Green Roof Runoff Impact

The technology addresses a wide array of environmental issues associated with urbanization.

Green roof runoff impact. Green roofs are lightweight engineered rooftops designed to promote the growth of vegetation while protecting the structural integrity of the roof. Research at penn state has shown that green roofs provide considerable reduction in the volume of stormwater leaving a developed site and they reduce the peak rates of runoff. Environmental and human health benefits of green roofs include air purification urban heat island amelioration lower building energy costs increased urban biodiversity reduced stormwater runoff and improved stream water quality. The amount will be dependent on the depth and type of substrate in the green roof system.

Green roofs are unique in that they have the ability to capture and retain a volume depth of rain from each rainstorm. In this paper an empirical formulation is compared to a conceptual framework to investigate the stormwater runoff coefficients. Green roof runoff does contain concentrations of some nutrients and other parameters but values are in line with other planted systems. Due to the volume reduction actual nutrient loadings from green roofs are less than asphalt roofing runoff or otherwise manageable at the downspout.

A green roof will typically intercept the first 5mm and more of rainfall providing interception storage.