Guide

Sun conditions and the neighbour's tree: is the tree taking the sun?

“Will the neighbour's tree take the sun?” The question is not ours. It is NEF, the Norwegian estate agents' own association, that asks home buyers to check it themselves, because they know the answer is often yes, and that it rarely appears in the listing. Below is why the tree is the most common surprise, why most maps do not show it, and what actually separates a deciduous tree from a spruce in December.

The short answer

Often — and in low-rise areas more often than the building next door. Vegetation accounts for between 23 and 50 per cent of what blocks the sun at measured addresses in Oslo, and in suburban areas trees take more sun than buildings do. In the dense inner city, buildings usually dominate. But wherever you live: the tree is almost never in the calculation — because it is not registered anywhere, the way a building is.

Why the tree is the most common disappointment

NEF, the agents' own trade association, says it plainly to home buyers: do not blindly trust that “good sun conditions” in the listing is true, and check for yourself whether “the neighbour's tree” will take the sun. It is not us saying the tree is the problem — it is the industry's own advice to its own customers. The reason is simple: a tree grows and casts shade long after the home was sold, and a viewing on an overcast day in March shows nothing about what a full canopy does to the August evening sun.

Why trees are missing from the map

A building has an address, a cadastral number and a drawn footprint — it is registered, and any map-based tool can fetch it. A tree has none of those. It stands there because somebody planted it thirty years ago, not because anybody reported it anywhere. Terrain-based services therefore calculate on what is registered, and the tree becomes invisible — not because it does not matter, but because it does not exist in the data they use.

Deciduous or spruce — and why December is a minimum figure

A deciduous tree loses its leaves in winter and lets more sun through exactly when you need it most. A spruce does not. The difference can mean more than an hour of sun around 21 December in suburban areas, while it is barely noticeable in the dense inner city, where other buildings take the evening sun anyway. We cannot tell from the elevation data alone whether a tree is deciduous, so we do not state a guessed figure. The laser scan was flown in spring, with leaves on the trees, and December is worked out as if the leaves stayed on. That figure is therefore a minimum: if a deciduous tree stands there, you get more sun than the figure promises, never less. If there is foliage between the sun and the wall, the report shows both ends — the minimum figure, and what gets through without leaves. We would rather say that than dress the figure up.

What no other tool does

Most maps and apps show you a shadow without saying what cast it. Soltreff names the obstruction: the report lists what takes the sun, numbered on a map of the address, so you can see whether it is the neighbour's house, the neighbour's tree, or the terrain — not just that something is in the way. That is the difference between being told there is shade and being told why.

See what takes the sun at the address →

We cover Oslo for now. The rest of Norway is coming.