Passive solar heating and cooling, sometimes referred to simply as passive solar design, is the process of using specific building systems to help regulate internal temperature by using the Sun's energy selectively and beneficially in an attempt to improve the energy efficiency. In these systems, the building itself or some element of it takes advantage of the natural energy characteristics of materials when exposed to the Sun. Generally these passive systems are simplistic with few moving parts, thus requiring minimal maintenance.
This engineering required to create these systems includes carefully selecting materials for the building envelope - including the building's walls, floors, roofs, windows and their glazing materials - and determining their proper orientation. Passive heating and cooling strategically captures or shades against solar radiation.
Solar heating and cooling systems take advantage of natural processes such as conduction, convection and radiation to warm or cool a building. Because of this, they require little to no external energy to function and can contribute to the energy efficiency of a home. When the Sun shines, the solar radiation heats buildings. This solar energy is converted into heat and transported by hot air or water into the building. By strategically capturing or shading against this radiation, the temperature of a home can be regulated.
Additionally, the heat gain from the solar insolation can be stored for future use. Capturing solar radiation in the winter helps to warm up the space, and shading from solar radiation in the summer cools the space. Hence, the use of insulation and thermal mass is crucial to prevent over-cooling of a space in the winter. Likewise, the use of shading technologies in combination with windows and glazing is equally important in preventing over-heating of a space in the summer.
Passive heating and cooling systems are used to avoid using air conditioning or a heater. Many of the most advanced techniques for home temperature control use passive methods to accomplish energy efficiency. There are a variety of different technologies that selectively harness or shield against the Sun's energy to heat or cool a building without using a heater or air conditioner. These technologies include operable windows, solar chimneys, solar walls, and trombe walls.
These technologies used to regulate internal space temperatures by capturing or venting heat from solar radiation. Shading technology can also be used strategically to reduce heating. By creating places where shade can be increased or decreased, the amount of solar radiation entering a space is reduced, therefore keeping the room cool without the use of an air conditioner.
These technologies can be used for a newly built structure and can also be incorporated into existing structures. Local climate is always the biggest factor when designing and implementing passive solar heating and cooling systems.
Here's an article with a more in depth discussion of architecture in passive solar heating and cooling.