Passive Terra Heating

Happy Winter Solstice! As the sun begins it’s journey back towards the hot days of summer I wanted to share some very interesting data. Today I went out and tested the floor of the bioshelter. Insulated from the outside ground, the floor seems to be acting curiously.

Imagine the top of a 400 square foot column of earth inside the bioshelter that goes strait down 4000 miles. With nothing but tons of rubble between my feet, and the earths core, where I stand is at a consent 50 degrees all winter long! How do I know this? Because I tested it with a temperature sensor stuck in the ground (actually it’s our kitchen’s meat thermometer, don’t tell anyone).

You might call this geothermal heating of the greenhouse. Which is true, although not actively controlled like in a house or power plant, with expensive fancy technologies. No, here I am describing passive heating, what we could call earth heat, or “terraheat”

No moving parts, no complex distribution, or outside energy required (unless you count the sweat it took to dig the trenches for the insulation around the greenhouse).

Many home owners experience this natural process all the time. As most concrete basements are a constant 55 degrees in the winter, and 65 degrees in the summer. I am finding that this phenomena is much more powerful then expected. The bioshelter seems to be experiencing as much as a 10 degree F gain from the ground.

A very important effect considering our site is very shaded in the heart of winter. I wonder if other passive solar greenhouses seriously consider the influence the ground has on interior temperatures.

I’ll continue to monitor our newly discovered terreheater and let you know what happens.


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