Fusion/Lüften und Raumklima/en
The airing traffic light compares the air in your rooms with the outside air and says whether airing makes sense now. The warning is a separate item: if a room stays too humid, the device shows a warning screen like the pollen warning. Both can be switched on and off separately (web interface → Anzeige → Lüften und Raumklima).
Requirement: room sensors
Each room needs a temperature sensor (°C) and a humidity sensor (%) with the same room name (page Sensoren, column "Raum"; example: "Küche Temperatur" and "Küche Luftfeuchtigkeit", both with the room "Küche"). External sensors (MQTT) with a reading not older than 15 minutes count. Wi-Fi signal, battery and uptime are not taken as humidity. The internal sensor in the case does not count because the device warms it itself. Up to 8 rooms are considered.
The traffic light (strip at the top of the sensor page)
| Display | Meaning |
|---|---|
| 🟢 Jetzt lüften (air now) | At least one room is humid, the outside air would lower the room humidity by at least 5 percentage points (calculated from the water content of the outside air, warmed to room temperature), air quality is not bad and pollen load not high. In rain it says "Lüften: Fenster kippen" (air: tilt the window) |
| 🟡 Lüften bringt jetzt wenig (airing helps little) | Room humid, but outside is not drier (rain, fog, warm humid air) |
| 🟡 Fenster besser geschlossen (better keep windows closed) | Room air is fine, but outside is unsuitable (bad air quality, high pollen load) |
| 🔴 Lüften nötig, aber draußen ungünstig (airing needed, but outside unfavorable) | Room too humid, but outside is currently unfavorable for airing |
| 🟢 Raumluft in Ordnung (room air fine) | No room is humid; the strip shows the highest humidity |
| ⚪ Lüften: keine Raumdaten (no room data) | No room has temperature and humidity sensor with the same room name |
What the strip shows: after the heading it shows the most humid room with its relative humidity (for example "Küche 61 % feucht") and the water content of the air outside and inside in g/m3 (grams of water per cubic meter of air), for example "draußen 8.1, drinnen 10.6 g/m3". Behind the room humidity it shows to roughly what percentage it falls after airing ("danach ca. 55 %"). If the air outside is absolutely drier, airing removes moisture from the room even in rain and even when the relative humidity outside looks high (cold air holds little water). In rain the strip advises tilting the window only.
How it is calculated: the absolute humidity (grams of water per m³) and the dew point are computed from temperature and relative humidity (Magnus formula). A room counts as "raised" from limit − 5 %, as "high" from the humidity limit (default 65 %, adjustable 50 to 80 %) and as mold risk from limit + 10 points. Outside, bad air quality (European AQI above 60) and high pollen load (according to your pollen warning and allergens) block airing.
Cool airing in summer
If no room is too humid but a room is warm (from the adjustable room temperature, default 24 °C), the traffic light says "Fenster auf: draußen kühler" (windows open: outside at least 2 °C cooler than the warmest room) or "Fenster und Rollläden zu" (windows and shutters closed: outside not cooler). If air quality or pollen block airing, "Fenster besser geschlossen" applies. Switchable under Anzeige → Lüften und Raumklima (Kühllüften).
The warning
With the warning switched on and a room 15 minutes above the humidity limit (5 minutes for mold risk), a warning screen (petrol blue, blinking) appears with the room, humidity, dew point and advice such as "Jetzt lüften: draußen ist es trockener" (air now: it is drier outside) or "Lüften bringt jetzt wenig. Besser heizen oder entfeuchten" (airing helps little, better heat or dehumidify). Up to three rooms are listed. Tapping confirms the warning. It returns once per phase when all rooms were fine for at least 20 minutes, or after 6 hours if the problem stays. The hold time keeps showering and cooking from triggering an alarm. When the room is fine again, the warning screen closes by itself.
To your phone: with ntfy set up and the switch "Lüften-Warnung", the same warning arrives as a message (high priority for mold risk), repeated at most every 6 hours, and an all-clear if you like. The phone message only exists while the warning is switched on.