An open window doesn't help much if there's little airflow through it. You gotta think about where the moisture is coming from and how it will get from here to there (and out) and what cold surfaces it might touch. Any bare metal forming a 'bridge' between the exterior and interior will conduct heat and therefor acquire a layer of condensate. Same goes for windows. That's why I either rip of the aluminum trim around my windows or when impractical, put a layer of some sorta plastic insulation (Coroplast strips adhered with carpet tape).
What you want to avoid is still moisture laden air 'pooling' and, because it's now colder, having less capacity to hold water vapour.. which then condenses. If you have cushions that are against a wall you'll probably notice that, after a bit, they've become damp along the back edge/bottom. What I do, when this happens, is to take one of my handy dandy 12v computer fans, pull the cushions out, and blow warm air along the corner/edge until it dries out. Same goes for my bed. Yup, it's a hassle, but it works well and is cheap. Got solar, so might as well us it. ..Willy.
