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Minimum efficiency ratings for replacement windows in Maine


October 23, 2014

Did you know there is a minimum energy efficiency rating for replacement windows in Maine? If  you are looking for a company to sell and install an energy efficient replacement window that meets and/or exceeds Energy Star requirements, then their window needs to meet strict guidelines from Energy Star and the National Fenestration Rating Council (NFRC).

So what are the Energy Star Qualifications for replacement windows in Maine?

A U-factor of 0.30 or less (any SHGC is allowed)
OR
A U-factor of 0.31 AND an SHGC of 0.35 or more
OR
A U-factor of 0.32 AND an SHGC of 0.40 or more

If you are left-brain (like me), then here is the definitions of U-Factor and SHGC:

  • U-Factor measures the rate of heat transfer and tells you how well the window insulates. U-factor values generally range from 0.25 to 1.25 and are measured in Btu/h·ft²·°F. The lower the U-factor, the better the window insulates. When you measure the heat transfer in a window, you would review the U-Factor. R-Value is generally used in measuring the amount of insulation in walls and attics. To figure what the R-Value would be for a window, divide 1 into the U-Factor (for example: If a window has a U-Factor of .30, the R-Value of that window is 3.33)
  • Solar Heat Gain Coefficient (SHGC) measures the fraction of solar energy transmitted and tells you how well the product blocks heat caused by sunlight. SHGC is measured on a scale of 0 to 1; values typically range from 0.25 to 0.80. The lower the SHGC, the less solar heat the window transmits.

For those of you who are more right-brain, here is a video from NFRC that simply explains choices in energy efficient windows:

Renewal by Andersen replacement windows and patio doors are Energy Star qualified. Call us at 207-985-8465 or fill out the form to the right to schedule a free, in-home consultation and project quote so we can help you select the appropriate Energy Star qualified windows and doors for your home.

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