Upgrading original crittall windows with vacuum glazing??

[selfbuildrookie]

I'm currently working on a listed house with original single glazed Crittall windows. We'd like to improve the energy efficiency of the house if we can, and would prefer not to go down the secondary glazing route. Does anyone know if it is possible to retrofit super slim vacuum glazing into existing metal windows? The only stuff I can find online is about retrofitting it into wooden sash windows...

[Iceverge]

Crittall windows are gorgeous looking but I fear the performance of the frames would be so poor any upgrade to the glazing would be almost meaningless.

[Mike]

Yes, the frames are a huge problem. You may, perhaps, be able to fix thin closed cell insulation tape to the inner face of the frame, but it may not look so good even if painted. The glazing itself would help, but may not be cost-effective, and you need to check that the hinges seem strong enough to take the extra weight, if you have opening lights.

 

Personally I'd probably choose secondary glazing; depending on the window design you may be able to get something made up to align with the metal frame. And weatherstripping is definitely a good idea. I've seen silicone bead weatherstripping work reasonably well - where you extrude a silicone bead along the edge, put a bond breaker tape on it, shut the window while the silicone cures to a 'custom fitted' profile, then remove the tape.

[tonyshouse]

You can still buy new Crittal windows and they have thermal breaks in the frames. Thin dg units will fit