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How to Pick Energy-Efficient Windows in Tampa, FL

According to the Department of Energy, windows are a major source of heat gain and loss. In Florida’s climate, heat gain can add approximately 25% to the cooling load of air conditioners. Replacing old windows with double- or triple-pane windows with low-E glass can lower cooling costs between 11% and 37% in your Tampa, FL home. If you are shopping for energy-efficient windows, here are things to look for.

Elements of Energy-Efficient Windows

Four elements affect a window’s energy efficiency:

  • Frame material, usually wood, vinyl, fiberglass or aluminum.
  • Glazing, such as single-, double- or triple-pane glass.
  • Gas filling and spacers.
  • Type of operation.

In warm climates like Florida’s, keeping solar heat from entering the living space is the most important factor in improving the energy efficiency of windows. Solar heat gain is expressed by the solar heat gain coefficient, which rates solar gain on a scale between 0 and 1. The lower the SHGC, the better the energy performance. Increasing the number of panes and adding coatings to glass block solar heat gain and improve energy efficiency.


Standard windows have one pane of glass, which allows the greatest transfer of heat and transmittance of light. Tinting single-pane glass reduces solar glare, has a moderate effect on heat transfer and reduces the amount of light.

Double-glazed windows have two panes of glass with an air gap between them. The spaces between the panes are usually filled with a gas that acts as a thermal insulator. Double-glazed clear glass results in a moderate reduction of heat gain compared to single-pane clear glass. Tinted double-glazed windows reduce solar heat gain by approximately 13% and reduce visible light. Low-E coatings on double-glazed windows significantly reduce solar heat gain. According to the National Fenestration Rating Council, replacing single-glazed clear glass with double-glazed clear panes can save approximately 17% on annual energy costs in southern climates.

Triple-glazed windows are made with three panes with gas fill between them. Triple-glazed windows with low-solar gain low-E coatings are up to 70% more efficient than standard double-glazed models. Although triple-glazed windows cost more, the added comfort and energy savings may make them worthwhile for your home.

When replacing windows, consider triple-glazed windows with low-E coatings with an SHGC rating of .25 or lower. This means that just 25% of solar heat is transmitted through the glass into the living space. In comparison, the SHGC value of single-glazed, tinted windows averages .73, and the SHGC of double-glazed, tinted windows averages .63. These numbers may vary depending on the manufacturing design and products.

For precise, professional window replacements and installations, call JMI Windows & Doors. We are a family-owned business with more than 22 years of service in the Tampa Bay area. We install PGT products, a leading industry manufacturer that includes generous warranties.

For more information about energy-efficient window replacements, call JMI Windows & Doors today.

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