Guide
Sun conditions at an address: how to look it up and read the answer
You have an address from a listing and want to know how much sun the home gets — not just which way it faces. Here is the lookup on Soltreff step by step: what you choose, what the map and the report show, what the figures mean, and what they cannot tell you. Free, no login.
The short answer
Type in the street and house number, choose the floor and the wall the windows face, and you get hours of direct sun through the year for exactly that floor and facade — computed from Kartverket's laser scan, in which the neighbouring buildings, trees and terrain actually stand. Under the figures sits a map showing what takes the sun, numbered, with direction and distance. Everything is computed in advance, so the answer comes straight away.
1. Type in the address
Start typing the street name and pick the street from the list. Then choose the house number. Every house number is marked “covered” or “not covered”, so you see before going on whether the address has a finished report. If you cannot find the street, or the house number is marked “not covered”, you are told so in the same place, and can tell us where we should cover next.
2. Choose the floor
If the address has homes on several floors, you get a list of the floors, taken from the dwelling numbers in the Matrikkel register. The answer is for the floor and the facade, not for the individual dwelling number: two flats on the same floor facing the same wall get the same figure. If there is only one home at the address, as in an ordinary house, the step is skipped.
Basements and lower ground floors we do not cover yet, and an attic whose top storey is missing from the calculation gets no report rather than a guess. Such floors are marked “not supported” in the list, with the reason.
3. Choose the facade on the map
A small map draws the building's outline with north up, and every wall can be tapped. The walls are named by compass direction and degrees, for example “SW (225°)” for a wall facing southwest. Choose the wall the windows or the balcony face. This is the one choice that decides the answer, so look at the floor plan in the listing if you are unsure which side the living room is on.
If the address is a house with no registered floor, we ask after the wall which height you want computed: the ground plan, or a storey above it. The address does not say where the terrace is, so that choice is yours, and the report states which height it used.
4. Read the report
At the top is the headline figure: hours of direct sun a year for that floor and that facade, and, where the building has enough walls that could hold windows, how it compares with the building's median. Four more figures follow. 21 December in minutes: a minimum figure where the scan is confirmed flown with leaves on the trees, and, where trees are in the way, a range as well (more on that below). Openness on a scale to ten: how much of the sun that could have reached this wall actually gets through. Sun index on the same scale: the sun here measured against a south-facing wall with nothing in the way at the same latitude. And visible sky as a percentage: how much of the sky the wall sees, whether or not the sun is in it.
Under the figures comes the year: twelve bars, one per month, with the sun at the foot and what takes it stacked on top in the same colours as the map. Behind the “Advanced” tab the same thing sits as a grid for the whole year, day by day and time by time. At the bottom is the sun's path for one day: pick a date and a time, and the report says whether the sun is on the window, behind the wall, below the horizon, or which numbered obstruction takes it. Days you want to keep can be added to the report.
The report can be shared as a link, or downloaded as a PNG or a PDF. The sources and the calculation version travel with both.
What the map shows
The obstruction map draws the building's outline with north up. The orange ring is the facade you chose, grey shapes are buildings, and numbered wedges point from the wall at what takes the sun. Each number appears again in the list under the map with what kind of obstruction it is — building, trees, terrain or outbuilding — how high it reaches, which direction it lies in, and, for each obstruction we can place, how far away the scan sees it. Each obstruction we can place has a link to satellite imagery, so you can see for yourself what stands there.
The obstructions are measured in the laser scan, not looked up in a register: we see that something is in the way, how high it is and in which direction. When we name a building, it is the nearest mapped one in the same direction. It says where the obstruction lies, not that this particular building casts the shadow. You pick the scale yourself, from fitted to 200 metres, and a horizon profile all the way round shows how high what stands in the way reaches in every compass direction.
What the figures mean
Hours a year are the hours the sun is on this wall, not the length of the day. A wall sees roughly half the sky, so the summer sun can be up for hours behind the wall without counting. That is also why the difference between two facades in the same building can be large.
December is a minimum figure where the scan is confirmed flown with leaves on the trees. We cannot tell whether a tree is deciduous or a spruce, so December is computed as if the leaves stayed on all winter. If foliage is in the way, the report also shows what gets through without leaves, as a range from the minimum figure upwards. Where we have not confirmed that the scan was flown with leaves on the trees, the report says so and calls the December figure an estimate, not a minimum.
Where the building has enough walls that could hold windows, the report shows the building's median, so you can see whether this floor and facade sit above or below the rest of the building. And because every address is computed the same way, from the same public data, figures from two addresses can be compared directly. The method says which sources the figures rest on, and what has been checked.
What the lookup cannot tell you
The weather. The sun is computed geometrically, without clouds. The hours are possible hours of sun given what stands around the home, not a forecast of how often the sun shines.
What has happened since the scan. The source data is a laser scan flown on one date, and the report states which. A building put up or a tree felled after that date is not in it. A new building that is in the register but not in the scan gets no report rather than a wrong answer.
Your exact window. The answer is for the wall at the chosen height, not for one particular window. On a long wall, one end can have something in front of it that the other does not.
The storey height in houses with no registered floors. There, the number of storeys and the metres per storey are estimates, taken from the roof height in the scan, and the report says so.
Documentation. The figures are indicative. If they are to be used in a sales prospectus, a valuation or a building application, they must be checked by someone who takes responsibility for them.
Common questions
Does it cost anything to check the sun conditions at an address?
No. Soltreff is free and needs neither a login nor a download. You type the address into the browser and get the report straight away.
Which addresses can I look up?
Addresses in Oslo, Bergen, Trondheim, Stavanger, Kristiansand and Akershus, plus parts of the neighbouring municipalities. Every house number in the search is marked “covered” or “not covered”, so you see the answer before you choose.
What does the map in the report show?
The building's outline with north up, the facade you chose as an orange ring, and numbered wedges pointing at what takes the sun. The list under the map says what each obstruction is, how high it is, which direction it lies in, and for each obstruction we can place, how far away it stands.
Is the figure for my flat or for the whole building?
For the floor and facade you choose. Every home on the same floor facing the same wall gets the same figure, and where the building has enough walls that could hold windows, the report also shows the building's median, so you can see whether your floor sits above or below the rest of the building.
Why is December given as a minimum figure, and does that hold everywhere?
Where the laser scan is confirmed flown with leaves on the trees, December is computed as if the leaves stayed on all winter, because we cannot tell from the elevation data whether a tree is deciduous or a spruce. If a deciduous tree is in the way, the home then gets more December sun than the figure promises, never less. Where we have not confirmed that the scan was flown with leaves on the trees, the report says so and calls the December figure an estimate, not a minimum.
We cover Oslo, Bergen, Trondheim, Stavanger, Kristiansand and Akershus for now, plus parts of neighbouring municipalities. The rest of Norway is coming.