Energy Efficient Windows

For your replacement window, Seattle Glass Doctor suggests using ENERGY STAR® or higher rated windows to reduce your energy bills by 7 to 15 percent (according to ENERGY STAR's website).

Not only that, but replacing your Seattle windows with energy efficient glass fixtures lowers your carbon footprint with less energy use and fewer emissions. As a bonus, ENERGY STAR rated windows can get you up to $200 in a federal tax credit.

To be an ENERGY STAR rated window, your replacement window requires:

  • U-Factor less than or equal to 0.30 or 0.32 Solar Heat Gain Coefficient (SHGC) of greater than or equal to 0.40
  • South-facing Western Washington windows ideally have a higher solar heat gain coefficient (SHGC) and a lower U-factor in order to decrease heat loss.
  • East and West (West especially due to summer sun) facing windows should be shaded or have a lower SHGC
  • Windows facing the North get little direct sun, making SHGC of less importance. A low U-factor is ideal for North windows to lower heat loss.


  • As a government backed program, ENERGY STAR assist home and business owners with using energy efficient products to protect the environment.
  • The Environmental Protection Agency (EPA) founded ENERGY STAR in 1992 as a way to label products as energy efficient, and in turn lower greenhouse gas emissions. Glass Doctor® of Seattle partners with ENERGY STAR for Seattle windows and the window replacement Seattle residents demand for responsible energy use.
  • The ENERGY STAR label applies to qualified appliances, lighting, electronics, office equipment, doors and windows. The EPA has now extended the program to new homes and commercial buildings.
  • Almost every replacement window Glass Doctor of Seattle sells meets the ENERGY STAR guidelines with Low-E insulated glass. We are committed to testing, educating customers, labeling, public outreach and training - all as part of our commitment to ENERGY STAR.


  • U.S. residents have saved over $16 billion on utility bills, and cut their greenhouse gas emissions by an amount that would be produced by 27 million vehicles.
  • A typical homeowner can save up to 30 percent (or $600 annually) with ENERGY STAR qualified products. This is in addition to the increased comfort and environmental benefits.

Remember the basics: window shade in the summer and heat gain in the winter do a lot to lower a home's energy use and costs. Properly sized roof overhangs can also contribute to conservation. Ideally, more windows will face the South, and fewer will face the West.

For more information about window glass, Glass Doctor of Seattle will be happy to speak with you directly.

Source: U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy: A Consumer’s Guide to Energy Efficiency and Renewable Energy, 2005.