R-value
noun
: a measure of resistance to the flow of heat through a given thickness of a material (such as insulation) with higher numbers indicating better insulating properties compare u-value
Examples of R-value in a Sentence
Recent Examples on the Web
Most experts agree the R-value of attic insulation should be at least R-30 (R-38 is preferable in northern climates).
—
Chad Murphy, The Enquirer, 2 July 2025
This backpacking-ready pad is made with reflective insulation, earning a three-season R-value of 3.2.
—Drew Zieff, Outside Online, 22 May 2025
An R-value of 5 or above is great for winter camping.
—Emily Pennington, Condé Nast Traveler, 13 Nov. 2023
Not only is that because sleeping-bag temperature ratings are self-reported by brands, thereby opening the category up to, well, lies, but that even with a best-case, accurately reported temperature rating, that number is calculated when paired with a 4.0 R-value pad.
—Wes Siler, Outside Online, 3 June 2019
Winter campers will want an R-value of 7 and above for sleeping on top of snow and in below-freezing temperatures.
—Maggie Slepian, Travel + Leisure, 11 Feb. 2025
Products like these provide, in most cases, par and above par R-values for the contractor, and that truly depends on the application on the project.
—Don Magruder, The Tennessean, 22 Sep. 2024
The walls have a thermal resistance or R-value of 80, so the homeowner benefits from energy savings on top of cost savings.
—Jennifer Castenson, Forbes, 15 Dec. 2024
The Tensor All-Season has an R-value of 5.4 and weighs just 18.2 ounces.
—Scott Gilbertson, WIRED, 29 Nov. 2024
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Chad Murphy, The Enquirer, 2 July 2025
This backpacking-ready pad is made with reflective insulation, earning a three-season R-value of 3.2.
—Drew Zieff, Outside Online, 22 May 2025
An R-value of 5 or above is great for winter camping.
—Emily Pennington, Condé Nast Traveler, 13 Nov. 2023
Not only is that because sleeping-bag temperature ratings are self-reported by brands, thereby opening the category up to, well, lies, but that even with a best-case, accurately reported temperature rating, that number is calculated when paired with a 4.0 R-value pad.
—Wes Siler, Outside Online, 3 June 2019
Winter campers will want an R-value of 7 and above for sleeping on top of snow and in below-freezing temperatures.
—Maggie Slepian, Travel + Leisure, 11 Feb. 2025
Products like these provide, in most cases, par and above par R-values for the contractor, and that truly depends on the application on the project.
—Don Magruder, The Tennessean, 22 Sep. 2024
The walls have a thermal resistance or R-value of 80, so the homeowner benefits from energy savings on top of cost savings.
—Jennifer Castenson, Forbes, 15 Dec. 2024
The Tensor All-Season has an R-value of 5.4 and weighs just 18.2 ounces.
—Scott Gilbertson, WIRED, 29 Nov. 2024
Cite this Entry
“R-value.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/R-value. Accessed 21 Jul. 2025.
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