Article #101 - How Do I Find the SHGC for my Windows?
The solar heat gain coefficient (SHGC) for your window may be found on the National Fenestration Rating Council (NFRC) label affixed by the window manufacturer prior to sale.
Most residential windows are rated by the National Fenestration Rating Council (NFRC), and most new residential windows should have an NFRC label. If your window does not have a label (either because the window has not been rated or because the label has been removed), you can either ask the window manufacturer to supply you with this information or look for your specific window in the NFRC products directory at the
National Fenestration Rating Council
website.
You may also be able to calculate the SHGC for your window if you have literature from the manufacturer indicating the shading coefficient (SC) value for the window.
The relationship between SHGC and SC is as follows: SHGC = SC*0.87.