After reviewing the development plan - Are soundproofing measures necessary?

The surcharge from the decentralized controlled residential ventilation to the centralized controlled residential ventilation is acceptable and I will probably order this as well. It is a system from Zehnder.

I already wrote that a general contractor's preference for decentralized systems can indeed also indicate a lack of competence, and I mentioned several "prefabricated" house consultants (Beuler and Freyermuth nationwide as far as I know, Zink probably not quite in Bavaria).

Blablabla. Honestly, at level 1 it doesn’t even notice visitors who have never been to our place.

We are not talking about the noise of the devices. That is manageable depending on the device and level (I have some myself). It’s about the fact that the original poster has to take noise protection measures due to noise from outside. And all the openings, of course, are a disaster in that regard.

Read carefully.

Advantage, I don’t have dozens of meters of ventilation duct in the wall/ceiling that I never get access to again.

Disadvantage, that you have dozens of devices running. Compared to a central system, you also have significantly louder devices (centrally you actually don’t hear anything) with more than just basic ventilation. Regardless, it doesn’t matter at all that you have ducts in the wall/ceiling. Nothing happens to them. Germ breeding grounds are old wives’ tales.

P.S. Of course, you have all electrical, water, and wastewater lines exposed on the surface and not in walls/ceilings, since you never get access to them again? ;)

Before it ends up being no ventilation at all for cost reasons, I’d rather take that.

That question does not arise because controlled residential ventilation is mandatory for the original poster. Otherwise, I agree with you. In new buildings, however, there are no rational reasons to use decentralized devices, since central systems have exclusively advantages in operation.

The additional cost from the decentralized controlled residential ventilation to the centralized controlled residential ventilation is acceptable and I will probably order this one as well Is a system from Zehnder. Is there anything worth knowing about it?

There are two series. The slightly more expensive one can be programmed and is much better adjustable. I think that is the Q series. I would choose that one.

The surcharge from decentralized controlled residential ventilation to centralized controlled residential ventilation is acceptable and I will probably order this as well. It is a system from Zehnder. Is there anything noteworthy about it?

Our Zehnder Q350TR has been running largely without problems for a few years now and mostly on level one. We don't hear anything, not even when it is set higher. The device is located in the utility room, right next to the kitchen, and there are no noise issues there either. For a while, a lot was reported here about this topic and also about the device; the search function here will help you further. I can warmly recommend the device.