ᐅ 20% Relative Humidity in a KfW 40+ New Build

Created on: 3 Mar 2023 08:43

Hello everyone, the title already describes the problem. Approximately 20% humidity in all living and sleeping rooms. We moved in about two weeks ago. That can’t be normal, right? I expected such low humidity only after 2-3 years, but not right from the start...

The first night in the house was really horrible. On top of that, we have been dealing with colds and coughing the whole time. We now have a humidifier running all night in the bedroom (starting in the evening, about 12 hours total) and wake up with around 35-40% humidity.

Could something be set incorrectly in the mechanical ventilation system with heat recovery, or is this low humidity normal in a new house?

What can we do? Apart from the bedroom, we don’t notice it being a problem in any other room. Enthalpy exchangers are supposed to increase humidity by a maximum of 5%, right?!

Thanks for your feedback and best regards

RotorMotor6 Mar 2023 11:02

#67

Nida35a schrieb:

Plus working in the garden, plus sitting on the terrace with the doors open for hours 😉

And that in both summer and the coldest winter!

KingJulien6 Mar 2023 11:12

#68

This is already going off-topic again and going in circles.

Can’t we at least agree on something for half a year 😉 regarding controlled residential ventilation (with EWT)?

Absolutely necessary: No
Comfortable: Definitely!
Cost: Treat yourself (or not)

WilderSueden6 Mar 2023 13:18

#69

KingJulien schrieb:

Absolutely necessary: No

I can only give a maybe. If you want sufficient air exchange in airtight houses, you have to manually ventilate thoroughly 6+ times a day. Nobody does that except the absolute ventilation enthusiasts, so in reality, it’s no longer just a matter of personal preference.

motorradsilke6 Mar 2023 13:24

#70

WilderSueden schrieb:

I can only say maybe. If you want sufficient air exchange in airtight houses, you have to manually ventilate thoroughly 6 or more times a day. Nobody does that except the absolute ventilation enthusiasts, so in reality, it’s no longer a matter of preference.

And that is simply incorrect. In practice, ventilating 2 to 3 times a day is sufficient. Otherwise, everyone living in airtight houses without mechanical ventilation systems would have problems. But that is not the case.

Oberhäslich6 Mar 2023 13:46

#71

So, for our house we chose the standard package with no extras. However, I really wanted the central mechanical ventilation with heat recovery because I don’t have the time or desire to open all the windows several times a day. In reality, very few people actually do that. Having fresh air all the time is definitely a big advantage, since the apartment often starts to smell musty after a while if many people are inside. Since we had to install a decentralized mechanical ventilation system anyway (KfW55 standard), we just added €5,000 (about $5,500) and ordered a central system instead. It probably doesn’t pay for itself financially, but you shouldn’t underestimate the importance of ventilation in such a tightly sealed building envelope.

WilderSueden6 Mar 2023 13:56

#72

motorradsilke schrieb:

And that is simply wrong. In practice, 2 to 3 times is sufficient. Otherwise, everyone living in tightly sealed houses without mechanical ventilation would have a problem. But that is not the case.

You still owe an answer about what your ventilation plan states regarding the nominal ventilation rate and why you believe you know better than the experts, and that twice is enough instead 😉
Sorry, but in this respect, you are like my girlfriend. Not interested in the basics, unwilling to engage with them, yet completely convinced of your own opinion.

ᐅ 20% Relative Humidity in a KfW 40+ New Build

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