Parametric Investigation of Optimum Thermal Insulation Thickness for External Walls

Omer Kaynakli

doi:10.3390/en4060913

Abstract

Numerous studies have estimated the optimum thickness of thermal insulation materials used in building walls for different climate conditions. The economic parameters (inflation rate, discount rate, lifetime and energy costs), the heating/cooling loads of the building, the wall structure and the properties of the insulation material all affect the optimum insulation thickness. This study focused on the investigation of these parameters that affect the optimum thermal insulation thickness for building walls. To determine the optimum thickness and payback period, an economic model based on life-cycle cost analysis was used. As a result, the optimum thermal insulation thickness increased with increasing the heating and cooling energy requirements, the lifetime of the building, the inflation rate, energy costs and thermal conductivity of insulation. However, the thickness decreased with increasing the discount rate, the insulation material cost, the total wall resistance, the coefficient of performance (COP) of the cooling system and the solar radiation incident on a wall. In addition, the effects of these parameters on the total life-cycle cost, payback periods and energy savings were also investigated.

Highlights

Energy conservation is an increasingly important issue for the residential sector, which accounts for a substantial share of global energy demand [1,2,3,4]
The parameters considered in the analysis are, respectively, the heating and cooling DDs, building lifetime, inflation and discount rates, insulation material cost, insulation installation cost, costs of energy sources for heating and cooling, external wall resistance, thermal conductivity of insulation material, coefficient of performance (COP) of the cooling system, and the solar radiation incident on a wall
The effects of heating and cooling DDs on the optimum insulation thickness, payback periods, total life-cycle cost and energy savings are shown in Figures 1 and 2

Summary

Introduction

Energy conservation is an increasingly important issue for the residential sector, which accounts for a substantial share of global energy demand (approx. 30–40%) [1,2,3,4]. The parameters considered in the analysis are, respectively, the heating and cooling DDs, building lifetime, inflation and discount rates, insulation material cost, insulation installation cost, costs of energy sources for heating and cooling (natural gas and electricity), external wall resistance, thermal conductivity of insulation material, coefficient of performance (COP) of the cooling system, and the solar radiation incident on a wall. The influences of these parameters on the optimum insulation thickness, payback periods, total life-cycle cost and energy savings were investigated. In most studies the effect of solar radiation was not considered in the calculations, which is one of the differences of this study

Mathematical Model

Results and Discussions

Conclusions