Decentralized ventilation only in individual rooms in new construction KfW 55?

The question of what a controlled residential ventilation system is for is, to me, now like asking: why a washing machine... I can also do laundry without washing it and that is cheaper

yes it is, and a controlled residential ventilation system probably doesn't pay off but always fresh air is so great

If central is not possible for cost reasons, then I would only do it in the bathroom....

For continuous operation in bedrooms, the devices are too loud for me.

We consciously decided on a central controlled residential ventilation system, I am working, my wife is studying, we are hardly at home during the day, I couldn't manage ventilation manually at all. It costs us 14k more and I didn't even think about amortization when making the decision. In fact, I had to give up something else for it (which can later be built without any problems), but it was worth it to us.

For me, the criterion for the controlled residential ventilation is not the amortization or anything else, but what I get out of it, and I get quite a lot...

And I have also spoken with builders who have one installed. They are glad they have it and everyone who waived it when building in recent years regrets it today.

Controlled residential ventilation only central, otherwise better nothing except bathroom exhaust.

Why only central? If I install a decentralized one in the bathroom, pantry, utility room and ventilate the other rooms, that should be fine, right? And in terms of cost, it would probably make sense as well?

If I install a decentralized system in the bathroom, pantry, and utility room and ventilate the other rooms, that should be okay, right?

If one decides at all "in favor of controlled residential ventilation," "central or decentralized" is a fundamental question on the level of "network topology" or comparable in IT between standalone PC and client/server solution. We have already had this principle discussion here, see:

Taking controlled residential ventilation as decentralized in order to opt for or against controlled residential ventilation room by room – in the sense of "we only take it for rooms where there is a high probability of mold formation if we do not manage to ventilate regularly enough" – I consider a misunderstanding of the technology. Controlled residential ventilation is not a mold prevention system, but a ventilation technology. Using it selectively only for "high-risk rooms" I consider misguided.

Therefore, I advise deciding "homogeneously" for or against it. The decentralized solution is not meant to allow omission on a room-by-room basis (with the naive idea that below, let’s say, two-thirds of the rooms it should be cheaper overall), but is a matter of principle: a single-room solution is like a "single workstation solution"; each standalone system must be individually sized, is not networked with the others, they cannot pool their capacities and each requires all components individually – the advantage compared to the central system is also the absence of networking (which is seen as an advantage since the duct network between the individual rooms is saved).

I consider decentralized as a last resort. I tested systems and found them disturbingly loud, especially at the switching point. Absolutely unacceptable. No idea how anyone could sleep with that. Better no [Kontrollierte-Wohnraumlüftung] than decentralized.