The primary objective of EPA's green roof is to absorb the precipitation which contacts the roof surfaces and release it at a reduced and measured pace. The green roof is expected to reduce peak flow and runoff volumes from rain and snowmelt events to mimic a more natural landscape. Reducing the peak flow will minimize deleterious impacts to the South Platte River from concentrated stormwater runoff.
Natural landscapes like forests, wetlands, and grasslands trap rainwater and snowmelt and allow them to filter into the ground slowly. In contrast, impervious surfaces like roads, parking lots, and rooftops prevent rain and snowmelt from infiltrating, or soaking, into the ground. In an urban environment with mostly impervious surfaces, rain and snowmelt remains above the surface, where it runs off rapidly in unnaturally large amounts.
Storm sewer systems concentrate runoff into smooth, straight conduits. This runoff gathers speed and erosive power as it travels underground. When this runoff leaves the storm drains and empties into a stream, its excessive volume and power erode streambanks and streambeds, damaging streamside vegetation and dramatically altering aquatic habitat. These increased storm flows carry sediment loads from construction sites and other denuded surfaces and eroded streambanks. They often carry higher water temperatures from streets, roof tops, and parking lots, which are harmful to the health and reproduction of aquatic life.
"Green roofs, garden roofs, vegetative roofs, landscaped roofs — no matter what you call them, they are here to stay. The movement toward energy savings and environmental stewardship is legitimate, and green roofs are a big part of it. Green roofs have a number of benefits; however, there are considerations that need to be dealt with whether you are a designer, contractor or building owner...." -more-
Maintenance and Life-Cycle Considerations by Nathan D. Griswold September 3, 2008
"The long-term success of a green roof revolves around two main objectives: water tightness and vegetation. A quality seamless waterproofing membrane should be the foundation of every green roof. This article addresses the six essential elements that are critical to the success of an extensive green roof’s vegetation: -more-
Vegetated roofs, otherwise known as “green roofs” are literally rooftop gardens. They have been used widely in Europe, especially in Germany, and they have three major benefits.
First, they act as added insulation, helping to keep the building cool in the summer and warm in the winter. They also protect the underlying roof by shielding it from extremes in temperature and from water—green roofs have been known to extend a roof’s life up to three times its normal expectancy, which also saves building costs. Finally, green roofs protect our watersheds by keeping stormwater, which might otherwise wash pollutants into the rivers, onsite.
The green roof at Friends Center is part of a larger stormwater management system... ...We have replaced the old roof with a standard Energy Star roof. On top of the new roof a growing medium was added where hardy Sedum plants are now growing.
The plants are specially selected species that can withstand hot, cold, and dry conditions. They require little to no maintenance, and will be a beautiful addition to the view from Center City high rises.
The story of the Center In the last 7 years the Penn State Center for Green Roof Research has been leading the way to greener cities in North America. Read more
Greenroof materials testing Penn State has an established program for testing green roof media and waterproofing materials using FLL and ASTM methods. Read more Research Projects Major projects include stormwater runoff quantity and quality studies, energy studies, plant growth and water use, media materials Read more Green roofs on campus The Penn State Office of Physical Plant has made a major commitment to using green roofs on campus buildings as a part of our effort to make a greener campus. -more-
All Things Considered September 25, 2008 · A building heralded as the greenest museum in the world opens Saturday in San Francisco. The California Academy of Sciences features a living green roof with native plants, insulation made from recycled blue jeans and a large canopy of solar energy panels.
Italian architect Renzo Piano tucked the building into the hills of Golden Gate Park — in both form and function, the museum fits into the natural world surrounding it. Wired Science heads back to the California Academy of Sciences to learn about the museum's living roof, which features 1.2 million native California plant species, solar panels and a natural ventilation system.
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