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A measure of the capacity of a material, such as insulation, to impede heat flow, with increasing values indicating a greater capacity. Also called R-factor.

[r(esistance) value.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(ˈɑrˌvæl yu)

a measure of the resistance of an insulating or building material to heat flow, expressed as R-11, R-20, and so on; the higher the number, the greater the resistance to heat flow. Compare U-value.
[1945–50; R, symbol for resistance]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
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The R-value of closed-cell spray foam elevates the value of the system, even if batts must be slightly compressed to fit in the framing cavity.
The product is available in a standard size, approximately 48 x 90 in., or custom lengths, and thicknesses of about 2 to 4 inches, netting up to 35 R-value.
r-value is a Pearson product-moment correlation coefficient.
At this point, there was strong positive Pearson correlation between glucose and insulin with positive r-value (r-value 0.851, p-value 0.032).
A unique property of Kanacrete is its engineered built-in thermal resistance, R-Value, within the panels.
Study done by Sunita Neupane and colleagues showed that serum uric acid concentration corresponds conclusively with Urinary Albumin Excretion (UAE) with an r-value of 0.323, and Pvalue less than 0.05.
The R-value on the top of the roof sheathing compared to the R-value on the underside of the roof sheathing, and the ratio changes based on climate severity.
Many quality attributes have been utilized to classify pork, e.g.: only [pH.sub.45min] (BENDALL and SWATLAND, 1988); [pH.sub.45min] and R-value (HONIKEL & FISHER, 1977); only lightness ([L.sup.*]) (MAGANHINI et al., 2007); pH at 24h post mortem ([pH.sub.24h]), [L.sup.*] and water-holding capacity (WHC), measured by percentage drip loss (PDL) (WARNER et al., 1997) or filter-paper wetness (FPW) (FAUCITANO et al., 2010); only [L.sup.*] and PDL (KAUFFMAN et al., 1993); and only [L.sup.*] and FPW (WARNER et al., 1993).
Federal Trade Commission (FTC) is calling for comment on the overall costs, benefits, necessity and regulatory/economic impacts of the commission's Trade Regulation Rule Concerning the Labeling and Advertising of Home Insulation, which is commonly referred to as the "R-value Rule."
Additionally, their R-value is very low, making frost build-up a potential problem.