Green Roof Stormwater Retention

Green roofs are covered with growing media and vegetation that enable rainfall infiltration and evapotranspiration of stored water.

Green roof stormwater retention.

Green roofs are very effective stormwater bmps. For all combined rain events platforms at 2 slope with. Lightweight green roof good stormwater retention xf301 sedum standard next level stormwater management 07 72 73 vegetated roof systems xf301 sedum standard is an extensive green roof system ideal for retrofits and new builds. The stormwater laboratory will allow the industry to compare different systems in an identical setting and provide solid performance data which civil engineers can use to model stormwater conditions for any given project and apply the green roof system that fits the civil engineer s stormwater retention and detention needs.

A typical extensive green roof of 3 5 inches depth will reduce the volume of runoff by about 55 in central pennsylvania and attenuate the peak runoff rates to the level of the pre development land use. Green roofs typically provide stormwater retention as they capture water preventing water from draining and then allow the water to evaporate only through evapotranspiraton processes. Their major drawback is the initial cost. The second study tested the influence of roof slope 2 and 6 5 and green roof media depth 2 5 4 0 and 6 0 cm on stormwater retention.

A green roof system atop a building helps manage stormwater and reduce energy costs for cooling. Evapotranspiration drives green roof retention. Designing green roofs to maximize stormwater retention enroll in course for 40 as our cities grow and communities become increasingly paved over the amount of impervious surfaces has increased dramatically. Retention deals with the water that never becomes runoff.

You can never increase the retention capacity of a vegetated roof unless you also increase. Green roof water retention and stormwater management retention is the process of holding water on the green roof i e preventing water from draining off the green roof.