Do Blackout Curtains Keep Out Heat?

Blackout curtains are wildly useful little suckers. They’re great for night owls who just want to sleep without the burning gaze of the sun. Their little-known additional benefit, however, is thermal control in your home.

Not only do Black Curtains keep out sunlight, but they help keep out heat, cold, and sound as well!

DreamyHome actually wrote about how to warm a cold room, and blackout curtains featured heavily there, so check it out! So without further ado, here’s everything you need to know about blackout curtains!

Blackout Curtains: How Do They Work?

Let’s start with an important distinction: curtains vs. drapes. The former is a single layer of fabric, generally designed to allow light to filter in. The latter, on the other hand, is designed in a multi-layered fashion. 

Both can come in blackout forms, but there is a minor difference. Blackout drapes will generally have a layer of “blackout” material in between the layers. In contrast, blackout curtains will be made out of the material entirely (or almost entirely).

In short, these function to block sunlight from entering your home thanks to a tightly woven fabric that simply doesn’t allow light through.

READ NEXT: Heating stuck on? Here’s why.

The Benefits of Blackout Curtains

Regardless of the form, blackout window coverings operate in a simple scheme – a tightly woven, thick material stops light from getting through your window. There are actually a few benefits to this, intended or otherwise:

  1. UV light is unable to get into your home unless you want it. This prevents damage and fading in your paint or wallpaper, furniture, and really just about everything. Believe it or not, UV light is pretty damaging to a number of things in your home, including you.
  2. They block sound! While it’s not true soundproofing, they can block some sounds both inside and out of your home. This is especially nice for those of us who like to sleep in pitch-black silence. This is especially useful if you live in an area with a lot of ambient noise (like a large city).
  3. Blackout curtains also keep out heat and cold. Since windows are the culprit of roughly ~25% of your home’s energy loss, this is a really nice bonus. Not only will they help you save money, but they’ll keep your home cooler in the summer and warmer in the winter. This is because they prevent outside air from mingling with your home’s air. It functions like a ship’s sail catching wind and will help thermally regulate your home.

Adding strips of electrical tape to secure your curtains to the wall might not look the best, but there’s an upside. It’ll improve all of the above effects – so if you really need one (or all) of these benefits, consider securing your curtains. And if they’re in the right place, guests will never even notice the tape!

The Many Forms of Blackout Curtains

As with most things in life, buying blackout curtains isn’t a one-and-done process. There are a lot of forms they can take, each with its own benefits and trade-offs. So what should you look for?


Generally, blackout curtains and drapes come in four styles: grommet, rod pocket, tab top, and pinch pleats. They’ll also come with a varied lining, each with their own uses.

  1. Grommet curtains use, well, grommets to secure them in place. In other words, the fabric is looped into metal rings that attach to a bar or other fastener.
  2. Rod Pocket curtains are the most common style you’ll see in older homes. You know the type – a bar goes through a pocket in the top which is then mounted to the wall.
  3. Tab Top curtains hang from a tab at the top. I know, this is really complicated, but don’t worry – we’re almost done.
  4. Pinch Pleat curtains are designed to look as though they’re pleated. This is accomplished by sewing fabric in bunches at the top to make it bunch up and fold. This is really just a style choice.


As for the lining, there are four main styles to look for:

  1. Foam-lined curtains are designed to keep their shape and remain relatively stationary. Their added benefit is that foam is a great sound dampener.
  2. Thermal-lined curtains are designed to, you guessed it, regulate temperature. They’re more likely to keep your home at its current indoor temperature (hot or cold). They also generally don’t work as well to actually block light.
  3. Privacy curtains are generally a soft cotton or poly blend designed to block out natural light and not much else. These are, in essence, just dark curtains, rather than actual blackout curtains.
  4. Blackout-lined curtains are, as the name implies, explicitly designed to block all light. They are generally heavier and stiffer than normal drapes, which allows them to stay in place more easily.

Material & Colour

Contrary to what the name might imply, blackout curtains come in a wide variety of colours now. You can get them in most shades; you just need to match them to your decor!

One of the more important decisions when picking blackout curtains or drapes, however, is material. Believe it or not, the material you pick could actually impact your health, so pay attention:

  • Vinyl curtains are still in production, despite the fact that they’ve been proven to release harmful toxins. Otherwise known as polyvinyl chloride (PVC), vinyl can cause severe liver damage. So just like your shower curtains, you should avoid vinyl for your regular curtains.
  • Heavy microfiber, especially in a triple-weave, is fantastic for blackout curtains (though sometimes more expensive). It will generally block at least 90% of natural light and will help with temperature control.
  • Polyester or a polyester blend is cheap – that’s its main benefit. It’s strong and durable, won’t shrink or wrinkle easily, and is easy to clean. This makes it ideal for those who don’t want to have to regularly clean their curtains.

A final note is that regardless of your fabric choice, it’s best to aim for a thicker material than you think you’ll want. All of the benefits of blackout curtains are improved by a thicker layer between you and your window.

Final Thoughts

Blackout curtains are useful for several things. Whether you’re a nightwalker who hates sunlight or you love the sunlight but work from home, they’re great. Blackout curtains keep out the heat, cold, sound, and (obviously) sunlight. They’re also great to put in rooms that have particularly drafty windows, or in areas with a lot of noise.

As a former graveyard shift cook, I can’t endorse the use of these suckers enough. Without them, I would have been a sleep-deprived mess.