About Sun Path·See sun angles, shadows and seasonal variation on your model.
What Sun Path does
Drops your Rhino model under a sky dome and traces the sun across any date or time, showing shadows on the building and on the ground. Useful for shading studies and seasonal comparisons.
- Input:
- .3dm + .epw
- Output:
- 3D / 2D sun path
- Modes:
- Single · Seasonal · Multi-day · Sun hours
How it works
Sun position is the same NOAA algorithm the professional tools use, checked against NREL SPA rather than asserted. Sun hours come from the same shadows you see: the shadow is the measurement, not a proxy for it.
- NOAA solar-position algorithm, the same family as Ladybug and Radiance's sunpath; validated against NREL SPA (Reda & Andreas, NREL/TP-560-34302).
- Sun hours on the ground and on facades come from the same sun samples, so the two overlays never disagree.
- Time step of your choice, from minutes for a single day to hours for a multi-day window.
- Shadow outlines export to SVG, DXF and Rhino as real geometry.
How to use it
- Load a weather file. Sun position depends on latitude/longitude — load an EPW first.
- Upload your model. A .3dm (or .obj / .fbx) of your massing + context.
- Pick an analysis mode. Single date, solstice comparison, or a custom multi-day range.
- Move the sun. Drag the date/time sliders to find your critical moments.
- Map sun hours. Optional: compute direct-sun hours per point over a date window as a ground heatmap, exportable to SVG / DXF / Rhino. Pick building layers to color their facades too.
- Animate or export. Play the full year, or export a video for presentations.
Best used for
- Shading and overshadowing studies on a representative day (equinox, solstices).
- Finding the worst-case moment before committing to a shading device or facade.
- Amenity sun-access screening against the usual thresholds — BRE 209 (2 h on 50% of area, 21 March), BS EN 17037 (1.5 / 3 / 4 h), DIN 5034-1.
- Getting shadow outlines out to CAD as real geometry for a drawing.
Not a substitute for
- A planning-submission overshadowing report — that needs a stamped study.
- Interior daylight levels or glare (use the Daylight tool).
- Sun-hours certification of any kind.
Known limits
- The sun counts as up slightly later and down slightly earlier than the NOAA calculator's refracted horizon, so day lengths read a little shorter. Stated rather than hidden: beam that low is blocked by real horizons the model does not have.
- A 1-hour window underestimates sun hours by roughly 3% against 5-minute stepping (Brembilla et al., BS2021) — drop to 6 or 10 minutes when the number matters, not just the picture.
- The sun is treated as a point, so shadow edges are hard — there is no penumbra.
- Only geometry you load casts shadows. Miss out the neighbours and the result is optimistic.
- Ground grid defaults to 1.5 m cells; fine detail below that resolution is not resolved.