Vacuum insulated glass (VIG) technologies are increasingly advertised as solutions for high-performance building envelopes, with center-of-glass thermal resistance values (R-values) in the range of R-16 to R-21. These values suggest that VIG units can approach or exceed the thermal performance of opaque wall assemblies, supporting the design of highly glazed facades that meet stringent energy codes and decarbonization mandates. The study presented in this paper reveals that the realized thermal performance of VIG assemblies is significantly constrained by system-level heat loss.
The authors present a methodology to assess the performance of glazed walls incorporating VIGs, identify where system losses occur, and suggest where system development should focus to realize the full potential of this technology. While there is room for further system development, the study discussed in this paper demonstrates that even in the nation’s strictest energy compliance framework, the Massachusetts Stretch Energy Code, it is possible to build an all-glass building with VIG.
This paper was published in Façade Tectonics (August 10, 2026).