Abstract

The existence of thermal bridges in building envelopes affects the energy performance of buildings, their durability and occupants’ thermal comfort. Typically the effect of thermal bridges on the energy performance is taken into account by implementing an equivalent U-value in 1D whole building energy simulation program. This treatment accounts for the effect of thermal bridges on the overall thermal resistance, while their thermal inertia effect is ignored.
This thesis investigates the dynamic effect of thermal bridges on the energy performance of residential buildings, surface temperatures and condensation risk through simulations. Three case studies, with different construction types, insulation levels and under different climatic zones, are used for the investigation. Simulation results show that the equivalent wall method and equivalent U-value method may considerably underestimate the heating load for cold climate and the cooling loads for the hot climate comparing with 3D dynamic modelling method, however, the equivalent wall method performs better than the equivalent U-value method.. With improving building envelope details, such as increasing of insulation level or implementation of thermal break in balcony slab, or with reduction of buildings' thermal mass, i.e. by using the wood construction instead of concrete construction, the significance of 3D dynamic method decreases. The milder of the climate, the greater the 3D dynamic effect is. In addition the 3D dynamic simulation increase the surface temperatures of junction comparing with that modelled using 3D steady state simulation, and then the condensation risk is lower.