A door sealing system includes a door seal for sealing either an upper or a lower side of a building door wing, and an air channel which enables, when the door seal is in the sealing position, air to circulate from a longitudinal side of the door seal to an opposite longitudinal side of the door seal. The door sealing system also includes at least one ventilator that guides air through the air channel. The door sealing system enables sufficient air to be exchanged even when the door wing is closed.