Green Roof Actual Evapotranspiration

In coutts et al.

Green roof actual evapotranspiration.

Actual evapotranspiration can be achieved by multiplying eto by ks. The plants in a green roof absorb water through their roots and then use surrounding heat from the air to evaporate the water while some roofs can reach temperatures of up to 90 f in the summertime these two features can allow green roofs to actually be cooler than the surrounding air temperature. Evapotranspiration drives water requirements and hence irrigation scheduling and is the driver of retention. Evaporation is the loss of water from any old surface such as leaves and stems soil particles or debris.

Green roof is one of the emerging lid technologies used for retaining rainfall volume and attenuating storm runoff peak flows. One truly cannot design a green roof without fully understanding the annual water balance and evapotranspiration rates of the plant palette in the making of green roof design. Even though the green roofs might be a quite simple system consisting of several layers all the processes within each layer must be controlled dynamically. In the literature available however it is still not clear how and how much the evapotranspiration affects the performance of a green roof.

Abstract previous research has shown that most of the green roof benefits are related to the cooling effect. Course eco roof and green technologies. Needless to say this is a task best left to the experts. 2013 the higher latent heat flux on soil with maximum value about 280 w m 2 compared to green roof with maximum value about 210 w m 2 suggested that wet soil freely evaporated while evapotranspiration from the green roof was limited by the lower surface temperatures and water uptake by vegetation.

Green roof systems which calculate the runoff by solving the water balance equation account for precipitation irrigation storage and evapotranspiration processes rossman 2015. Green roofs on campus. She pang 2010. Green roofs reduce storm water runoff through soil moisture retention and evapotranspiration berndtsson et al.

After irrigation there was a substantial increase in latent heat flux for both green roof and bare soil. If it s hot and windy the roof dries faster than if it s cool and still. On a green roof it s the same.