Question 1

What does Luften actually do?

Accepted Answer

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.

Question 2

Do I need a temperature sensor?

Accepted Answer

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.

Question 3

How does it decide?

Accepted Answer

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.

Question 4

What about the blinds?

Accepted Answer

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.

Question 5

Why does it ask which way my window faces?

Accepted Answer

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.

Question 6

Will it send me notifications?

Accepted Answer

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.

Question 7

Can the widget stay current without opening the app?

Accepted Answer

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.

Question 8

Can I choose what “comfortable” means?

Accepted Answer

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.

Question 9

Is the weather on this page real?

Accepted Answer

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.

Know when to open the window.

Set which way it faces.

Blinds down before the heat.

Shut when the rain comes.

Let the cool night in.

Without opening the app.

Air, then close

The widget

Only when it changes

Fresh in the background

Your home stays at home.

Your sensors stay home

Weather for your address

No account

Good to know.

Fresh air, at the right time.