Heliodon: where the sun falls on any address, any day
Heliodonwhere the sun falls
Hours of direct sun per day
024681012+ h
Full sun 6 h or more
Part sun 4 to 6 h
Part shade 2 to 4 h
Full shade under 2 h
Sun calendar
direct sunshadedsun down
Drag to turn · right-drag to move · scroll to zoom · click anything for its sun calendar
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Heliodon
A heliodon is the lamp-on-an-arm that architects use to shine a "sun" on a model. This one uses the real sun, on a 3D model of any place, built on the fly from open map data.
What it does
Light & shadow: the sun for any date and time, with shadows from buildings, trees, fences, hedges and the hills and mountains up to 25 km away.
Sun hours: how many hours of direct sun each patch of ground or roof gets per day, for one day, a month, the growing season or the whole year. Plant labels use the same classes: full sun is 6 hours or more.
Click anything (a garden, a window, a roof) for its sun calendar: every day of the year down the side, every 15 minutes across.
How far to trust it
It assumes a clear sky. It tells you when the sun can reach a spot, not the weather.
The sun's position is accurate to about 0.02°, checked against NREL's algorithm (pvlib). Sunrise and sunset are within a minute.
Buildings come from OpenStreetMap. Many have a mapped height; the rest are estimated from storeys or building type, and roof shapes are often guessed. Small details like sheds, balconies and garden walls may be missing, and trees are only there if someone mapped them.
Terrain is about 2 m resolution near the centre, 20 m out to 5 km and 100 m beyond. Deciduous trees let more light through in winter.
Keys
Space play the day · ← → time · ↑ ↓ date · S sun path · P save image · H hide the interface