Guide
Sun on a plot: will it get sun once the house is finished?
Most tools that answer questions about the sun answer for the ground where you are standing today. That is not the same question as what the second-floor window gets once the house is built. Below is why a plot is harder than a finished home, what the terrain tools actually show you, and what decides the answer.
The short answer
No free service can say exactly how much sun a window you have not built yet will get. The terrain tools show you the sun at ground level today, not at window height in a house that does not exist. What they can answer, and what actually decides the answer, is below — and we can give you a figure for the closest thing you can check: the house next door, at the height you are planning to build at.
Why a plot is harder than a home
When you check a home, you have a house to calculate from: a wall with a given height and direction, on a given floor. On a plot, none of that exists yet. Any tool that works out a sun figure for the plot therefore has to guess a height — and most guess ground level, that is, zero metres above the terrain. That is the height a pedestrian stands at, not the height a second-floor window will have. The higher you build, the more of the neighbouring buildings and trees drop below the horizon, and the more sun you get. A figure calculated from the ground therefore says nothing certain about the house that will stand there.
What the terrain tools actually give you
offentligdata.no shows sun figures for Norwegian addresses, free. But the service states itself that the shadow is calculated “from mountains and hills based on elevation data” — terrain alone, at ground height. Neither a future house, neighbouring buildings nor trees are in that figure. Norkart and Easy Eiendom draw the property as a 3D model you can turn; Easy Eiendom is free, while Norkart sits behind a login and costs 99 kroner per property. But without a building to place in the model you still have only the terrain and what already stands around it — not the finished house. Neither of them asks how high you are planning to build, because neither was made for the question.
If the plot has no address at all, it often gets worse: lookup services are built around addresses and property pages, so a bare plot can be hard to look up in the first place.
What actually decides the answer
Three things determine how much sun the plot gets once the house is finished, and none of them is the terrain alone.
How high you build. One more storey lifts the window above the neighbour's roof or the neighbour's tree. It is often the single factor that changes the answer most, and it is precisely the one the terrain tools do not ask about.
The neighbour's trees. A building is on the map; a tree usually is not. The estate agents' own association points to the neighbour's tree as the most common reason the sun does not turn out as expected — see why the tree decides more than you think.
The terrain itself. A slope or a hill some distance away can take the morning or the evening sun however high you build. This is the only one of the three that the terrain tools actually calculate.
The closest thing you can check today
We cannot work out a figure for a plot with no building on it — that would be exactly the same guess the terrain tools make, with a different face on it. What we can do is work out a real figure for a real house: the house next to the plot, on the floor closest to the height you are planning to build at. The neighbouring buildings, the neighbour's trees and the surrounding terrain are already in that figure, because that is exactly what Soltreff counts. It is not the plot's own figure, but it is the closest thing any free tool offers today.
We cover Oslo for now. The rest of Norway is coming.