With the proliferation of glass coatings, options and styles, not to mention ever-more complex and demanding building codes, choosing the right window, while also satisfying customer expectations, is more demanding than ever.

Making the right choice ensures homes won’t be too hot or cold and helps lower energy bills—key considerations for homeowners. Making the wrong choice can have dire results.

“Worst case scenario is having an inspection fail,” says Cliff MacDonald, Andersen Windows & Doors product manager, who’s been in the industry since 2003. “Failing an inspection usually involves removing product from the rough opening and replacing it, and that is a significant additional cost and time to remedy. No one wants that to happen.”

So, the first place to start when it comes to choosing windows is ensuring they meet energy code requirements. While a patchwork of state, local, and municipal codes make that challenging, MacDonald mentions builders can turn to some helpful online tools to get clarity. One of the best is energycodes.gov, which tracks energy codes state-by-state and offers a number of resources. He also encouraged builders to work with local code officials.

But following the building code is just the start, because windows offer a number of options—glass coatings, panes, and grilles to name a few—that will meet code, depending on how those options are mixed and matched.

“One potential challenge builders face is fully understanding how window and door features and options can influence thermal performance,” MacDonald says.

Fortunately, the National Fenestration Rating Council (NFRC) labels windows to help compare windows in multiple performance categories including U-factor, visible transmittance, solar heat gain coefficient (SHGC), condensation resistance, and air leakage.

While all those categories are important, U-factor is most often used in determining which window to use in which climate, according to the International Association of Certified Home Inspectors. Here’s a summation the organization’s U-factor guide by climate:

• North: In this climate, the U-factor should be less than or equal to 0.30 for windows. Low U-factor windows are most important and will be most effective in this colder climate area where minimizing heat loss is critical to energy efficiency.
• North and Midwest: In these climates that use both heating and cooling, the U-factor should be less than or equal to 0.32 for windows. Higher heating bills indicate the need for windows with a lower U-factor.
• South and Central: While these climates also typically use both heating and cooling, the U-factor should be less than or equal to 0.35. A low U-factor can be helpful during hotter seasons, though a low solar heat-gain coefficient is more important in such situations.
• South: In these climates that are cooling-dominated, the U-factor can be less than or equal to 0.60. Such low ratings can ensure heat is kept out on hot days when combined with a low solar heat-gain coefficient.

But considering climate and code are just the start when it comes to window choices. Next, it’s important to find out what the customer’s expectations are. For example, MacDonald says a growing number of homeowners want their windows to be certified with the latest Energy Star 7 requirements, along with Home Energy Rating System (HERS) ratings and Passive Home standards—all of which increase the efficiency requirements of windows and the complexity of choosing the right one depending on the climate.

Energy Star’s more stringent requirements are a good example, MacDonald says. “There’s a lot fewer dual pane options that can meet Energy Star 7 and more of a need for triple pane, particularly in the Energy Star northern zone.”

But no matter what type of code or standard builders are opting to meet, it’s imperative the window is backed by the best industry standards for resiliency and durability. To that end, MacDonald says builders should always make sure the window and door products are NFRC certified.

NFRC certified ratings also assess whole unit performance, not just the center of glass performance. That’s key because some manufacturers publish only “center of glass” performance, rather than the “whole unit performance,” which includes center of glass, edge of glass, sash or panel, and frame.

Another key is to ensure the manufacturer has received the Window & Door Manufacturers Association (WDMA) Hallmark certification, an industry-wide recognized certification process.

“It means that third party inspectors come into our manufacturing plant and audit our process and design on an annual basis,” MacDonald says. “So, you know that we’re making the product that we say we’re making and that it’s going to meet the performance level on the label.”

Learn how Andersen Windows & Doors can help you choose the right windows for your next project.