Modeling the transient response of heated precipitation on a green roof

This thesis was conducted at The Cooper Union for the Advancement of Science and Art from the time period of February, 2009 to April, 2010. Experiments were conducted in the Water Resources Fluids laboratory at 51 Astor Place for the duration of February, 2009 to May, 2009. Experimental research was continued at 41 Cooper Square until April, 2011.;Through the use of tankless heaters, heated precipitation was delivered onto 2 ft by 4 ft models of a conventional roof and a vegetated roof containing a 3" depth of granular soil and a drainage layer. The precipitation events varied in duration and precipitation source temperature, from 57 degrees to 107 degrees Fahrenheit over a period varying from 5 minutes to 11 minutes.;Retainment of stormwater through the vegetated roof was observed ranging from 0.05 cubic feet for a 2-year storm and 0.286 cubic feet for a 25 year storm. Hydrological responses of the vegetated roof were observed in the range of 1:10 minutes for a 100-year storm to 4 minutes for a 25-year storm. No correlations could be mapped with the storm water retainment behavior of the vegetated roof.;Thermal analysis reveals the capacity of the vegetated roof to regulate temperatures to a narrower range as opposed to the conventional roof, as observed in the roof discharges. The green roof has the capacity to delay heat transfer responses by 2.5 minutes with a 2% temperature ratio difference in temperature rises or decreases. The temperature differences in the responses of the two roofs were as large as 17 degrees Fahrenheit for a precipitation event of 107 degrees Fahrenheit. The measured results were compared to the output of a porous media energy transport program, VS2DH, in order to model the results. A sensitivity analysis was used to test the range and confidence of hydraulic parameters used, with hydraulic parameters narrowed to the properties of Silty Sand. The modeling was extended to include the heat loss contributions of the drainage layer. Success of the program ranged from 0.07 to 6.5 degrees differences between VS2DH modeling outputs and measured results.