Influence of thermal bridges on the insulation performance of curtain wall panel systems

Thermal insulation plays a key role in saving energy consumed by buildings. To obtain a high level of insulation performance, repeated thermal bridges should be minimized. These bridges may cause a substantial heat loss through the building envelope. Recently, the application of curtain walls has been rapidly increasing. However, thermal bridges frequently occur in the non-vision panel system in which the insulation materials are installed because of the numerous metal members passing through the insulation layer. The aim of this study was to analyze the influence of thermal bridges on the insulation performance of curtain wall panels in terms of the energy performance and internal surface condensation risk. A three-dimensional steady state heat transfer simulation was performed for four types of panel systems: insulation-joined metal sheet, insulation-separated metal sheet, bracket-fixed metal panel and screw-fixed metal panel. The heat loss, effective U-value, lowest internal surface temperature and lowest temperature factor of each panel system with and without thermal bridges were calculated and compared.