@Jonas ,
There are probably a few different ways to do this depending on what behavior of the fans you need to capture.
I think the simplest is probably just to generate a list of the different fan flow rates for each zone depending on that zones’s ventilation requirements and the floor area. You can see that the Set EP Airflow component can accept lists of flow rates that align with the zones:
MultipleFanFlowRates.gh (483.2 KB)
There are some other ways of tricking the DOAS of some of the templates into now having any heating or cooling. Also, you can always write an OpenStudio measure to assign the exhaust fan object that @MingboPeng has pointed out. However, I would only resort to this if the first method doesn’t work for you somehow.