Author(s)

N. Simões, J. Prata, A. Tadeu

Abstract

In this paper we analyse the influence of linear thermal bridges (LTB) on the overall thermal performance of the building envelope. Two different models are used: a 1D heat transfer model that does not take into account the 2D dynamic heat flow through the LTB, and a 2D heat transfer model that computes the energy through the LTB. The first is used to evaluate overall energy balance of the building envelope, while the latter assesses heat transfer through the LTB. The results are then compared to estimate the importance of modelling the LTB. The compatibility of the two numerical approaches is verified by computing the heat transfer through a 1D multilayered wall. This comparison showed that similar hourly results are obtained by the two models. The proposed approach is then applied to a building that is considered to be representative of the Portuguese building stock. The results show the contribution of LTB to the overall thermal performance of the building envelope and demonstrate the importance of assuming 2D heat transfer through the LTB in the dynamic simulation of buildings. Thus, we may conclude that a simplified analysis using a 1D modelling approach could lead to major errors when estimating building loads.

Keywords

linear thermal bridges, reference building, building energy simulation, 2D heat transfer, transient analysis