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Solar architecture

Megaron house
Sunlight has influenced building design since the beginning of architectural history. Advanced solar architecture methods were first employed by Ancient Greeks and in Ancient Chinese, who oriented and planned their buildings toward the sun to provide light and warmth. The Megaron House* in XIX century discovered by archaeologists in central Greece at Sesclo, was built more than 4000 BCE and - is a classic example of passive solar design.

*The Megaron house, or "Great hall" house was a large rectangular room with fire in the middle, sometimes with a curved apse at one end and with a porch at the other end.

The common features of passive solar architecture are orientation relative to the Sun, compact proportion (a low surface area to volume ratio), selective shading (overhangs) and collecting and storage inertia heat by thermal mass. When these features are tailored to the local climate and environment they can produce well-lit spaces that stay in a comfortable temperature range.
The most recent approaches to solar design use computer modeling matching together solar lighting, heating and ventilation systems in an integrated solar design package.
Solar power technologies and Active solar equipment such as pumps, fans and switchable windows are as complementary for passive solar building design techniques and improve overall building system performance.

Passive solar techniques of building design

Solar energy collection and utilization systems in the houses that do not use external energy are classified as passive solar technologies. Passive solar technologies are means of using sun-light and sun-heat for useful energy in the building without use of active mechanical systems. Passive solar buildings aim are to maintain interior thermal comfort throughout the sun's daily and annual cycles whilst reducing the requirement for active heating and cooling systems. Passive solar building design is important part of green building design.

Passive solar technologies include:
  • direct and indirect solar gain for interior building space heating,
  • solar facades;
  • solar water heating (solar thermal) systems;
  • use of thermal mass (for ex. solar walls) and phase-change materials* for slowing indoor air temperature swings;
     *A phase change material (PCM) 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. Heat is absorbed or released when the material changes from solid to liquid and vice versa; Thus, PCMs are classified as “latent heat” storage (LHS) units to Organic PCMs (Paraffin, Fatty acids), Inorganic (Salt hydrates) and them mixes.
  • solar cookers;
  • the solar chimney or thermal chimney for enhancing natural ventilation - a way of improving the natural ventilation of buildings by using convection of air heated by sun (has been in use for centuries, particularly in the Middle east, as well as by the Romans);
  • solarium on the south-side of a buildings
  • passive cooling and ventilation is the use to reduce energy consumption during summer cooling and ventilation, as well as night air natural cooling;
  • other technologies convert sunlight into usable heat (water, air, thermal mass), or collecting energy for future use, without or with little use of other energy sources;
Active solar technologies for buildings

Active solar technologies for buildings are employed to convert solar energy into usable electricity, light, heat, cause air-movement for ventilation or cooling, or store heat for future use.
Active solar technologies uses electrical or mechanical equipment, such as photovoltaic arrays, pumps and fans, solar thermal collectors, solar thermal absorption cooling equipments to increase the usable energy and heat in the ordinary building systems. Active photovoltaic and solar-thermal systems, via small pumps, fans with PV supports, can have significantly higher solar savings fractions than passive solar technologies due to enhanced own energy generation and short inner energy transfer. An interesting hybrid approach is to use photovoltaic’s to power directly pumps, fans, hot water boilers or DC (direct current) appliances as a escape lights, LED lights, halogen lights, UPS or other battery chargers, etc..Active solar is also renewable.
A computer analysis, using thermodynamics and heat transfer software, can be used to compare the performance of various active and passive solar thermal strategies.
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