Optimal Design of Green Roofs: Mathematical Model and Experimental Evidence

Abstract

Green roofs ease the heat island effect and decrease stormwater runoff. Optimizing green roof design helps achieve these goals more efficiently. This dissertation proposes energy and mass models of green roofs and validates them through experimental evidence. The energy and mass transfer models proposed in this dissertation can be programmed in any simulation tools, and benefits architects and engineers optimizing their green roof design. The mathematical models of green roofs were validated by the measured soil temperature and water content of the Golda Meir Library green roof. Using energy and mass balance models, this research found the effects of the surface color, soil depth, and plant types on the surface temperature of a green roof. The green roof surface temperature can be reduced by lighter surface colors, shallow soil depth, and the use of plants with lower internal leaf resistance and larger leaf size. It also found the effects of the vegetation coverage, soil porosity and depth and plant types on stormwater runoff reduction. The stormwater runoff can be reduced by higher vegetation coverage, larger soil porosity (void fraction) depth, and the use of plants with lower internal leaf resistance and larger leaf size.