The effect of moisture transfer on heat transfer of roof-wall corner hygrothermal bridge structure

Abstract

Due to effects of moisture transfer, the hygrothermal bridge could be developed at building corners, and increase the thermal conductivity of building materials. Three different types of roof-wall corners (ring beam, double beam column and shear wall structure) were studied. When considering moisture transfer, effects of different air states, structural types and wall materials on the thermal performance of the hygrothermal bridge were evaluated and heat losses of the structure were compared. Given the periodic boundary conditions, the dynamic thermal response of the hygrothermal bridge after moisture transfer was analysed. Among three types of corners, the increase of heat flow through the most detrimental point of the ring beam structure corner was the largest (34.7%) after considering moisture transfer. The heat flow loss rate of the shear wall structure was the lowest (15.2%). When clay brick was used at the corner rather than aerated concrete for walls, a lower proportion of latent heat flow and higher (8.6%) heat flow loss rate were shown after considering moisture effects. Furthermore, the dynamic thermal response was influenced by multi-dimensional and moisture effects. The time lag was reduced with increasing humidity, while the thermal bridge effects increased the deterioration of the time lag.