W/(m²·K)
watt per square meter kelvin
Heat transfer coefficientexact by definition
The watt per square metre kelvin is the SI unit of the heat transfer coefficient, the h in Newton's law of cooling and the U in the building equation Q = UAΔT: the heat crossing one square metre per kelvin of driving temperature difference. It is the coherent SI combination and its factor of 1 is exact. It is also the reciprocal of RSI.
Watch out: The film coefficient h and the overall coefficient U share this unit but are not the same thing. U bundles the two surface films and every layer in between; h describes one surface alone. Still air gives about 8 W/(m²·K), forced air 25 to 100, flowing water 500 to 10 000, and condensing steam 5000 to 15 000.
| 1 W/(m²·K) | 1 W/(m²·K) |
Solvers that use heat transfer coefficient