Passive Solar Energy for Heating and Cooling a House

Passive solar is a type of architectural design which uses the sun's energy to heat and cool a building. It differs from active solar in that the energy is not converted to electricity before it is used. Passive solar buildings don't need fans or pumps in order to maintain an optimal temperature within a home. It's possible to build a passive solar house for about the same price as a traditional house. Therefore, it offers a considerable cost savings over solar panels if you're building a new home. However, a passive solar house design can be easily combined with active solar devices for maximum energy savings.

Passive solar houses can get most or all of their heating and cooling from the sun's energy. It can also provide a significant amount of a home's lighting, as well. This can dramatically lower a home owner's energy bills, especially in climates that are very cold in the winter or very hot in the summer.

Passive solar houses are oriented on an east-west axis. One wall faces directly south, and has a large window area to let the in solar energy. The north side of the house typically has no windows or very small, heavily insulated windows. The east and west walls are proportionately smaller than the north and south. The house must have considerable thermal mass in the form of concrete masonry or water enclosed within a wall or roof pool.

There are three types of passive solar systems. In direct gain the sun's energy directly heats the thermal mass within the building. Indirect gain systems have a thermal storage wall or roof pond which stands between the sun and the living space. It absorbs the heat from the sun and then radiates it into the house. Isolated gain passive solar systems use a thermal storage device that is isolated from the house. This often consists of a convective loop filled with water. Part of the loop is a solar collector. Another portion serves as a storage tank for the heated water. Isolated gain systems may also use a sun room to collect heat for redistribution through the house.

Eaves and deciduous trees on the south side of the house can help to provide cooling during the summer. Also, eliminating the windows on the western wall can help. Thermal mass is also helpful to prevent a house from heating up during the day, since it takes time for the mass to absorb and radiate its heat energy within the home. Roof ponds also aid with cooling in hot climates when the pond's surface is exposed to the night air. Using a light-colored surface in the walls which are most impacted by the sun in summer will also provide considerable cooling.

Passive solar water heaters are also available on the market that get their heat directly from solar energy. Typically, these devices are flat and slender, with the water held in coils which have been painted black for the best heat gain. They are typically more expensive than electric or gas water heaters. However, they can save users a tremendous amount of money on hot water over time.

You can purchase inexpensive passive solar house plans on the Web. You can also hire an architect to design your passive solar house for you. Some custom home designers also specialize in passive solar construction.

Passive solar has the potential to revolutionize the house market. If used in both homes and businesses, it could help to end the current global energy crisis.

Edward Mazria, "The Passive Solar Energy Book." Rodale Press, 1979.

"EERE Consumer's Guide: Passive Solar Home Guide." U.S. Department of Energy Website.