A model is presented for the calculation of transient combined radiative and conductive heat transfer in a semitransparent layer of advanced fiber polymer. This model is based on optical material properties. Different boundary conditions were examined. Each side of the layer was exposed to hot or cold radiative surroundings, whereas each boundary was heated or cooled by convection. Emission within the layer and internal reflections depended on the layer refractive index. The reflected energy and heat conduction distributed energy across the layer and partially equalized the transient temperature distributions. The numerical method is an implicit finite difference procedure with nonuniform space and time increments that has been expanded to include external convection and incident radiation. (c) 2006 Wiley Periodicals, Inc.