ᐅ KfW 70 without a ventilation system

Created on: 11 Feb 2011 09:40
D
Diin
Hello everyone,

maybe someone here can give us a good tip, as we are quite uncertain about a ventilation system.
We are planning to build a house (solid construction) according to KfW 70 standards, with underfloor heating, a fireplace, and a solar system. That much is already decided.

We received an offer from Company A for a ventilation system with heat recovery, and the salesperson recommended it to us.

At Company B, the ventilation system is significantly more expensive, and the salesperson told us that since the house is so well insulated, moisture would not be an issue... where would it come from? The rest could be regulated by normal airing anyway.
(I also think he realized that his ventilation system would have blown our budget and now I worry that he advised us against it just for that reason!)

My husband and I are laypersons, but my instinct tells me that the better the house is insulated, the more problems I would have getting rid of moisture and stale air inside the house, right?
After all, a blower door test does show that there is very little air circulation.
Am I completely wrong?
We are a bit torn now, since such a system is not exactly cheap! But is it necessary, or just a nice extra?

Thank you very much for your help!
€uro
2 Feb 2014 09:48
Bauplane schrieb:
....I cannot understand at all the often claimed necessity for a mechanically controlled ventilation system to remove moisture. In my opinion, this investment along with the associated ongoing costs can be avoided with a uniformly and well-insulated building envelope.
Exactly! However, fear of mold can be used to drive good business

Best regards
P
perlenmann
3 Feb 2014 08:31
I'm just wondering where the air that the range hood exhausts is being replaced from? Whether it causes mold or not is another matter, but for me, not having to ventilate right after showering, being able to leave immediately, no musty smell in the bedroom in the morning, and cat urine that doesn’t stink up the whole house, are worth it.

Also, I’ve become a bit of a wimp. I find it really uncomfortable now when visiting somewhere and having to quickly open a window. It’s disgustingly cold outside.
B
Bauexperte
3 Feb 2014 10:51
Hello,
Bauplane schrieb:

I live in a prefabricated house that is very well insulated and sealed (not yet KfW 70),
Hmm ... a "very well insulated" prefabricated house and it’s not even KfW 70 yet

Regards, Bauexperte
Mycraft3 Feb 2014 13:30
Well, it’s kind of a contradiction, isn’t it... I wouldn’t want to miss my mechanical ventilation system, either... always warm inside the house and always fresh air...
B
Balinge
6 Feb 2014 08:52
Yeah, I agree.
If the house smells like cat poop and opening the windows lets in environmental noise, children shouting, exhaust fumes, and dirt, then a controlled mechanical ventilation system is definitely the way to go.
P
perlenmann
7 Feb 2014 10:26
Bauplane schrieb:
Children crying


In my case, the mechanical ventilation system doesn't help with that.

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