My home is a 20 year colonial style house in Connecticut. On cold winter mornings (below 20 – 22 degrees), condensation forms on many/most of the windows. Indoor humidity ranges from 42% – 48%. Windows are double-hung, double-pane, low-e, argon filled.
Why does this happen? And, how to I prevent or minimize this?
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https://www.calculator.net/dew-point-calculator.html?airtemperature=68&airtemperatureunit=fahrenheit&humidity=50&dewpoint=&dewpointunit=fahrenheit&x=37&y=13
If you keep your air temperature at 68 degrees and see relative humidity of 50%, the dew point of the air is a bit over 48 degrees. Surfaces at temperatures below that will wet from condensation as the air contacts the cooler surface.
Two ways to reduce this are to either reduce the humidity, or increase the temperature of the interior window surfaces.
At purchase, you could select frame materials with a eye to reduced thermal conductivity, or higher glass R values.
You can also increase the air circulation which can warm up the interior surfaces of these windows. (and also increase heat loss through the windows)
Another way to handle it is to make sure you have coatings on the window parts that resist damage from the moisture that will collect.
thank you - this info is helpful - these were supposed to be the 'top of the line' windows when we built the house - moisture is mostly at the bottom and the sides of the glass - makes me wonder if the wood frame has a lower R-value than the thermopane glass. It also has gotten worse after we installed heavier window blinds and when we replaced our furnace with a newer one that had a better quality humidifier. One option (which I don't really like) is to set the humidification level lower - but then the house just feels too dry in the winter.
I would lower the humidity gradually to find a lower comfort level. Take it down into the 30’s and maybe increase your air movement via a slow speed on a ceiling fan.
There are no aquariums or other spot humidity producers present?
Wow 30 per cent is really dry esp if you have a combustion heating source- and if you live in. A mixed climate you cnat let it swing much more than up to 50 in summer or else real problems with interior wood expanding and contracting each year…a seasonal 30 per cent humidity just isn’t practical in most climates outside of desert,, Florida and Rockies imo…
Same issue here in upstate NY. Anderson 400 Series windows. When we get that really cold -20, etc. (with windchill) the windows seriously condense. Automatic Aprilaire humidifier, but even then keeping it around 35% is almost "too dry".
Have noticed the same thing (heavier blinds/curtain make it worse for some reason). I did find if I run the ceiling fan on low it does help a lot (but makes everything else feel cold).
I know that the Anderson windows have a metal (aluminum maybe?) thingy (I don't know what it's called, but if you look in between the panes of glass you can see it go all around the window) and that can transmit the cold more easily vs. some other material. Or so I was told. I wanna say Marvin or Pella (I think) uses a vinyl/fiberglass/some other material than the metal band that Anderson does and supposedly has less issue of sweating on the windows.
If your ceiling fan has a reverse setting, try that. Here it washes the walls with air movement vs. the straight down. It makes a big difference.