Accurate measurements are reported of the radiative heat transfer between parallel surfaces of uncoated and doped tin oxide coated glass. The infrared properties of the tin oxide coated glass are calculated by a novel approach by fitting a three parameter Drude model to reflectance measurements at a specified angle, and over a restricted range of wavelengths. Estimates of the radiative heat transfer between uncoated and coated glass surfaces are calculated from a consideration of the directional spectral emittances and the blackbody spectrum. This procedure gives results that are in more consistent agreement with experimental measurements than results obtained by considering the hemispherical total, or directional total emittances.