Space heating means heating the space inside a building. Today many homes use solar energy for space heating. There are two general types of solar space heating systems: passive and active. Hybrid systems are a combination of passive and active systems.

Passive Solar Homes

In a passive solar home, the whole house operates as a solarcollector. A passive house does not use any special mechanicalequipment such as pipes, ducts, fans, or pumps to transfer the heat that the house collects on sunny days. Instead, a passive solar home relies on properly oriented windows. Since the sunshines from the south in North America, passive solar homes are built so that most of the windows face south. They have very few or no windows on the north side.A passive solar home converts solar energy into heat just as aclosed car does. Sunlight passes through a home s windowsand is absorbed in the walls and floors. To control the amount of heat in a passive solar house, the doors and windows are closed or opened to keep heated air in or to let it out. At night, specialheavy curtains or shades are pulled over the windows to keepthe daytime heat inside the house.In the summer, awnings or roof overhangs help to cool the houseby shading the windows from the high summer sun.Heating a house by warming the walls or floors is morecomfortable than heating the air inside a house. It is not so drafty. And passive buildings are quiet, peaceful places to live. A passive solar home can get 50 to 80 percent of the heatit needs from the sun. Many homeowners installequipment (such as fans to help circulate air) to get more out of their passive solar homes.When special equipment is added to a passivesolar home, the result is called a hybrid system.

Active Solar Homes

Unlike a passive solar home, an active solar home uses mechanicalequipment, such as pumps and blowers, and an outside sourceof energy to help heat the house when solar energy is not enough.Active solar systems use special solar collectors that look likeboxes covered with glass. Dark-colored metal plates inside theboxes absorb the sunlight and change it into heat. (Black absorbsmore sunlight than any other color.) Air or a liquid flows throughthe collectors and is warmed by this heat. The warmed air orliquid is then distributed to the rest of the house just as it wouldbe with an ordinary furnace system.Solar collectors are usually placed high on a roof where they cancollect the most sunlight. They are also put on the south side ofthe roof in a location where no tall trees or tall buildings willshade them.