Abstract: Between regions of different air pressure, a door pivots on an axis located a substantial distance from the nearest edge; this edge moves inwardly as the door pivots about the door axis in a first phase of opening movement to relieve the difference in pressure on opposite sides of the door; pivot links then carry the door about a second axis, parallel to the first axis, in a second phase movement which moves the entire door outwardly to the open position.

Abstract: An illumination and ventilation system for buildings and other enclosures utilizing at least one closure unit mounted in one or more sides of the building or other enclosure. The closure unit has a frame within which are a plurality of pivotally mounted, independently, movable, downwardly extending, blades. The blades are mounted within the frame with the pivot axii of the blades parallel and lying in a sloping plane when the closure unit is installed in the side of a building, or other enclosure. In a rectangular plan building or enclosure, four or more closure units should be employed; one or two for the windward side or sides, and three or two for the nonwindward and leeward sides. With this system, the windward and leeward and nonwindward closure units, will operate independently of each other and will be individually responsive to the net resultant wind pressures on each side of the building.

Abstract: A counterforce assembly is described for use with doors that are exposed to high pressure differentials on the two sides thereof which result in large forces acting on the doors which tend to maintain the same closed against a door jamb and make the same difficult to open. The assembly includes a counterforce panel. The panel is typically hingedly mounted and has one major side thereof covered by a pressure shield. The covered side is vented to the low pressure side of the door and maintained at the low pressure while the other major side of the panel is exposed to the high pressure side, so that the panel is exposed to the same pressure differential as is the door and a resulting net force acts on the panel.