Optimized mitigation of heat loss by avoiding wall-to-floor thermal bridges in reinforced concrete buildings

Abstract

With the improvement of thermal insulation performance of building exterior walls, the proportion of heat loss caused by thermal bridges is increasing rapidly, especially for those buildings with a self-insulation wall. Currently, the Chinese government is boosting the use of self-insulation walls due to its advantages in long service life and convenient construction. However, energy loss through thermal bridges is a crucial problem. Wall-to-floor (beam included) thermal bridge (WFTB) is a primary form of the thermal bridge with the most massive heat flux. In this study, the thermal performance of WFTB was investigated with real scale (1:1) experiments and numerical models. On the basis of the distance between the beam and exterior wall surface (D), three types of WFTB structures are defined, i.e., exposed beam structure (EB, D = 0), entirely wrapped beam structure (EW, D = Dwall, the wall thickness) and partially wrapped beam structure (PW, D = 0-Dwall). The energy-saving potential of different WFTBs is ranked as PW (when D = 0.67Dwall) >EW > EB. The temperature spatial variation, which is related to the thermal stress of WFTB, is reduced by both the increases of D in PW and the thickness of the insulation layer at the overhanging structure (δ). Moreover, if expanded polystyrene board (EPS), one commonly used insulation material, is used as the insulation layer material, the δ is suggested to be 0.06–0.07Dwall, considering the effectiveness of the thermal insulation, structure safety, and the insulation material saving.