Main Page | See live article | Alphabetical index Thermal resistance is the temperature difference across a unit area of a material of unit thickness when a unit of heat energy flows through it in unit time. It is the reciprocal of thermal conductance. The units of thermal resistance are, in the SI system, K.m²/W. In the building trade, the traditional non-metric R-value is sometimes used instead, with units ft² °F.h/Btu. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.