Building Materials - Radiation Constants
The radiation constant is the product between the Stefan-Boltzmann constant and the emissivity constant for a material.
The radiation constant is the product between the Stefan-Boltzmann constant - σ - and the emissivity constant - ε - of a material.
The radiation constant for some typical products:
Product | Radiation Constant (10-8 W/m2K4) | Emissivity Constant - ε - |
---|---|---|
Black body | 5.7 | 1 |
Brass, dull | 1.3 | 0.22 |
Brick, red | 5.3 | 0.93 |
Cast iron, rough oxidized | 5.1 | 0.9 |
Copper, polished | 0.28 | 0.04 |
Cotton | 4.4 | 0.77 |
Glass | 5.1 | 0.9 |
Lampblack paint | 5.5 | 0.96 |
Oil paint | 5.4 | 0.94 |
Paper | 3.1 | 0.55 |
Plaster | 5.6 | 0.98 |
Sand | 5.1 | 0.9 |
Silk | 4.3 | 0.75 |
Silver, polished | 0.17 | 0.03 |
Tin, unoxidized | 0.23 | 0.04 |
Water, 0 - 100 oC | 5.4 | 0.95 |
Wood | 5.1 | 0.9 |
Wool | 4.3 | 0.75 |
Wrought iron, dull oxidized | 5.4 | 0.9 |
Wrought iron, polished | 1.6 | 0.25 |
Zinc, tarnished | 1.4 | 0.25 |
σ = 5.6703×10-8 (W/m2K4) = 0.1714×10-8 (Btu/(h ft2 oR4)) - Stefan-Boltzmann Constant
ε = emissivity coefficient of the object (ε = 1 for a black body)