Humidity control with no HVAC

Hi there
I am looking for a solution to control the humidity levels in rooms without any central ventilation systems. My model only contains a geothermal heat pump with radiator panels and want to use it without air handling.
My first method was to use the hb_window_open - because in reality opening the window would be the solution - but it can only be associated with one vent_control that has just temperature parameters. My second method was to use the ironbug exhaust_fan tool to make zone equipment that forces in outside air, but I did not found a way to connect a schedule that is based on humidity of the room. Does someone has a tip how to achieve this? An airloop is OK if it only mimics the room fan without heating or cooling it.

thank you a lot!