When is the best time to open my windows?

Best ventilation happens when the outdoor temperature is at least 2°C cooler than indoor and humidity is below 70%. In summer that's typically early morning (5–8 AM) or after sunset. In winter, short bursts (5–10 min) of cross-ventilation a few times per day.

Should I open the windows when it's hot outside?

No. If the outdoor temperature is higher than indoor, opening windows brings warmer air in and worsens comfort. Keep them closed and shaded during the hottest hours, then open at night when temperatures drop.

What humidity level is too high for ventilation?

Above 80% relative humidity outside (especially when warm), opening windows makes indoor air feel sticky and can promote mould. Wait for drier hours or use a dehumidifier.

Is it safe to leave windows open at night?

In most weather, yes. Cool night air can drop indoor temperature by 2–5°C in 30 minutes. Check the live recommendation above before going to bed; OpenWindow.live combines temperature, humidity and air quality.

How does OpenWindow.live decide?

We compare your outdoor real-time data (OpenWeather + AQICN) against your indoor reference temperature (configurable). Hard NOs: AQI very poor, outdoor warmer than indoor, humidity > 80% in warm weather. GREEN: outdoor cooler by 2°C+ with clean air. Otherwise yellow with a partial-ventilation tip.

🪟 OpenWindow.live

Soll ich jetzt in Düsseldorf lüften?

Live-Entscheidung für Düsseldorf. Alle 30 Minuten aktualisiert.

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Wann ist die beste Zeit zum Lüften in Düsseldorf?

In Düsseldorf sind frühmorgens (5–8 Uhr) und spätabends (nach Sonnenuntergang) meist am besten, wenn die Außentemperatur unter die Innentemperatur fällt.

Kann man in Düsseldorf nachts lüften?

In den meisten Fällen ja. Lüften kann die Innentemperatur in 30 Minuten um 2–5°C senken, wenn die Außenluft kühler ist.

Welche Außenluftfeuchte ist zu hoch zum Lüften?

Über 80% wird die Luft beim Lüften schwül. Besser auf trockenere Stunden warten.

Soll ich jetzt in Düsseldorf lüften?

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