Experts say that opening the windows at night and closing them during the day is no longer the best strategy against the heat

Titelbild Ventilator

As it gets hotter outside, many people ventilate their homes at night. However, at very high temperatures, this is hardly sufficient. Because your apartment stores the heat in the walls and furniture. If you really want to be prepared for the heat, you need to take other measures these days.

When one is close to suffocating in the heat during the day, many look forward to finally letting in the cold air in the evening. But the popular tip and trick “ventilate at night, keep windows closed during the day” is no longer as effective, as experts explain.

By now, structural measures are more important than pure ventilation techniques. Because at very high temperatures, the heat remains inside the buildings. Even when it is significantly cooler outside than inside.

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Structural measures against heat are becoming increasingly important as temperatures rise

Maybe you know the situation: You open all the windows in the evening, but the temperatures in the apartment do not really drop. Experts call this the ventilation paradox: Walls, ceilings, and furniture store the heat of the day and only slowly release it again in the evening or morning when ventilating. It would only get really cool when cold air reaches the furniture or walls long enough (via rnd.de).

Therefore, pure ventilation is often no longer sufficient. Long-term, other measures are more important: building protection, shading, renovation, and air-conditioned refuges. This includes primarily structural measures that could be implemented to reduce the temperature inside the building. According to experts, meaningful structural measures include the following points:

  • Exterior roller shutters, blinds, awnings, or sun sails.
  • Insulation, especially on the roof, at the top ceilings, and on heavily exposed exterior walls.
  • Windows with thermal insulation glazing or low g-value. This glass lets through only a little solar energy and heats up the room more slowly.
  • Light-colored facades and reflective surfaces, because they absorb less solar heat.
  • Green roofs or facades, if structurally possible.
  • Good air tightness and a ventilation concept to prevent warm outside air from entering uncontrolled during the day.
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Such measures become difficult especially in a rental apartment, where structural changes are rarely possible without further ado. Here, ventilation and shading remain the first choice. This is stated, among others, by the German Federal Environmental Agency.

Especially critical are attic apartments and large window areas facing south or west, where heat accumulates significantly. If possible, external solutions are always better than internal shades, as they intercept the sun before it reaches the glass.

As long as the night cools down, night ventilation helps a lot. However, if the nights remain warm, more structural protection is needed; otherwise, the apartment will get hotter day by day and cool down little at night. And the popular trick “ventilate at night, keep windows closed during the day” helps only to a limited extent then.

MeinMMO editor Benedikt Schlotmann lives in an attic apartment and here, structural measures are only difficult to implement. The best change that was possible were pleated shades on the windows. Because they keep the heat out and keep the temperatures within a reasonable range: I live in an attic apartment and this purchase has saved me from the current summer heat for years

This is an AI-powered translation. Some inaccuracies might exist.