The radiant energy properties of fibrous materials may be described by an effective surface emissivity, which is a function of the material construction. The important parameters are porosity and the emissivity of the solid component. The layered construction leads to a unit cell model determining radiant heat transfer through the material to the environment. Geometric absorption cross sections are used as radiation view factors in a pseudoenclosed configuration. The emissivities are obtained by comparison to a material made from black fibers and are in qualitative agreement with experimental measurements.