Economic optimum of thermal insulating layer for external wall of brick

Abstract

This paper analyzes the technical and economic optimum thickness of a thermal insulation layer of an external wall. The observed wall was made of brick and the used thermal insulation material was polystyrene. The heat transfer through the wall takes place in the stationary regime. The mathematical model consists of algebraic equations for investment, exploitation and saving. The graph-analytical method was applied to solve the mathematical model. The applied optimization criterion is the minimum payback period of the investment. The numerical results obtained by the simulation are presented graphically. The optimum thickness of the thermal insulation layer can be seen from the diagram. Based on current prices in Serbia 2013 the techno-economical optimum thickness of thermal insulation layer (polystyrene) is 9 cm. The minimum payback period is 1.96 years.