Failed double-glazed unit and thermal efficiency

[SaudisLoveAudis]

Hi All,
I hope you are well.
Do you know what is the drop of thermal efficiency when the unit fails?
I think there are a couple of stages of the failure.
On some units I can clearly tell it failed but some can still be transparent but once I look closer I can see the marks on the inside.

 

[SaudisLoveAudis]

no one? I don't need precise number just to know roughly if the efficiency drops in half or something like that.

 

[big-all]

havent got a clue
but iff you work out the average heat loss through windows
lets assume your bills are £2000 a year and you can attribute say 8% to windows and doors thats £160 a year now your failed units are say 5% off your windows thats £8 a year but the actual loss may be half or double so £4-£16 off a £2000 bill
but purely a guess

 

[Notch7]

Hi All,
I hope you are well.
Do you know what is the drop of thermal efficiency when the unit fails?
I think there are a couple of stages of the failure.
On some units I can clearly tell it failed but some can still be transparent but once I look closer I can see the marks on the inside.

A significant drop, 50% is likely