Marvin and the experts at Fine Homebuilding magazine team up to share a few smart window selection tips that can deliver long-term value.

Tip 1: Understand the Consequences of Low Quality Windows

Low-cost windows can be pricier than they first appear. Like any weak link in the building envelope, poor-performing windows require a larger HVAC system and ducting, which is pricier up front and also more costly in the long run. “With insulating values as low as U-0.18, windows can have a huge impact on a home’s energy efficiency rating and a cascade effect on the cost of the overall project,” said Brett Dillon, a longtime builder and developer in Texas, who chairs the technical standards committee for ResNet, a nonprofit that trains and rates residential energy auditors.

The math is easy, but not all builders and homeowners respond to it. “A lot of people don’t know how much they pay for energy and don’t really care,” Dillon says. “But everyone cares about comfort.” By the time a new homeowner complains about drafty windows, condensation, or rooms that overheat in summer, it’s too late to rip out underperforming windows. Often the builder’s or homeowner’s solution is to upgrade the entire heating and cooling system. Interestingly, complaints about draftiness can usually be traced to low-quality windows with cold glass, not air leakage, says Steve Baczek, an architect outside Boston. “People say, ‘This window feels drafty,’ but it’s really not a draft. The radiation rate of the window is too high and you feel the cold,” he says. “It’s the same reason that basements feel cool. Your body is losing heat at a much higher rate as it tries to warm the cold walls.”

Tip 2: Understand Various Window Types and Their Performance Attributes

Windows are available in a wide array of types, styles, and packages. To get the most energy efficiency and durability for your dollar, you have to break down the window into its parts. The first consideration is the type of window itself— in other words, how it functions. Dig through any manufacturer’s website and you’ll find double hung, casement, sliding, tilt-and-turn and so on. Mostly these are aesthetic choices based on the style of the home and outside the scope of this article, but there are two types of air seals around the window that you should know about.

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Casements, awnings and tilt-and-turns all swing outward or inward, and when locked, they are pushed or pulled tightly against their weatherstripping. From an energy-efficiency standpoint, their compression seals give those windows a distinct advantage over windows that slide, either sideways or vertically (such as single- and double-hungs). So if you’ve been dead set on double-hungs, you might want to consider adding some windows that swing instead of slide. You’ll get better insulation, with all other things being equal.

Texas builder Matt Risinger agrees: “Get as many awning or casement windows as you can. They seal better, and their screens are on the inside, so they stay cleaner and are easier to take off in winter.”

Tip 3: Choose the Right Frame Material

After basic functionality, the choice of frame material has the greatest impact on price and performance. Frame materials are generally the weak link in a window’s thermal performance, and at 15 percent to 20 percent of the overall surface, the frame has a big impact on U-Factor. But there is also durability and weatherability to consider. The longevity of window frames, claddings and finishes varies widely. Selecting the appropriate windows based on the environment is critical—especially in regions with extreme weather.

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For example, fiberglass windows, whether they’re made completely of fiberglass or clad, have superior weatherization and insulation properties when compared to alternative materials. This makes them ideally suited for homes built in harsh locations and in homes that are taking energy efficiency seriously. With its very low conductivity, fiberglass is also the best insulator among window frame materials. And it shrinks and expands at the same rate as glass, making its air-seals as durable as the rest of the unit. Its long-term stability also ensures that fiberglass windows will operate like new for decades to come.

Tip 4: Understand EnergyStar Recommendations

ENERGY STAR® recommendations are given for four climate zones in the United States—the mostly heating zone (Northern); two combination heating and cooling zones (North/Central and South/Central); and a mostly cooling zone (Southern). Every qualified window will list the zones it is certified for. The ENERGY STAR standard is a good benchmark for energy-conscious architects and builders, but every house is unique. To choose the best performing windows, it’s still recommended to work with a supplier to take into account factors such as site orientation and the size and number of windows.

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Tip 5: Select the Right Glazing Package

The glass—called glazing—is the other critical component in your window package. While manufacturers tend to pick a frame material and stick with it, they offer a wide range of glass configurations and coatings—all of which have a big impact on energy efficiency. In fact, the top U.S. window manufacturers get their glass from just a few factories, who specialize in combining the high-tech coatings, films, spacers and gases that go into today’s glazing units.

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Two-pane insulated units are now standard, and that step alone has greatly reduced the U-Factor, or the amount of heat a window lets through.

The next big step up is adding a third pane, which can lower the window’s overall U-Factor even further. Some designers and builders of low-energy homes have relied on European triple-pane windows as part of a superinsulated building envelope. However, these window packages are traditionally cost-prohibitive for many clients. Double-pane windows and domestic triple-pane units can offer performance at less expense. Still, experts advise finding more cost-effective ways to improve a building’s thermal envelope before going to three-pane units.

“As we start building more airtight and insulated homes, triple-glazed will start to make more sense,” Risinger predicts. “Here, we aren’t quite there yet.”

Tip 6: There is no Label for “Durability”

The National Fenestration Ratings Council provides a label on every window that gives reliable numbers for its energy-efficiency. But performance, comfort and overall value aren’t just about initial energy-efficiency. If windows aren’t strong and durable, that performance won’t last. Windows can even become a nuisance. “There’s nothing worse than busting your butt all day at work and then coming home to find sticking windows, rotting siding and more stuff to fix,” Dillon says. “It’s a big reason why more people are renting.” Choosing windows that will save energy, stand up to the weather and perform like new for decades might seem like a lofty goal, but today’s technologies put it well within reach.

