When selecting window products for a client, builders and architects must be sensitive to both the requirements laid out by state and local building energy codes and the window preferences of the customer.
Depending on the type of construction, Texas law currently requires residential buildings to meet the 2015 International Energy Conservation Code (IECC) or the 2015 International Residential Code (IRC). Both codes specify maximum prescriptive SHGCs and U-factors by climate code.
The National Fenestration Rating Council (NFRC) is an international coalition that administers testing, certification and labeling of windows, skylights and doors. NFRC sets energy test standards, administers ratings by independent labs and provides builders, retailers and consumers reliably compare one product to another through the NFRC energy performance label. The energy code generally requires use of NFRC ratings to determine code compliance or use of a limited default table.
For an excellent overview of Selecting Energy Efficient Windows in Texas, consult the Efficient Window Collaborative's Texas Factsheet.