Understanding Energy-Efficient Windows: Energy Efficiency Ratings
Next generation replacement windows have a long list of energy efficiency ratings. Evaluate these ratings before selecting replacement windows for your home. The following rating overview will allow you to make a more cost-effective decision.
- R-Value: This rating reflects the insulation’s ability to resist heat transfer. A greater R-value translates into superior heat resistance. As a result, you should always consider a product’s R-Value when selecting insulation for the home. Installing high R-value insulation in attics, behind garage doors, and within walls can help to significantly reduce heat transfer indoors. This reduction in heat transfer also helps your HVAC unit run more efficiently.
- U-Factor: U-factor, like R-value, is a measure of heat transfer. However, U-Factor specifically measures the heat flow resistance of a window. Originally utilized by the National Fenestration Rating Council, U-factor ratings make it easy to locate a high-quality window. Low U-factor scores reflect greater resistance to heat transfer. For example, the most energy-efficient windows are given U-factors between 0.30 and 0.15.
- SHGC: Solar Heat Gain Coefficient is another energy efficiency rating designed by the National Fenestration Rating Council. This rating represents the fraction of solar radiation allowed through a window pane. Expressed on a scale of 0 to 1, low SHGC ratings are given to windows that admit a small fraction of radiation into the home. EnergyStar.gov recommends windows with SHGC of 0.40 or less for homes in temperate climates. Conversely, homes in hotter climates require windows with SHGC ratings below 0.27.
- VT: Homeowners looking for maximum energy efficiency should also be aware of visible transmittance ratings. After all, the best windows allow in maximum visible light without harmful UV radiation. Similar to SHGC, VT is a fraction of visible light that passes through window panes. Look for a window with a high VT rating if you want to take advantage of natural light in your home.
First Choice Windows is your number one choice in energy-efficient doors and windows. Our customer-first attitude helps us meet a diverse set of client needs. Contact us at (203) 987-3131 to learn more.
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