Hey folks. We are in a first winter in our new home, passive solar, off grid, no forced air, wood stove. So far passive solar has been plenty of warmth for us so we've not had any fires. We are experiencing what I would call very high levels of condensation on our south facing "passive solar friendly" windows. They are wood clad, high SHGC (0.62) windows. And virtually no condensation on our normal, low-e windows that have a SHGC of around 0.2. Six inch walls, very sealed up house. We run vent fans in the bathroom and in the kitchen during use, always. Indoor and outdoor humidity is about the same, usually around 50% or 60% this time of year. Thoughts? Suggestions? Admonishments? Thanks! M.

My rule is if the weather is not below 60 degrees F outside I do not open windows or attic fan. Because 60 degree air at 100% humidity warmed up to 73 degrees comes out at just above 50% humidity. I target 50% humidity all year around. I would also limit use of fans that pull outside air when humid.

We have different windows on every side of the house like you are describing...we do get inside condensation in the morning put I will watch if it is by window coating/location. We have fiberglass windows so we don't have worries about the moisture/water and ICF walls. How cold is it getting inside in the morning?

When I had my insulation business, the number we shot for during the heating season was 30% to 40%. Windows are always the weak link. Use a hygrometer to find the source. Each person in a house throws about a quart of water in the air exclusive of washing and cooking. Also being in the window business, high SGCH refer to Solar heat gain not the u-Value of the window so they can still have condensation form on them, especially along the lifting rail and the meeting rail. Lower your humidity and the problem should disappear at least until you hit really low temps.