Thermal, Economical and Environmental Optimization of Insulation Thickness in Residential Building's Wall

In this study, dynamic transient model (Exact model) rather than annual heating and cooling degree-days method (crude and approximate one) was applied to calculate the annual heating and cooling loads in order to optimize the insulation wall thickness. Concrete and Expanded polystyrene (EPS) were considered as the main wall and insulation material respectively. One dimensional transient heat transfer problem for multilayer walls was solved to obtain the temperature distribution within the wall. In order to determine the optimum thickness, which minimizes the total cost of insulation and energy dissipation, the economic analysis was carried out for the lifetime of 25 years. Both heating and cooling loads are taken into account in the optimization process. Time lag and Decrement factor are also calculated for the un-insulated and insulated wall. Environmental aspects of energy consumption including fuel consumption and pollutant emissions are also investigated. Annual total fuel consumption and pollutant emissions were obtained for a wall with optimum insulation thickness and the results were compared with an un-insulated wall. The results demonstrated that the application of insulation materials in the optimum thickness decreases the total heating and cooling demands significantly. It is also found that using the insulation in buildings decreases annual fuel consumption and pollutant emissions considerably.