How to Calculate the Shading Coefficient

Windows are things that most people take for granted.
Homemade shadeHomemade shade
Glass has been around since the beginning of civilization. Archaeologists have found evidence of glass being manufactured in the Middle East as early as 3000 B. C. As the science and engineering of glass have become better understood, many advances have been made. In the late 1950s Sir Alastair Pilkington introduced the "float" glass production method, which is still used to manufacture approximately 90 percent of the glass produced today.

Step 1

Locate the National Fenestration Rating Council (NFRC) label on your window. Most new residential windows are rated by the NFRC, and should have a label.

Step 2

Note the solar heat gain coefficient (SHGC) on the label. It has replaced the shading coefficient (SC) as the standard indicator of a window's shading ability. SHGC is expressed as a number between 0 and 0.87. SC is expressed as a number between 0 and 1. You can use the following formula: SHGC = SC --- 0.87.

Step 3

Divide SHGC value by 0.87 to compute SC.

Things You Will Need

  • National Fenestration Rating Council (NFRC) label

About the Author

Yvonne Bernard began her writing career in 1994. She has written articles for “Design News” and published an engineering text book, “Environmental Engineering,” for McGraw-Hill. Bernard is also a member of several engineering societies. She has a Bachelor of Science in mechanical engineering from the University of Illinois.