Green Roof Definition Epa

A green roof or rooftop garden is a vegetative layer grown on a rooftop.

Green roof definition epa. A green roof or living roof is a roof of a building usually commercial that is partially or completely covered with vegetation and a growing medium planted over a waterproofing membrane. The green roof at the epa regional office is an extensive modular design meaning that the plants are growing in 2 x 4 trays made of recycled plastic. These two mechanisms reduce temperatures of the roof surface and the surrounding air. It may also include additional layers such as a root barrier and drainage and irrigation systems.

These trays cover 20 000 square feet or almost 60 of the 35 000 square foot total roof surface above the 8th 9th and 10thfloors of region 8 epa headquarters. They are particularly cost effective in dense urban areas where land values are high and on large industrial or office buildings where stormwater management costs are likely to be high. Green roofs provide lasting benefits that include. They capture water when it rains slowly releasing it through evaporation and plant use.

Green roofs are covered with growing media and vegetation that enable rainfall infiltration and evapotranspiration of stored water. A green roof is a vegetative layer grown on a rooftop. Green roof runoff does contain concentrations of some nutrients and other parameters but values are in line with other planted systems. Green roofs have a layer of plant material that absorbs water like a sponge.

Using green roofs in cities or other built environments with limited vegetation can moderate the heat island effect particularly during the day. Green roofs can significantly reduce the amount of rain water that would otherwise run off an impervious roof surface. As with trees and vegetation elsewhere vegetation on a green roof shades surfaces and removes heat from the air through evapotranspiration. Green roofs provide shade remove heat from the air and reduce temperatures of the roof surface and surrounding air.