Optimal insulation thickness of walls using improved Particle swarm optimization

Abstract

Abstract Uninsulated external walls and inappropriate insulation of buildings are the main reason for energy losses. In this study, novel configurations of multi-layer pre-fabricate wall elements were used to enhance the ability of energy-saving and decrease the payback periods and investments in residential houses in five cities in Iran with different energy demands. Also, an optimization strategy is applied to determine optimum insulation thickness for external walls. The evaluation process is based on using natural gas and electricity in Iran’s buildings for heating and cooling, respectively. The optimum required insulation thickness in Cities with different climates according to their degree/day value for four different insulation materials (extruded polystyrene, glass wool, rock wool, and polyurethane) is achieved using a novel optimization method (Improved PSO). According to the obtained results, annual cost saving for 1 m 2 of the wall in case of simultaneous heating & cooling is more than cooling and heating alone. However, for the payback period, simultaneous heating & cooling has a lower payback period than cooling and heating alone. The results revealed that the cost of rock wool is higher, and the cost of polyurethane is higher than the cost of all other insulating materials in Ardabil. Also, the optimal insulation thickness for the Ardabil city with hollow brick walls and heating and cooling needs is x = 0.015 m and x = 0.005 m for the XPS, respectively.