Green Roof Runoff Impact

In the summer a green roof can typically retain between 70 80 of the run off.

Green roof runoff impact. Due to the volume reduction actual nutrient loadings from green roofs are less than asphalt roofing runoff or otherwise manageable at the downspout. The amount will be dependent on the depth and type of substrate in the green roof system. In germany between 40 100 of rainfall can be retained dependent. Green roofs are lightweight engineered rooftops designed to promote the growth of vegetation while protecting the structural integrity of the roof.

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. In this paper an empirical formulation is compared to a conceptual framework to investigate the stormwater runoff coefficients. A green roof will typically intercept the first 5mm and more of rainfall providing interception storage. Green roof runoff does contain concentrations of some nutrients and other parameters but values are in line with other planted systems.

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.