When temperatures start soaring, many people do the same thing: close the shutters as early as possible to keep the heat out. It sounds like common sense, and in many cases it does help. But what if that habit isn’t as effective as you think?
During heatwaves, plenty of homeowners and renters find themselves dealing with overheated rooms even though their shutters have been closed all day. The problem often comes down to something many people overlook: the windows themselves.
Once the sunlight heat gets through the glass, it can linger for hours, making indoor spaces feel stuffy and uncomfortable. That’s why an old-school trick is getting renewed attention as people look for simple and affordable ways to keep their homes cooler without relying entirely on air conditioning.
The Real Problem Might Be Your Windows, Not Your Shutters
Closing the shutters can definitely help, but it’s not always enough on its own. Some shutters don’t completely block sunlight, while other windows may have little or no external protection at all.
When sunlight hits a window for hours, the glass absorbs heat and gradually transfers it indoors. Even if curtains or blinds are closed, part of the heat has already made its way through. That’s especially true for windows that face south or west, which tend to get the strongest sun during the hottest part of the day.
This is why some rooms can feel like ovens by late afternoon, even when the shutters have barely been opened. Fans may help move the air around, but they’re often just circulating warm air that’s already trapped inside.
Because of this, some people are turning their attention directly to the glass itself. Instead of trying to block heat after it enters, the idea is to stop as much of it as possible before it gets through the window.
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An Old Household Trick Is Making a Comeback
One solution attracting attention is something called Meudon white, a natural powder that’s been used for decades for cleaning and DIY projects.
Mixed with water and brushed onto windows, it creates a thin white coating that reflects part of the sun’s rays. The goal isn’t to make a room completely dark. Instead, it helps reduce the amount of sunlight and heat entering through the glass.
Many people compare the effect to frosted glass. Rooms remain bright, but the sunlight becomes softer and less intense. That’s why the technique is often used in rooms that receive strong afternoon sun, such as living rooms, kitchens, or attic bedrooms.
Another reason for its popularity is that it’s temporary. Once the hot weather passes, the coating can simply be wiped away with water and a cloth.
A Simple and Affordable Way to Help Keep Rooms Cooler
What makes this trick appealing is how inexpensive it is compared with many other cooling solutions. It doesn’t require electricity, installation work, or expensive equipment.
Of course, it’s most effective when combined with other good habits, such as airing out the home early in the morning or late in the evening and keeping windows closed during the hottest hours of the day. While it won’t replace air conditioning, many people see it as an easy way to reduce heat buildup indoors, particularly in rooms with large sun-facing windows.
