Franka Kruse-Gering

June 26, 2026, 1:19 pm | Read time: 4 minutes

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1. Mistake: Thinking curtains are enough against heat

Closed curtains or pleated blinds do block sunlight, but they only help against heat to a limited extent. The sun’s rays have already penetrated the window glass and warm the curtain, which then releases the absorbed heat into the room.

External shutters, venetian blinds, or awnings are much more effective. They block the sun’s rays before they reach the window. The Consumer Advice Center also recommends external sun protection as one of the most effective measures against summer overheating. With shutters that have ventilation slits, it can be beneficial not to close them completely. This allows air to circulate between the shutter and the window pane, reducing heat buildup.

2. Mistake: Ventilating at the wrong time

When the apartment becomes stuffy, windows are often opened. On hot summer days, however, this can have the opposite effect. If the outside temperature is higher than the temperature inside, additional heat enters with the fresh air. Instead of cooling down, the apartment heats up further.

It’s better to use the cooler morning hours or the night for ventilation. Then, warm air can escape from the rooms, and cooler outside air can flow in. A short cross-ventilation, where opposite windows are opened simultaneously, is particularly effective. This completely exchanges the air within a few minutes.

During the day, it’s advisable to keep windows closed and block direct sunlight as much as possible. The Consumer Advice Center also advises against continuous ventilation during the hot daytime hours, recommending instead the cool morning and night hours for thorough air exchange.

Also interesting: Warning! Expert cautions against popular heat trick

More on the topic

Better Sleep in Summer How to Beat the Heat in Your Bedroom

Effective Measures Tips to Keep Your Home Refreshingly Cool During Summer Heat

3. Mistake: The wrong furniture in the wrong place

Not only windows and sunlight affect how warm an apartment feels–the furnishings also play a role. It’s particularly popular to place a sofa, armchair, or dining table directly in front of a large window front. In summer, however, this can be a disadvantage. The heated window panes release heat into the room, which is especially noticeable right by the window. Sitting in these spots is particularly uncomfortable with a lot of sunlight.

But it’s not just the location of the furniture that’s crucial, but also its material. Heavy upholstered furniture, thick carpets, or dark textiles can retain heat longer and contribute to a room feeling warm even in the evening. Light, airy fabrics and a reduced setup often feel more refreshing and can improve the perception of warmth–even if they only slightly affect the actual room temperature.

Large cabinets or shelves should also not be placed directly in front of windows or in areas where they obstruct air circulation. This way, the apartment can ventilate better during the cooler morning and night hours, and the heat stored during the day can be released more easily.

4. Underestimating additional heat sources

On hot summer days, every degree counts–including those generated inside the apartment. Many household appliances emit heat into the room during operation, which can further increase the room temperature. Ovens and stoves, as well as dryers, dishwashers, or powerful computers, release some of the energy they consume as heat into their surroundings.

This is especially noticeable in smaller apartments or open-plan kitchens. Using the oven for several hours on a hot afternoon or running multiple electrical appliances simultaneously heats the apartment even more.

If it can’t be avoided, it’s worth using these appliances during the cooler morning or evening hours. In summer, dishes that don’t require an oven or grilling outdoors can also help keep the apartment cooler.