Thermal resistance
Thermal resistance is
- 1) the temperature difference across the structure when a unit of heat energy flows through it in unit time or
- 2) 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, in first meaning K/W and second meaning K·m²/W (see closer two different definitions general / buildings in thermal conductance). In the building trade in the USA, the traditional non-metric R-value is sometimes used instead, with units ft² °F·h/Btu.
