Does the sun reach
your window?

Azima is the light check for Vienna: a browser tool that calculates, for one address and from the City of Vienna’s official roof model, when direct sun reaches the window — per floor and compass direction and, with a floor plan, per room. Checking is free; the report as a PDF costs €9.50. It is part of Vienna Living Map and runs without an account.

It depends far less on the compass direction than on what stands opposite. In a narrow Gründerzeit lane a south-facing flat can be in shade by early afternoon, while a fourth floor in the same house keeps the sun for hours. The light check calculates the real obstruction horizon around one address — for every compass direction the height the sun has to clear — and compares it against the sun’s path for that day.

Building heights come from the City of Vienna’s generalised roof model (LOD2.1, CC BY 4.0) — eaves and ridge, measured, not estimated. Where that is missing, an OpenStreetMap entry counts. Terrain comes from the Copernicus elevation model, the sun’s position from astronomy. Nothing is guessed.

Then no number appears — only the reason and the coverage figure. An invented hour of sunshine is worse than no answer, because afterwards nobody believes the correct one either.

A lot. Sun maps stop at the house wall; here the calculation runs up the facade. In a deep lane the low winter sun never reaches the ground floor but still clears the neighbours’ roofs higher up — that difference is measured from the same real building heights, and the check says whether it exists at this address.

Yes — and it stays on your device. Drop or paste the PDF of the sales plan, an OpenImmo export, an IFC model or an image of the plan onto the page: it is read in the browser, room by room, with a check that the areas add up to the stated total. After that the check knows the rooms and calculates the hours of sun for each date across the year. There is no upload, no endpoint, no account. You can verify it in the network tab: nothing leaves.

Yes, as an image. Copy the floor plan in the listing or save a screenshot and paste it into Azima with Ctrl+V (Mac: Cmd+V) — or drop the image file onto the drop zone. willhaben is only an example here: any listing image or scan takes the same path, and there is no connection to any portal. The image is read on your device and never uploaded; afterwards the recognised rooms can be corrected.

Room names are read by text recognition in the browser. Where the square metres are legible in the image, they count. Where the digits are too small — the rule for screenshots from listings — the rooms are measured from the drawing as fields between the walls and converted to square metres via the stated floor area of the listing. In testing, large rooms came within a few percent of the plan figure, small closets considerably further off; the result says so, and under “Stimmt etwas nicht? Räume korrigieren” (the correction panel; the tool speaks German) every figure can be changed. The position of the rooms relative to each other is not taken from the image.

Yes, as a real PDF. From the light check a short sheet: address and hours, the measured horizon drawn as a roofline with the sun’s path across it, the course of the year, the sun load per room, the surroundings, aircraft noise, the data coverage and the limits of the calculation. From the stage, in addition, the report of about 17 pages. Both are generated in the browser, so nothing is sent anywhere. The limits travel with it on purpose: a sheet gets passed on and later stands without the page that explained it.

To OpenStreetMap, for the neighbouring buildings — and nowhere else. Nothing travels back to this site; the result stays on your device. You can check that in the network tab.

Checking costs nothing — no account, no sign-up, no tracking. The report as a PDF with your floor plan costs €9.50 (beta price, €19 after the beta) once; Premium for agents and developers €39 a month, reports without a limit. Free preview: every page, hours for one room on one day. Vienna Living Map stays free.