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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:

Building Materials - Radiation Constants
ProductRadiation 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)

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