Hygrothermal bridge effects on the performance of buildings

Although the thermal bridge effects on the building energy performance have been presented in the literature, the multidimensional hygrothermal analysis of the building envelope is still a challenge due to many difficulties such as modeling complexity, computer run time, numerical convergence and highly moisture-dependent properties. However, their effects are of paramount importance due to the local increase of heat and mass flux densities so that moisture can be easily accumulated around internal corners, increasing mold growth risk and causing structural damage. Therefore, for analyzing the effects of building lower and upper corners, a multidimensional model has been developed to calculate the coupled heat, air and moisture transfer through building envelopes. The algebraic equations are simultaneously solved for the three driving potentials — temperature, vapor pressure and gas pressure gradients — to improve the numerical stability of the discretized model. In the Results section, the coupling of the upper corner, wall, lower corner (with different types of foundations), ground and floor are analyzed in terms of temperature and relative humidity profiles, vapor flow and heat flux, showing the importance of a detailed hygrothermal analysis for accurately predicting building energy consumption, mold growth and structural damage risks.