subject: Green Landscape Design Los Angeles - Green Roofs [print this page] Rooftop gardens and green roofs have a two fold effect: they contribute to cooling the structure on which they are cultivated, and they utilize storm water that would otherwise run off to storm drains. Plant surfaces do not rise more than a few degrees (Celsius) above the ambient temperature. As a result, plants cool the area that they inhabit by anywhere between 4 and 11 degrees Celsius. In fact, it was calculated that "the temperature in Tokyo could be lowered by 0.110.84 C if 50% of all available rooftop space were planted with greenery. This would lead to a savings of approximately 100 million yen per day in the city's electricity bill." In addition, as more and more areas become urbanized, permeable surfaces are replaced by impermeable surfaces, sending more and more water to our oceans and streams (this water is warmed by radiant heat, and therefore increases the temperature of said water ways.) Rooftop gardens can reduce this run off, and act as a permeable surface which can assimilate and utilize rain fall.
Several things will need to be considered when installing a rooftop garden. First, a determination will need to be made as to how much weight the proposed structure can support. Every effort should be made to keep the accoutrements of your rooftop garden as light as possible. Second, a rooftop garden will be more susceptible to wind, and therefore the plant material should be chosen accordingly. Third, while rainfall will account for some of the irrigation necessary for the plant material to survive, artificial means of irrigation and drainage will need to be provided.
The Difference Between Rooftop Gardens and Green Roofs: These two terms are often used interchangeably, but they are actually two distinct types of landscape applications. Simply put, a rooftop garden is an actual garden, with a variety of plant material, which is meant to have a visually pleasing aesthetic appearance. A Green Roof is more utilitarian, and, in its simplest form, consists of only one type of plant. A green roof is generally one type of vegetation that covers an entire roof (such as a grass roof.)
