Influence of external shading on optimum insulation thickness of building walls in a tropical region

This study aims to optimize the thicknesses of insulation layers in external walls of continuously used building in a tropical region according to shade level. The investigation is carried out under steady periodic conditions for various wall orientations using a Simulink model constructed from H-Tools (the library of Simulink models). Walls are assumed to be insulated using expanded polystyrene material. The shade level of the building site is assumed to be varying from 0 to 97% with an increment of 25% or 22%. Yearly cooling load is calculated and used as input to an economic model for the determination of the optimum insulation thickness. It is seen that as shade level increases, optimum insulation thickness decreases at an average rate of 0.035 cm, 0.029 cm and 0.036 cm per percentage of solar radiation blocked for south, north and east/west oriented wall, respectively. Results also show that energy savings vary between 46.89 $ m−2 and 101.29 $ m−2 and payback periods vary between 3.56 years and 4.97 years depending on shade level and wall orientation. •The effect of external shading on optimum insulation thickness is investigated.•The investigation is carried out by using an explicit finite volume method.•Intercepting the direct solar radiation has a great effect on peak cooling load.•The optimum insulation thickness with respect to shade level is determined.