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While staying with some relatives, I noticed that all their windows experience terrible interior condensation at night and am wondering about what they can do to prevent it.
The house is kept to 70 degrees with gas-powered hot water baseboard heaters, and the windows are vinyl double-paned units. The house is 2x4 frame construction with interior drywall, exterior stucco, and I'm being told that the walls are uninsulated(!!!).
They live in a colder part of the high desert southwest where the humidity is very low during the day but rises at night, and where the temperature gets down into the single digits at night during the winter. During this season, the interior of their windows become entirely covered with condensation at around 8 or 9 PM every night without fail. It's kinda weird. What's causing this, and what can they do about it?