The applications of passive solar energy are varied and plentiful. From simple tasks like heating a room or boiling a pot of water, all the way up to more complex applications like providing a building’s entire heating, cooling, and lighting needs. A common use of passive solar energy is in heating.
Passive solar heating captures the sun's energy and converts it into heat, while passive solar cooling reflects the sun's energy away from a home or building. Both passive solar heating and passive solar cooling can improve the energy efficiency of a home or building, but they are not typically used together.
Solar heating is considered passive when the building design and materials capture and store heat from the sun without the need for mechanical systems or external power sources. Warmer air has more energy than cooler air and moves to the place where there is less energy (i.e. cooler rooms). This natural process can be improved through the use of passive design elements, such as thermal mass and insulation. However, the use of fans and blowers to circulate the heated air would be considered active solar heating.
Passive solar design can reduce heating and cooling energy bills, increase spatial vitality, and improve comfort. Inherently flexible passive solar design principles typically accrue energy benefits with low main-tenance risks over the life of the building.
In this type of passive solar technology, sunlight is directly captured and used as heat energy. An ideal example would be the use of large sun-facing windows in buildings, which allow light (and therefore, heat) to penetrate and warm the interior directly.
The sun's energy is captured by an aperture, such as a window and then transferred to the thermal mass. The heat from the thermal mass is then distributed to the rest of the home or building through pipes. Isolated gain Passive Solar Heating is most effective in climates that are not too hot or too cold.