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Off The Grid

I'm going to live off-grid. Read my blog and learn how to do it yourself!

In august, during the “Do It Yourself 2.0” workshops set up by Cohabitat, I ran a workshop in which I taught how to build a simple and affordable solar thermal collector that is suitable for domestic hot water.

Of course I made a lot of video and photos so that I could edit it all into a short video. Here’s the video. The commentary is in Polish, but below you find a translated transcript. (more…)

Passive solar energy use

Passive solar technology is simply a set of techniques for using sunlight for useful energy without the use of any active mechanical systems.  These methods convert sunlight into usable heat (passive solar heating — hot water, warm air, and heat stored in thermal mass), cause air-movement for ventilation, and store heat for future use.  Passive cooling is the use of the same design principles to reduce summer cooling requirements.

Solar design (also called solar architecture) requires a basic understanding of how the sun moves in the sky over the year, and how this movement affects the sunlight that reaches a specific location at different times in the summer in the Northern Hemisphere.  The sun rises as well as sets to the north of the east-west line, and is high overhead at noon.  In the winter, the sun is much lower at noon and rises and sets at points that are further to the south.  It is possible by taking advantage of those changes to build a house that is naturally cool in the summer and warm in the winter. (more…)

History of Solar Energy Usage

We often think that modern societies were the first to use solar energy. Not true! Early cave dwellers preferred caves that had openings facing southeasterly that allowed the morning sun to warm them up without overheating in the warm months.  Native Americans in the Southwest oriented their pueblo dwellings.  So the low winter sun would keep the buildings by direct solar radiation, cliffs and overhangs blocked the sun during the summer months, helping to keep the dwellings cooler when the sun was high in the sky.

The ancient Greeks, with a climate that was sunny almost year-round, built their houses to take advantage of the sun’s rays during the moderately cool winters and to avoid the sun’s heat during the summer.  Modern excavations of many classic Greek cities show that individual homes were oriented towards the South and entire cities were planned to allow equal access to the winter sun.  It is interesting to note that by 500 B.C., when the Greeks had almost completely deforested their whole country and needed to find a reliable alternative fuel source, they chose solar energy. (more…)

What is solar energy

Solar energy is a term that refers to the direct use of sunlight to produce heat or electric power.  The sun’s energy is plentiful, but it is thinly distributed over a large area. It must be collected and concentrated in order to produce usable power. The amount of solar radiation per unit of flat area is above 1,000 Watts per square meter.

Heat used in a solar thermal system is guided by five basic principles: heat gain; heat transfer; heat storage; heat transport; and heat insulation. Here, heat is the measure of the amount of thermal energy an object contains and is the product of temperature and mass. The higher the temperature of a substance, the more heat it absorbed. Of course, some materials require more heat to become warmer than others — this is caused by differences in so called specific heat of substances. (more…)

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