Paper Conference

Proceedings of Building Simulation 2021: 17th Conference of IBPSA


A critical review and cost-benefit analysis of green roofs in the United States: an optimization-based energy performance simulation study

Deva Shree Saini 1,2, Tarek Rakha 1
1 School of Architecture, Georgia Institute of Technology, Atlanta, GA, USA
2 Hastings Architecture, Nashville, TN, USA

Abstract: A widespread recognition and growing literature of simulated and empirical data exist that suggests that green roof improves building energy efficiency through its various mechanisms. A comprehensive literature review previously carried out showed significant energy saving figures ranging from 12 to 60%. On the contrary, a simulation study on green roofs conducted in this research showcases negligible energy-saving figures. It was observed that the insignificant results were due to high Rvalues of the original roof assembly. This study, therefore, performs optimization to obtain the best set of green roof design parameters that could maximize its energy savings on a well-insulated conventional roof. But the optimization was only able to achieve maximum energy savings ranging from -4.4 to 2.77%. With marginal energy savings, green roofs may be perceived as a costly investment with high installation and operation costs. This research thus presents the other more beneficial aspects of green roofs as key factors in establishing it as a sustainable measure by performing a cost-benefit analysis (CBA). It demonstrates that green roofs may be limited in energy savings performance, but can outperform conventional roofs from an ecological and social point of view.
Keywords: green roof, energy-savings, insulation, optimization
Pages: 564 - 572