It could be the most sensible solution is to do – Nothing!
“IG” is Insulated glass – sometimes AKA “thermopane” or “thermal”
These are 2 or 3 pane windows with air sandwiched between the panes. Sometimes, the air is just air . . . or it could be an insulating gas like argon.
The windows are sealed “AirTight” and can last anywhere from 10 to 25 years depending on many factors (Crazy weather, Human jostling (Raising and lowering), Human cleaning (Pressure Washers etc), wood frame deterioration, or just because the seal pops.
If you’ve got these windows in your house, odds are good that one or more have failed seals. You wouldn’t have the “foggiest notion” – would never know – until they begin to develop fog between the glass panes.
Because it’s not easy to identify which windows have failed seals and which don’t, most home inspectors will see one fogged window and add a nice CYA in their report something like: “Fogged Window(s) noted. Recommend a qualified window expert evaluate and replace as required”
Comments like these leave Agents, Buyers, and Sellers in the lurch because no-one knows WHICH windows have bad seals.
Everyone’s walking on egg shells hoping this doesn’t turn bigger than life . . . replacing windows can get expensive fast.
I’m dealing with such an issue now and did a lot of research (because that’s what a real estate strategist does), and have learned some ways to deal with them . . . The most prevalent solution is that if the fogging isn’t bothering you, don’t fix it – You’re not losing enough insulating benefit to justify the expense.