A new low-temperature hermetic composite edge seal for the fabrication of triple vacuum glazing

High performance low-cost vacuum glazing is a key development in the move to more energy-efficient buildings. This study reports the results of experimental and theoretical investigations into the development of a new low-temperature (less than 200˚C) composite edge seal. A prototype triple vacuum glazing of dimensions 300 mm x 300 mm was fabricated with a measured vacuum pressure of 4.8x10-2 Pa achieved. A three-dimensional finite-element model for this prototype triple vacuum glazing with the composite edge seal was also developed. Centre-of-pane and total thermal transmittance values for this small prototype of the triple vacuum glazing were predicted to be 0.33 Wm-2K-1 and 1.05 Wm-2K-1, respectively. It was predicted using the developed model that the thermal performance could be improved by reducing the width of the composite edge seal and by the use of soft low-emissivity coatings on the glass surfaces. Detailed three-dimensional isothermal contour plots of the modelled triple vacuum glazing are presented.