Showing posts with label passive solar energy. Show all posts
Showing posts with label passive solar energy. Show all posts

Friday, May 9, 2008

Passive Solar Energy Designs


Here are a few video clips which show how to take maximum advantage of the sun's light and heat using passive solar energy designs:

Thursday, May 1, 2008

Passive Solar, Active Solar and Photovoltaics


There are three different ways to harness the sun's energy: passive solar, using architectural design and natural materials to absorb the sun's energy; active solar, utilizing the sun's heat by means of solar collectors; and a third way in which solar energy can be harnessed is through the use of photovoltaic systems.

Passive solar is the capturing and storing the suns' energy - light and heat - without the use of any mechanical devices. As the solar radiation strikes windows, walls, floors, and other objects within the room it is converted to heat. A good example of a passive solar energy system is a greenhouse.

Active solar uses devices to collect, store, and circulate heat produced from solar energy. Active solar energy technologies convert sunlight into heat by using a particular energy transfer fluid. This is most often water or air but can also be a variety of other substances.

Photovoltaic systems directly convert sunlight into electricity using a semiconductor material such as silicon. The electrical energy from PVs can be stored in batteries for use when there is no sun (during cloudy days or at night).

Thursday, April 24, 2008

Solar Energy and the Ancient World


Cliff Palace at Mesa Verde (Anasazi Indians)

Energy from the sun has been used by people for centuries. As early as the 7th century B.C., ancient people used simple magnifying glasses to concentrate the light of the sun into beams so hot they would cause wood to catch fire. The Greeks and Romans use magnifying glasses to burn the sails of enemy ships. It was first applied to use in 212 B.C., by the Greek scientist Archimedes. Solar energy was used to defend the harbour of Syracuse (Sicily) against the Roman fleet. Archimedes used a mirror or "burning mirror" as they had called it, to set fire to Rome's wooden ships while standing on shore.

From ancient time people have also used solar energy for drying, cooking, heating baths and warming their homes. Without electricity, mankind learned to orient their buildings to capture the heat of the sun during the day.

The Greeks were the first to use solar architecture, over 2,000 years ago. They learned to build their houses to take maximum advantage of the solar energy. The sun's rays entered their homes during the winter, but weren't able to enter during the summer. There were entire cities built this way. The Romans, Egyptians, Chinese, and Native Americans also warmed their homes through passive solar energy designs. Anasazi Indians build cliff dwellings with southern exposures, providing passive solar heating and cooling.

The Romans first of all put glass in windows, which allowed the sun's light to pass through but trapped its heat. They even built glass greenhouses so they could have fresh fruits and vegetables all winter.