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ooopie
Registered Users
Posts:4
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| 05/27/2008 2:24 PM |
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I have a pretty good understanding about insulation & heat transfer etc, but I can't quite figure out how it all affects earth sheltered homes, and how to maximize the benifit of that technique. Maybe some of you could help explain...
As I understand, the deep earth provides a fairly constant temp. thermal mass, say 55 degrees. Even so, in the winter I like my house closer to 70 degrees, and would not want the earth sucking up the heat from my house. Therefore, I would want to insulate the house from the earth that is sheltering it, which seems to somewhat negate the whole idea in the first place.
I can understand how the earth keeps things cool in the summer, but would it still have that effect if it was separated from the house with lots of insulation?
Is it possible to get comfort and energy efficiency in both the summer & winter (I'm in the northeast) using earth sheltering?
Do I choose insulation or thermal mass? Can I have both?
Thanks
-Jon
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PanelCrafters
Registered Users
Posts:1277
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| 05/27/2008 5:07 PM |
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Posted By ooopie on 05/27/2008 2:24 PM
As I understand, the deep earth provides a fairly constant temp. thermal mass, say 55 degrees. Even so, in the winter I like my house closer to 70 degrees, and would not want the earth sucking up the heat from my house. Therefore, I would want to insulate the house from the earth that is sheltering it, which seems to somewhat negate the whole idea in the first place. The benefits of Earth sheltering are: The constant Earth temperture(assuming that all parts of the Earth sheltered structure are below the frost line), and the elimination of Air Infiltration. Thermal Mass plays no part in these benefits.
I can understand how the earth keeps things cool in the summer, but would it still have that effect if it was separated from the house with lots of insulation?
Is it possible to get comfort and energy efficiency in both the summer & winter (I'm in the northeast) using earth sheltering?
Do I choose insulation or thermal mass? Can I have both? Basically what Earth sheltering does, is reduce your Delta T, to lower that you would have with exposed walls. The Earth, using your example temp, is always 55°. So, you have a year round constant Delta T of 15°. Compare that to winters in the NE where the temp could be 0° and having a Delta T of 70°! Insulation or Mass? No question, Insulation! You could incorporate some interior thermal mass if there is a way to charge it(South facing windows). And, you should have only one one energy cost: Heating. Over time, with constant ground temps(and no external heating), the indoor temperature or your structure will be the ground temp(55°). No A/C needed.
Good Luck! |
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....jc
If you're not building with OSB SIPS(or ICF's), why are you building? |
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Alton
Registered Users
Posts:244
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| 05/27/2008 5:20 PM |
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ooopie,
I wrote you out a long explanation about insulation versus thermal mass for earth sheltered homes. Somehow or other I lost it before it was sent. So to be succinct, this time I will list some references with a brief explanation. Maybe your local library has the following listed book.
Earth Sheltered Housing Design, Guidelines, Examples, and References by the Underground Space Center, University of Minnesota, see pages 60 - 66 for a discussion of insulation versus thermal mass of the surrounding soil.
Just in case you can not locate this book, one conclusion was that the insulation should get thinner the deeper the walls were in the ground. This method would insulate the upper part of the wall while allowing the thermal mass of the surrounding soil to temper the lower part of the wall that was well protected by the earth.
Companies like the following also may have some good info on your question.
http://www.terra-dome.com/
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