Ventilation in new buildings (central vs. decentralized), noise disturbance

Thank you very much for all the answers here. Currently, I am leaning towards installing decentralized devices from Meltem. Three times each via the two-room system, so that one bathroom/toilet is ventilated and another room (bedroom, children's room, study) is ventilated. Then an additional standard device in the living room. This puts me at about 5k€ in material costs and I think the installation will be very quick and easy (flush-mounted set --> install directly into the wall + lay 2-3 pipes).

This way I cover all rooms at least partially, meet my minimum requirements, stay within budget, and don’t have to lay pipes throughout the entire house (or have them laid) and accordingly box in ceilings.

Am I being too naive here? Are the installation costs actually higher so that in the end I come close to a central system, and might I even have to watch out for statics when laying pipes between rooms? Or do I have to consider more when installing the fans than just covering all rooms? I think the details such as air exchange rates / air volumes etc. are not fully covered here (but as I said, I am not afraid to still ventilate with the window if necessary). Also, I can imagine it being unpleasant if, for example, I am sitting in the study and the demand ventilation in the guest bathroom starts, that suddenly much more air is blown into the study or the fan becomes louder. Furthermore: Do I have to cut slots into the individual doors so that the air can circulate between the rooms?

Thank you very much! Kiri

Does anyone of you have any advice for the OP kiri123?

I would like to invite you to us in Bernau. Maybe you can combine the visit with a trip to Berlin. We can also do the consultation on a Saturday.