Comparison of Different Insulation Materials with Thermal Conductivity Coefficients Based on Density and Temperature for Two Climate Zones

Abstract

The selection of insulation material and the determination of the optimal insulation thickness are very important for saving energy and ensuring thermal comfort. There are numerous studies in the literature for determining the optimum insulation thickness. In these studies, the thermal conductivity coefficient (k) of the insulation material is taken directly from the standardized tables and the optimum insulation thickness is calculated. In real applications, the k value of the insulation material varies depending on the production conditions, density and temperature. For this reason, the density of the insulation material and the operating temperature should be considered when determining the optimum insulation thickness. In this study, expanded polystyrene (EPS), extrude polystyrene (XPS), glass wool and rock wool with different densities were used as insulation materials, coal and natural gas were used as fuel. For Konya and Sivas provinces, which are in the 3rd and 4th climate zones of Turkey, a comparison was made using the degree-day method as a function of energy cost, and the insulation thicknesses were determined as a function of density and temperature. As a result of the calculations for the k value of the insulation material for Konya, which is in the 3rd climatic zone, the optimum insulation thickness was found to be 0.076 m for EPS with a density of 30 kg·m−3, 0.037 m for XPS with a density of 30 kg·m−3, 0.082 m for glass wool with a density of 100 kg·m−3, 0.051 m for rock wool with a density of 150 kg·m−3. When coal is used as fuel, the optimum insulation thicknesses for EPS, XPS, glass wool and rock wool are 0.092, 0.061, 0.104, and 0.078, respectively. As a result of the calculations for the k value of the insulation material for Sivas province, which is in the 4th climate zone, the optimum insulation thickness for EPS with density of 30 kg·m−3 was found to be 0.086 m, for XPS with density of 30 kg·m−3 was found to be 0.044 m, for glass wool with density of 100 kg·m−3 was found to be 0.092 m, for rock wool with a density of 150 kg·m−3 was found to be 0.058 m. When coal is used as fuel, the optimal insulation thicknesses for EPS, XPS, glass wool and rock wool are 0.098, 0.069, 0.106, 0.081, respectively. When comparing the insulation materials, although the unit price of the XPS material is higher, its optimal thickness is lower than that of the other insulation materials in all situations due to its low thermal conductivity.