Ah, misunderstood. Obviously you can save a lot of energy if the ventilation system goes down, when you are not at home. However in my house the radon level then goes up, so I have stopped those flows.
Am controlling an EC roof fan (https://shop.systemair.com/en/tfsr--160--ec--sileo--black/p104994) with a qubino 0-10v dimmer.
