How to tell if your windows are energy efficient
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ENERGY STAR qualified, windows, doors, and skylights: Show
Though ENERGY STAR does not require any specific technologies, certain product features are common in many certified products. Performance CriteriaWindows, doors and skylights protect you from the elements just like a winter coat. But like a winter coat, you should pick the windows, doors and skylights that make the most sense for your climate. While some windows, doors and skylights are better at keeping you warm, others excel at keeping you cool.
Common Product FeaturesMany ENERGY STAR certified windows, doors and skylights have some or all of the product features detailed below. But these features are not required. Learn more about what makes it ENERGY STAR. Anatomy of an Energy-Efficient WindowFraming MaterialsENERGY STAR certified windows come in a variety of framing materials.
To learn more about efficient window technologies, visit the Efficient Windows Collaborative. Anatomy of an Energy-Efficient DoorAnatomy of an Energy-Efficient SkylightWith the current emphasis on energy efficient windows, the National Fenestration Rating Council has designed an energy-performance label to guide contractors and homeowners in their search for the perfect window. Since the climates in different parts of the United States vary widely, checking the label before ordering the window can make a big difference in how much the window can help your client keep energy costs to a minimum. But what do all those numbers and codes on the
label mean? Once you know what to look for, you'll be able to find exactly the right windows. Here's a quick tour: NFRC Certified (upper left corner) indicates that the National Fenestration Ratings Council has licensed the window's manufacturer and certified the window's performance in accordance with NFRC's standards. The upper right corner identifies the window's manufacturer, model, style and the materials used in its construction. Energy Performance RatingsThe U-factor. The rate of heat loss from a building is indicated in terms of the U-factor (U-value). U-Factor ratings for windows generally fall between 0.20 and 1.20. The lower the U-value, the greater a window's resistance to heat flow and the better its insulating value. (The window's insulating value is indicated by the R-value, which is the inverse of the U-value.) The solar heat gain coefficient (SHGC) indicates how well a product blocks heat from the sun. The SHGC is the fraction of incident solar radiation admitted through a window and absorbed and subsequently released inward. SHGC is expressed as a number between 0 and 1. Again, the lower the number, the better: A low SHGC means the window transmits less solar heat. Additional Performance RatingsVisible transmittance is an optical property that indicates the amount of visible light transmitted. VT is expressed as a number between 0 and 1. The higher the VT, the more light is transmitted. Air leakage* is expressed as the equivalent cubic feet of air passing through a square foot of window area (cfm/sq. ft). Heat loss and gain occur by infiltration through cracks in the window assembly. The lower the AL, the less air will pass through cracks in the window assembly. Condensation resistance* measures the ability of a product to resist the formation of condensation on the interior surface of that product. The higher the CR rating, the better that product is at resisting condensation formation. While this rating cannot predict condensation, it can provide a credible method of comparing the potential of various products for condensation formation. CR is expressed as a number between 0 and 100. For more information on NFRC ratings, visit the organization's website at www.nfrc.org. * This rating is optional and manufacturers can choose not to include it. How do you test windows for heat loss?The Antiquated Candle Test: If you have a candle around, light it and hold it up to a closed door or window—not too far away and not too close. If the candle flame flickers and sputters, that's bad news; if the candle goes out, the news is far worse… You need a new door.
What type of windows are most energy efficient?Window Style
In terms of operable windows, hinged-sash windows such as casement and awning windows are typically the most energy efficient as they create a firm weathertight seal when closed.
How do I know if I have ENERGY STAR windows?1. Look for the ENERGY STAR label when buying new windows. The label shows the climate zones where that window will perform best. based on your climate zone.
How do you tell if windows are well insulated?How to Tell If You Have IGU Windows. Light a match and hold it next to the glass. Make sure you don't get too close.. View the reflection in the glass. If you see a single reflection of the flame, it is single-pane glass, which means your window is not an IGU.. |
