Abstract: A series of double pane glass panels of a standard length and width, thereby decreasing cost, are installed between a pair of parallel studs in partially upright position, with a longitudinally flanged spacer strip or strip sections attached to the inside edge of each stud for spacing the panels from a single, hollow duct-collector, or a series of connected, hollow duct-collector sections which correspond in length and width to the panels. The duct-collector acts not only as a conduit for movement of air through the device, but is also specially constructed to simultaneously transfer heat to the air. Thus, the front wall of the duct-collector is dimpled inwardly, with the outside and inside surfaces of the front wall being black and the remaining inside walls of the duct-collector sections having a bright, reflecting finish.