The effect of moisture transfer on the inner surface thermal performance and the thermal transmittance of the roof-wall corner building node in high-temperature and high-humidity areas

Most of the previous references regarding the influence of thermal bridges on building energy consumption were based on the theory of heat transfer. Due to the multi-dimensional effects of heat and moisture on the corners, the heat transfer as well as the moisture accumulation can increase drastically. Therefore, ignoring the moisture transfer process will lead to deviations in the thermal calculation of the roof-wall corner. In this study, the multi-dimensional analysis is performed for the heat and moisture transfer at the roof-wall corner in high-temperature and high-humidity areas. Specifically, the influences of material thermal conductivity setting methods, the change of beam height and the change of column cross-sectional area on the inner surface temperature and heat flux are studied in this paper. Finally, the linear and point thermal transmittance of the building node are corrected. The results demonstrate that setting the thermal conductivity to a constant value will cause the maximum total heat flow through the inner surface to be underestimated by 10.4%. After considering the moisture transfer, the influenced zone of the thermal bridge increases by 52.4%, and the overall thermal transmittance of the building node increases by about 55%-77%.