Vacuum-glazed windows : A review on recent projects’ methods, results, and conclusions

Abstract

Windows are relevant for the design and performance of buildings for several reasons, such as daylight and natural ventilation provision. However, window constructions are considered as weak spots in the thermal envelope compared to opaque elements. This is due to increased heat transfer in comparison with fullfledge insulated opaque elements. Moreover, thermal bridges, mold growth, water penetration and draught are phenomena that occur often in window constructions. To tackle these, windows have been undergoing different improvements (e.g. multi-layer glass panes, rubber seals, foil add-ons on glass pane, etc.) majorly addressing their hygrothermal and acoustical performance. Vacuum glass products (VGs) are highly insulating glass products that are offered on the market with reasonable degrees of vacuum-upkeep today. While the development of such glass products has been widely published, little R&D efforts have been observed targeting the integration of such VGs into contemporary and existing window constructions. The present contribution reports on recent projects focusing on the integration of highly insulating VGs into historic and new window constructions. In existing windows, significant improvement of the thermal performance can be reached. New windows, tailored to the requirements of VGs provide extraordinary performances, if properly designed and integrated in the building envelopes.