A question about IG and film application

[McCoyH]

If the u-value of an IG unit is around .30 and you apply a film with a 1.00, how can you calculate your resulting u-value?

And a couple questions about Low-e... Are low-e coatings always applied to S2 and S3 on an IG unit? And if so/not, can you apply a film over a unit with low-e coating?

Thanks guys!

[Tinitman]

Those questions should be answered by your manufacturer. They should have all that information.

[Tintguy1980]

If the u-value of an IG unit is around .30 and you apply a film with a 1.00, how can you calculate your resulting u-value?

And a couple questions about Low-e... Are low-e coatings always applied to S2 and S3 on an IG unit? And if so/not, can you apply a film over a unit with low-e coating?

Thanks guys!

It's still 30. You need Window5 software to calculate (I am presently learning how to use it), but I was able to get the info from my Vista film-to-glass chart for 20 different glazing units without having to use the software.

LowE coatings from about 6 years ago back are usually found on surface 3; LowE from about 6 years ago to present for the most part place the high performance LowE coating on surface 2.

The older LowE coatings have strict film-to-glass guidelines whereas (newer) LowE allow many films to be applied since their high performance coating has solar energy rejecting capabilities.

So you can apply film to LowE IG units, just clarify whether they are high performance LowE or the older type before throwing up a film. It's not recommended to apply film to single pane LowE glass (which is rare to find) for a couple of reasons; 1) it'll neutralize the LowE effect and 2) you cannot remove the film without damage to the LowE coating.