Green roofs can save energy
November 7, 2007
Green roofs may be next the eco-building design wave. A green roof is planted with vegetation to allow for water absorption. Green roofs are widely used in Europe. Supposedly, green roofs last twice as long as conventional roofs and require very little maintenance. Roofs that need replacement less often also reduce re-roofing landfill waste. In addition, green roofs can save energy on heating and cooling costs, and insulate against sound. They reduce the amount of ceiling insulation needed and eliminate the need for roof drains. As an extra bonus, the vegetation is aesthetically pleasing. Some people even grow herbs and vegetables on easily accessible roofs to save on food costs.
Additional benefits of green roofs include reducing storm water runoff and management ponds. In some commercial areas, they satisfy the green space requirement without requiring a decrease in the available parking area. They also reduce the heat island effect in cities and filter the air.
A roof must be properly engineered to supply the correct structural support for a green roof. There will be a vapor control layer, then thermal insulation, a support panel, a waterproof root repellent layer, and a drainage layer. On top of all that, there is a filter membrane, the growing medium (which may or may not be soil), and finally, the plants.
A green roof sounds like a great idea, particularly in areas where rain falls. But, what about in Nevada? Since we receive little precipitation through the summer, we would need to put sprinklers or other irrigation on the roof for plants to grow. Another concern is whether there is a qualified roofing contractor in this area with expertise in green roof installation and maintenance. I’m sure few houses are currently built to support the weight of soil, vegetation and water, but perhaps they can be retrofitted.
If you would like more information on green roofs, go to http://www.greenroofs.org.
On a different note, I would like to respond to a letter to the editor of the Nevada Appeal about the apparent conflict my article on feeding birds had with the article on bears and not putting out birdseed. The topic of my article was whether or not to feed birds. Bears are a factor in any decision about feeding birds. The Nevada Department of Wildlife says in their rules for keeping you and bears out of harms way, “use removable bird feeders for temporary placement,” and, “the feeding of wildlife including birds may inadvertently attract bears.” In heavy winters, bears might hibernate all winter and leave bird feeders alone. However, in more mild winters, such as we have had lately, they wake up and go looking for food. If they find a food source, like a feeder, they may not return to their den to continue their winter sleep.
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For more information on gardening, contact me, 887-2252 or email@example.com, or your local University of Nevada Cooperative Extension office. Check out many useful horticulture publications at http://www.unce.unr.edu. “Ask a Master Gardener” by e-mailing firstname.lastname@example.org.
— JoAnne Skelly is the Carson City/Storey County Extension Educator for University of
Nevada Cooperative Extension.