Energetic renovation of old buildings - is a ventilation system necessary or not?

What would be the concrete advantage of a central ventilation system compared to a decentralized one?

if the house offers unused chimney flues, that is very advantageous:

common practice is to supply the immediate living area with fresh supply air and to extract the used air on the same floor in the area of contaminated air. For example, supply fresh air in the living room, extract exhaust air in the kitchen area. The air then passes through the floor. From the exhaust shaft it goes to the heat exchanger, which preheats the fresh supply air.

For this purpose, we sealed off 2 (unused) chimney flues at the top and only installed/drilled supply/exhaust air connectors into the air shafts. This way, only one additional fresh air hole to the outside was necessary, through which the heat loss of the heating system (in the basement) is additionally picked up and utilized. This also ensures that the basement is always forcibly ventilated and dry.

Of course, what is possible also depends on the floor plan.

So here is a clear vote for the central solution.

After about 3 months of operation, the air filters in the air conditioning unit are black. So all dust that is spared from the living rooms.

According to my understanding as a layman, I would have to supply all rooms to be ventilated with a supply line in a central ventilation system. Especially on the ground floor, where no structural changes are to be made, this is rather difficult. In the upper floor, which is practically being gutted, that would of course be feasible. And indeed there is a chimney with a shaft that is no longer in use.

You could also install a central controlled residential ventilation system in the upper floor/attic and run the supply and exhaust air ducts on the ceiling there and ventilate the ground floor with ceiling vents (i.e. from above). It depends on what you are doing and where you might find space and floor build-up height for that. But it is recognized like this and is often done this way in new buildings (e.g. with us :) ).

Anyway, find yourselves a competent planner.

Oh yes, if possible, a vote from me for central as well. BUT in the case of renovation, there is usually no space for the piping. That’s why I am now living with a decentralized solution. However, it also works very well and quietly. It is also significantly cheaper and apart from electricity and core drilling, I didn’t need to carry out any further work. Room height therefore remains unchanged.

Does anyone here have experience or recommendations on when a ventilation system is useful or even necessary and when not?
What problems should I expect if I do without it?

Regards and thanks
Christian

None at all, you just have to ventilate yourself. The question is whether the comfort is worth it to you or if you prefer to ventilate yourself anyway.

Thank you very much in advance for your feedback. The tendency is rather towards a ventilation system. I will probably get in touch with a suitable specialist company here. As part of our renovation, the floor on the upper floor will be completely open, i.e. theoretically one should also be able to get ventilation openings through the ceiling on the ground floor (it is a wooden beam ceiling between the ground floor and the upper floor). But how the ducts can be laid on the upper floor, I cannot currently imagine... The floor structure must not become too high, as the renovation and, for example, the staircase from the ground floor determine the height on the upper floor (last step). And we only want to lower the ceiling here to a limited extent – we actually want to use the room height as best as possible here. Regards Christian

Well, how does it look? Is there already a stiff breeze blowing?