When does the living room get sun?
The answer depends on three things: which way the room faces, the season, and what is blocking the view outside. Here is how to work it out yourself — and how an app can show it to you instead.
Short answer: The sun rises in the east, peaks in the south and sets in the west, but when and how high it stands changes with the season. A south-facing window gets sun for a large part of the day, all year round. An east-facing window gets morning sun, a west-facing window gets afternoon and evening sun. A north-facing window rarely gets direct sun at all, only diffuse daylight. The only way to get a precise answer for your particular room is to calculate it from the house's actual north direction and latitude — or use software that does it for you.
The three things that decide the answer
There is no single answer that applies to every living room — but there are three factors that together give the answer for yours:
- Which way the window faces. Not the house's facade in everyday speech, but the actual compass bearing. "South-facing" in a property listing is often an approximation — the real angle can be off by 20-30 degrees from due south, and that shifts the hours of sun noticeably.
- The season. The sun stands much higher in the sky in summer than in winter, and it is up for far more hours. A window that gets plenty of sun in June can stand almost in shadow in December, even facing the same way.
- What shades it from outside. The neighbour's house, trees, a rise on the horizon. The sun's calculated path tells you when it could shine in — not whether something actually blocks it.
How to work it out yourself, roughly
You do not need software for a rough estimate:
- Find the house's north direction. A compass on your phone, or a map with a north arrow, is enough for a rough judgement.
- See which way the window points, relative to north. Due south gives the most sun overall. East and west split the day between them. North gives the least.
- Remember that the sun's height changes with the season. In winter the sun sits so low that it can reach far into a south-facing room, even with an ordinary overhang — while in summer it stands so high that the same overhang shades most of the direct sun. That is actually desirable: cool in summer, warmed by sun in winter.
- Go and look for yourself, at different times of day, if you can. No calculation beats seeing it with your own eyes, if you have the time for it.
That gives a reasonable estimate. If you need to know precisely — for example to place a terrace or judge whether a new building will shade your living room — that requires an actual sun calculation, not a guess.
How much sun does the garden get in December?
December is the yearly test for any south-facing facade or terrace. Around the winter solstice on 21 December, the sun sits at its lowest point of the year — often only 10-15 degrees above the horizon at midday, at higher latitudes. That means two things at once: the day is short, and even what sun there is arrives at a very shallow angle. A building, a fence or even a hedge that casts barely any shade in summer can easily shade the whole garden in December, because the sun never climbs high enough to clear it.
If you want to know whether a terrace gets winter sun, December is the season to check — not summer, when almost everything gets sun. That is also why "south-facing terrace" in a listing does not automatically mean sun in December: a tall hedge to the south, invisible in a summer sun calculation, can block the whole low winter sun.
How is the sun's path calculated?
The sun's position in the sky at a given moment can be calculated mathematically from three things: latitude (how far north or south of the equator the site lies), date (the earth's position in its orbit around the sun) and time of day (the earth's rotation at that moment). From those three you can calculate the sun's altitude above the horizon and its azimuth — the direction it stands in, measured as a compass angle from north.
Combine that with the building's own north direction, and you can calculate precisely when the sun sits at an angle that hits a particular window directly, and how far into the room the rays reach at that moment. It is the same calculation whether it is done by hand with a formula, in a spreadsheet, or automatically in an app — it is astronomy, not guesswork, and it gives the same answer for the same place and time, regardless of who calculates it.
What can NOT be calculated without the right inputs
The calculation is only as good as what it is told. If the software or the formula does not know the house's actual latitude and north direction — only an assumed default direction — the result is a guess, not a measurement. That is a trap many sun studies fall into: a slick animation of the sun moving across a 3D model, built on an assumed north direction, because the real one was never set. Always ask: "where does the north direction in this picture come from?" — if the answer is "it's just set that way to look nice," the calculation cannot be trusted.
What HouseSense does
In HouseSense, the sun's position is calculated from the house's actual latitude, longitude and north direction, once they are set on the house. You can drag a time wheel in the 3D model or the walkthrough and watch the shadows move in real time, or jump straight to the equinoxes and solstices to compare seasons. If the house's location or north direction is not set, the app falls back to a generic sun arc and says so clearly — it never pretends a guess is a measurement.
What you still need to remember
A sun calculation shows where the sun would stand if nothing were in the way. It does not automatically know whether the neighbour's house, a tree or a rise in the land blocks it — that is something you need to observe yourself, or add as extra information. The best answer always combines both: a calculation for the underlying pattern, and a couple of visits on site for what the map cannot see.