This content originally appeared in Fine Homebuilding magazine.

Posted by:Marvin

Marvin is a fourth-generation family-owned and -operated business, headquartered in Warroad, Minnesota, with more than 5,500 employees across 15 cities in North America. The Marvin portfolio of products for builders, architects and homeowners is designed to provide exceptional solutions for any project with a focus on creating better ways of living. Marvin products are distributed nationally through a network of independent dealers and are also exported internationally. Visit to learn more.

32 replies on “6 Tips for Choosing Energy Efficient Windows

  1. I have been looking into getting new windows for the bathrooms in my house but I am not sure how to choose the ones I want. You talked about how getting energy efficient windows means selecting the right glazing package by looking at the films, spacers, and gases that go into the glazing process. I never would have thought to look into the process that deeply but it makes sense that it helps with finding the right kind of windows. Thanks for the great advice about windows.

  2. If you choose the energy efficient windows then its really benefited for you as it provides light, ventilation and security to your home. But before choosing the energy efficient window you have to keep few important points in your mind. As there are different variety of window materials are there so you have to choose which type of material will give best energy efficient and mainly casement and awning windows are more energy efficient. Also select the windows which have low maintenance so that you can save energy and time.

  3. Thanks for going over some things to think about to make sure you pick an energy efficient window. I’m glad that you mentioned that you need to pick out the right materials for the frame, because it can really impact on the performance of a window. It sounds like it could be good to research about these different materials so that you know which ones would be ideal for the climate you live in.

  4. It’s interesting that you’ve mentioned how the glasses’ configuration and coatings are where the biggest impact is when determining the best windows for energy efficiency. That’s perfect to learn since we are scheduled to visit some shops tomorrow to find the best residential windows for our newest estate. I’ll be sure to jot down all the important points you’ve mentioned so that we can get the best windows for our needs. Thanks!

  5. I like that you talked about how fiberglass windows can resist hard weather conditions easily. I have been looking for windows to install in my new house. I can see how it would be smart to use fiberglass because my new area has pretty intense weather fluctuations.

  6. I didn’t know that windows could have a huge impact on a home’s energy-efficiency rating. I have been thinking about getting new windows, but I don’t know if I need too. If I could get a lower energy bill, that would be a huge benefit for me. I will have to choose some new windows.

  7. The windows in my living room are leaking air, and I’m worried that it’s affecting my heating bill. Thanks for pointing out that fiberglass has really good insulation and weatherization properties when compared to other materials. I’ll have to find someone who could probably use fiberglass to give me some new windows.

  8. I respect Marvin as an excellent window manufacturer but I would like to bring your attention to the poor choice of photo for your article. The design of the roofs on the house are a disaster waiting to happen. Collecting water on your roofs and creating bottlenecks in drainage are bad news. Even if the house shown is not subject to snow and ice dams, the 3 roofs pouring water into one scupper and downspout are going to result at some point in water entering the building and causing rot. As an Architect who does lots of renovations, I see this often. Too much effort spent without consideration for proper shedding of water. Try sending that photo to the folks at and you’ll get an earful.
    Again, I know Marvin is not the designer, but your windows will suffer with that design. I have taken the Marvin factory tour and I was very impressed. Keep up the good work.

  9. I liked what you had to say about the frame material being just as important as the window. I would have thought that it wouldn’t matter, but I like that you put it into perspective with the frame taking up fifteen to twenty percent of the surface of the window. My husband and I will be looking at what materials we should use for optimal performance.

  10. It’s interesting that you talked about how fiberglass windows can withstand stronger weather. My wife and I have been looking for someone to install windows in our new home. It would be nice to try fiberglass because we have strong winds where we live.

  11. This is some really good information about choosing energy efficient windows. I liked that you pointed out that the material the frame is made out if will make an about 15 to 20 percent difference in how effective the window is. I wonder if that is the same for energy efficient doors.

  12. Thanks for the tips for choosing energy efficient windows. It’s great to know that two-pane insulated glass is the standard for windows now. Is having two panes the same as being double glazed? If so, I’ve heard that helps with energy efficiency a ton.

  13. I have recently been thinking about getting some of my windows replaced and I wanted to look up some tips. I really appreciated how this article talked about to get the most energy, efficiency, and durability for your dollar you have to break down the window into its parts. I will have to keep this in mind as I search for the perfect window.

  14. It was informative when you said that energy efficient windows work differently depending on the home, so it is best to have the place inspected prior to installation to make sure that the right type is used. My mom has been considering the use of energy efficient vinyl windows for the house upgrade, and I really thought it was a good idea. Now I realized that we need a go signal from the professional first before we can use it. Thank you for posting.

    1. Hi Aleshire, we’re glad that this post was helpful for you! A professional can also help you learn about the differences in window materials (vinyl vs. fiberglass vs. wood/aluminum) to make sure you’re making the best choice for the ultimate longevity and performance of the windows. You can find a Marvin dealer in your area to do a home visit and help answer your questions by entering your zip code here:


  16. I love the tip that you gave to consider the impact that energy-efficient windows can have on your home. My wife and I have been talking about getting new windows, but there are so many options that we could choose from. It can be confusing to decide which windows to get. When we choose, I will be sure to consider energy-efficient ones, so we could have a good impact on our home.

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