Green Roof Runoff Impact

In germany between 40 100 of rainfall can be retained dependent.

Green roof runoff impact.

Stormwater response of a green roof is indeed highly impacted by the climate conditions and by the green roof structure itself and this conditions make generalization a very difficult task. The technology addresses a wide array of environmental issues associated with urbanization. In the summer a green roof can typically retain between 70 80 of the run off. 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.

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. In this paper an empirical formulation is compared to a conceptual framework to investigate the stormwater runoff coefficients. 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.

Green roof runoff does contain concentrations of some nutrients and other parameters but values are in line with other planted systems.