Looks like that is an insulated glass window, if it is that is a good start. What is the humidity range in the house? Chances are it is too humid and if it is I don't believe those indowWindows will help much.

Good point. This is our First winter in the home. No wonder my skin isn't as dry as usual!

The companies that push those interior storms will never tell you that but if the dewpoint in the house is too high when the moisture hits the cold of the glass you get condensation, when it is very cold well you know the rest. Not saying interior storms would not help but it will not be the end all solution.

Gotta know interior humidity levels and set points. There comes a time when if the temps are low enough outside, you are going to have issues with too high an RH no matter what window performance you get.

If I know the outdoor temp, indoor temp, and indoor humidity level, can someone explain to me the math to figure out if I will have condensafion on the window interior? Thanks

The first step is to determine the dew point in your house. Use the dew point table below. Assume the inside air temp is 75 F and the inside relative humidity is 35%, this would give you a dew point of 45F. Any time your window surface temperature dropped below 45F, you will get condensation. Calculating your glass surface temperature is pretty complex. You are seeing ice at the edge of your glass, showing the variation in U-value at different points on the window (it's colder at the edge of the glass). If you know the RH and interior temperature, condensation or ice on the window gives an indication of how well your windows are doing. A "good" window will not form condensation at lower outdoor temperatures for a given interior RH. However, as can be seen from the chart, at high relative humidities, condensation is going to form on the best windows.

Where are you located and what temp? In MN the temps have been below zero. At that rate, it is almost impossible to avoid condensation, even frost or ice even on a good window, and with a reasonable RH. You also have to consider if you have blinds closed, etc. That will almost be a guarantee at that point.

The interior storms are good in concept, however it is nearly impossible to get a 100% seal. If you don't, it will actually make the condensation worse, as it makes the window colder but still allows moisture migration.

Bottom line, if it is 20 degrees, you could can probably fix this by addressing the RH or getting a better window. If it is below zero or near, what you are seeing may not be able to be fixed unless you want to get the house super dry.

Helpful chart above. Here is a link to a calculator as well.

http://www.dpcalc.org/

We are seeing a high volume of condensation calls lately as well. Always do when we get subzero temps. The Rh required to avoid condensation when it is below zero outside would be pretty uncomfortable... Not sure if that is the case for you or not.

Thanks, everyone. Yes, we are in WI and the ice I showed was after a super cold night with blinds drawn. I've been leaving them halfway up until we get some higher temps. It's good to know that some of this is to be expected and not because of defects.

Interesting information and points made. Sorry if this is too far off-topic. Of particular interest to me as house under construction will have wood interior windows, is suggestion to keep blinds open when outside temps are cold to very cold. While I am sure this helps with condensation, it is exactly during those conditions especially at night that I'd think about wanting and closing honeycomb shades that offer some R value. Since my thought about shades is more about energy savings rather than privacy, the recommendation here for cold weather has me re-thinking the potential pay back for shades.

Good points lite1. The cellular shades would indeed improve efficiency, however it would be at the expense of additional condensation, particularly in a brand new home... Not a great combination with wood windows... Classic case of trade-offs.

+1. Much like wall insulation, it a cold climate, exterior is better. It keeps the interior surface warmer.