20% humidity in KFW 40+ new construction

I would actually like to have a controlled residential ventilation system throughout the entire house, but it is simply not standard with our builder and probably too expensive for us. (To be honest, we haven’t even inquired about it yet because I just assume it would be too expensive for us... but maybe we should at least ask) That it is not standard now doesn’t seem unusual either. In this respect, I always find the comments that it simply DOES NOT work today and that it would be clearly below standard somewhat odd and partly just unrealistic. For me, that doesn’t mean that a controlled residential ventilation system would be unnecessary, but I also find the statements that everything else is rubbish exaggerated.

Our controlled residential ventilation consumes about 1 kWh every day (24h operation) with an average air exchange of about 0.33 per hour, which is about 365 kWh/year. Without enthalpy heat exchanger, but with a mixing air control that regulates the indoor humidity.

Now the counter calculation is still missing, what the controlled residential ventilation system itself consumes. I’ve googled a bit and found values from 200 to 500 kWh/year. So even assuming 200 kWh to 500 kWh for ventilation, I would save 300 kWh, that’s 60 euros per year. So it wouldn’t pay off in my lifetime, even if electricity prices rise.

If it is only about saving costs, you should probably only calculate the operation of the ventilation system for the heating season/in winter and not for the whole year. However, of course, once you have gotten used to the comfort, you don’t want to turn it off anymore. Ah, and of course there are people who save energy not just for 60€ in their wallet but also for the environment. ;-)

If it's only about saving costs, you should probably only calculate the operation of the ventilation system for the heating season/in winter and not for the whole year. However, of course, once you get used to the comfort, you don't want to turn it off anymore. Oh, and there are of course people who save energy not only for €60 in their wallet but also for the environment. ;-)

Of course, you have to calculate for the whole year if you use it all year round. There's nothing against saving energy if you want to (and can afford it, since the investment has to be made first). But what bothers me is that controlled residential ventilation is always presented as absolutely necessary and supposedly such a great saving opportunity. If I take the aforementioned 365 kWh, there is still a difference of less than 200 kWh. Some people will "waste" that on something else. Would it actually be permissible to install a controlled residential ventilation system with a chimney just like that (because exhaust hoods don't work without additional measures)?

Would it actually be allowed to install a controlled residential ventilation system just like that with a chimney (because an exhaust hood does not work without additional measures)?

Only with a differential pressure switch that shuts off the controlled residential ventilation system in case of negative pressure.

A controlled residential ventilation system is not there to save something but rather to achieve a gain in comfort and also to handle the problem with moisture largely automatically. We all know that comfort always costs something, but in this case, the comfort even brings something ;)