[snickerer]

I use similar decentralized (single-room) ventilation units here in Northern Germany: https://www.bayernluft.de/de/frame.cgi?page=start.

I am super happy with them. We now always have air that feels fresh and warm in winter, and the humidity has dropped significantly.

There are two types of such ERV devices:

1. Those with only one air channel that switches directions periodically. They use a heat storage element in the airflow. OpenERV belongs to this group.

2. Those with two separate air channels for intake and exhaust at the same time. The air does not mix but passes through a heat exchanger. Bayernlüfter works like this.

The only thing I don't like about Bayernlüfter is that it is not open source. It is controlled by a Raspberry Pi (or a similar clone), and I don't have access to it.