Tom Shafer

Energy cost savings: Do premium window features matter?

February 04, 2012

My replacement window customers all seem to want pretty much the same thing, and it has to do with energy -- energy-efficiency, energy savings, Energy Star -- even what some refer to as energy-tinted glass. Since most of a window is glass and the insulating qualities of the glass are going to determine its energy efficiency, choosing the best glass for your circumstances is the most important decision you can make before purchasing a window.

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Every window company promotes its own brands of glass, but all of them are very similar -- so how do you choose? Additional features offered by one manufacturer or another can sway your decision. Some offer special coatings to keep your windows dirt-free or features that improve the windows' insulating values.

Is premium glass the best choice?

Learn to look past the well-advertised premium names and ferret out the features that you're willing to pay for. Here are a smattering of the top-of-the-line glass units from well-known window manufacturers. See for yourself what distinguishes one from another:

Atrium Super Spacer nXt™ warm edge sealing system. Atrium distinguishes its 8700 Series glass units with a warm edge spacer that boosts the insulating properties of these windows. When this spacer system is used in conjunction with their low-e glass and argon gas between the panes, the windows' u-value is .30. Using low-e and krypton gas improves that even further, to as low as .26.

Silver Line (an Andersen company) Premium 9500 series. These highly-efficient replacement windows, with low-e3 coating and argon gas, rate a .30 u-value but they are not branded individually. You'll hear them referred to as simply Silver Line's low-e3 glass. On the other hand, Andersen promotes its Series A window glass as HP (high performance) Low-E4 SmartSun with a u-value of .29. The low-e4 is low-e3 with a special additional coating that minimizes dirt build up by filling the pits in the glass to create a very smooth surface. A chemical process activated by UV sunlight allows the built-up dirt to wash off with the next rainfall -- similar to the coating you apply to your car's windshield.

Milgard SunCoatMAX®. Milgard's premium glass, SunCoatMAX, is a triple-glazed (three pieces of glass) unit. Filled with argon gas between the layers of glass, these windows achieve a u-value of .26; filled with krypton gas the u-value drops even further, to .23. SunCoat® is Milgard's standard low-e product.

JELD-WEN® Energy Saver Max. JELD-WEN's Max product, like Milgard's Max product, is triple-glazed. They achieve a .28 u-value with an argon gas filling in the two spaces between the layers of glass.

Weather Shield® Zo-e-shield. Weather Shield delivers triple-glazed performance in a double-pane window with their premium line, Zo-e-shield. They go so far as to say it can save you 30 percent on your heating bill. A map on their website shows you how much you can save in energy costs. Zo-e-shield also protects home furnishings from fading by blocking most UV light, and their Easy Care coating keeps the windows clean.

These are only a small sampling of window brands. Do not be swayed by names like Super, Max or Ultra. What's more important is whether the u-value and Solar Heat Gain Coefficient (SHGC) of the replacement windows you're considering meets or exceeds the Energy Star requirements in your part of the country. Purchasing glass with better ratings can result in a decrease in heating and cooling costs, and that may be worth the additional expense.

About the Author

Tom Shafer has decades of experience in window sales, marketing and product development. He's worked closely with window design engineers in testing, design, and building code interpretation. Past employers include United Windows and Doors and Norandex, MI Windows. He currently works at a home improvement retailer.

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