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Posted on Nov 21, 2018 by Sam Heer

The Importance of ENERGY STAR® Certification for Window Glass

An ENERGY STAR® certification is your assurance that the replacement windows you’re buying will help reduce your energy bills. Window glass is a major component of every replacement window ever made and is crucial to window energy efficiency. Renewal by Andersen® of Central Illinois takes an in-depth look at what ENERGY STAR certification means for window glass.

Energy Envelope

To understand how energy efficiency relates to window glass, take a look at how energy efficiency works in relation to the rest of the house. Every home has an energy envelope, which consists of the attic and the exterior walls, along with the entry doors, skylights and windows. Ideally, this enclosure should have enough insulation to prevent heat transfer, which causes heat loss during cold days and heat gain during hot days.

Window Glass

Conventional insulation works well on the attic and exterior walls, but windows are different. Glass is a naturally conductive material, so traditional single-pane glass has negative effects on the home’s overall energy efficiency. Therefore, replacement windows must have two panes to meet the minimum requirements for an ENERGY STAR certification. By eliminating contact between interior and exterior surfaces, the window conducts less heat. This helps reduce indoor heating and cooling requirements, resulting in energy savings.

High-Performance™ Low-E4® Glass Packages

Every Renewal by Andersen replacement window bears certification from ENERGY STAR thanks to our High-Performance Low-E4 glass packages. Each double-pane assembly features non-conductive spacers and tight seals to ensure zero contact between interior and exterior glass panels. The airspace can be optionally filled with an insulating custom argon gas blend. The low-emissivity coatings selectively block unwanted UV and infrared rays while allowing natural light as much as clear glass does. Combined with our exclusive Fibrex® material frames and precise installation process, you can rely on our ENERGY STAR-certified replacement windows to help you save on your energy bills.

To learn more about our energy-efficient replacement windows, call Renewal by Andersen of Central Illinois today at (866) 693-6707. You can also fill out our contact form to schedule a free consultation and estimate. We serve many areas in and around Springfield and Decatur, IL.


"I would recommend RBA of Central Illinois for QUALITY windows and doors. Compared to our old cheap, thin vinyl windows, Andersen blows them away. You can easily tell by how well the sliding doors fit and close, and how heavy duty they are. We also cannot hear the wind rushing through the house in inclement weather anymore! And the black window frames we went with are amazing to look at. Aaron, Al, Darrell, and Cory all were professional and went all out to finish the job, given the weather they had to deal with. I would definitely recommend. They were also on top of communicating with me given the weather delays, and what I could expect for them coming out. Five stars!"

Eric L.

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