Thermal Curtains Lining Efficiency
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One of the most frequent questions we get from our readers is how efficient thermal curtains are. We understand the need for measuring, tracking and benchmarking is part of the human nature, however we can’t give a straight answer to the above mentioned question. If you insist, the best answer is “it depends”. What are the factors that influence thermal efficiency, we are going to see in this article.
Not all windows offer the same thermal insulation level. Older ones, with cracked wooden carpentry and with only one layer of ordinary glass will always provide less insulation than modern windows with double panes made of LowE glass and filled with an inert gas, usually Argon, with silicone sealing and with frames organized in chambers that help providing superior thermal insulation.
Some manufacturers went even further, so even triple glazed windows are available for those who need superior thermal comfort. If you have such a modern type of window and you add a thermal curtain to it, you probably won’t feel too much of a difference.
However, if you add an insulating curtain or drape to an old window, you won’t need measuring instruments to tell you that the thermal resistance of your window has significantly improved.
Other window treatments
Cellular window blinds or insulation shutters have a positive effect in preventing thermal exchanges at the window glass level, therefore they may be just enough for an efficient insulation, thus making insulating curtains redundant.
If your windows are orientated towards North, they will be less exposed to direct sunlight, therefore those rooms will always be colder than rooms which have the windows facing South.
R-value and u-value
The two parameters most commonly used to express thermal insulation are the r-value and the u-value. Usually, windows manufacturers and retailers state only one of the two values on their products. Let’s see why and how the two parameters are in relationship, so one of them is enough to define the thermal insulating properties of a window or door.
Types of Thermal Curtains and Drapes
There are very few differences between thermal curtains and drapes and ordinary ones, the main one being the lining. While normal curtains don’t have a lining, unless we need them to blackout, thermal curtains are made of two layers: one decorative layer, made of curtain fabrics such as silk, velvet, cotton or anything else, and one insulating layer which is made of a special material that does not conduct heat. Sometimes, this material may have a reflecting surface which will act as a barrier for thermal transfers.
Where to Use Thermal Curtains or Draperies
You can use insulated window coverings in virtually any room in your house. However, if you want to use them in bathroom, make sure that they are made of either waterproof materials or fabrics that can be washed in the washing machine.
Because of the high humidity in bathrooms, curtains and drapes that are made of thick fabrics will absorb a lot of water, get damp and eventually mildew, which is very difficult to remove once you’ve got it. So, by all means, if you want thermal curtains to keep you away from cold drafts while you’re taking a bath, remember to have them short and thin.
Types of Thermal Window Coverings
Any window covering which prevents the temperature exchange is a thermal one, or an insulating one. They can be anything, from exterior shutters, roller shutters, thermal shades or blinds, insulating curtains or drapes. In some areas, you can find in stores some thermal insulating kits for windows which consist of a very thin, transparent layer of insulating plastic which is attached to the windows with the help of heat from a blow dryer. Although they distort a bit your outside view, they can be an excellent solution to keep you warm over the winter.
When it comes to thermal curtains, there are multiple choices, depending on the method of hanging them at the windows: tab top, rod pocket, pinch pleated or eyelet. Many of them have two functions: thermal and blackout. This is why such curtains make a great choice for children’s rooms, because small kids may have troubles in falling asleep if they see light.
A special type of thermal curtains is the separate insulating lining attachment. This means that the thermal layer is not attached to the original curtain, but hung onto a separate track or rod. This is a good choice if you don’t want a permanent insulating setting, as you can detach them when you don’t need them anymore. Besides, they are easier to clean and in case you decide to change your regular curtains because of redecorating, you won’t have to change the thermal curtains too.
How Thermal Curtains Affect the R-Value
Thermal curtains can be a cost effective way to increase the temperature in your home with a few degrees during cold winter days. Although it is rather hard to believe, movable insulation means such as lined thermal curtains, thermal shutters, blackout cellular shades cordless top down bottom up or shades are contributing in such degree, that they can improve the R-value of your windows surface with 5-6 points. I can’t tell how much this means in degrees, but I promise you the difference is obvious.
In order to be more clear, let me tell you that the R-value is a parameter which defines the thermal insulation efficiency. An R-value of 1 is very poor, and that’s exactly the case of single glass pane windows. So, if you have such windows and you don’t have enough money to replace them with double glass panes, low-e ones, or to add another set of windows on either the interior or the exterior side, you could consider investing in insulated curtains. These are probably the cheapest window coverings with insulating properties.
In future articles, I’m going to detail more on the types of fabrics and linings used for thermal curtains, on how to make your own insulating curtains and on where to buy them, in case you don’t like sewing that much. I’ll also try to seek for coupons and promotions from retailers and stores and I’ll publish them here, in a special section of the site.
How to Make Your Own Thermal Curtains at Home
Thermal curtains are one of those things that can be made by anybody who can sew and who has access to a sewing machine. Supposing that you already have window curtains, all you need to do is add an insulator lining and make sure to seal the ends of the curtain, in order to prevent air circulation nearby the windows. However, you should keep in mind that in case you have those lightweight, sheer, voile curtains, the lining will be visible from inside the room. In such cases, if you want to avoid that, the best solution is to add insulated drapes in front of the curtains, and keep them tied-back to the sides when not needed.
The first step in making a thermal curtain is measuring your windows. The curtain should be bigger than the windows, in order to provide an efficient insulation. Allow a few extra inches to the left and to the right, as well as at the bottom. There’s no need to have it touch the floor. In case you are not making the curtain from the scratch, but only lining an existent one, take it off the window and measure it, as the lining needs to be almost the same size – you can make it about one inch smaller, in order to avoid it becoming visible when hung at the windows.
Here are two options: one is faster, but leaves the outer side of the curtain a bit uglier, as the seeing will be visible. The other one is nicer but requires more attention when sewing: you first sew three edges, then flip the curtain and only then sew the final edge. In this way, the first three will be looking very nice and well finished. For the first case, the lining needs to be a bit smaller than the curtain, while for the second option, the two of them need to be exactly the same size.
The lining material with insulating properties can be found as such in home and garden stores, so you’ll have to buy it.
Cut the lining with great care, so it fits the curtain, then sew them together. Start with the top of the curtain, then sew the other edges. For the best result, it would be ideal that you use pins to fix the two fabrics together, then see if you did it correctly, and only after that proceed to assembling them together.
For optimal energy efficiency, your thermal curtains need to be attached to the walls, not only to the curtain rod. If you allow gaps between the curtain and the wall, there will be drafts that will push cold air inside the room. An excellent and very cheap way to fix the insulated curtain against the walls is Velcro tape. Another idea is to sew magnetic straps inside the lateral edges of the curtain, then have metallic straps attached on the walls. I don’t know how much this costs, but it can’t be as cheap as Velcro.