House temperature vs mould / moisture

[Аdministrаtоr]

Another question, we're currently living reasonable comfortably at a temperature of 17°C (~62° F). I wonder if we could even go lower? I have read about people that put the heating at 7°C (45°F) but then I fear about dampness of the house, moisture and finally even mould etc... isn't that an issue if you go too extreme with the temperature? What do you consider reasonable?

[Monkey Uncle]

Another question, we're currently living reasonable comfortably at a temperature of 17°C (~62° F). I wonder if we could even go lower? I have read about people that put the heating at 7°C (45°F) but then I fear about dampness of the house, moisture and finally even mould etc... isn't that an issue if you go too extreme with the temperature? What do you consider reasonable?

It depends on the dewpoint, which is related to how moist the outside air is and how much extra moisture you are adding to the indoor air through your activities (cooking, laundry, showers, etc.).  If the outdoor temperature gets down into the teens or low twenties F at night, that means the external dewpoint is at least that low, and you should be o.k. with an internal temp of 45 F, as long as you aren't adding tons of moisture to the indoor air.  But I'd start to get concerned about pipes freezing in external walls or the crawl space. 

I sometimes let my house get down into the low 50s F, but I don't have a crawl space nor any pipes in external walls.  I've never had any problems with moisture in the winter, except for condensation in the a/c ductwork, which is located in the unheated attic and doesn't have any air flowing through it in winter.  I solved that problem by sealing it off better so that warm, relatively moist air from the living space doesn't rise into the ducts where it can cool enough to condense the moisture.

[MayDay]

In the fall and spring, when the outside air temp is close to the house temp, the heat will not kick in.  This is when you have issues.

In the dead of winter when its 0 and the humidity is really low, and the heat kicks in frequently, with a possible exception that it isn't a brand new super air tight house.

ETA: if you are in a dessert you are probably fine regardless, and if you are in a very humid area you might want to buy a hygrometer and measure to make sure.

[Аdministrаtоr]

Yeah I'm not in the desert but in a relatively humid, old house. I've done all kinds of restorations and needed insulation (roof insulation, new rooftiles, replaced doors/windows etc...) to keep the heat in. Still, especially in places where there's a lot of humidity (kitchen, bathroom, bedroom) combined with low temperatures, gives problems. We ventilate quite well fortunately. I thought we could ventilate even more and maybe we could lower the temperature even further.

[gaja]

Sometimes it is more cost effective to remove moisture than to increase the heating. Do some calculations, and maybe some simple tests if you find a cheap alternative.

[gt7152b]

I have more problems with mold forming in the summer from not running the AC. I just use a de- humidifier instead. It costs way less to run than HVAC.