Example
How much sun did a workers' flat in Sagene get?
At Sagveien 8 stands a timber house from 1848. The Workers' Museum shows a 21-square-metre flat inside it, furnished as it might have looked around 1920. We ran the address through Soltreff exactly as we would with any home for sale — the same lookup, the same report, nothing built specially for the occasion.
The report
Sagveien 8 is registered with dwelling numbers, so Soltreff can answer for a particular floor: the second floor, facing south-east — the wall that gets the most sun of the three the building has. The answer: 2,296.8 hours of direct sun a year, and 30 minutes on 21 December. Openness 7.2 out of 10, sun index 6.6 out of 10 — both above the building's median.
What takes the sun
Three obstructions are mapped, all classified as buildings, from three different directions. One due south does most of the work; two smaller ones come from the east and matter far less. The report states the direction and the height of each obstruction, and how many hours each of them takes. How far away the obstruction itself stands is something the tool does not yet establish — it states only which mapped building lies nearest in the same direction, and that is not necessarily the building casting the shade.
That is why the answer is south-east and not south. The south-facing wall has the neighbour directly in front of it; the morning sun from the south-east comes in beside it. An app that shows you the sun's path does not tell you this, because it does not know where the neighbouring building stands.
And in winter
30 minutes on 21 December. Sagene lies low, the sun stands under seven degrees in midwinter, and then the building to the south decides everything. The figure is a minimum, not an estimate: we count all foliage as dense, so the real figure can be slightly higher, never lower. Here there are no trees in the way — all three obstructions are buildings — so the minimum figure and the best case land on the same minute, and the report shows 30–30.
What you should know about this figure
We calculate on the building, not on the museum's particular flat. Sagveien 8 is registered in Matrikkelen as a residential building with registered dwellings, so the floor count comes from the dwelling numbers and the storey height is derived for this building in particular — the best basis our method has.
The screenshot above is the same report any visitor gets for this address, taken straight from the service — not an illustration.
Elevation data: © Kartverket's laser scan, flown 18 May 2024 (CC BY 4.0 / NLOD). Building data: © Matrikkelen, the public register of buildings and addresses (NLOD). Building outlines: © OpenStreetMap contributors (ODbL).