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Posted on Jan 28, 2019 by Sam Heer

3 Qualities of a Good Replacement Window

Whether you’re looking to replace aging windows or completely remodel your home, the choices for replacement windows are staggering. There used to be a time when options were extremely limited. Today, you can pretty much customize colors, shapes and styles, and even choose from an ever-growing list of types to fit any functional and design needs.

To help you make sense of all these different choices, here are a few factors to consider when deciding on new windows.

Solar Heat Gain Coefficient

In modern windows, most of the radiant heat from the sun is reflected back into the environment by the glass panes. However, a fraction of this heat passes through. This fraction is defined as the window’s SHGC, or solar heat gain coefficient. Almost all ENERGY STAR® windows will have an SHGC rating, but their efficiency will vary by type, manufacturer and glass composition.

According to Renewal by Andersen® of Central Illinois, the Department of Energy recommends an SHGC rating of at least 0.35 to 0.60 for Illinois. This allows enough of the sun’s heat to offset heating bills in the winter without being too much of a burden on your air conditioner during other seasons.


U-factor, put simply, is windows-talk for heat resistance. When it comes to U-factor ratings, you should always look for a high number. So far, the ceiling is about 0.30 for premium high-performance, double-pane replacement windows. The closer your windows’ rating is to this number, the more efficient it is as an insulator.

Visible Transmittance

If SHGC measures heat transference, VT or visible transmittance pertains to light. The Lighting Research Center numbers a lot of health benefits from allowing adequate natural light into your home, and if you want to gain these advantages, you want a window with a high VT.

Renewal by Andersen of Central Illinois is proud to say that our window installations follow all efficiency requirements, earning our products an ENERGY STAR certification. Call us today for a free in-home consultation at (866) 693-6707. We serve Decatur, Springfield, IL, and nearby areas.


"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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