Sun path and shadow
How the «Sun & shadow» section calculates the sun path and the shadows on the 3D model of the surrounding buildings, what can be set, and where the limits are.
Overview
The «Sun & shadow» section extrudes the buildings around the site in 3D and shows the sun path and the shadow at the chosen time. A shadow analysis needs a model of all surrounding buildings; this section builds the model and its shadows in the browser, without modelling in Rhino or SketchUp. It serves to clarify layout and orientation in the design stage. The simulation is part of the Pro pass (Pricing).
How to use
- Open the «Sun & shadow» section. If there is no 3D model yet, it is built first in the 3D section with «Build 3D»
- Choose the day: 21 June (summer solstice), 21 March (spring equinox), 23 September (autumn equinox) or 21 December (winter solstice)
- Set the time with the slider. Sun position and shadow follow
- If needed, switch on «Cast shadows only»
- Fix the view with «North up» or «Plan view» and press «Save PNG»
Settings
| Setting | Value or range | Description |
|---|---|---|
| Day | 21 June · 21 March · 23 September · 21 December | Reference day for sun path and shadow |
| Time | Standard time (CET, UTC+1) | Without daylight saving time |
| «Cast shadows only» | On · off | On: surface colours stay fixed and only the shadows of neighbouring buildings appear. Off: surfaces facing away from the sun also darken |
Method
Sun position
Solar altitude and azimuth are calculated from latitude, longitude, date and time with the solar position algorithm of the US agency NOAA (National Oceanic and Atmospheric Administration). No external service is queried. The noon altitude can be checked with 90° − |latitude − declination|; the declination is about +23.4° at the summer solstice and about −23.4° at the winter solstice. Values for Charlottenburg, Berlin (52.51° N, 13.33° E), in CET, calculated with the same algorithm:
| Charlottenburg | Sunrise | True noon | Noon altitude | Sunset |
|---|---|---|---|---|
| Summer solstice 21 June | 03:50 | 12:08 | 60.9° | 20:26 |
| Spring equinox 21 March | 06:16 | 12:15 | 37.4° | 18:15 |
| Winter solstice 21 December | 08:22 | 12:05 | 14.1° | 15:47 |
Sunrise and sunset here are the moment the centre of the sun reaches 0° altitude (without refraction); published tables differ from this by a few minutes. True noon shifts with the date because of the equation of time (up to about ±16 minutes). For comparison, the noon altitude at the winter solstice in the other cities: Cologne 15.6°, Karlsruhe 17.6°, Stuttgart 17.8°.
Time reference
All times are standard time (CET, UTC+1) without daylight saving time. From late March to late October the clock shows one hour more: 12:00 CET is 13:00 CEST. On 21 June, sunrise in Charlottenburg is shown as 03:50 CET, which is 04:50 CEST on the clock.
Reference days
| Day | Sun path |
|---|---|
| Summer solstice (21 June) | Highest and longest |
| Equinoxes (21 March · 23 September) | In between. The sun rises in the east and sets in the west |
| Winter solstice (21 December) | Lowest and shortest |
Shading
| Type | Condition | Test |
|---|---|---|
| Self-shading | The surface faces away from the sun | N·L ≤ 0 |
| Cast shadow | The surface faces the sun, but something blocks it | Facing the sun and blocked |
If both are shown, whole buildings turn grey and the shadows of neighbours are hard to read. «Cast shadows only» keeps the surface colours fixed and leaves only the shadows of neighbouring buildings; this suits plates. «North up» turns the view to north without changing tilt or zoom. «Plan view» looks straight down; shadow lengths are read most accurately in this view.
Limitations
Simulation for orientation only, not legally binding. The sunlight simulation is not a demonstration of compliance with DIN EN 17037 or DIN 5034-1.
The model contains no trees, awnings or retaining walls. Heights: Berlin: LoD2 3D building models from Geoportal Berlin; where LoD2 is missing or implausible, the ALKIS height or storeys × 3.2 m (estimated). Cologne: LoD2 3D building model from Geobasis NRW. Stuttgart and Karlsruhe: LoD2 3D building models from the LGL. Building applications need a model from surveyed data and a specialist study.
Sun hours map
The 3D shadow shows one time of day. The total over the day is shown by the sun hours map and the «Sun hours» plate.
Related guides
Example plates: Geoportal Berlin (dl-de/zero-2.0) · Geobasis NRW (dl-de/zero-2.0) · Datenquelle: LGL, www.lgl-bw.de (dl-de/by-2-0) · © OpenStreetMap contributors (ODbL)