Simultaneous changes of temperature and moisture of thermal conductivity of EPS insulation material and its impact on building energy performance

This paper investigates the simultaneous changes of combined temperature and moisture content on thermal conductivity, k-value, of polystyrene (EPS) building insulation material. In building energy analysis, the heat transfer through its envelope usually neglect the transport of moisture in the porous structure of the envelope and a constant thermal conductivity, k-value, of thermal insulation material is used to assess the heat transfer through the building envelope. In reality, the building envelope is subjected to the combined thermal and moisture gradients so that an accurate heat transfer determination requires a simultaneous calculation of both sensible and latent effects. Actually, the k-value is a complex function of temperature, moisture content, and density, which requires more accurate evaluation to lead to data that are more realistic to achieve a precise building energy assessment. The findings revealed that the impact of the change of these parameters on the cooling load calculation is significant, especially at a high operating temperature and moisture content.