Study of the economical and optimum thermal insulation thickness for buildings in a wet and hot tropical climate: Case of Cameroon

In Cameroon, these last centuries, an increase in energy demand for cooling and heating in buildings has been witnessed all over the world. Solutions must be proposed by researchers and specialists of buildings to remedy this situation. In this study, a literature review on the thermal insulation applications to external walls of buildings was presented, and a case was investigated in a tropical wet and hot climate. The economic model including the cost of insulation material and the present value of energy consumption and the cost over a lifetime of 22 years of the building, were used to find the optimum insulation thickness, energy saving, and payback period, for buildings in Cameroon. Materials that extruded polystyrene were chosen and used for two typical wall structures (Concrete block (HCB) and compressed stabilized earth block wall (CSEB)). The yearly cooling transmission loads, according to wall orientations and percentage of radiation blocked were calculated using the explicit finite-difference method under steady periodic conditions. As a result, it was found that the lowest value of optimum insulation thickness (0.09 m) and energy savings (79.80%) were obtained for the south-oriented wall, while the payback period (4.73years) was the highest on the same face compared to all wall orientations. Insulation optimum thickness was higher in the HCB wall (0.0983 m) than in CSEB wall (0.0958 m), however, the payback period was the weakest for the HCB wall compared to the other wall type.