This is because windows have a significant impact on heat loss. “It’s not as efficient as a wall,” says Michelle Blackstone of the National Window Rating Council, which sets efficiency ratings for products like windows, doors and skylights. Although windows make up about 10 percent of a home’s surface area, heat transfer through windows can account for 30 percent of the energy used for residential heating and cooling, according to the U.S. Department of Energy.
Window treatments help reduce heat transfer, but not every room requires the same product. For example, a room drenched in sunlight requires something different than a room covered in shade or in a cooler climate.
Before purchasing a new treatment, determine what conditions your windows typically encounter, whether that’s hot summers, cold winters, or a combination of the two. Then head to the Attachments Energy Rating Board’s product database, which identifies different product models and their performance capabilities.
What if the product that gives your room the best efficiency boost doesn’t align with your design vision? Experts say installing almost any treatment is better for reducing heat transfer than doing nothing, but consider pairing your favorite model with a more energy-efficient one to double the effect.
“A layered approach is best,” says Esfera Jensen, principal designer and CEO of Nufacet Interiors, a luxury residential interiors firm in the New York City area. For example, she often combines cellular shades with curtains in her clients’ homes. “Not only is it beautiful, but it also provides a lot of energy efficiency functionally as well.”
You won’t reap the benefit of a lower utility bill unless you use your window treatments correctly — which means they should be adjusted as the day progresses. If you’re not inclined to change the position of your shades as the sun moves across the sky, there are options for automatic or “smart” window treatments that do the work for you.
“There are certain systems available today that you can adjust based on the sunlight actually hitting the windows, and you can adjust and change them based on your schedule,” as well as weather settings and expected sunrise and sunset times, says Tracy Christman, executive director of product development and strategy at Budget Blinds. Extra bonus? Auto-adjusting window treatments can give the impression that someone is home when you are on vacation.
Not sure which type of window treatment will work best for you? Here’s expert advice on what makes the most sense in different situations — and what to look for when shopping.
Shades can boost energy efficiency, but different styles excel at different tasks. Christman uses Roman shades in her home in Scottsdale, Arizona, which she says work well year-round in her area, which has fluctuating temperatures. During the hotter months, the shades keep the house “nice and cool, but they also keep it warm in the winter,” she says.
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The Department of Energy notes that Roman and roller blinds do the best job of blocking sunlight but provide only “a small amount of insulation” — a trade-off that may be worth it for a home that sees mostly hot days with occasional low temperatures.
On the other hand, cellular shades, with their honeycomb-like fabric pockets that trap air, can increase energy efficiency in both cold and hot climates. Specifically, the department says cellular shades reduce window heat loss by at least 40 percent when the heat is on, and by 60 percent during the cooling season.
With any shades, Jensen prefers thicker fabrics with tighter weaves to increase insulating potential and reduce air circulation in the outer fabric and lining or backing.
Energy efficiency varies greatly with curtains and fabrics as they can be anything from light and airy sheer curtains to luxurious velvet panels.
The upside to fabrics, of course, is that it’s easy to change the look of a room by swapping out panels, says Stephanie Harvey, who oversees energy efficiency programs at Hunter Douglas, a window covering company.
“A lot of times, we sell a lot of white and off-white in our shades and shades, so I think curtains give you that option to add color, to change up more in your design, there are just more directional options and patterns and colors available.” Says.
If you go this route, more layers of lining, as well as thicker, tighter-woven fabrics, will prevent further heat transfer, whether you’re running the air conditioner or turning up the heat. If your home does not experience strong sunlight or weather conditions, breathable or sheer fabrics are your choice.
“You can also not only tie the curtains, but tie the blinds, and the binding will make those curtains thicker (and) will also provide more energy efficiency,” Christman says.
Curtains can trap heat and prevent it from escaping, according to Christman. Jensen adds that she would consider it for clients who “feel like they need an extra insulating factor or additional elements to soften the sunlight in the space.”
But from a design perspective, Jensen says curtains may not look natural in homes that aren’t farmhouse or coastal in style. If you choose blinds, Jensen says, install them on smaller windows where the view won’t be disrupted, such as a sunny kitchen facing a neighbor’s property.
While vertical and horizontal blinds may block sunlight as they are drawn, they “do a poor job of preventing air circulation” regardless of the material. In this regard, Jensen says, having blackout curtains is like not having any window treatment at all.
Even if you don’t care about energy efficiency, it’s best not to use blinds, Jensen says. “They’re old, and they don’t really look as good (as other options)…but aesthetics aside, they don’t really work as well as cellular shades or other products.”
Bridget Reed Murawski is a freelance writer in Washington, D.C