Green Roof Definition Epa

It may also include additional layers such as a root barrier and drainage and irrigation systems.

Green roof definition epa.

Using green roofs in cities or other built environments with limited vegetation can moderate the heat island effect particularly during the day. Green roof runoff does contain concentrations of some nutrients and other parameters but values are in line with other planted systems. 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.

They capture water when it rains slowly releasing it through evaporation and plant use. A green roof or rooftop garden is a vegetative layer grown on a rooftop. Green roofs provide lasting benefits that include. Due to the volume reduction actual nutrient loadings from green roofs are less than asphalt roofing runoff or otherwise manageable at the downspout.

Green roofs provide shade remove heat from the air and reduce temperatures of the roof surface and surrounding air. 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 can significantly reduce the amount of rain water that would otherwise run off an impervious roof surface. These two mechanisms reduce temperatures of the roof surface and the surrounding air.

Green roofs have a layer of plant material that absorbs water like a sponge. 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. As with trees and vegetation elsewhere vegetation on a green roof shades surfaces and removes heat from the air through evapotranspiration.