Exploring novel solutions for incorporating vacuum glazing in new and existing window constructions

This contribution discusses recent progress in development of windows equipped with vacuum glass. Vacuum glazing is commonly understood as glass products consisting of two parallel glass panes with a very narrow gap. Moreover, they feature a tight edge seal and house a grid of distance pillars. During production the gap is evacuated. As a result, vacuum glazing products widely eliminate convective heat transfer and minimize conductive heat transfer. As such, they represent highly-insulating glass products that regularly feature U-values in the range of triple-glazing, or even below (about 0.2 to 0.3 W.m -2 .K -1 ). While the research pertaining to the development of vacuum glass can be traced back to the first patent of 1913 [1], relatively few research efforts have been conducted regarding the application of vacuum glazing in window constructions. In this context, the present contribution focuses on the application of vacuum glass products in window constructions. Toward this end, two application cases are addressed in detail. One effort addresses the application of vacuum glass in new window constructions. The major objective of this effort is the reduction of heat flow through the window construction. Thereby, innovative paradigms involving multiple operation, size, and construction options are considered. The second case deal with the potential of vacuum glazing products in view of deployment in thermal retrofit of existing buildings. This application case does not only focus on the thermal performance of the windows, but also on the necessity to protect the appearance of heritage building facades (including those of the historical window constructions). As such, vacuum glazing products provide an alternative to replacing existing windows with high-insulating triple-glazed products.