Primary seal deformation in multipane glazing units

Abstract

Quadruple glazing has become a high-end standard in the field of sealed insulating glass units. With more than three glass panes a set of internal heat-related technical problems emerges. Durability, being the most pressing problem, requires careful management of the primary sealant deformation, especially under summer environmental conditions. Namely, the role of the primary seal in insulating glass units is to protect their humidity-sensitive, low-emissivity coatings from moisture and the quality of such protection is a key factor in durability. In this paper, a new methodology is proposed for a feasibility assessment of a new multipane insulating glass unit design, where proper design enables avoidance of excessive strain on the primary seal. It focuses on the calculation of the primary sealant strains, which are nonhomogeneous and multiaxial according to different loading conditions. This approach leads to analytical expressions that enable convenient identification of the critical location on the primary sealant. Finally, feasibility is assessed with the proposed methodology for the newly developed highly insulative six-pane facade unit by means of a comparison of the calculated strain state with the anticipated allowable strains, based on technical practice.