Sole-water heat pump only with decentralized ventilation system?

Apropos, where is your project located or are there regional threads here as well? We are from Essen :)

I built on the other side of the Rhine in 2014/2015 and am now gutting and renovating a two-family house for myself (also here at the Lower Rhine). Once with centralized controlled residential ventilation and now with a decentralized variant.

A neighbor, how nice :) We also gutted a two-family house, but the whole thing with controlled residential ventilation... as already described... Since we are still in the preliminary planning stage, building application and so on, it is not really an issue yet. My better half is a building technician for automation and a KNX trainer, really EVERYTHING has been tried out in the past and even here the line between sense and nonsense is rather narrow ;)