Solar Energy & Architecture

Identification

• The simplest form of solar architecture is passive design. Most systems require very little maintenance and make little use of mechanical systems. The basic principles of passive solar design involve an understanding of solar exposure levels throughout the year, and a basic knowledge of natural energy movements like conduction and convection. Sustainable Sources, an info-site for green construction, credits passive solar design with "having been shown to produce buildings with low energy costs, reduced maintenance, and superior comfort."

Building Integrated Photovoltaics (BIPV)

• Photovoltaic panels act as solar collectors and transform raw thermal energy into electricity. The days of bulky solar panels bolted to residential rooftops are on the way out. The latest generation of solar panels are called Building Integrated Photovoltaics or BIPV. This approach to solar architecture makes solar panels an integral part of the building aesthetic. Solar power can now be drawn from an overhead awnings or the rooftop's shingles. The Whole Building Design Guide acknowledges BIPVs as saving materials and electrical costs while simultaneously adding to a building's architectural value and appeal.

Direct Gain

• As a direct result of the Earth's tilt, the south side of a building in the Northern hemisphere always receives the most sunlight. Therefore, south-facing glass windows provide the simplest form of solar heating. In direct gain systems, the thermal energy of the sun is collected by the very walls and floors of the building. Materials like concrete and substances like water are excellent collectors of thermal energy. In the heat of the day, these materials gain thermal energy through conduction and when the air cools at night, the energy is given off into the living space to naturally restore an equilibrium. According to Sustainable Sources, if one-half to two-thirds of the total interior surface area of a building is constructed of thermal storage materials, the direct gain system can make use of 60 to 75 percent of the sun's energy.

Indirect Gain

• An indirect gain system uses convection and the greenhouse effect to heat and redistribute solar energy. Instead of allowing sunlight to directly reach interior surfaces, the thermal energy is cut short just at the south-facing window. A wall of water intercepts the solar rays and the convection process radiates the thermal energy into the walls. According to Sustainable Sources, temperatures on these water walls can easily exceed 100°F.

History

• Builders have incorporated solar energy into their architecture for thousands of years. Ancient Greek cities like Priene were arranged in a south-facing pattern and utilized passive solar heating and cooling. The California Solar Center points to 5th century BC archaeological evidence from Aristotle and Socrates that proves the ancient Greek's knowledge and respect for solar architecture. The ancient Romans improved on the Greek design by covering south-facing windows with panes of glass. A 1st century BC Roman architectural writer named Vitruvius later created a building code that included winter rooms facing the southwest falling sun.