# Thermal emittance

Thermal emittance or thermal emissivity (${\displaystyle \varepsilon }$) is the ratio of the radiant emittance of heat of a specific object or surface to that of a standard black body. Emissivity and emittivity are both dimensionless quantities given in the range of 0 to 1, representing the comparative/relative emittance with respect to a blackbody operating in similar conditions, but emissivity refers to a material property (of a homogeneous material), while emittivity refers to specific samples or objects.[1][2]
1. ^ a b Eco-efficient materials for mitigating building cooling needs : design, properties and applications. Pacheco-Torgal, F., Alchapar, N. L. Amsterdam [Netherlands]. ISBN 978-1-78242-401-7. OCLC 905919280.{{cite book}}: CS1 maint: others (link)