system. The combination of the umbrella effect (shading and insulating) and evaporative cooling moderate temperatures at street level.
- Improved air quality: Every square foot of green roof can filter about 7 ounces of dust and smog particles per year. Through the process of photosynthesis, plants covert carbon dioxide, water and sunlight/energy into oxygen and glucose, which reduces the amount of greenhouse gases in the atmosphere.
- Enhanced aesthetics: Green space is visually appealing and inviting. People feel better and are more productive when they have a natural view. Barren rooftops become habitable spaces with walkways, patios and seating, thereby adding useable space to buildings.
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Green Roofs Benefit the Planet
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