Formula and example
How it is calculated
Heat flow = λ × A × ΔT ÷ d; thermal resistance per unit area = d/λ
Worked example
λ = 0.04 W/(m·K), an area of 10 m², a thickness of 10 cm and a temperature difference of 20 K give 80 W.
Things to check
- The result covers one layer. A complete wall also requires the other materials and heat transfer at both surfaces.
- A negative sign indicates heat flow opposite to the direction defined by the chosen temperature difference.