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Heat transfer through soil

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bjomor

Mechanical
Joined
Jan 17, 2009
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Im trying to understand the heat model of a house. This is a geodesic dome 20 m in diameter, shaped like half a sphere. Most of the ground inside will be left as dirt/lawn, some will have concrete on top. This is in the tropics but near the mountains, so the temperature varies some. Summer days 35 C / nights 20 C, winter days 25 C / nights 5 C. I want to try have an inner temperature around 25 C, but keep my heating/cooling bill as low as possible.

My idea is to use steel bars for the dome, with 10 cm thick EPS foam sheets covering the entire outside save a few windows, and then cover it all with 0.5 mm painted Aluminum sheet. The purpose of the aluminum is to reflect away heat radiation from the sun and protect from rain etc. The EPS will give insulation against conduction/convection. Is the idea correct?

The hard part for me to understand is how the earth/soil ground of the dome will affect the air temperature inside. The soil has some thermal mass, so I hope it will act as a “buffer” releasing heat in the night and absorbing heat in the day. Or will this benefit get lost because heat is quickly transferred to/from adjacent outside areas?

Im trying to understand if the ground inside the dome will help me even out the temperature, or if the ground will counteract so I would better off putting EPS foam on the ground too. What is the rule of thumb for earth/soil?

Thanks in advance for any tips.

 
The ground, at depth, inside should look like a heat sink at a a roughly constant value.

TTFN

FAQ731-376
 
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