Their major drawback is the initial cost.
Green roof stormwater runoff.
Due to the volume reduction actual nutrient loadings from.
They capture water when it rains slowly releasing it through evaporation and plant use.
Green roofs aim to help eliminate excess stormwater.
Therefore green roofs have an important role to play in the urban realm.
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.
In urban areas like.
Green roof runoff does contain concentrations of some nutrients and other parameters but values are in line with other planted systems.
Green roofs can help to reduce both storm water volume rate of run off entering the drainage system.
Green roofs have a layer of plant material that absorbs water like a sponge.