Code Requirements

Beginning November 1, 2016, the 2015 International Energy Conservation Code (IECC) went into effect for all construction other than single-family homes. And on September 1, 2016, the 2015 International Residential Code went into effect for one- and two-family homes and low-rise multifamily buildings. The 2015 IECC requirements are presented in the table below or click here for a two page guide to window requirements under the 2015 IECC.

Climate Zones/Packages for Texas IECC Code Compliance

2015 IECC Solar Heat Gain Coefficient (SHGC) and U-factor Requirements in Texas

Solar Heat Gain Coefficient (SHGC)

Texas currently requires a maximum 0.25 solar heat gain coefficient (SHGC) for windows, glazed doors and skylights in all construction in climate zones 2 and 3, and a 0.40 SHGC in climate zone 4. This is true of both new construction and remodeling projects. Builders can incorporate future energy requirements in today’s buildings, providing a good head start on saving homeowners money in energy bills.


U-factor requirements also improved significantly in the 2015 IECC. While low U-factor windows are important in all climate zones, low U-factors are particularly important where buildings are heated more often (as in climate zones 3-4).

Air Leakage

The code requires that residential windows be labeled to show that they meet the IECC's air infiltration requirements of less than or equal to 0.30 cfm per square foot of window area.