Windows are among the structural components of a building that greatly influence the indoor thermal environment. Since they are largely affected by solar radiation, controlling heat radiation from window surfaces is of particular importance. The present study was performed with the recognition that, in order to calculate air- conditioning energy, the radiative component and the convective component of radiant heat must be known separately as they exhibit different heat transfer characteristics. This paper describes a heat quantity-based shading coefficient measuring apparatus capable of direct and specific measurement of the heat gain from solar radiation from the window surface. It then introduces a method for measuring the solar radiation-shading coefficient separated into a radiative and a convective component. The paper further describes the basic measuring principle of the apparatus, its calibration and its sensitivity constants relative to the long wave and short wave output of a net radiometer.
