Effect of moisture transfer on heat transfer through exterior corners of cooled buildings in hot and humid areas

Abstract

In building thermal calculation, the exterior corner is a typical thermal bridge. The heat flow through this part is more concentrated and significantly larger than that through the surrounding walls. The effects of moisture on heat transfer through corners are not taken into account due to the complexity of moisture transfer. Storage and transfer of moisture will change the thermal conductivity of porous building materials and lead to latent heat flow. Neglecting the effect of moisture transfer can contribute to large errors in the calculation of heat transfer through corners, especially in the areas with high temperature and humidity. Therefore, this paper mainly analyses the process of heat and moisture transfer in the exterior corners of cooled buildings in hot and humid areas. Different outdoor environments and corner structures influence the heat and moisture transfer in the corners. Simulation results are compared with the calculations that ignore moisture effects. In addition, two typical cities, one in hot-humid area and the other in cold-dry area, are compared under cooling conditions. Finally, the correction of the average thermal transmittance of the exterior corners was determined in major cities of China. The results show that the thermal bridge effect is aggravated by moisture transfer, and heat loss at the corner is significantly affected. The impact level is related to the outdoor relative humidity, column materials, column width and insulation thickness. The correction values of the average thermal transmittance of the exterior corners (7–25.6%) in hot and humid areas of China are generally higher than that in other areas. • The hygrothermal performance of building corners is analyzed. • Moisture effects on heat transfer under different conditions are quantified. • Simulation results in different areas are compared. • Correction of average thermal transmittance of corners is determined.