Understand, the clay wall is thermal mass, and the two layer plastic is the insulation.

The clay wall is usable anywhere, like the water barrels. They use this in Arizona for Earth ship houses. In the summer, the thermal mass is curtained with white curtains; to control the temperature.

The wallipini just accesses the heat that is present underground. Here it can be used to lower the temperature, as it remains about 60 degrees.

Here the frost line is 18" deep.

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