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7 Things to Consider When Assessing a Window’s Performance

It’s not enough for your windows to be beautiful; they should improve your indoor comfort too. Investing in high-performance windows can give you significant savings on energy and repair costs.

There are certain things you need to consider when determining the energy efficiency of a window. Here are some factors that affect a window’s overall performance from one of the most trusted window contractors, Renewal by Andersen® of Spokane.

1. U-factor – This is the measure of heat loss or gain through a glass. The lower the U-factor, the better insulation the window provides. Low U-factors are specifically recommended for warm climates but are beneficial in colder climates as well.

2. Solar Heat Gain Coefficient (SHGC) –  SHGC is the amount of solar radiation that enters through a window. Windows with lower SHGC transmit less solar heat to your home.

3. Visible Transmittance (VT) – VT is how much visible light passes through a window. It’s different from SHGC, as some windows have special coatings that block visible, infrared and ultraviolet light. Choose Renewal by Andersen of Spokane, your window replacement expert, for windows that provide protection against the harmful effects of UV light. Our Low-E4® SmartSun™ glass blocks 95% of UV rays that enter your home.

4. Condensation Resistance (CR) – This determines how well a window resists condensation on its inner surface. A high CR means a product can highly resist condensation.

5. Sound Transmission – High-performance windows excel in blocking sound from the outdoors. Tightly sealed windows won’t only provide better insulation but they can also make your home quieter.

6. National Fenestration Rating Council (NFRC) – The NFRC has created a window energy rating system based on overall product performance. You can find the NFRC label on products that are ENERGY STAR®-certified.

7. ENERGY STAR – The Department of Energy and the Environmental Protection Agency has established ENERGY STAR for products that meet specific energy performance criteria. Check if a window is ENERGY STAR-certified to ensure you’re getting an energy-efficient product.

For energy-efficient and durable windows, choose Renewal by Andersen of Spokane. We are your leading provider of window and door replacement services. Call us at (509) 202-4090 or fill out our online form for a free consultation. We work with homeowners in Spokane, WA.


"Shawn and Jon framed and installed two windows in our bedroom and my daughters room. They look beautiful and they did a great job framing the window and cleaning up when they left. Awesome Guys and they did Awesome work, what a team!"

Theresa Wickham

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