Efficient Windows

Characteristics of Energy Efficient Windows

For a highly efficient window that will meet both the 2009 IECC and 2012 IECC in all Texas climate zones, we recommend selecting a window with no more than 0.35 U-Factor and no more than 0.25 Solar Heat Gain Coefficient.

An energy efficient window in Texas is a window that reduces heat exchange, particularly the solar heat gain. Solar heat on windows is the biggest contributor to costly air conditioning bills. Energy efficient windows in Texas should have a solar heat gain coefficient (SHGC) of no more than 0.30, although SHGC values of 0.25 and lower are preferable.

What is solar heat gain coefficient?

SHGC is the fraction of solar heat transmitted through a window system. A window with a solar heat gain coefficient (SHGC) of 0.4 means only 40% of the heat from the sun is transmitted through the window.

How is solar heat gain reduced?

The installation of a low-E window system with a can significantly reduce solar heat gain while allowing most of the visible light to enter.

For a more detailed description of the key components of an energy efficient window system, please follow the links below:

For a more thorough description of high-performance window characteristics, we highly recommend that you visit the Efficient Windows Collaborative.

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