How old are the windows?

@ShadyWillowFarm Not very old-I just moved in like 17 months ago, so maybe 2 years. They are probably cheaper vinyl windows. Condensation is the worst in the morning. Goes away pretty much during the day.

What is the humidity in the house? Typically this will happen with windows that are actually doing there job and well sealed. The dew point because of the interior humidity level and the temperature of the glass.

@millworkman . Humidity is sitting between 40-50 in the house. Slightly higher in the master bath.

I assume that you are referring to the inside surfaces that you can touch? Depending on temps, and it's a wee bit chilly where you are, anything outside of the LOW-LOW 40% is already too high. If you get near the 50% mark, you don't stand a chance.

Based on the overnight lows, you probably can't be out of the 30's and not have issues with regards to RH.

https://iaq.works/humidity/the-best-winter-season-indoor-humidity-range-for-your-home/

@Windows on Washington Ltd . Ok. I am assuming as we get deeper into winter the humidity will drop naturally? It is sitting at mid 40's to 50 now. Anything else I can do to lower it?

The humidity, exterior, will drop with the colder temps. But the indoor conditions are entirely a result of your management of the moisture.

@Windows on Washington Ltd . Mine just seems to sit in the mid 40's currently. How can I manage better?

Myriad of resources out there to read. Short list:

• Run bath fans for at least 10 minutes after you are done bathing
• Reduce indoor plants
• Run range fans while cooking
• Reduce humidistat settings if so equip on your HVAC equipment
• Get a stand along RH gauge that is accurate

@Kyle McGilligan-Bentin, curious what part of wisconsin is home? I am in the NW near MN border and our low's have been single digits the past couple nights, so thinking you areeast side near the lake?

Do you have blinds/shades/curtains that you are closing at night? If so then you need t leave them open at least a few inches to ensure air circulation over the glass. That should help cut down on condensation if that is the case.

Previous posts have been dead on and offered great practical advice for getting rid of the condensation, but I am going to offer a bit on the physics side of things to maybe help explain why that was such good advice....other than it works, which is pretty much the whole point of course, but I am a geek, so here goes.....

The only way to prevent window condensation is by either raising window glass temperature above the dew point or lowering the moisture level of your home to drop the dew point. That's it, the only two options.

People love to talk about dew point, TV weather guessers love to mention dew point, but what exactly is it?

Dew point is defined as saturation vapor density, or 100% relative humidity, or as the transition temperature between evaporation and condensation. The temperature of the dew point is based entirely on the moisture level of the air and is independent of the air or surface temperature. While dew point temperature can be calculated based air temperature and relative humidity, to reemphasize, dew point is based entirely on the amount of moisture in the air and is unaffected by air temperature.

So why is this important?

If your window glass is above the dew point temperature they are dry, if the glass temp is below dew point temperature, the glass is wet. You can only change the dew point by changing the moisture level. Thats why (from WoW) :

• Run bath fans for at least 10 minutes after you are done bathing
• Reduce indoor plants
• Run range fans while cooking
• Reduce humidistat settings if so equip on your HVAC equipment

will actually work, because all of these suggestions will lower the moisture level in a space which will lower the dew point.

Relative humidity on the other hand is dependent on both moisture level and temperature. Raising room temperature without changing the moisture level will lower RH but will not affect the dew point, while lowering room temperature will raise the RH level, but again does not affect the dew point.

Raising and lowering the RH by changing room temperature will affect your comfort but will not affect whether or not you have wet windows.

Actual example (well real calculations at least):

Consider a home at 65°F with a relative humidity reading of 40%. In this scenario there are 6.25 grams of water in a cubic meter of air in the home which equates to a dew point temperature of 38°F. If the window glass is less than 38°F then condensation on the glass is likely to occur.

What if rather than 40% RH we try 30% RH to see if that helps?

Well we can lower the Rh by raising the air temp to 75°F which lowers the Rh to 29%. Did this fix the problem? Nope, you still have wet windows because warming the room to lower the RH still doesn't change the dew point so it doesn't affect the formation of condensation on the glass. Raising air temperature did nothing to lower the dew point which is still 38°. But lowering RH by lowering moisture in the air will also lower the dew point and that should help.

"Do you have blinds/shades/curtains that you are closing at night? If so then you need t leave them open at least a few inches to ensure air circulation over the glass. That should help cut down on condensation if that is the case."

^^This is what I was going to say.

"Mine just seems to sit in the mid 40's currently."

Are you saying that you do not have a humidifier in your home that is bringing the levels to the 40s? If you do not, it is very odd to have indoor humidity in the 40s when the outside temps are in the teens, which should make the air quite dry. Do you use your exhaust fans in the bathroom? And if you do, are you sure they are venting properly? What about your basement and foundation? Do they seem moist year-round?

@RoyHobbs I do not have a humidifier that is bringing it to the 40's. All rooms pretty much sit in the low 40's besides the kitchen and bathroom which are are higher. I am running a high efficiency boiler if that matters.

@RoyHobbs . Basement is sitting at high 30's and low 40's.

You did not answer the questions about your blinds, your bathrooms' exhausts, or whether you are seeing excess moisture in your basement or foundation. Nor respond as to whether you plan on implementing any or all of the bullet points listed above by @Windows on Washington Ltd and reiterated by @oberon476. Nothing more to say here.