In the developed world, building energy consumption accounts for 20–40% of total national energy use, with a substantial portion lost through windows. The Vacuum Insulated Glass (VIG) — two glass panes separated by a sub-millimetre evacuated gap, hermetically sealed at the edges and supported by an array of small pillars — delivers thermal performance well beyond conventional double or triple glazed units, with commercial products now achieving centre-of-glass U-values approaching 0.35 W m⁻² K⁻¹. This presentation introduces the fundamental science and engineering of VIG, and considers its current state of standardisation and market readiness. With ISO standards published and industry adoption growing, the question is no longer whether VIG works but whether the market believes it!