Passive solar

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Passive solar

For the application of passive solar technologies in buildings, see passive solar building design
Passive solar building design

Passive solar buildings aim to maintain interior thermal comfort throughout the sun's daily and annual cycles whilst reducing the requirement for HVAC....
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Passive solar technologies are means of using sunlight for useful energy without use of active mechanical systems (as contrasted to active solar

Active solar

Active solar technologies are employed to convert solar energy into usable light, heat, cause air-movement for ventilation or cooling, or store heat for future use....
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Passive solar technologies are means of using sunlight for useful energy without use of active mechanical systems (as contrasted to active solar

Active solar

Active solar technologies are employed to convert solar energy into usable light, heat, cause air-movement for ventilation or cooling, or store heat for future use....
). Such technologies convert sunlight into usable heat (water, air, thermal mass), cause air-movement for ventilating, or future use, with little use of other energy sources. A common example is a solarium

Solarium

The word ...
on the equator

Equator

The equator is the intersection of the Earth's surface with the Plane perpendicular to the Earth's rotation and containing the Earth's center of mass....
-side of a building. Passive cooling

Passive cooling

Passive cooling refers to technologies or design features used to cool buildings without power consumption, such as those technologies discussed in the Passive house project....
is the use of the same design principles to reduce summer cooling requirements.

Technologies that use a significant amount of conventional energy to power pumps or fans are active solar

Active solar

Active solar technologies are employed to convert solar energy into usable light, heat, cause air-movement for ventilation or cooling, or store heat for future use....
technologies. Some passive systems use a small amount of conventional energy to control dampers, shutters, night insulation, and other devices that enhance solar energy collection, storage, use, and reduce undesirable heat transfer

Heat transfer

Heat transfer is the transition of thermal energy or simply heat from a hotter object to a cooler object . When an object or fluid is at a different temperature than its thermodynamic system or another object, transfer of thermal energy, also known as heat transfer, or heat exchange, occurs in such a way that the body and the surround...
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Passive solar technologies include direct and indirect solar gain

Solar gain

Solar gain refers to the increase in temperature in a space, object or structure that results from Solar energy. The amount of solar gain increases with the strength of the sun, and with the ability of any intervening material to Transmittance or resist the radiation....
for space heating, solar water heating

Solar hot water

Solar hot water is water heated by the use of solar energy.Solar heating systems are generally composed of solar Solar thermal energy collectors, a fluid system to move the heat from the collector to its point of usage....
systems based on the thermosiphon

Thermosiphon

Thermosiphon refers to a method of passive heat exchange based on natural convection which circulates liquid in a vertical closed-loop circuit without requiring a conventional pump....
, use of thermal mass

Thermal mass

Thermal mass is the capacity of a body to store heat, and is calculated as the product of mass the body and the specific heat capacity for the material , and typically is measured in units of J/?C or J/K ....
and phase-change materials

Phase Change Material

A phase change material is a substance with a high heat of fusion which, melting and solidifying at a certain temperature, is capable of storing and releasing large amounts of energy....
for slowing indoor air temperature swings, solar cooker

Solar cooker

A solar oven or solar cooker is a device which uses sunlight as its energy source. Because they use no fuel and they cost nothing to run, humanitarian organizations are promoting their use worldwide to help slow deforestation and desertification, caused by using wood as fuel for cooking....
s, the solar chimney

Solar chimney

A solar chimney ? often referred to as a thermal chimney ? is a way of improving the natural Ventilation of buildings by using convection of air heated by passive solar energy....
for enhancing natural ventilation, and earth sheltering

Earth sheltering

Earth sheltering is the architectural practice of using soil against building walls for external thermal mass, to reduce heat loss, and to easily maintain a steady indoor air temperature....
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More widely, passive solar technologies include the solar furnace

Solar furnace

A solar furnace is a structure used to harness the rays of the sun in order to produce high temperatures, usually for industry. This is achieved using a curved mirror that acts as a parabolic reflector, concentrating light onto a Focus ....
and solar forge

Solar forge

A solar forge is a device that uses the power of the sun to melt materials, such as asphalt. A large Fresnel lens, usually rectangular and several feet long on each side, is positioned as a lid of a hollow standing cylinder ....
, but these typically require some external energy for aligning their concentrating mirrors or receivers, and historically have not proven to be practical or cost effective for wide-spread use. 'Low-grade' energy needs, such as space and water heating, have proven, over time, to be better applications for passive use of solar energy.

Advantages and comparisons to active solar

Passive solar systems have little to no operating costs, often have low maintenance costs, and emit no greenhouse gases in operation. They do, however, need to be optimized to yield the best performance and economics. Energy conservation

Energy conservation

Energy conservation is the practice of decreasing the quantity of energy used. It may be achieved through efficient energy use, in which case energy use is decreased while achieving a similar outcome, or by reduced consumption of energy services....
reduces the needed size of any renewable or conventional energy system, and greatly enhances the economics, so it must be performed first. Passive solar technologies often yield high solar savings fraction

Solar savings fraction

In discussing solar energy, the solar savings fraction or solar fraction is the amount of energy provided by the solar technology divided by the total energy required....
s, especially for space heating; when combined with active solar technologies or photovoltaics

Photovoltaics

Photovoltaics is the field of technology and research related to the application of solar cells for energy by converting sunlight directly into electricity....
(for example, to power pumps or fans), even higher conventional energy savings can be achieved.

Passive solar

Advantages and comparisons to active solar

See also

External links