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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 four the building has. The answer: 2,298 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, which sits at 891 hours.

Sagveien 8, Oslo municipality · Floor 2: on facade SE (137°), this floor gets roughly 2,298 hours of direct sun a year — above the building median.

Direct sun per year2,298 h
21 December30 min
Openness 7.2 / 10

How much of the sun that could have reached this wall actually gets through. 10 means almost nothing is in the way — neither neighbours nor trees.

Sun index 6.6 / 10

The sun here, measured against a south-facing wall with nothing in the way at the same latitude. 10 is what such a wall would get; both the direction the wall faces and the surroundings pull it down.

Spread across the year

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
sun1. building2. building3. buildingother obstructions
What does the height of the bars show?

The height is the hours the sun is up and in front of this wall, not the whole day length. A wall sees about half the sky, so the summer sun is up for hours behind the wall without counting here. That is also why the steps between months are uneven: a roofline is a threshold, not a gradual change. The month the sun clears it, a whole slice of the day goes from shade to sun at once.

behind the wall04:0022:4212:0005:4215:24
↑ 04:00 · ☀ 13:18 · ↓ 22:42
18h 42m above the horizon
9h 48m of direct sun on this facade

21 June, 12:00

The sun is on the window, 51° above the horizon.

Worked out from the stored horizon for this wall and floor, without clouds. In practice the changeover between sun and shade is soft by a couple of minutes either way. The time is Norwegian local time.

Compared with the building

The building median is 891 hours. The middle half falls between 309 and 1,893 hours.

What takes the sun?

The obstructions are measured in the laser scan: we see that something is in the way, how high it is and which direction it lies in. When we name a building, it is the nearest mapped one in the same direction — that says where the obstruction is, not that this particular building casts the shadow. “Building” and “trees” say what kind of obstruction it is, not which one.

Sagveien 8 · SE (137°)

123NSEW5 m

The orange ring is the facade you chose. Grey shapes are buildings. The numbered wedges point at the obstructions in the list below. See the area in satellite imagery →

  1. 1. buildingblocks 608.3 hours a year · direction 152.3–222.3° · 13.3 m high · the nearest mapped building in the same direction stands 11.9 m awaySee this obstruction in satellite imagery →
  2. 2. buildingblocks 146.6 hours a year · direction 54.3–78.3° · 12.5 m high · the nearest mapped building in the same direction stands 11.9 m awaySee this obstruction in satellite imagery →
  3. 3. buildingblocks 26.5 hours a year · direction 79.3–86.3° · 50.4 m high · the nearest mapped building in the same direction stands 11.9 m awaySee this obstruction in satellite imagery →

How to use these numbers →

Calculated from Kartverket's laser scan, flown 18 May 2024, with leaves on the trees. The sun is worked out geometrically for the sun's own centre, without clouds. December counts the leaves as dense, so the figure is a minimum. How?

Elevation and building data: © Kartverket (CC BY 4.0 / NLOD) · Building outlines: © OpenStreetMap contributors (ODbL).

Calculation version v2 · source data 01/01/2007, 04/07/2010, 30/04/2012, 11/06/2013, 08/12/2014, 09/05/2015, 20/06/2015, 07/07/2015, 26/09/2015, 22/11/2015, 01/12/2015, 03/12/2015, 01/06/2016, 05/06/2016, 13/06/2016, 31/07/2016, 30/10/2016, 02/05/2017, 25/05/2017, 01/06/2017, 06/10/2017, 12/10/2017, 29/05/2019, 31/05/2019, 06/04/2020, 19/04/2020, 30/05/2021, 30/08/2021, 18/04/2022, 03/05/2022, 06/05/2022, 07/05/2022, 28/05/2022, 30/07/2022, 18/05/2024, 04/06/2024, 21/06/2024, 24/06/2024, 07/04/2025, 22/06/2025, 08/10/2025 · report retrieved 02/09/2026

Open this report in Soltreff →

The link re-runs the lookup in the service; it does not show a stored answer. If we recalculate, the link moves with us — and the figures on this page can then sit a step behind until we update them.

What takes the sun

Three obstructions are mapped, all classified as buildings, from three different directions. One lies south and south-west and takes 608 hours a year — more than the other two together. The other two come from east-north-east and east, and take 147 and 27 hours. 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.

The building has no wall facing due south — the four are south-east, south-west, north-east and north-west. The other one that catches sun, the south-west wall, ends at 1,390 hours, almost a thousand behind south-east: an 18-metre building stands in the way to the west and south-west, and that one alone takes 1,023 hours a year. The south-east wall has clear morning sun instead. 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 prints one number instead of a range.

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).

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