June 30, 2025, 10:13 am | Read time: 3 minutes
If the temperature in your home rises due to summer heat, quick cooling is needed. Some people turn to a supposed trick involving aluminum foil to provide relief. However, experts warn against it: The alleged trick can do more harm than good.
If heat builds up in the apartment, some measures are supposed to help. To avoid high temperatures indoors, a trick with aluminum foil is said to help against the heat. This supposed trick is also recommended online. However, it is not advisable, as an expert explained to myHOMEBOOK upon inquiry. In the worst case, the window could break. What’s behind this?
Follow myHOMEBOOK on WhatsApp now
Aluminum Foil Against Heat? Experts Advise Against the Trick
Sticking some aluminum foil to the window is supposed to keep the apartment pleasantly cool even in summer temperatures. The sun’s rays are meant to be reflected by the shimmering foil, preventing them from entering the apartment. While this sounds plausible and straightforward, it can negatively affect the window panes.
“Basically, you shouldn’t stick anything to the inside of windows,” explains Pantea Khaledpour from the Window + Facade Association (VFF) upon inquiry from myHOMEBOOK. “The aluminum foil is intended to add an internal sunshade, but without sufficient ventilation, it causes a high thermal load on the glass, which can lead to glass breakage.”
About the Person: Pantea Khaledpour is a spokesperson for press, communication, and marketing at the Window + Facade Association (VFF) in Frankfurt/Main. The association represents the interests of manufacturers, installation companies, and industry and trade partners.
Related: When Not to Ventilate in the Heat
And What if You Stick the Foil Outside?
In many cases, the aluminum foil is applied to the inside of the window, likely for simplicity. Is it better to attach it outside? “Sticking aluminum foil to the outside of the windows leads to similar problems if the foil only covers parts of the glass,” says the association spokesperson. “This results in thermal stresses on the glass, similar to a shadow, which can lead to glass breakage.” You would have to cover the entire outside, which would make the room dark, and that’s not a good solution either.
Simple Trick to Combat Condensation on Windows! Does It Really Work?
Aluminum Foil in Flower Pots to Combat Pests–Expert Shares Her Opinion
Which Methods Really Help Against Heat in the Apartment
So, the aluminum foil trick on the window is not recommended. But how can you protect yourself from the heat instead? “Products for external and internal sun protection are generally recommended,” says the association. Specifically, this includes awnings, indoor blinds, or roller shades. An external sunshade is more efficient, “as most of the sunlight is blocked before it reaches the glass.”
More Tips Against Heat in the Apartment
Especially in attic apartments, the heat is often unbearable. Find out what options are available for cooling here. Whether drying damp laundry indoors helps lower the room temperature is discussed in this article. And here you can learn how to get your garden and plants through the summer.