Passive solar technology is the use of special siting, design, or building materials that take advantage of the sun’s position and availability to provide direct heating or lighting. Passive solar systems also take into account the need for shading devices to protect buildings from excessive heat from the sun.
Design is the primary difference between a passive solar home and a conventional home. Passive solar homes and buildings are specifically designed to take advantage of natural sunlight and heat. Passive solar design uses a building’s windows, walls, and floors to collect, store, and distribute solar energy in the form of heat. Conversely, in the summer, passive solar design rejects heat. For example, buildings designed for passive solar heating usually have large south-facing windows (the south face receives the most sunlight). Materials that absorb and store the sun’s heat can be built into the sunlit floors and walls, which will then absorb heat during the day and slowly release the heat at night.
Roof overhangs, awnings, and landscaping are other elements that may be incorporated into passive solar designs.
Daylighting is the use of natural sunlight to illuminate a building’s interior. High-efficiency windows and skylights that optimize the use of natural light can replace artificial electrical lighting and significantly reduced energy consumption.
The best way to incorporate daylighting into a home depends on the home’s climate and design. South-facing windows are most advantageous for daylighting and moderating seasonal temperatures. They allow most winter sunlight into the home but, when properly shaded, little direct sun during the summer.
Skylights are roof coverings that admit natural light. Energy-efficient skylights help minimize heating, cooling, and lighting costs. Glazing, operation and use, and shape all determine a skylight’s energy efficiency. High performance skylights incorporate reflectors or prismatic lenses to help offset heat gain during peak daylight hours.
Unlike standard framed-in skylights, tubular skylights do not contribute to heat loss or gain because they are smaller and better installed. Tubular skylights have a small, clear dome on the roof that allows sunlight to enter a highly reflective tube. This tube guides the sunlight to the ceiling. A translucent diffuser lens then disperses the natural light throughout the interior space. Commercial scale tubular skylight systems are also available and are sometimes tied to lighting controls.