Window treatments like curtains, blinds, shades and awnings have the power to seriously boost energy efficiency. The right window treatments, also called window attachments, can keep your home cooler in the summer and warmer in the winter. They can also cut your utility spending throughout the year.

"For a typical home, the window area is less than 10% of the overall shell. But the Department of Energy has estimated that windows can account for up to 50% of the energy that flows in and out of the home," said Tom Culp, owner of Birch Point Consulting in Wisconsin and a board member of nonprofit public interest group the Attachments Energy Rating Council. "Windows have an oversized importance in your home's energy performance and your energy bills."

How do curtains and blinds save energy?

Window treatments can make your home more energy efficient in a couple of different ways. How they can help and the right window treatments to purchase for energy savings depend on the time of year and the climate where you live.

When it's cold and dark in the winter, the right window treatments can act as a barrier, preventing your home from losing heat through leaks or cracks around your windows. They can also keep cold, drafty air from entering your home. 

"You have a lot of energy going in and out of your home through the windows," said Culp. "A blind or shade will provide an insulating layer to help block some of that heat loss, especially at night."

In warm, sunny weather, blinds, shades, films and other treatments block the sun,  keeping your home cooler during the hottest times of the day. In colder climates, sunlight can be beneficial in winter and the shoulder seasons. 

"The sun coming in your window can be good or bad. Where I live in Wisconsin, it helps to warm your house and offset heating costs," said Culp. "If you're in the South, maybe the sun isn't your friend in the summer. A blind or shade can block some of that sunlight and stop that extra heat from coming in and adding to your air conditioning costs. It really depends on where you are in the country and your specific application."

Not all window treatments are created equal. To get the most value and find the right product for you, it's important to understand the different window treatments available. 

Insulated cellular shades

Also called honeycomb shades or cellular shades, these pleated fabric shades are considered the most high-performing window treatment option in terms of R-value, which measures the performance of a building's insulation. Their honeycomb shape creates a layer of air that blocks heat or cold from entering your home. They also have the most potential to help you save on energy. Insulated cellular shades reduced energy use by 20% in one study conducted by the U.S. Department of Energy. 

Thermal curtains

Thermal curtains resemble everyday fabric curtains, but they differ from decorative curtains in a significant way. They're made from multiple layers of thick, insulating fabric designed to hold in cool or warm air and prevent leakage or drafts from windows. 

Thermal blinds

Thermal blinds are year-round window treatments that create a heat-reflecting barrier on your home's windows. Similar to insulated cellular shades, these blinds often have honeycomb-shaped pockets to trap a layer of air that acts as a thermal barrier between the window and your home. An aluminum layer on each side of the blinds reflects heat out in the summer and into your space in the winter. 

Window quilts

A window quilt works the same way as a quilt made for your bed. By sewing layers of fabric together with an insulating layer between them, a window quilt blocks air from getting in or out through your windows. They also completely block the sun, making them do double-duty as blackout curtains, and can help reduce outside noise. Window quilts are available in roll-up and pull-up models to allow for more flexibility, though some are designed with velcro or snaps to attach the treatment around all four sides of the window. 

Window films

Unlike the other window treatments on this list, which are attached to the interior or exterior of your windows to help with energy efficiency, films are applied directly to the glass. Window films reduce warming from the sun's heat as well as glare and UV rays, but because they're not adjustable, they're better for warm, sunny climates rather than cold ones. Because window films are tinted, they provide privacy while allowing you to see outside, unlike curtains and blinds. 

Awnings

When attached to your home's exterior above windows, awnings block sunlight, preventing solar heat gain in your home. Fixed and adjustable models are available, and you can install a single awning over a window or a longer awning that can shade the windows over one entire side of your house. Like window films, awnings may be a better option for homeowners in warm climates, as blocking the sun will require more energy to heat your home in winter.

 

Lowering blinds on a sunny day can keep your house cooler.

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How do you find energy-efficient curtains and blinds?

On AERC's residential product search page, you can find certified window treatments and even filter and sort to find products that fit your needs and climate. While you probably have an idea of whether your home is more in need of cooling or heating for more of the year, the organization also has a climate zone map that can help you choose whether the AERC's cool or warm rating is more relevant to your home. 

You can also look for products with the AERC's Energy Improvement Label when you're shopping in person. Each rating label includes a number for how well the product performs in cool climates as well as warm climates.

Regardless of the window attachments you choose, you'll get the most energy savings when they're adjusted regularly according to conditions outside. Another Department of Energy study found that 75% of window coverings stay in the same position every day, and more than half of U.S. households don't adjust their window coverings daily. Culp sees that fact as an opportunity for automation to make energy-efficient window treatments even more effective. 

"What automation can do better than most homeowners is open your window treatments when it's advantageous for you and closed when it's not," he said. "You can control it yourself from an app or it can be set to be run optimally. It knows when it will save you the most energy and the most money so that you get better performance."

Will regular curtains and blinds improve efficiency?

"All window attachments will have an impact, from basic mini-slat blinds to decorative sheers to high-performance insulating cellular shades," Culp said. 

The curtains or blinds you can pick up at a department store or big-box store haven't been designed specifically for energy efficiency. They may reduce your energy use somewhat, but you'll likely see a bigger impact on your utility bills with a product that's labeled as energy efficient and an AERC rating that makes sense for your home and your climate. 

Frequently asked questions