this post was submitted on 21 Jun 2023
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We've got an insulated house, heat it properly, ventilate it, but still see humidity levels of 70%+ in bed rooms. How to fix that? (lemmy.nz)
submitted 1 year ago by [email protected] to c/[email protected]
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We built a house 7 years ago and it's insulated and has double glazing. I've installed Home Assistant with temp sensors in the bed rooms and seeing 70%+ humidity levels. Temperature is always above 16c

We ventilate it, but still it's 70% in the bedrooms. WHO recommends 40-60%, so we're a bit worried.

Living room is around 55% during the day when we have the heat pump set at 21c.

As it's pretty humid outside I think it's almost impossible to get it lower, but are there any other tips? I don't want to run dehumidifiers. Would an HRV like system help?

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[–] [email protected] 3 points 1 year ago* (last edited 1 year ago) (1 children)

Oh that's a slightly different thing I think. It is referring to ventilating the attic with the outside. Not ventilating the attic with the living space which is what the DVS/HRV thing is. Ventilating the attic with the outside is generally a good thing for various reasons. I might have messed up the terminology. But I don't think attic ventilation between the attic and outside will solve your problem.

[–] [email protected] 3 points 1 year ago (1 children)

Yeah, definitely don't want air from the attic.

I read somewhere else that just a positive pressure system is not sufficient, you need a balanced one, especially in well insulated houses. Ie fresh air in, stale are out. If I install something I want it to be right.

That would mean a couple of thousand dollars.

Food for thought. Going to try with opening windows more often first and a small dehumidifier, especially when drying clothes.

[–] [email protected] 3 points 1 year ago (1 children)

Positive pressure is definitely not as good. But if you plan ahead you can always modify into a balanced system later. In my last house when I installed positive pressure I also added an additional vent in the soffit in case I wanted to turn it into a balanced system in the future. But the positive pressure solved the condensation problem so didn't end up upgrading to balanced. You could also do balanced without mechanical heat recovery.

Maybe as an experiment try blow a fan pointed out an open window and see if it makes any difference to the humidity?

[–] [email protected] 1 points 1 year ago (1 children)

Thanks again for all the tips, much appreciated! I learn more and more about it.

Yes, will try the fan.

What type of system did you install? Just a simple fan or a more sophisticated one? If you want to be ready for balanced I guess your fan needs to be ready as well?

[–] [email protected] 2 points 1 year ago

I installed ducted air con and instead of having a separate system for ventilation, for cost effectiveness I routed it from the outside through the air con system. So the aircon pulled the air from both the return vent in the house (90%) and from the outside (10%). You only need a small amount of mechanical airflow from the outside to reduce moisture levels. And had another vent hole with cover on the soffit for future but not ducted into the air con.