Originally Posted by mackerel
Before worrying about taking moisture out of the air, have folks given a thought to where it's coming from? As an energy auditor, I see a lot of houses here in Maine that have damp basements. Many run dehumidifiers. Many just put up with a musty smell that makes everyone sick. I tell people over and over: Use a fan over the kitchen stove, and in the bathroom. Get an energy star fan with a humidistat switch. Paint the basement concrete so it can't be a source for ground moisture evaporation. If you have a dirt floor crawlspace or basement (all too common here), put a membrane (usually builders plastic, but occasionally something better like EDPM) over it. Seal the moisture down.
I deal with a heating climate. Few of my clients use air conditioners before I get there, and I hope none do afterwards. If they do, I look for problems with ceiling/attic insulation. Fix that and AC isn't needed here.
If cool dry air comes into a house and warms up, the relative humidity drops. That makes the air suck moisture out of wood, skin, plants, whatever. When it escapes, at some point it reaches the dew point and water condenses out, regardless of venting.
In this maritime climate in the summer, if people have windows open, especially basement windows, the moist outside air comes in and condenses in the crawl space or basement.
So really the best way to dry air would be a heat exchanger system that first cools it, removing water, and then warms it again by running it past incoming air that's being cooled, or taking waste heat off the cooling machinery. Ideally, this would have very little energy consumption in the process. I'm thinking of the water purification distillation units in Gaviotas that left the clean water only 3°C warmer than the incoming water, despite having just been through a solar evaporator.
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