Controlled residential ventilation with heat recovery --- a confusing maze?

We are going with massive construction and a clinker facade, so without ETICS. This way, our house still "breathes" a bit, which was important to us.

Since I have a neighbor who argues similarly and I don’t want to ask him out of kindness:

The requirements for the airtightness of buildings apply regardless of the chosen wall construction. So why should your house "breathe"? And how does your house "breathe" away the CO2 and other air pollutants?

It may be true that depending on the chosen interior plaster/wall construction some moisture compensation is possible – but what happens to the moisture inside the wall if it is not or not sufficiently ventilated away? Eventually, the wall is "full." And natural cross-ventilation through joints is basically not possible due to the energy-saving ordinance!?

Maybe someone can give me a hint here...

I somehow feel that some people expect too much from the advertising claims of "red lime plaster"... but I am also happy to learn more.

"Breathing" walls come from the fairy tale realm of dowsers. If walls breathe, then it is a serious construction defect, as if full of holes.
And yes, moisture diffusion is higher in some wall constructions than in others. But that is completely irrelevant, because moisture diffusion through the walls has no effect on the moisture content inside the house. The amounts that can diffuse through the walls are far too small to have any effect.
Moisture can only be removed from the house by ventilation.

Hello, I also believe that this should be done right away when building a new house. Our exterior walls are monolithic (so without ETICS) and still we decided on a decentralized ventilation system. Advantages and disadvantages of central and decentralized can be read everywhere... for us the deciding criterion was the cost. As has already been said here, it costs about half as much. In the utility room, technical room, and bathroom we have exhaust fans and in the rest of the rooms there are fans with heat recovery. Because the fans are always running, we only have a humidity of about 55-65% in the house (depending on the weather). In new buildings it is usually higher, so that it is very important to ventilate properly especially in the first years. We are spared that now, since it happens automatically.

@VillaMo To: How long have you been living in the house? The topic of humidity is interesting even in winter... I've heard it can get too dry then.

And how about the noise?

In summary, when it comes to controlled residential ventilation, you have to consider the following (the list can be supplemented in bullet points) + = positive / - = negative / o = neutral

+ Fresh air, pollutants from furniture, floors
+ Moisture from construction is automatically removed
- Noise from outside may penetrate more easily (especially with decentralized systems)
- Possible odor nuisance from outside odors
- Possibly dry air in winter
o Costs
o Maintenance (filter replacement)

If one point in this list is negative, it is clearly the costs, at least in the case of a central system. Noise disturbance from outside is a bigger problem without (central) controlled residential ventilation when the windows are opened for ventilation, I think. Sound transmission through the system itself can be an issue, but it should not be at least on the low settings with correct installation (minimum duct length).

We have only been living in the house for just under 2 months, so I cannot contribute any experience regarding winter yet. Regarding noise, there is a slight humming sound... from the fan, of course... But we do not find it disturbing. Depending on the manufacturer, there are also sound insulation kits that can be additionally installed. Furthermore, the position of the fans apparently also affects the noise level. So you have to ensure that it is mounted in a suitable position. I read that in a brochure from our fan manufacturer. Noise from outside can sometimes be heard very faintly. However, we do not find it disturbing so far... I suppose it also depends on the location of the house (quiet area or not?). Possibly, this can also be further minimized with such sound insulation kits.