The Department of Energy states that heat gain and heat loss through windows are responsible for 25%–30% of residential heating and cooling energy costs. Windows are, for lack of a better description, actual holes in your home.
Installing energy-efficient windows lowers energy bills and reduces greenhouse gas emissions, enabling you to save money and use less energy.
In this article, we’ll explore how much energy-efficient windows cost, the options available, and how much they could save you on electricity. Then, we list five of the most energy-efficient windows per the Energy Star website.
Let’s dive in.
Key takeaways
According to the Department of Energy, heat transference through windows accounts for 25%–30% of residential heating and cooling energy costs.
Triple-pane windows improve the home's energy efficiency by as much as 40% over double-pane windows.
Low-E glass reduces energy loss by as much as 50%.
Installing energy-efficient windows in your home could save $253 to $568 a year.
What makes a window Energy Star?
Energy Star-rated windows are known to be the top for energy performance. To be included, they must meet several criteria. They include:
An Energy Star partner must manufacture the window. Energy Star partners commit to offering products that earn this distinction. There are currently 189 Energy Star window manufacturing partners.
The National Fenestration Rating Council (NFRC) must independently test and certify the windows.
The window's NFRC rating must meet or exceed the U.S. Environmental Protection Agency (EPA) guidelines.
How to choose an energy-efficient window
Energy-efficient or energy-saving windows are best known for preventing cool or warm air from escaping your home. When you install energy-efficient windows, you ultimately increase your home’s insulation. Therefore, less heat and cool air have the chance to escape, saving you money and reducing your energy usage in the process.
When purchasing windows, compare the U-factor and the Solar Heat Gain Coefficient (SHGC). The U-factor indicates how well the window insulates. The typical range for U-factor is from 0.20 to 1.20; the lower the value, the better. The SHGC indicates how much solar heat penetrates the window. The SHGC typically ranges from 0 to 1. The lower the value, the less heat that passes through the window.
Choose from the Energy Star Most Efficient 2024 Windows, Doors & Skylights list for the most efficient windows and to recoup some of the cost via a tax credit.
Various features work together to ensure a window delivers the best U-factor and SGHC. Look for these features to find the most efficient windows for your home.
Double-pane versus triple-pane window
Double and triple-pane windows are exactly what they sound like–windows with two or three layers of glass instead of one. If you have an older home with single-pane windows, you may have storm windows installed on the outside to prevent air leakage and provide an extra layer of insulation.
However, single-pane windows are seldom sold for residential use anymore. Instead, manufacturers implement double—and triple-paned glass to lower the window's U-factor. A study published in the March 2022 issue of the ASHRAE Journal showed that triple-pane windows improve the home's energy efficiency by as much as 40% over double-pane windows.
Low-E glass coating
A low-emissivity (low-E) coating is an extremely thin, metallic oxide layer on the surface of one or more of the window's panes and can be applied to any type of glass. Low-E glass reduces energy loss by as much as 50% by filtering the ultraviolet light from the sun without reducing natural light. Therefore, applying a low-E coating keeps the indoor air cooler when it’s hot and warmer when it’s cold outside.
If your older windows don't have a low-E coating, you can apply an inexpensive window film that can last until you have the means for a whole-house window replacement.
Gas fill
To up the ante in efficiency technology, manufacturers fill the space between double or triple glass panes with argon or krypton gas. Both gasses are clear, odorless, and non-toxic. Typically, argon is used in double-paned windows, and krypton is reserved for triple panes because the space is narrower and the gas is denser. These gasses slow, or even stop, thermal energy from passing through a window.
Spacers
Spacers separate a window's glass panes and provide a direct connection between the outside and inside of your home. They allow for thermal expansion and pressure differences. Spacers also prevent moisture from entering the window and gas from leaking out. Look for highly insulated spacers, such as 100% polymer structural foam rather than metal, to reduce the amount of heat transfer.
How much can energy-efficient windows save you on your electricity bill?
The Department of Energy claims that installing energy-efficient windows in your home could save you anywhere from $253 to $568 a year. Energy loss can cost homeowners hundreds of dollars a year—often without their knowledge. To calculate your savings, we recommend conducting your own home energy audit to determine how much energy-efficient windows can save you on your heating and cooling costs.
How much do energy-efficient windows cost?
The average cost of energy-efficient windows, including labor, ranges from $287 to $4,614.
The exact cost of your new energy-efficient windows will vary depending on the brand, window type, frame material, and efficiency features you’d like installed.
The 5 best energy efficient window brands in 2024
Windows with an Energy Star certification are the most efficient windows you can install in your home, particularly if they make the "most efficient" list.
Alpen High Performance Products
Alpen High Performance Products' picture windows top the Energy Star Most Efficient Windows list. Alpen creates its residential windows using lightweight suspended-film technology with a fully insulated fiberglass or fiberglass-reinforced uPVC framing system. They are made in the USA and have U-factors as low as 0.11.
OKNA Windows & Doors
Ranking highest among casement and double sliding windows, OKNA features a uPVC fusion-welded beveled frame and sash, triple weather stripping, a warm edge spacer system, and a full fiberglass mesh screen. It also has a limited lifetime warranty.
Marvin
Unsurprisingly, one of the most popular names in windows would be the highest ranking for the most popular window style–double-hung. Marvin's Ultimate wood-framed double-hung windows come in six species options for the interior, painted or primed with six stain colors to choose from. On the exterior, you can choose from three species in 19 colors or customize your own.
Interstate Window & Door Company
The leader in awning-style windows, Interstate Windows are available in CompositeWood or vinyl frames. Its Model 6800/6802 vinyl casement features four-point welded corners, high-quality weather stripping, and low-E glass/argon gas as a standard option. Interstate's CompositeWood is a proprietary mix of specialty polymer and acrylic resins. These casement windows come in various colors, have slim line hardware in various finish options, and standard low-E glass/argon gas glazing.
innotech windows + doors
The leader in dual-action Energy Star-certified windows is innotech's Defender 88PH+. This tilt-and-turn model features a European PVC frame reinforced with galvanized steel and is available with triple glazing and various color finishes. With this window, you can enjoy a minimum 0.12 U-factor.
The bottom line
Whether you need windows for a new home or a window replacement project, energy-efficient windows are an excellent choice to save you money. While they may be more expensive than an economy-grade window, energy-efficient windows provide plenty of long-term benefits, especially when considering your wallet. Energy-efficient windows are well worth the investment.
Frequently asked questions
The most efficient windows feature triple glazing filled with krypton gas, a low-E coating, a non-metal frame, and warm-edge spacers. Look for the lowest U-factor you can find.
Typically, window efficiency is measured by the U-factor. However, you can calculate the R-value of a window by dividing 1 by the U-factor noted on the window's label. Ordinarily, a single pane of glass will have an R-value of 1. So, an R-value of 3 or higher would be suitable for a window.
Alpen High Performance Products, OKNA, Marvin, and innotech have the highest-rated windows on the Energy Star Most Efficient 2024 Windows, Doors & Skylights list.
Wood, fiberglass, and vinyl windows are comparable in terms of energy efficiency. Metal window frames are best avoided for optimal efficiency.
Carol J Alexander is a home remodeling industry expert for Fixr.com. For more than 15 years as a journalist and content marketer, her in-depth research, interviewing skills, and technical insight have ensured she provides the most accurate and current information on a given topic. Before joining the Fixr team, her personal clients included leaders in the building materials market like Behr Paint Company, CertainTeed, and Chicago Faucet, and national publications like This Old House and Real Homes.