[KaiserPro]

> winter you can turn down the ventilation to a minimal

The problem is that the Heat exchanger actively draws moisture out, as it has a huge cold surface area that forces water out of the air. If you don't change the air it feels stuffy.

[netjiro]

You can buy heat exchangers with very high efficiency and good moisture reclamation or suppression for a slightly higher cost. The problem is usually that the customer does not look into the details and the construction company can increase profits by buying cheaper versions.

A good modern ventilation energy exchange unit for a 300m2 house can be <30dB, >90% efficiency, and return a lot of humidity.