Yahoo Answers: Answers and Comments for How do u calculate rvalue (Measure of thermal resistence)? [Physics]
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From Eon.n.Eternity
enUS
Sun, 21 Feb 2010 20:06:45 +0000
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Yahoo Answers: Answers and Comments for How do u calculate rvalue (Measure of thermal resistence)? [Physics]
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From Anonymous: Rvalue is measured in meter²·°C/Watt (in the ...
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Sun, 21 Feb 2010 20:49:48 +0000
Rvalue is measured in meter²·°C/Watt (in the stoneage units used in the US, that's ft²·°F·h/Btu). Materials may be rated in R/inch, R/meter, etc. To calculate the Rvalue of a wall, you calculate the Rvalue of each layer by multiplying the R rating of the material times the thickness; then you add the Rvalues of the various layers. The system is not perfect. In particular it has trouble with combinations of conduction, convection and radiation barriers.