I'm in the process of renovating my failed double glazing.
One thought occurred - my MIG welder can use Agron Shielding gas and new windows are argon filled. A gas bottle is £6 so how much will it save on gas bills....
Well Thermal conductivity (w/m K) Argon = 0.016 Air = 0.0257
So argon = 62% of air (i.e. transmits less heat/cold not surprising since it is used in double glazing!)
If at a first guess I say the average year round temperature dfference between indide and out is 10 degrees C
If my average semi house in the UK has an external window and door area = 12m^2
Then I guess window area = 8m^2
The difference in thermal conductivities (extra heat conducted by air) = 0.0257 - 0.016 = 0.0097 (call it 0.01 w/m K)
So 0.01 x 10 degrees (temp diference) x 8m^2 (glass area of house) = 0.8 watts
Say my heating is on for 3 hours in the morning, 6 in the evening = 9 hours/day = 9 x 365 = 3285 hours/year
so 3285 hours x 0.8 watts = 2628 watt hours/year = 2.6kw
And at 10p/kwh for electricity cost = 10p x 2.6 = 26p / year.
I'm thinking filling the windows with argon is not worth it!
If I've made any errors etc let me know. Also this may be a best case scenario since conductivity of the silicone that seals the window I expect to transfer a lot of heat (compared to the air) and reduce the argon's effectiveness.