Energy-efficient window- film failure

You had to look closely at the aluminum perimeter strip separating glass panes to notice that these double-pane windows had an intermediate sheet of clear film installed to increase their thermal efficiency.

I don’t know what causes film to fail but it’s pretty easy to see the film when it does!

That would most likely be the “Heat Mirror” glazing system. Haven’t heard of too much failure in it. Some of the highest R values in IG units.

Nice view…in a wavey sort of way



Interesting… they are putting film in between the panes… most manu. of IG units will Void your warranty for application of film to exterior of panes…

Can think of lot’s of problems and bene’s of such film.

I’ve seen an IGU that had exploded from application of tint/film on interior side of IGU… side # 4 (depending on Manu.) heat built up between panes…POP!!

Milgard was gonna fix it anyway… how nice, the customer didn’t know not to tint the window


If I remember corectly, Heat Mirror has been around since the mid-late 1980’s so they have lots of experience with product development and working out the problems. I have had samples of their “tuned” glass since 1995 or so and met a company technician at a trade show in Toronto in the 1992-4 period.

Thanks Brian,

Just looked up some of the Heat Mirror info.

Learn something new everyday!

Still a bit sided myself as to adding films on existing IGU’s.

The Heat Mirror internal film was something I hadn’t run accross.


It really is pretty invisible unless it does whatever this one did.