We too had a similar experience with ice buildup. The only time we had ice inside our house in the past was with our original 1940 windows. So, you can understand my frustration when I noticed ice on the inside of my NEW, “energy efficient” windows. Apparently these windows have an issue with condensation building up, something that the sales rep declined to mention. To lessen the problem, we are to turn the humidity down, not have window treatments, and wipe down the windows. AFTER the fact, they send you a pamphlet explaining how you are supposed to coddle these windows, live in a dry house, have no window treatments, wipe them down, etc. Really? All of this is very peculiar to me since half of our house has windows by another manufacturer, all of which have window treatments (blinds and curtains) and we have NEVER had ice on the inside of the windows, even on the coldest days on record. And, the only condensation that forms on these windows is in the bathroom after a warm shower but even that evaporates shortly thereafter.
We were also told that we need to close these windows very gently or else they won’t latch (the top will slide down)! From my inspection, the latch is the root of the problem. The seal is not tight or well insulated, allowing very cold air in, making the window around this area very cold on the inside, further exacerbating the problem. I do not recommend this company or their product. It is a shame too because the installers did such a great job and they came recommend to me. When I have a spare $5,000, I am ripping these out for new quality windows. I guess you get what you pay for and I should have forked over $1,000 more for windows that were not so high maintenance and truly energy efficient.