Defining the U-factor for Windows
U-factor is a measure of how quickly a window, door, skylight, or similar item transmits non-solar heat flow. As the International Association of Certified Home Inspectors explains, this rating was created by the nonprofit National Fenestration Rating Council. This organization directs an independent rating and labeling system for the energy efficiency of windows and other building components. The popular Energy Star program touted by the U.S. Department of Energy relies on many of the measures from the NFRC.
The U-factor is listed prominently on the labels of most quality windows. It’s generally between 0.20 and 1.20.
Using U-factor to Select Windows
There are a couple of ways to use the U-factor to select windows. If you want to keep it simple, remember that a lower U-factor equals greater energy efficiency. Then, look for a window with a lower U-factor when purchasing windows.
Taking the time to expand your understanding of the U-factor for windows can be worthwhile because different U-factors are better in different locations. For the best results, you’ll want to learn about another energy-efficiency rating: the solar heat gain coefficient.
Defining Solar Heat Gain Coefficient
Solar heat gain coefficient is the amount of solar heat that passes through a window. As Energy.gov reports, SHGC can be either directly transmitted or absorbed and gradually released. A lower SHGC means less passive heat gain and greater shading ability. In contrast, a higher SHGC indicates a higher capability for gathering solar heat.
Like the U-factor, the SHGC appears on the labels of windows from reputable manufacturers. Its value ranges from 0 to 1.
Using the U-factor and the SHGC to Select Windows
Some things naturally work together. Like peanut butter and chocolate, the U-factor and the SHGC play off each other with ease. According to Energy.gov, it’s important to review your climate zone before deciding on a new window and use the following guidelines based on your region:
- Northern: If you’re in the colder north, look for a window with a U-factor less than or equal to 0.30 and any SHGC. Alternatively, for equivalent energy performance, look for a 0.31 U-factor and an SHGC greater than or equal to 0.35. Or, you could go for a 0.32 U-factor and an SHGC greater than or equal to 0.40.
- North-Central: In the north-central strip (remember to view the map!), Energy Star recommends a U-factor of less than or equal to 0.32 and an SHGC of less than or equal to 0.40.
- South-Central: In this southern strip, the experts recommend a U-factor of less than 0.35 and an SHGC of less than or equal to 0.30.
- Southern: Finally, in the deepest part of the south, you’re encouraged to get windows with a U-factor equal to or less than 0.60 and an SHGC of equal to or less than 0.27.
Many energy-efficient windows come with informative labels with color-coded maps that indicate which regions they are suitable for. Purchasing your windows from a reputable supplier can also be a fantastic way to get assistance in securing the best product for your needs.
Exploring Other Considerations for Windows
When shopping for windows, efficiency is an obvious consideration. Understanding the U-factor and SHGC helps there. Other considerations include the following:
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- Price: Most folks have a budget. Working with a knowledgeable retailer can help you pinpoint the best value.
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- Materials: Should you opt for vinyl, aluminum, or fiberglass? Would wood be a better option? Modern windows are available in multiple materials, each with its own pros and cons.
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- Sizes, shapes, and profiles: There are many kinds and styles of windows, so the options are amazing. However, proper measurements are essential if you want a good fit.
When you’re in the market for new windows, American Window Company can assist you in locating your perfect window. Whether you’re wondering about U-factors or debating the merits of vinyl or aluminum, our team of experts is happy to answer your questions. With our extensive selection of windows from trusted manufacturers, we’re sure to have the ideal window for your needs. Contact American Window Company today to discuss your project.
