By Catherine McDonald
July 22, 2009
Roof gardens have existed since ancient times. The first known historical references to such gardens were in ancient Mesopotamia, built from the fourth millennium until around 600 B.C. Today, roof gardens range from the humble (a small container garden) to the extravagant (an acre or more filled with several different styles of gardens). * Beyond just being aesthetically pleasing, roof gardens have practical benefits, too. Some environmental benefits of roof gardens include the following: * Thermal insulation (warms in winter and cools in summer) * Noise insulation
* Wildlife habitats
* Rainwater detention
* Reduced air pollution (plants help trap particulates and gaseous emissions) One of the main advantages of a roof garden in an urban area is the alleviation of storm water buildup. Many major U.S. cities cannot handle all the storm water that rushes into pipes at once. Roof top gardens help slow down the storm water so that it doesn’t overwhelm the pipes. The alternative that many cities are facing, especially in the East, is to just increase the size of the pipes—a solution that could cost the cities billions of dollars. Roof gardens provide a less-expensive and more environmentally friendly answer to the problem. In Toronto, a recent study explored the benefits of an aggressive green roof strategy to that city. Assuming that all available green roof area was used, the study estimated that the city would save over $250 million combined in the areas of air quality, building energy, sewer overflow, and storm water. From a business standpoint, adding a roof garden to a building’s design has many advantages as well. Prospective tenants find the idea of an oasis in the city appealing, and they are willing to pay more money for units in buildings with roof gardens or terraces. Roof gardens can also significantly boost the value of a home. Pierre Wilter of London-based Urban...