Dominique Morau

Simple Model for the Theoretical Survey of the Green Roof Thermal Behavior

A green roof is an option for the improvement of a building thermal comfort. The objective of this work is to compare respective behaviors of a green roof and a concrete watertight roof vis-a-vis external requests in wet tropical zones. The canopy being considered as uniform, the electric analogy method was used to establish the mathematical models associated to both studied systems of roof. Based on these models, a Matlab computing code was worked out. It ensues from simulation results that in diurnal period, the green roof concrete support top face temperature is lower than that of the concrete watertight roof top face, whereas in night-period the opposite occurs. These results which highlight the energy benefit of the green roof are in agreement with the experimental measurement results obtained at the Laboratory PIMENT of the University of La Reunion. Besides, results of sensitivity analysis done with Fourier Amplitude Sensitivity Test enabled to identify a certain number of the most influential parameters of the proposed model. The above mentioned computing code also forms a help tool for the choice of plants to be experimented on the green roof.

Life Cycle Analysis of Green Roof Implemented in a Global South Low-Income Country

Environmental protection becomes a global challenge currently. Green roof is one of the innovative concepts to face this battle. An increase in its use is noticed in urban areas worldwide. But a question arises: what are the environmental consequences of the green roofs’ life cycle? In this paper, the environmental performance of two complete systems of lighter and heavier green roofs implemented in a global south low-income country are analyzed and compared in order to determine the potential impacts of both types of green roof systems. For proposing solutions aiming at reducing environmental loads of green roofs, Life-Cycle Assessment (LCA) approach was used in the present study. For this purpose, the approach consists of the following phases: definition of the objective, life cycle inventory, characterization of impacts, and interpretation of results. LCA calculations were done with the help of OpenLCA software. Results show that, non treated materials and / or imported ones are more environmentally impactful. Hence, it is profitable to reduce the use of cement, gravel, virgin plastics, and soil as well as imported materials whose transport is done by plane. In addition, use of natural fertilizer for amending the growth substrate and water from well for watering the green roof, is also recommended.