What are thermal curtains?

Last Updated on February 24, 2018 by Dave Farquhar

What are thermal curtains? Thermal curtains are thick curtains with multiple layers of fabric and a layer of foam to help block the flow of heat. This helps you save energy, while also having sound dampening effects.

Thermal curtains work similarly to blackout curtains. But since their intended purposes are slightly different, a thermal curtain might have some shortcomings as a blackout curtain, and vice versa. If you want a curtain to do both, make sure it actually states that it does both. Otherwise, I recommend getting dark-colored thermal curtains. A blackout curtain may not block as much heat as you would like. Similarly, a light-colored thermal curtain might let in more light than you like.

How thermal curtains work

what are thermal curtains?
Thermal curtains contain a layer of foam. Their insulating properties are especially noticeable with older windows like this one. They provide energy efficiency while not detracting from the appearance of historic windows.

Windows do a much worse job of blocking heat than walls do. This makes windows a source of heat in the summer and a source of cold in the winter. Thermal curtain panels put an extra layer of insulating foam in between the weather, the window, and you. This provides a vapor barrier, reduces heat loss, and saves energy costs.

You’ll feel the effects of thermal curtains most in houses with older windows. If your house has certain requirements for windows due to historic preservation, thermal curtains can be a good way to add some energy efficiency without breaking those requirements. If your house has old single-pane windows with aluminum window frames, those are very good candidates for thermal curtains. Thermal curtains will improve the energy efficiency in rooms with older windows for a fraction of the cost of replacing the window. They are much less expensive than even the cheapest window, and without the hidden costs and fees. I found I could replace four or five sets of curtains for about the cost of one window.

Thermal curtains also help in rooms with newer, energy-efficient windows, but the effects won’t be as great. Still, since the cost of thermal curtains has really come down in the last decade or so, they are an inexpensive energy efficiency upgrade. At one time you had to buy the at specialty stores, but today even discount stores carry them. Eclipse is the name of one common brand.

Do thermal curtains work in the summer?

Thermal work effectively in all seasons, although they tend to make a bigger difference in the winter.
Thermal curtains can keep heat out in the summer and keep heat inside in the winter. The more direct sunlight a room receives, the greater the effect thermal curtains have in the summer. In a room with a lot of shade, you won’t need them as much in the summer. But because of their ability to keep warm air on one side and keep it from passing through, they work in both summer and winter, when you need them the most.

Most people associate thermal curtains with the winter, but I first installed thermal curtains in the summer. One week when an extended power outage left us without air conditioning, I experimented by putting foam sheets in the windows to block heat. When I saw how effective it was at keeping the day’s most brutal heat at bay, I went out and bought thermal curtains.

Thermal curtains helped me lower my energy bill in spite of rates going up. To the tune of 19 percent. If you don’t happen to be on budget billing, thermal curtains can recoup their own costs very quickly. Even if you are on budget billing, they’ll help you have a better year next year.

Using thermal curtains

Thermal curtains are no more difficult to install than any other ordinary curtain. The only thing you may need to consider is their extra weight.
Due to their thickness, thermal curtains block a lot of light in addition to blocking heat. As a result, some people will open the curtains in rooms that aren’t getting a lot of sun. Just be sure to close them again at night, before leaving for work during the day, and before direct sunlight starts hitting the room.

Due to their low cost, thermal curtains are a good option when you can’t afford to replace aging windows with inefficient window frames and panes. They also maintain effectiveness once you are able to afford to replace those windows. After all, even the best window has a lower R value than the wall around it.

If you want, you can double up and put insulated thermal blinds in the windows as well. Changing curtains is easier, so I always do those first.

Thermal curtains use the same curtain rods and hardware as any other curtain. They may be slightly heavier than your old curtains, especially if you had sheers, so you may need a heavy duty curtain rod. In some cases, I’ve found I need to replace the screws that came with the mounting hardware with longer screws so they will hold better. But they are no more difficult to install than any other ordinary curtain. If you can install a regular curtain in 10 minutes, you can install a thermal curtain in the same amount of time. Even if you have to install a curtain rod, you should be able to get it done in less than half an hour, total.

Old books on energy conservation recommended closing curtains at night, saying it doesn’t help much but also doesn’t cost anything. Closing thermal curtains at night also doesn’t cost anything, and it does help. Quite a bit, in fact.

What if you can’t get a thermal curtain in a design you want?

Thermal curtain liners allow you to convert any other curtain into a thermal curtain if you need or want to do so. They are slightly smaller than the other curtain and attach with clips.
Thermal curtains come in a lot of designs, but you probably won’t find kid-themed curtains in anything other than a solid color, for example. If you can’t get a thermal curtain in the design you want, there is an alternative. Eclipse sells thermal curtain liners to convert other curtains into thermal curtains.

Get a thermal curtain liner in the length you need, then install the liner behind the other curtain. This gives you the benefit of a thermal curtain, while letting you use any design you want. The liners themselves are normally white, so they won’t interfere with whatever design is on your other curtain. They attach to the other curtain with clips, so you don’t have to hang a second curtain rod to use them. They are slightly shorter than curtains, so they can hide behind the curtain and not change the other curtain’s appearance.

If you wanted, you could conceivably double up, installing a liner behind a thermal curtain as well, to get an extra layer of insulation. The only problem I could see is the possibility of a light-duty curtain rod not being able to support the weight. But if you use anything other than the cheapest curtain rod in the store, you should be fine.

Thermal curtain liners aren’t much less expensive than an inexpensive set of thermal curtains. But if they let you combine energy efficiency with the design you or your kids want for a particular room, they’re probably worth it. They’re certainly better than going without.

What are thermal curtains, in conclusion

In the end, thermal curtains are an unheralded but very effective way to save money and energy costs. I’ve been using thermal curtains myself for the better part of a decade and I recommend them highly.

They look and work like any other thick curtain would, except the extra layer of insulation helps to keep you more comfortable. Replacing old conventional curtains with thermal curtain panels is a cheap and quick home improvement project that gives your house a nice energy efficiency upgrade, as well as a quality of life upgrade.

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