Analysis of Thermal Bridge's Performance of New Window's Installation in the Building Envelope with External Thermal Insulation

The amount of energy consumption in a building is affected not only by the components’ performance، but also by the building envelope components’ installation method. The negligence of the good practice methodology can have a huge impact on the thermal bridges، increasing the average thermal transmittance up to 40%. In this paper، the thermal performance corresponding to different positions of the fixed frame، without sub-frame and with different sub-frame materials including wood and steel for double-glazed windows has been analyzed. Besides، in these cases، different configurations of thermal insulation has been considered. The evaluation of thermal bridges due to different models in a sample wall، insulated externally، has been carried out using THERM program. The linear heat transfer coefficient has been calculated for each model and the impact of each parameter on the thermal performance has been evaluated. The results show that the position of the frame، the sub-frame material and the configuration of the thermal insulation around the window frame affects considerably the thermal performance.