Greenhouse (1) comprised of a ridge beam (4) extending some distance above its roof (5) defining two elongated side zones (6, 7) at either side of the ridge beam (4). The ridge beam (4) is comprised of one or more elongated hollow spaces (8) and with one or more closable openings (9) in both side zones (6, 7). The openings (9) fluidly connect the exterior (10) of the greenhouse (1) with its interior (13) and may be closed at one side and opened at its other side depending on the direction of the wind.
