Abstract: The invention relates to a ventilation device for a window, having at least two essentially parallel panes of glass arranged in a common frame, thus forming a double window having an air space between the panes of glass, and an intake opening communicating with the air space and with either the interior or the exterior of a building, where the ventilation device also has a drive unit. Such a ventilation device has at least one air direction control unit arranged in connection with the window and where the air direction control unit (10) has a body, having a first throttle and a second throttle, and a device for operating the throttles between an open and a closed position. The body also has an opening communicating with the interior of said building, an opening communicating with the exterior of the building and a third opening communicating with the air space.