Roof gardens, located on rooftop or upper-story terraces, go some way to restoring to nature an equivalent amount of biodiversity-bearing soil and growing area to the land covered by the building. What is lost in not being continuous with the ground surface can be made up for by careful, intensive cultivation of various species.
In a dense urban environment they can provide much needed greenspace for people to come up and enjoy.
Roof gardens provide good insulation, protecting apartments or offices below from the hot sunlight striking the building from above in summer, and keeping warmth rising from below from escaping. The layers of moist soil, mulch and plants act as a thermal sink, stabilising the building's temperature despite outside variation.
Balancing the Built and Natural Environments. Chris Johnson. 2002. Terrace gardens on upper floors of apartment buildings (plus front and back gardens) would help restore to each block the same quantity of landscape as existed before European settlement.
Fresh Veg City. Chantal Martineau. 2004. Adding vegetation to the city's rooftops can improve air quality, reduce excess water runoff and regulate the interior temperature of a building, thus cutting energy consumption.
Kensington Roof Gardens. One and a half acres of gardens on top of a multistory building on Kensington High Street, London create a haven from the noise of the streets below.
Roof Garden. Wikipedia. 2007.8 Besides the decorative benefit, roof plantings may provide food, temperature control, architectural enhancement, and recreational opportunities. Available gardening areas in cities are often seriously lacking, which is likely the key impetus for many roof gardens.
Rooftop Gardens. Melissa King. 2003. Rooftop gardens provide a patch of greenery for people living in the city, making cities a healthier place to live. The main challenge of rooftop gardening is exposure to the elements.