Standard Test Methods for Optical Properties

There are numerous international standards related to optical properties of glazing and shading by ISO, CEN and ASTM. There are also national standards in many countries. In the U.S. we continue to refer to NFRC technical documents at least until efforts at harmonization are successful.  These standards duplicate each other in many cases and reference each other in a complicated way. Here is an attempt to explain the current state of affairs:

• solar optical properties of specular materials
  
• infrared optical properties (emittance) of specular and diffusing materials
  
• solar optical properties of diffuse materials and shading systems