Double Diffusive Convection Heat and Moisture Transfer Inside a Planted Roof Building Under Hot-Humid Climate: Case of Lomé City in West Africa

Abstract

Planted roofs have been investigated as a passive cooling technology for energy efficiency purposes in buildings. More quantitative data on this topic are required to solve a lack of information for many specific regions. This study is focused on a numerical investigation of the thermal comfort inside a green roof rectangular ventilated cavity in a hot and humid climate like the one of Lomé in west Africa. The left vertical is heated and partly saturated with water to provide humidification of the indoor air. Transfer dimensionless equations are solved using an implicit finite difference scheme, the Thomas algorithm, and the Gauss-Seidel iterative method. We analyze the effects of inlet airflow on the thermal process inside the ventilated and planted enclosure have been investigated. The comfort temperature range deduced from the data is 25°C < T_c < 27°, and that of the indoor air humidity is 49% < Hr <60%. The different ranges obtained are significant and lead to improving inside thermal comfort. The solar flux of 350 W.m^-2 , the average value in the case of Lomé city, was used to establish a heat transfer correlation to predict heat transfer through the roof with a relative error not exceeding 4%. This model can be very useful for engineers in the design and optimization stage of a green roof in practical buildings.