Solar Air Heating


IMG_1601[1]Sunlight is more efficient at generating heat than it is at generating electricity, and one of the most straightforward applications is a solar air heater which preheats ventilation air. The primary component of a solar air heater is a large-area of vertical solar-absorbing cladding that is installed on the south side of a building and offset from the structural wall by an air gap. Ventilation air is pulled through small perforations within the cladding or through an intake at the bottom. The cladding heats up as it absorbs solar energy and transfers that heat energy to the ventilation air that rises within the air gap. The cladding is then ducted to an HVAC unit which heats air further (if needed) and ventilates the building.

Manufacturers claim that a solar air heater will even lower summer cooling costs because the cladding shades the structural wall from direct sun. Various system configurations are possible for a retrofit. For a new-build, the cost of the cladding may represent only a small (if any) incremental cost. Furthermore, the system is likely to be very long-lived since the cladding does not incorporate any moving parts. STEP has worked on evaluations of solar air heating systems through the Solar City Partnership and will continue to examine them in future projects.