Slim retrofit
Potential to retain suitable existing frames rather than replace the whole window.
Delivery partner · PassivGlas
Keep the character. Improve the glass.
Vacuum insulated glazing can deliver strong thermal performance in a much slimmer unit than conventional triple glazing,making it worth surveying where existing frames, heritage detail or limited glazing depth matter.
Check likely suitabilityHow it works
A very thin vacuum does the insulating.
Two panes are separated by a tiny evacuated gap and discreet support pillars. Removing almost all the air greatly reduces conduction and convection through the centre of the glass.
Survey-led fit
Frame condition, opening size, edge detail and installation determine the real result.
Thermal + acoustic
Product configuration can address heat loss and sound, subject to the relevant specification.
Where it may fit
Especially interesting where thickness matters.
Period, listed or conservation-sensitive properties, subject to consent
Sound timber, aluminium, steel or suitable uPVC frames
Sash and casement windows where bulky units change the appearance
Occupied retrofit programmes seeking to reduce unnecessary frame replacement
What the survey must still prove
Frame condition, dimensions, seals, exposure, safety requirements, planning constraints, glass build-up and installation detail. A positive website check is not product approval or a performance guarantee.
Request a glazing surveyFocused check
Is your property worth surveying?
A few answers will identify the evidence Max needs next. It will not guess a saving from a window type alone.
Interactive assessment
PassivGlas suitability
What glazing is there now?
Evidence note · reviewed 30 September 2026
Performance depends on the exact glass, frame and installation.
PassivGlas publishes calculated thermal data using recognised NFRC and EN 673 methods. Centre-pane and whole-window performance are different, and installed results vary. Max will request the current product-specific data sheet, certificates and warranty terms before specification. We do not claim Passivhaus Institut product certification.