KfW 40+ funding with photovoltaic and ventilation system

First, the air is always dry in winter (even without controlled residential ventilation), and second, you can also choose a variant with moisture recovery.

Germs develop in moisture. But you yourself write that the air is too dry for you. You have to make up your mind. Both are not possible ;-)
Apart from that, the systems do not "get filthy" if you treat them properly (regularly change filters).

Thanks for the answers.
Of course, with regular filter changes, that doesn't happen.

We were offered a decentralized system; if I understand correctly, the rooms can be controlled individually?

We were offered a decentralized system; if I understand correctly, the rooms can be controlled individually?

Property. Yes. However, there are also networked systems.

We are currently facing the decision of whether we want to achieve Kfw 40 (plus) or "only" 55. From an economic perspective, the architect recommended an efficient condensing boiler (including solar thermal). Also because the gas line has to be laid anyway due to a gas fireplace.

Somehow, I am rather reluctant about that and would prefer to invest in a "future-proof" system. Always relying on fossil fuels is not so cool. And if you then power the heat pump with your own photovoltaic system, that is already efficient.

And heat pumps are becoming cheaper and cheaper, right?