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Energy Star Windows: What Does the Rating Mean?

Although you have likely heard the term used before, many homeowners remain in the dark as to what choosing Energy Star windows truly entails. A joint effort of the EPA and US Department of Energy, an Energy Star rating can be given to a variety of products, ranging from kitchen appliances to siding, and use of these products can even earn you tax credits. Energy Star windows are rated on two features: U-Factor, which is a measure of how well it insulates heat, and SHGC, which is a measure of the fraction of incident solar radiation, basically meaning how much sunlight it lets through. Both are rated on a scalEnergy Star Windows - Energy Star Logoe of zero to one, with zero meaning 100% effective and one meaning it does not insulate or protect at all.

Some of the features that make Energy Star windows more efficient and affect these ratings include:

  • Low-E Glass
  • Better Materials for Frames
  • Gas Fills
  • More than One Pane of Glass
  • Steel, Foam, Fiberglass, and Vinyl Warm Edge Spacers

When you’re choosing Energy Star windows, it’s important to recognize that the criteria for Energy Star products vary throughout the four US climate zones. Florida is classified in the “Southern” zone, and our energy needs are “mostly cooling.” What this classification means is that our Energy Star windows must be extremely adept at cooling, but they may not necessarily be fit for use in Northern states, which also require protection from winter weather. For replacement windows to have an Energy Star rating in Florida, they must have a U-Factor of no greater than 0.65 and an SHGC of no more than 0.40, meaning they must provide substantial protection against solar radiation, but they do not have to be especially effective at keeping heat in the home. These requirements are in contrast with those for Energy Star windows in the Northern climate zone, which necessitate a U-Factor of no greater than 0.35 and can have any SHGC, meaning they must provide exceptional insulation of heat, but they can let any amount of solar radiation through.

For more information about Energy Star windows, or to order for your project in Tampa, Orlando, Naples, or any other city in Florida, e-mail or call Home-Pro today at 1-800-789-6653. We’ll be happy to serve you with a large selection and extremely fast, professional service.
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