Thermal Emissivity Of Coated Glazing: The Thermes Project

Emissivity is a key property in determining the energy-saving capability of glazing. Glazing manufacturers in Europe are obliged to determine the emissivity of their coatings according to the standard EN 673. The emissivity is determined from the spectral reflectance, which until 10 years ago was normally measured using a dispersive (grating) spectrophotometer equipped with a reflectance accessory. In the 1990s, manufacturers of spectrophotometers have stopped producing these instruments and completely switched over to producing the more modern Fourier Transform (FT) version instead. However, for the purpose of the glass industry, these new instruments and their accessories proved to be generally less suitable.