Window element - wherein the window element comprises a window frame by means of which the window element is securable in walling of a building, - wherein the window element comprises a sash frame secured to the window frame, - wherein the window frame has an inner closure surface which faces the sash frame and encircles at least in U-shape and against which the sash frame in the closed state of the window element bears so as to form a gap between the sash frame and window frame, - wherein the sash frame in the closed state of the window element has an outer region and an inner region, - wherein as seen orthogonally to a closure plane containing the inner closure surface the outer region extends towards the window frame and the inner region extends away from the window frame, - wherein the outer region and the inner region adjoin one another in the closure plane, - wherein the sash frame has in the outer region a receiving groove for receiving fitting elements and in the inner region a contact region which as seen in the closed state of the window element in the closure plane engages over the window frame, - wherein the receiving groove has an encircling inner edge and an encircling outer edge defining a respective inner plane and outer plane extending parallel to the closure plane, but spaced from one another and from the closure plane, wherein the spacing of the inner plane from the closure plane is less than the spacing of the outer plane from the closure plane, - wherein the window element comprises a regulating element by means of which an air flow flowing out of a window element rebate through the gap between sash frame and window frame or conversely and in that case also passing the regulating element, is regulated, - wherein the regulating element comprises a closure element which in the closed state of the window element bears against the inner closure surface, - wherein a flap is arranged at the closure element to be pivotable about an effective axis of rotation and is movable relative to the closure element between an open setting and a closed setting, - wherein a cross-section effective for the air flow is at a maximum in the open setting of the flap and at a minimum in the closed setting of the flap and - wherein the flap in the closed setting bears against the sash frame or against a profile member arranged at the sash frame and in the open setting is spaced from the sash frame or from the profile member arranged at the sash frame, characterised in that the regulating element as seen orthogonally to the closure plane is disposed exclusively between the inner plane of the receiving groove and the contact region. - wherein the window element comprises a window frame by means of which the window element is securable in walling of a building, - wherein the window element comprises a sash frame secured to the window frame, - wherein the window frame has an inner closure surface which faces the sash frame and encircles at least in U-shape and against which the sash frame in the closed state of the window element bears so as to form a gap between the sash frame and window frame, - wherein the sash frame in the closed state of the window element has an outer region and an inner region, - wherein as seen orthogonally to a closure plane containing the inner closure surface the outer region extends towards the window frame and the inner region extends away from the window frame, - wherein the outer region and the inner region adjoin one another in the closure plane, - wherein the sash frame has in the outer region a receiving groove for receiving fitting elements and in the inner region a contact region which as seen in the closed state of the window element in the closure plane engages over the window frame, - wherein the receiving groove has an encircling inner edge and an encircling outer edge defining a respective inner plane and outer plane extending parallel to the closure plane, but spaced from one another and from the closure plane, wherein the spacing of the inner plane from the closure plane is less than the spacing of the outer plane from the closure plane, - wherein the window element comprises a regulating element by means of which an air flow flowing out of a window element rebate through the gap between sash frame and window frame or conversely and in that case also passing the regulating element, is regulated, - wherein the regulating element comprises a closure element which in the closed state of the window element bears against the inner closure surface, - wherein a flap is arranged at the closure element to be pivotable about an effective axis of rotation and is movable relative to the closure element between an open setting and a closed setting, - wherein a cross-section effective for the air flow is at a maximum in the open setting of the flap and at a minimum in the closed setting of the flap and - wherein the flap in the closed setting bears against the sash frame or against a profile member arranged at the sash frame and in the open setting is spaced from the sash frame or from the profile member arranged at the sash frame,