The disclosure relates to a method for operating a ventilation system with a mixing chamber into which air is supplied via a first supply duct and via at least one further supply duct. Air is removed from the mixing chamber by a removal duct. The supply of air—volume control—into the mixing chamber from the supply ducts is controlled in each case via flaps with a plurality of flap leaves and/or a plurality of flap units each having a plurality of intercoupled flap leaves. According to the disclosure, the flap leaves and/or the flap units are activated individually, and an individual opening position of the respective flap leaves or of the flap units with the flap leaves is made possible.