Shading by neighbouring buildings — the figure an orientation cannot give you
Almost every listing states an orientation. It describes a rotation, not the arrival of light. Anyone writing about sunlight in a listing should have the neighbouring buildings in the calculation — otherwise the advert makes a claim the viewing disproves.
The common tools compute indoor light from a compass and outdoor light, if at all, from a bought-in shadow map. That is two truths about one property: the facade knows about the building opposite, the room behind it does not. Azima computes both from the same geometry — the hour at the window IS the hour in the room behind it.
Try it on one address →What is computed — and where it stops
The figure only a measurement produces is the obstructed time: how long the sun would geometrically be there while a neighbour takes it away. It separates position from weather and season from built form — and it is, frankly, the most uncomfortable number in the report. It stays in all the same.
Frequently asked
May I put the figure into a listing?
Yes — the PDF is made for that and carries its limits with it so they are not lost on the way. What does not work: passing the number on without the sentence that says what it is not.
How is this different from a shadow map?
A shadow map shows the shadow on the ground at a moment in time. Here a WINDOW is summed across the whole day, in hours, per room, with the obstructed time beside it. One is a picture, the other is a number in a report.
How accurate is the neighbouring geometry?
As accurate as the official model: buildings as volumes with measured heights. Projections, bay windows and roof structures are simplified in it. The sheet states the coverage, and where it is thin it says so.
Does the figure change when they build next door?
Yes, and that is the point. The report carries a date and its data basis — it is a measurement from one day, not a guarantee for ten years.
Do you compute the interior too?
The sun is computed at the facade and assigned per room to the best-placed window. What the glass, the curtain and the furniture make of it we do not compute — and do not claim.
All measurements · For agents & developers · The light check
Neighbouring heights from the City of Vienna building model (CC BY 4.0), supplemented from OpenStreetMap (ODbL). The address never leaves the browser: the calculation runs on the device.