Abstract
Residential electricity prices in Saudi Arabia sharply increased by more than 250% in early 2018. In this study, to improve the thermal insulation efficiency of non-insulated houses, the respective effects of internal and external insulation on heat transfer through different types of brick walls with reinforced concrete floor slab were predicted by implementing a multi-scale finite-element modelling method. The results demonstrated that the efficiency of external insulation is 50% higher than that of internal insulation, and insulating a concrete brick wall is more economical than insulating a red clay brick wall. Furthermore, although external insulation saves approximately 16% more energy per year than internal insulation, the time required for the amount of energy saved to offset the cost of installation is longer.