Solar Housing

Passive Solar

The U.S. Department of Energy defines passive solar design as the practice of heating, cooling, and lighting a building through the direct use of sunlight and the heat it produces through natural ventilation. Passive solar design does not involve the use of mechanical and electrical devices, such as pumps, fans, or electrical controls, to move the solar heat. Passive solar design incorporates a variety of site [Page 695]and building design techniques to maximize the benefits provided by the sun, shade, and wind, such as

• maximizing southern solar exposure by orienting homes so that the longer dimension runs east-west,
• planting deciduous trees or other vegetation along south-facing elevations in four-season climates to provide shade and reduce solar exposure during warm months,
• providing windows on south-facing elevations and selecting energy efficient windows suitable for the local climate,
• orienting windows to capture breezes during the warmer months for the best natural ventilation, and
• constructing building walls from dense materials, such as adobe, concrete, earthen plaster, bricks, and stone, that have the capacity to store heat and then release it as the surrounding temperature falls during cold months.

Passive solar design can be readily incorporated into the design of new homes and may reduce—or eliminate in some climates—the need for a central heating and cooling system, which can result in a significant savings in construction costs. Because the sun's energy is free, incorporating passive solar site and building design techniques can be an effective way to reduce ongoing energy costs in a home over time.

The incorporation of site and building design techniques to support passive solar is increasingly being required by local zoning codes and subdivision regulations in the United States. Regulations typically include provisions requiring the east-west orientation of local streets and the orientation of homes to maximize solar exposure.

Active Solar

Active solar uses specially designed boxes called solar collectors—typically located on the roof—to capture solar energy and convert it into heat that may be used to warm spaces within the home or to produce hot water. When used for space heating purposes, active solar requires the use of mechanical systems, such as pumps or fans, to distribute heat throughout the home. Most of the site and building design techniques noted for passive solar can be used to enhance the efficiency of homes with active solar systems but are not required. One exception to this rule is the practice of maximizing southern solar exposure by orienting homes so that the longer dimension runs east-west, which is essential to the effectiveness of both passive and active solar. In the case of active solar, an increased emphasis should be placed on the orientation of the home's roof planes, in addition to building walls to allow solar collectors to be mounted flush with the roof plane.

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