Solar Space Heater Demonstration

Active Solar Heating

The solar space heater is an example of Active Solar Heating, since the heated air is drawn through the collecter using a small fan. This compares with Passive Solar Heating where the circulation of heated air depends on natural convection.
There are two types of active solar heaters

• Recirculated: air from the building is heated by direct sunlight when it passes through the solar collector, then circulated back to the building. This type of collector usually consists of a dark collector material, covered with durable plastic glazing. A fan is used to suck air from the building through an inlet at the bottom of the collector, through the collector where it is heated by the sun, and back through an outlet at the top from where it is distributed to the living areas. The solar heater could easily be connected to existing ducted air heating systems.
• Ouside ventilation: outside air is drawn directly through the collector, and circulated through the building. The design of this collector is very simple, consisting of a dark sheet of performated metal. The sheet absorbs energy from the sun, and heats the air forming a thin layer of warm air at the surface. A fan draws the warm inside the building. No cover glazing is used. Despite this, the performance of the heater is apparently not significantly effected by the wind. This type of solar heater is known as a Transpired Solar Collector, developed by NREL, and available commercially as SolarWall, in Canada and the US. The transpired solar collector is useful where there is need to improve the air ventilation of a building (eg in offices), and where the outside air is pollution free. Transpired Solar Collectors claim up to 70% efficiency, or twice the efficiency of conventional collectors.