Heat-mirror coatings are important as transparent insulation for a host of applications, including building window glazings. They reduce thermal emittance of glass and polymeric substrates, thereby decreasing the effective radiative loss of a glazing or window assembly.Properties of coa~ings and substrates, as well as various window designs, are detailed. The paper reviews heat-mirror deposition technology including chemical vapor deposition using hydrolysis and pyrolysis reactions, DC and RF sputtering using reactive, biased, and nonreactive techniques, In the moaels shown in Figs. 3-5 only generalized reflections are 15 detailed. A more exact study has been cone recently.All surfaces should exhibit a finite reflectance. One also expects partial transparency of some substrates over 2-5 microns. In addition, to complete the models the effects of convective and conductive heat• ~