How is Solar Energy used?

Part 1 Passive Use of Solar Energy

Solar Energy Part 2: Active

How is Solar Energy used? Important question, since it is the main source of any energy on this planet.

The sun shines more or less depending on your geographical location. And there is more than one way to collect and use the solar energy.

On the one hand, Solar Energy can be used passively.

1940 M.I.T. Solar House #1 Cambridge, MA. Courtesy

For example, a building is built in a way that as much sunlight as possible can enter, so less electricity is needed. Also the house can be built so the sun can be used to warm up the house.

Passive Solar energy is used since humankind began erecting buildings

The Greek and the Chinese are known to have oriented their buildings to the south to catch the light and warmth.

The Romans actually had a "right to light".

In the Middle Ages there was competition in Europe between the Bishops who was building the Cathedral catching the most light. The erection took generations, so the bishop who started the project never lived to see the final building.

The famous Cathedral of Chartes in France is a result of the competition with Notre-Dame in Paris.

West facade of Notre-Dame de Chartres
©Atlant

The "battle" between Bishops and masons was so intense that cathedrals were rebuilt several times to keep up with the newer - lighter -cathedrals

So from ancient times on buildings were erected according to the sun's position and built in a way that the sunlight is used optimally for using and storing the energy passively and being light.

Also there are system for passively heating up water by sunlight to save heating energy. In ancient times with warm climate it was enough to let the water heat up in the sun

Direct solar water heating systems. (A) passive; (B) active
Courtesy Jwhferguson/wikimedia

Today modern technology helps to passively heat up water even in colder climates using a collector.

The technology for building solar optimized buildings improved dramatically in the last decades, from the first MIT solar house from 1940 to modern low energy houses.

These buidlings use computers to optimize solar lighting, heating and ventilation systems in an sophisticated package.

©Creative Commons, Jeff Kubina

The most modern, ultra-low energy buildings are called "Passive House" and need no or nearly no additional energy. Ideally no extra heating system is installed.

Around the world there are about 20.000 passive houses, mostly in Europe.

Solar Energy Part 2: Active

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