Abstract: A composite sheet material exhibiting a low emittance characteristic at both of its outer surfaces for limiting radiant heat transmission therethrough comprises one composite sheet structure including a base layer of sheet material having high strength, resistance to tearing, stability, and body, and a first layer of material having a low emittance characteristic disposed in intimate contact with one surface of the base layer. A second composite sheet structure includes a protective layer of sheet material that is generally transparent to radiant energy in the infrared range of the energy spectrum and a second layer of material having a low emittance characteristic disposed in intimate contact with one surface of the protective layer.