The device consists of a folded tube stuck through a window. This box can be constructed of old windows, scrap lumber, and cheap insulation. The beauty of this device is that it produces a generous flow of warm air when the sun shines upon it, but it has no moving parts. The solar window box will not work in space because it relies on gravity to operate, but gravity can be replaced, in this instance, by small fans to direct the flow of air. Operation of the solar window box is fairly simple.
Sunshine enters the system through a glass panel, and heats a metal plate, called a plenum.
My glass face is made from old storm windows. I use a sandwich of two windows to increase the amount of insulation. The warmed plenum heats the air just above it, and causes it to rise. The warm air pushes out the top of the tube, and a vacuum is created at the bottom end of the plenum. The vacuum causes heavier cold air to be pulled in through the bottom if the tube.