The moment summer temperatures start getting out of control, people everywhere do the exact same thing: close the shutters, block the sun, and hope the apartment doesn’t turn into an oven by mid-afternoon. It sounds smart, but according to experts, fully shutting your shutters during a heatwave might actually make your home feel even warmer.
As temperatures keep rising every summer, more homeowners are trying to survive the heat without running the air conditioning all day long. Shutters are usually seen as the easiest solution because they keep sunlight out and darken the room almost instantly. But there’s a small detail many people overlook, and it changes everything when it comes to keeping indoor spaces cool.
Fully Closed Shutters Can Secretly Trap Heat
Closing shutters completely may seem like the ultimate defense against the sun, but it can create a problem most people never think about. When shutters are fully sealed, hot air gets trapped between the shutter and the window glass.
Once sunlight hits that space, temperatures rise quickly and the heat has nowhere to go. Instead of protecting the room, the hot air stays pressed against the glass for hours and slowly warms up the inside of the home.
This happens even faster on windows facing direct sunlight during the afternoon. Top-floor apartments and attic rooms usually feel it the most because they already heat up faster than the rest of the house.
The surprising part is that many modern shutters are actually designed to avoid this issue. Those tiny ventilation gaps people barely notice are there to help air circulate. When everything is completely sealed shut, that airflow disappears and the heat builds up much more easily.
Experts now recommend leaving shutters almost closed instead of fully shutting them. Keeping a small opening at the bottom can help air move around while still blocking most of the sunlight.
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The Goal Isn’t Darkness, It’s Airflow
A lot of people assume the darker the room, the cooler it will stay. But experts say airflow matters just as much as blocking sunlight. One of the best things to do is close shutters early in the morning before the sun starts heating the windows directly. Once the glass becomes hot, the room will naturally start warming up throughout the day.
Then, later in the evening, opening windows and lifting shutters helps push the trapped heat back outside once temperatures drop. It’s one of the oldest cooling tricks out there, but it still works surprisingly well.
Roof windows need even more attention because they receive stronger sunlight for longer periods. That’s why many roof shutters are specially designed to keep some air moving while still protecting the room from direct heat.
Shutters also help protect furniture, wooden floors, and curtains from UV rays during the summer months. But according to specialists, using them correctly matters more than simply keeping them fully shut all day.
