Feb 28

R vs U Value

A customer recently inquired about R vs U Value, what do they mean and how do you read them.

Always eager for the opportunity to learn something I began my research.  I found this information on The Green Building Advisor that explains it well.  Happy Learning!


“R-value is a measure of a material’s resistance to heat transfer. Before 1945, resistance to heat flow was measured by referring to a material’s U-factor. The lower a material’s U-factor, the better the material is at resisting the flow of heat. Because many people assume that high numbers on a scale are “better” than low numbers, insulation manufacturers found it hard to market insulation by bragging about low U-factors. So the R-value — which is simply the inverse of U-factor — was proposed by Everett Shuman, the director of Penn State’s Building Research Institute. Since R = 1/U, the higher the R-value, the better the insulation.”

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