Luften Support

Window advice not making sense? Here are quick fixes and the most common questions.

Talk to the developer

A bug, an idea or advice that seems off. Every email gets read.

Troubleshooting

Luften says Home access is turned off

Open Settings › Privacy & Security › HomeKit and turn on Luften, then come back to the app. Until then, Luften estimates your room's temperature.

My sensor isn't listed

Luften lists every accessory in the Home app that reports a current temperature. Check that the sensor shows a temperature in the Home app and belongs to one of your homes there. If several are found, pick a room or a single sensor in Luften's settings, for example to leave out an outdoor sensor.

The widget shows an old room temperature

iOS only lets apps read Home sensors while they're open. Set up an hourly Shortcuts automation: “Get the state of” your sensor's Current Temperature, then Luften's “Update Indoor Temperature”. The widget and alerts then stay current without opening the app.

I don't get any notifications

Allow notifications for Luften in Settings, and keep Background App Refresh on (Settings › General › Background App Refresh). Luften notifies you only when the advice changes, and iOS decides how often the background check runs.

The weather is for the wrong place

Luften always shows the weather for your saved home address, not for where you are right now. Change it in Luften's settings under Home.

The compass shows magnetic north

For true north the compass needs your rough position. Allow location access for Luften while using the app, hold your iPhone flat at the window and wait a moment for the reading to settle.

Frequently asked questions

What does Luften actually do?

It compares the weather at your address with the temperature in your room and tells you what to do with the window: open it, air the room for a few minutes, or keep it closed. On hot, sunny days it also says when to lower or raise your external blinds. The weather comes from Apple Weather, the room temperature from a sensor in the Home app.

Do I need a temperature sensor?

No. Without one, Luften shows the outdoor temperature and advises as if your room were at your comfortable temperature, a little warmer on hot days. With a temperature sensor in the Home app it uses the real reading, and a humidity sensor makes the advice better still: it then knows when the room is damp or the air outside muggy.

How does it decide?

In order: a storm or strong gusts keep the window closed, so do rain and snow, and so does muggy air. A humid room gets aired when the air outside is drier. Below 10 °C outside it suggests airing briefly, 5 to 10 minutes, instead of leaving the window open. When it's at least 2 °C cooler outside and the room is above your comfortable temperature, open up; when it's warmer outside, keep it closed. If rain is due within the hour, an open window becomes a short airing. The thresholds follow guidance from MeteoSwiss, the German Weather Service, the German Environment Agency and REHVA.

What about the blinds?

External blinds stop the sun's heat before it reaches the glass. On a hot day, when the sun is on your window or about to be, Luften tells you to lower them. It tells you to raise them again once the sun has moved on, after sunset so the heat can escape, and when gusts get strong enough to damage the slats.

Why does it ask which way my window faces?

So it knows when the sun actually reaches that window: an east window gets the morning sun, a west one the afternoon, a north one hardly any. You set it once with the compass, holding your iPhone flat at the window. It's optional, and it also puts the sun and moon in the right place in the app's window.

Will it send me notifications?

Only if you turn them on, and only when the advice changes: from open to airing to closed, or when it's time to lower or raise the blinds. A change of reason, say from rain to snow, doesn't notify you again. iOS decides how often the background check runs.

Can the widget stay current without opening the app?

Yes, with one automation. iOS only lets apps read Home sensors while they're open, but Shortcuts can read them in the background. An hourly automation with “Get the state of” your sensor's Current Temperature, followed by Luften's “Update Indoor Temperature”, keeps the widget and alerts up to date.

Can I choose what “comfortable” means?

Yes. Set your comfortable room temperature between 18 and 25 °C (21 °C to start). Luften won't suggest opening the window to cool the room below it. Tap any temperature to switch between Celsius and Fahrenheit.

Is the weather on this page real?

Yes. The day on this page is Saturday 19 July 2025 in Zürich, hour by hour from the Open-Meteo weather archive: a cool morning, a hot, cloudy noon, a downpour at three and a muggy evening. The room temperature is Luften's own estimate for a home without a sensor, and every piece of advice is worked out with the app's rules.

Requirements

An iPhone or iPad with iOS 18.5 or later and an internet connection for the weather. A temperature or humidity sensor in the Home app is optional. Luften doesn't need an account.