Modeling Solar Energy Transfer through Roof Material in Africa Sub-Saharan Regions

As a result of the global warming, the atmospheric temperature in sub-Saharan regions of Africa may drastically increase, thus worsening the poor living conditions already experienced by people in those regions. Roof’s thermal insulation capacity may play key role in reducing indoor thermal comfort cost. In the present study, effort is put to model heat transfer through roofs in south Saharan regions. Validation of the model was achieved using the slightly sloppy galvanized aluminum-iron sheet roof. Atmospheric data were hourly measured during April and June in Ouagadougou, Burkina Faso. Solar energy values increase from ？W/m2 in the morning to a maximum of ？W/m2 in the early afternoon. Ambient temperature follows the same trend as solar radiation with a maximum at °C. Wind speed varies from 0.5 to ？m/s. The measured roof inner wall temperatures agreed excellently with the developed model with a Nash-Sutcliffe Coefficient of Efficiency of 0.988. Energy flux entering the room through the roof varies from ？W/m2 earlier in the morning to a maximum of ？W/m2 in the earlier afternoon. These results shall help to better design human habitat under changing climate conditions in the sub-Saharan regions. 1. Introduction Ever since the appearance of human beings on earth, beside food and other basic needs, shelters, or dwelling places have been of major preoccupation. Human beings have set up their homes utilizing materials from the nature. To protect themselves from rain, heat, wind, cold, snows, or any sort of enemies, human beings have invented, at very early ages, habitat which has evolved from the caves, natural physical dwellings to the modern houses known today [1]. One of the most important elements of a house is its roof. Indeed, in sub-Saharan countries and most countries on the earth, roof must stand rainy seasons and during periods of elevated heat must provide certain comfort [2]. The effectiveness of the roof in terms of comfort and sustainability requires the thermal insulation capacity and the mechanical strength of materials employed. The shapes of roof are adapted to the type of climate of a given region [3]. Over the world, there are more than 30 types of roof [4]. Moreover, many factors contribute to the differences among the types of roof. The most important factors are the technology, the materials, the environment, and the mere habit [4]. For instance, plat roof dominates in dry regions, while cone shape roof dominates in semi-dry regions such as some parts of Africa. Short eaves gable roof type is widely observed both in Europe and North