HOM: incidence-angle-dependent window transmittance

What is the problem? Currently the transmitted solar radiation through window surfaces is only taken into account with the use of the solar heat gain coefficient g=0.789 without consideration of the incidence-angle-dependent window properties according to ASHRAE 140.

How do we want to solve it? Describe the solution you'd like

Use the angle of incidence (AOI) and the index of refraction of glass (INDRG) to calculate to window transmittance at different incidence angles.