Rooftop and vertical gardens can be energy self-sufficient; irrigated by natural rainfall and water pumped to the plants with the energy created by solar cells.
A 1000mm annual rainfall is enough to support a self-sufficient rooftop or vertical garden. Choose the right plants for the local climate and they will thrive with little maintenance.
Traditional rooftops, covered in black asphalt, are heat-absorbing surfaces that create the “urban heat island effect”, in which city areas tend to be two or three degrees hotter than the surrounding countryside. On a 23- degree Celsius day, the temperature on a black tar roof can rise to 45 degrees, while a green roof will maintain the ambient temperature. A report in Bio Science estimates that green roofs can reduce air conditioning costs by 25% and electricity by up to 50%.
Thanks to new technologies and growing green awareness, city councils worldwide are waking up to the advantage of giving buildings a living skin.
In parts of Germany, new buildings must now have garden roofs by law.
Earlier this year, London’s city council released a statement encouraging developers and building owners to install green roofs on their buildings.
Chicago, a pioneer in the green roof policy, has more skyscraper gardens than any city in the world.
And Tokyo recently introduced policies requiring green roofs to be installed on 20 percent of all flat surfaces.
Photo credit :: flickr "rich people rooftops NYC" by jwilly
Source :: The weekend Australian magazine, June 2008
photo credit ::