Sun path and shadow diagrams
How the «Sun & shadow» tab computes the sun path and the shadows on the 3D model of the surrounding buildings, and what can be set.
Overview
The «Sun & shadow» tab extrudes the buildings around the site in 3D (BAG outlines, 3DBAG heights) and shows the sun path and the shadow at the chosen time, in the browser. Use it at concept stage for layout and orientation.
How to use
- Open the «Sun & shadow» tab. If there is no 3D model yet, build it first on the 3D tab
- Choose the date: 21 June (summer solstice), 21 March (spring equinox), 23 September (autumn equinox) or 21 December (winter solstice)
- Set the time with the slider. The sun position and the shadows follow it
- If needed, turn on «Cast shadows only»
- Fix the view («North up» or «Plan view») and save as PNG
Settings
| Setting | Value or range | Description |
|---|---|---|
| Date | 21 June · 21 March · 23 September · 21 December | Reference day for the sun path and shadows |
| Time | Standard time (CET, UTC+1) | Without summer time. Between the last Sunday of March and the last Sunday of October, add 1 hour for clock time |
| «Cast shadows only» | On · off | On: only shadows cast by neighbouring buildings show. Off: faces turned away from the sun also darken |
Method
Solar altitude and azimuth are computed from latitude, longitude, date and time with the NOAA solar position algorithm. No external
service is called. Theoretical noon altitude in Delft (52.01° N), 90° − |latitude − declination|:
| Date | Declination | Noon altitude |
|---|---|---|
| Summer solstice (21 June) | +23.44° | 61.4° |
| Equinoxes (21 March · 23 September) | about 0° | about 38.0° |
| Winter solstice (21 December) | −23.44° | 14.5° |
The low winter sun makes shadows in the Netherlands long: at 14.5° a 10 m building casts a shadow of about 39 m at noon.
Limitations
Indicative simulation, not a regulatory assessment. The model has no trees, awnings or retaining walls, and buildings finished after 2022 may have no 3DBAG height.
Sun hours map
The 3D shadow shows one time of day. The total over a day is on the sun hours map and the SUN HOURS plate.
Related guides
Example plates: BAG (Kadaster, CC0) · © 3DBAG by tudelft3d and 3DGI (CC BY 4.0) · BGT, NWB, AHN4 (CC0) · Kadaster, Beeldmateriaal.nl, PDOK (CC BY 4.0) · © OpenStreetMap contributors (ODbL)