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Engineering ToolBox > Radiation Constants of some common Building Materials
The radiation constant is the product between the Stefan-Boltzmann constant - σ - and the emissivity constant - ε - of the material. The radiation constant of some common materials can be found in the table below.
| Product | Radiation Constant x 10-8 | |
| W/m2 oC4 | Btu/(h ft2 oF4) | |
| Black body | 5.7 | 0.173 |
| Brass, dull | 0.152 | 0.036 |
| Brick | 5.16 | 0.156 |
| Cast iron, rough oxidized | 5.09 | 0.154 |
| Copper, polished | 0.119 | 0.028 |
| Cotton | 4.23 | 0.128 |
| Glass | 5.13 | 0.155 |
| Lamp black | 5.16 | 0.156 |
| Oil paint | 4.30 | 0.130 |
| Paper | 4.43 | 0.134 |
| Plaster | 5.16 | 0.156 |
| Sand | 4.20 | 0.127 |
| Shavings | 4.10 | 0.124 |
| Silk | 4.30 | 0.130 |
| Silver | 1.19 | 0.0046 |
| Tin | 0.26 | 0.0077 |
| Water | 3.70 | 0.112 |
| Wood | 4.17 | 0.126 |
| Wool | 4.30 | 0.130 |
| Wrought iron, dull oxidized | 5.16 | 0.156 |
| Wrought iron, polished | 1.55 | 0.047 |
| Zinc, dull | 0.152 | 0.036 |
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)