Thermal resistance (R value) of earth
Thermal resistance (R value) of earth
(OP)
Hello.. would anyone know why I could get typical R values of earth fill? I am looking into the feasability of replacing the thermal insulation of a couple feet of earth with some sort of insulation.... this would be for the roof of a buried concrete structure. We could then try to reduce the amount of earth fill on top of the structure. thanks in advance!





RE: Thermal resistance (R value) of earth
http://irc.nrc-cnrc.gc.ca/fulltext/nrcc43093/
RE: Thermal resistance (R value) of earth
RE: Thermal resistance (R value) of earth
Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.
RE: Thermal resistance (R value) of earth
www.neptune.on.ca/~geotherm
RE: Thermal resistance (R value) of earth
RE: Thermal resistance (R value) of earth
RE: Thermal resistance (R value) of earth
Rather than focusing on the "dirt", why not determine how much insulation you need and then figure out how much soil you should replace? And remember that the insulation is a lot lighter than soil, so you can create a significant reduction in dead load by using Styrofoam or similar lightweight hydrophobic closed cell material instead of soil. The reduction in the roof load alone might be enough to justify the increased construction cost.
Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.
RE: Thermal resistance (R value) of earth
RE: Thermal resistance (R value) of earth
Thermal Mass is different than heat transfer resistance. R-Value is heat transfer resistance only. Typical R-value for earth is 0.25 per inch; however, the thermal character of the soil mass is quite different than that of material designed and used primarily for heat transfer resistance (R-value) like polystyrene or fiberglass. When changing from soil to a less massive "insulating" material, you should understand the design performance with regards to heat capacity of the building and/or soil mass (K-value). A massive soil wall or roof can store heat energy to even out the temperature swings of day--lightweight insulation does not perform this way. The thermal value you get from 18-inches of soil far surpases the 4.5 R-value (0.25 per inch). Other factors such as water and vegitation can signifcantly change the performance of an earth sheltered home or building.
RE: Thermal resistance (R value) of earth
RE: Thermal resistance (R value) of earth
Most of your questions are answered in a book by John Hait, "Passive Annual Heat Storage (PAHS). Think heat flow when comparing the two. You can not just replace one with the other and get the same response (heat/storage/flow). Hope this helps.