If you live in a climate with especially hot or cold weather, you probably already know that curtains are more than window dressing, as they help regulate light and heat. Replacing windows is a good strategy for reducing energy bills and planet-heating emissions, as well as increasing your comfort, but this can also be pane-fully expensive. It's also not an option for renters.
Thermal curtains, on the other hand, are a comparatively inexpensive method to help keep rooms warmer or cooler. During summer, thermal curtains block solar gain and reduce the amount of heat that can get through windows.In winter, they are an insulating barrier between the chilly outside air and warm inside air. Made of several layers of materials and fabric, they are designed to provide thermal resistance (known as R-value) and prevent thermal transmittance conductivity (known as U-value).
It can be challenging to find these curtains made of sustainable fabrics and materials. Still, the layers can improve the overall energy efficiency of a home or office. They can reduce heat loss by up to 25% in the winter months and reduce solar gain by 33% in summer months. Despite the fact that they often include polyester, we believe that the energy savings are worth it.
Here are some of our favorite thermal curtains on the market today:
Best Overall
Moondream 2-in-1 Thermal & Blackout Curtain
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Moondream offers multiple OEKO-TEX Standard 100 certified options. This independent certification for textiles guarantees that fabrics were produced without the use of harmful substances. The innovative lining has been independently tested and shown to cut heat loss by 46% during winter months, and can keep a room up to 5 degrees cooler in the summer, compared to a window without any window treatment.
This panel is 99.97% polyester. The reinforced, rust-proof 1.6-inch diameter grommets allow for easy and durable hanging on most curtain rods. It's easily adjustable to the height of your window with included iron-on tape. They are also light-blocking and machine-washable, making them our top overall choice.
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For those on a tight budget, Target offers this mega-affordable room-darkening thermal panel. It's made of 100% polyester and is OEKO-TEX certified. That means it won't emit funky fumes or chemicals into your room.
It's available in multiple colors. Order online and have it delivered, or pick it up at a location near you and block out the lights tonight before bedtime.
Best Indoor/Outdoor
Deconovo Thermal Insulated Blackout Curtains
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This single-panel option comes in multiple sizes and multiple colors. The darker the color, the greater the light reducing capability.
The innovative triple-weave construction blocks out most of the sun's UV rays. Grommets are sized to fit most curtain rods. They are machine washable.
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Best Noise-Reducing
NICETOWN Thermal Blackout Curtains
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Tired of hearing your neighbor's dog bark while you try to sleep? NICETOWN'S thermal curtains feature a black yarn layer sandwiched between insulating microfiber layers. They seamlessly block out 99% of sunlight and reduce external noise. Home theater lovers will also love the sound-block ability of these curtains.
They are topped with 1.6-inch grommets that are suitable for hanging on most standard curtain rods. One of the 20 colors options is sure to match your favorite duvet cover. They can be machine washed.
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Even though they’re white, when combined with the a liner these curtains block out both light and noise (be sure the "blackout lining" option is selected). They're ideal for use in the living room, bedroom, or to create total darkness for your home theater system. They have two hanging options: pole pockets or back tabs.
Available in both a pure white and ivory option, the curtains are made from OEKO-TEX Certified cotton, which means they're free from concerning chemicals commonly used in textile manufacturing. The lining is polyester and comes with curtain hooks. Both the curtains and linings are Fair Trade Certified and machine washable. Pottery Barn is also part of the Better Cotton Initiative, which helps train cotton farmers to care for the environment.
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Velvet curtains can add a warm, cozy feeling to your decor, and even more so when they’re lined with an insulating layer. These ones are available in nine colors, including pink, burgundy, grey, gold, navy, taupe, teal, white, and vanilla. They are made from polyester and OEKO-TEX Standard 100 certified.
Each pack contains two curtain panels, which can be machine washed in cold water.
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Most thermal curtains are thickly lined and block the majority of light from street lamps and the sun. However, for people who are very sensitive to light, these curtains can have a total blackout effect when hung properly. Another 100% polyester curtain, they are machine washable and also offer insulation thanks to a thermal lining. However, the “faux silk” fabric that faces into the room is quite shiny, which isn’t to everyone’s taste. Note that these panels are also sold individually.
For the best light-blocking, be sure the curtain rod is placed higher than the window, so that the grommets are fully above the window pane. It’s also better to have a curtain rod that hugs the window closely, so that there’s not a gap that light can shine through.
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If you don’t need a set of curtains, this single panel is a great option. It comes in ten colors, and is machine washable. It has a durable 3-layer white lining that reflects light and helps keep rooms cool in the hotter months, while adding insulation to your room in the winter that prevents heat exchange by up to 40% according to the manufacturer. These curtains can also reduce outside noise, and have an attractive woven texture on the side that faces into the room. They’re 100% polyester.
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Perfect for any room with a patio door, this extra-wide single panel curtain is an energy-efficient alternative to vertical blinds. It not only improves heat retention, but also block noise and light, and is machine washable.
Made a soft 100% polyester blend, it's recommended for sliding doors that measure between 36 and 65 inches wide and the grommets have a 1.6 inches diameter opening. The reverse side is the same color as the front panel. The curtain rod is not included.
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Final Verdict
What to Look for in Thermal Curtains
Layers
Most thermal curtains are made with three layers of material (but two and four layers are available). Like any curtain, there is a layer of decorative fabric that faces into the room. These are typically made of woven materials like cotton, polyester, linen, wool, or silk.
Then there is a middle layer composed of thermally resistant material like foam, felt, flannel, or thick cotton batting. The third layer, known as the backing, protects the inner layer from sunlight, and sometimes condensation that forms around windows. Sometimes a fourth layer is added to serve as the vapor barrier.
If you live in a particularly hot area or want a window treatment for West or South-facing curtains, choose light-colored backings to reflect light and reduce solar gain.
R-Value
The higher the R-value of a material, the more insulation it provides. A standard curtain has an R-value of R-1. But a properly fitted insulating curtain can boost that to R-6.
Get the most bang for your buck by hanging your curtain as close to the window frame as possible. Choose those that drop to the windowsill or floor.
Once you've hung the curtain, consider sealing it on all sides with Velcro, magnetic tape, or self-adhesive weather stripping to reduce thermal transmittal most-effectively. You can add a valance above the drape to reduce air infiltration. Eliminate gaps by generously overlapping the curtains in the middle.
Curtain Header
The curtain header refers to the way a curtain attaches to the rod. The four most common curtain header types are grommet, channel, top tabs, and curtain rings. Tabs and curtain rings tend to leave a lot of space at the top of the widow, so we don't recommend these styles for thermal curtains.
Most of the curtains on this list use grommets, which are easy to put up and tend to make the pleats of the curtain look nice and even. However, channel-style curtains can also be great for thermal and blackout curtains, because they have the fewest gaps or perforations in the fabric to let light and air through. But a downside of channel style curtains is that they can be fussy to get them to hang nicely and pleat evenly.
How to Use Thermal Curtains
Open your curtains during less hot parts of the day in summer or warmer parts of the day in winter. This will also alleviate condensation build-up. Close them at night to reap the benefits of their insulating, privacy, and sound-reducing properties.
For even more insulation, you can combine curtains mounted on the outside of the window frame with a blind that's mounted inside the window frame.
Why Trust Treehugger?
Heidi Wachter has been writing about health and the environment for over a decade. A DIY devotee, she is always seeking out sustainable ways to reduce the energy footprint of her 107-year-old home.
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