Aluminum Foil On Windows: What Is the Purpose Of It?

In the last few years, many places in the world have had almost unbearably hot summers and high temperatures. In the past, the heat was blocked out by building houses with extremely thick walls that isolate warmth and throwing cold water on the roof after sundown. Some people even put wet reeds on windows that lowered the inside temperature when the breeze would pass through them.

Today, the most common cooling option is air conditioning, also called the AC in short. The issue with the AC is that it tends to use up a lot of electricity, which leads to higher bills. But placing aluminum foils on windows can also partially stop heat from coming into the house. This way you don’t need to use AC and you can save money on cooling. In this article, we’ll explain how aluminum foil prevents heat to enter the house and what are the benefits of using it. So, let’s start!

Is It Safe To Put Aluminum Foil On Windows?

So Is It Safe To Put Aluminum Foil On Windows? It is completely safe to use aluminum foil on the windows as they are toxin-free and because they remain stable at extreme temperatures. People mainly use aluminum (tin) foil on their windows to prevent heat from entering the house.

Does Aluminum Foil Keep Heat Out?

Aluminum foil also referred to as tin foil is a must-have item in the kitchen. People mostly place their meals in plates or bowls and cover them with tin foil when they want to save them for later. This technique is effective for food preservation because the aluminum foil is heat-proof.

Other than as a food cover-up, tin foil is used as a protective barrier placed over baking trays while cooking in the oven. Besides keeping out heat, tin foil isolates other factors that contaminate food such as odor, moisture, germs, oxygen, and light.  Additionally, it preserves the freshness of the food by keeping in wanted moisture, scent, and flavor.

Tin foil is amazing for many uses but when it comes to keeping heat out of a home, it can also serve that purpose. The foil does reflect some light away from the windows and that way blocking the heat to enter, but the foil itself does warm up after time. This means, that the heat is not just disappearing into thin air, it’s accumulating in the foil. The best way to use the maximum isolation power of the aluminum foil is to place the shiny side towards the outside and to add a layer of cloth or cardboard to the matt side facing towards the inside space.

You can see how to do it in the video below.

Does Aluminum Foil Keep The Cold Out? 

Aluminum foil on windows does keep the cold out to a certain degree but not completely. To stop the cold from entering your home’s true windows, there should be another insulating material like bubble wrap, added on top of tin foil. After winter is over, both can be removed.

Health Concerns About Aluminum Foil

There have been some speculations that using aluminum foil can cause safety hazards and that it can be very harmful to people. Thankfully, that isn’t the case. There hasn’t been any proof of the harmfulness of tin foil in any type of circumstance. Not as a window cover nor as a food cover.

Aluminum is strong enough to withstand high temperatures and summer sunlight without melting and it does not radiate harmful toxins into your house when it is exposed to sun and high temperatures. Therefore, nothing harmful can happen because the aluminum foil is placed on your windows. After all, if any of this were true, the tin foil wouldn’t be approved for common use around food.

People have also been scared that tin foil on windows can attract lightning strikes making your house a bigger target for getting hit by lightning. This as well is a lie. Aluminum has no connection to lightning. Therefore, having tin foils on your windows won’t attract nor repel lightning. The only way aluminum can be dangerous is if you eat it or its dust specks are breathed in, in manufacturing factories. Otherwise, aluminum can’t hurt humans.

If you want to know more about the safety issues of aluminum, you can read this medical article about the Symptoms of aluminum toxicity.

Reasons To Use Aluminum Foil On Your Windows

Aluminum Foil On Windows

Other than sun protection, aluminum foil has other useful benefits why people can use it on their windows. Here are a few reasons named below:

1. Glare Protection

Windows let through beautiful sunlight and airiness into the house, but sometimes they let through aggravating sun-caused glares as well. Because intense sunlight glares shine at certain angles, they can come in the way of doing things around the house. They might be interfering with using the bathroom mirror in the morning or watching TV at noon. If that is the case, a cheap but effective way to stop the glare is to put tin foil on your windows.

2. Room Darkening

Many people do not like getting woken up by sunlight. It might be because they work night shifts and want to sleep during the day, or they just like to sleep longer. Either way, there are multiple solutions to this issue. Some are getting blinds, room-darkening shades, or thick curtains installed. Although simplest of them all in to use a tin foil.

If you are in a rented apartment or just do not want to spend a lot of money at the moment, placing aluminum foil on your windows will do the job perfectly for a few dollars of expense. Tin foil seals out light and creates a much darker environment in the room. A great thing about aluminum foil is that it fits tightly all the way to the edges of any window because it’s thin and can be adjusted to any shape. Because of this, the light-blocking effect is even more precise.

3. Have Privacy

People use all sorts of window coverings such as blinds, shades, drapes, curtains, and shutters. Other than blocking light, they are used for maintaining privacy as well. Privacy is a very important part of everyday life. Some things just aren’t meant to be seen by every neighbor passing by. Using tin foils might not be the best long-term solution, but it does come in handy as a quick and cheap short-term option. Tin foil isn’t the most aesthetically pleasing either, but it is extremely inexpensive, and it does the job well. Paper also works but not nearly as well as tin foil.

4. To Save On Utility Bills

The amount of energy most households use to maintain a fresh and cool living space temperature during the summer is big. This is because the temperatures are getting higher and higher every year and the most efficient way to cool your home is to use the air conditioning system.  

