°F·h/BTU

Fahrenheit hour per BTU

Thermal resistanceexact by definition

The Fahrenheit-hour per BTU is the customary US unit of absolute thermal resistance, equal to 1.895634 K/W. The relation is exact by definition, being the reciprocal of the exact 0.52752792631 W/K, though the decimal shown is a rounding of that exact ratio. It is the reciprocal of a UA value in BTU/(h·°F).

Watch out: Do not confuse this with the R-value of insulation, which carries an extra per-square-foot and is a different quantity type entirely. This unit is °F·h/BTU; R-value is °F·h·ft²/BTU.

1 °F·h/BTU 1.8956342 K/W