Abstract: A unitary structure is provided comprises a frame, including perimeter portions, transparent panels, a pair of spaced rollers rotatable about parallel axes, and a sheet rolled up on the rollers. The sheet has separate and distinct portions which have varying light transmission properties for affecting the amount and/or wave length of natural light that passes through the sheet. Each sheet separate and distinct portion has the approximate height and width of the chamber defined by perimeter portions of the frame. Synchronous motors for rotating the rollers are disposed in cavities formed in the frame perimeter portions, and photoelectric control components are also provided. Vents are provided in the frame adjacent the top and bottom for selectively allowing or preventing the passage of air into the chamber.

Abstract: The solar gain through a window assembly is maximized in cold weather, and minimized in warm weather. The window includes first and second transparent sheets with an open volume between the sheets. A selective light reflecting device is disposed in the open volume, allowing passage of light from one sheet to the other in cold weather, but preventing passage in warm weather. A vent in a first frame, mounting the first sheet, selectively allows the passage of air from the exterior of a building containing the window assembly to the volume between the reflecting device and the first sheet, the air being circulated and then passed back to the exterior of the building. Another vent, in a second frame mounting the second sheet, allows circulation of air from the interior of the building, between the transparent sheets, and back to the building interior.