Most people let ACs run continuously throughout the summer months and end up receiving huge electricity bills afterward. A way to lower the cost of cooling is by placing aluminum foils on windows and glass surfaces. The tin foil works as a bumper for heat by redirecting sunlight elsewhere. That way the air conditioning can have a break occasionally which will save you significant amounts of money during the summer.

5. Car Window Covers

Many people cover their car windows with tin foil for the same reason they cover their house windows. Aluminum blocks heat by redirecting sunlight. That way less heat enters the car during the unbearably hot summer months. Although we advise you to buy special aluminum covers for this so that you do not have to use a new foil every time.

How To Put Aluminum Foil On Windows

Now that you are familiar with the possibilities of aluminum foil and how it can benefit you, we will now explain how to use it correctly. Underneath we will explain how to place aluminum foil on windows in a few simple steps.

1) Purchase A Quality Aluminum Foil

Aluminum foil is quite cheap. That’s why it shouldn’t be an issue to purchase larger amounts of it. You will need more if you want to cover multiple windows and in case some of it tears while applying. Our advice is to look for the more expensive tin foil on the shelves because the cheapest ones won’t hold up very well. The cheap foil will be very hard to apply because it will keep breaking and dividing in the wrong places. Don’t worry, the most expensive tin foil will still be drastically cheaper than curtains or blinds but will serve you for a long time. You can find it HERE

2) Measure Your Windows

This step can be done first or second, it’s up to you. If you measure windows as the first step you will know how much tin foil you actually need. You can also just buy a rough amount and come get more if you end up missing a little bit. You should measure the height and width of the window and multiply those to measurements with each other to get the surface area of one window. Use a tape measure for this.

Do this for each window if they aren’t the same size. When measuring, take into consideration that you are only covering the glass, not the frame of the window. Adding the area numbers of all windows together gives the overall area of foil you need.  

3) Cut and Tape The Aluminum Foil On Window

After measuring, cut or tear the aluminum foil into the shape of the window. Place it on the glass and secure the ends with wall-safe tape. It can be masking tape or scotch tape, for example. From time to time, it will be necessary to swap out old foil for a new one and replace the tape because it will lose its stickiness because of exposure to heat and light.

It’s important to point out that this shouldn’t be a permanent solution if the window is in a very visible place. The reason for this is the fact that it will look suspicious to your neighbors. Additionally, the glare coming from the metal shines in all directions which can be distracting to drivers and aggravating for pedestrians.

Moreover, the look of foil is not very luxurious and clean, therefore getting something nicer should be an end goal. If the window is not visible to anyone but you, this shouldn’t be a big issue. Tin foil is used long term mostly for ceiling windows that no one sees but tend to have glares peeking through them.

Things To Consider Before Putting Aluminum Foil On Windows

Most often, people use ordinary aluminum foil on windows to protect them from sunlight. The plus of this material is obvious – it’s low cost and it’s easy to set. But are there some disadvantages to this method and are they safe? Here are a few facts you should know.

  • Aluminum is Toxin-Free

Cooking items that you use in kitchens such as pots, cookers, and pans are made of aluminum. The reason why these materials are made of aluminum is that they remain stable at extreme temperatures, unlike other materials that can release toxins when they are exposed to high temperatures.

When you place aluminum on windows, they can withstand temperatures as high as 212 °F (100 °C). The aluminum foil keeps radiant heat and it is reflecting the sunlight away.

  • Neighbors Might Find It Strange

Adding aluminum foil to your windows may invite suspicion to your neighbors. Anyone who sees windows covered with aluminum foil will start wondering why it is on the window and what is the reason for it. Some people when they notice this can even report suspicious activity to the police without asking you why you put it on.

  • Aluminum Foil Is Legal

Placing aluminum foil on the window will not get you into trouble as far as the law is concerned, as they are allowed. Although it would be advisable to inform your neighbors and tell them the reason why you put aluminum foil on your windows. Keep in mind that putting aluminum foil on windows can also sometimes interfere with indoor air quality and your ventilation system.

Disadvantages Of Using Aluminum Foil

  • Little light. This method of sun protection has many disadvantages, the main one is that sunlight does not enter the room at all. 
  • Not aesthetically pleasing. The next drawback of aluminum foil on windows is not an attractive appearance. In the modern world, the aesthetic side is of great importance, and windows have become not only a protective and protective structure, but also a full-fledged element of the interior.
  • Easy to tear. The household wrap is a material that tears easily, so you may get in trouble during the gluing process.
  • You are not modern. Sticking foil on windows is still a relic of the past, like, for example, gauze instead of a mosquito net. Today, there are more attractive and convenient ways to protect a room from the sun.

Can Aluminum Foil Damage Windows?

Aluminum foil can damage windows but only slightly. The only possible damage could be thin and short scratches on windows that can be fixed with a buffing material. Other than this rare damage occurrence, aluminum foil is safe to use for window wrapping.

If you want to learn more, you can also read our article Smart HVAC System Explained.


People cover their windows with aluminum foil to block out heat and light during the summer and thus save money on electricity bills. They also often use it to cover their car windows to stop heat from entering or just regular house windows to add privacy. Whichever way the foil is being used as a cover, there is no reason to worry about safety because aluminum is safe for humans. This technique has been used for years now by many and has never created a safety issue. This option might not be the best for long-term window covering but it’s an excellent way to quickly block out the sun. If you have any more questions, feel free to reach out!

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