R-value
[ ahr-val-yoo ]
/ ˈɑrˌvæl yu /
noun
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.
Origin of R-value
1945–50;
R, symbol for
resistance