RC-Network based thermal bridge calculation method for transient heat transfer analysis of multidimensional building envelope details: A frequency response analysis-based method

Abstract

Thermal bridges have a significant impact on the overall energy performance and thermal comfort of buildings. Proper accounting of thermal bridge effects through model coupling leads to more accurate predictions of heating and cooling loads and narrows the performance gap between the design and the actual energy consumption of buildings. In this paper, a dynamic thermal bridge calculation method is introduced in a frequency domain to transform a broad range of multidimensional building envelope assemblies to thermally equivalent RC-Network simple models. RC-Network model with three resistances, four capacitances, and internal and external surface resistances at the ends is found to represent multidimensional thermal bridge assemblies more accurately with minimal computational time. The method is applied for the simulation of diverse two- and three-dimensional thermal bridge details of lightweight and mass constructions exposed to hourly varying sol–air temperature boundary conditions, and the results are compared to reference solutions obtained from transient finite element modeling of the original thermal bridge details. The highest RMSE of the proposed RC-Network model for the lightweight and mass construction details are 0.12 W/m2 and 0.37 W/m2, respectively. The low RMSE values reaffirm the good performance of the method and its appropriateness for the calculation of hourly heat flux through multidimensional thermal bridge details.