Solar & Daylight Data
Solar Altitude & Azimuth: Choi Wan, Hong Kong
How to research solar altitude & azimuth for a specific site in Choi Wan — the controlling authority, source documents, and checks to run before you rely on a number.
On this page
Last updated September 2, 2026 · Location data from the [GeoNames HK dump](https://download.geonames.org/export/dump/HK.zip) (CC BY 4.0, snapshot 2026-08-31, GeoNames ID 12689060). Regulatory starting point: [Hong Kong Buildings Department](https://www.bd.gov.hk/en/resources/codes-and-references/codes-and-design-manuals/index.html). Figures are illustrative — verify against the current locally adopted edition for the site. Solar-method context: [NOAA Solar Calculation Details](https://gml.noaa.gov/grad/solcalc/calcdetails.html); the Harth monthly table uses a simpler declination and geometric-daylight approximation whose stated limitations must be retained. Project-date refinement reference: [NREL Solar Position Algorithm](https://midcdmz.nrel.gov/spa/).
Direct answer
For Choi Wan at 22.3339, 114.2137, the declination-only solar-noon altitude is approximately 88.9° at the June solstice, 67.7° at an equinox and 44.2° at the December solstice. Refine these geometry checks with the project date, civil time, facade azimuth, terrain and local horizon. The reproducible location record is GeoNames ID 12689060 in administrative area KWT, at 22.3339, 114.2137; replace it with the surveyed parcel point before relying on the result. As a transparent geometry check, declination-only solar-noon altitude is about 88.9° at the June solstice, 67.7° at an equinox and 44.2° at the December solstice. Representative 21st-day geometry ranges from about 10.6 hours in December to 13.4 hours in June; this excludes atmospheric refraction, terrain and obstruction effects. The cited national authority is a discovery starting point; current local documents and a named qualified reviewer control project use of this solar altitude and azimuth record.
Content and cited inputs reviewed by Scott Barrington, Harth founder and architectural technology specialist · Published 2026-08-26 · Updated 2026-09-02.
What must be verified for Choi Wan?
Choi Wan is represented here at approximately 22.3339, 114.2137 for discovery and workflow planning. A project address, parcel, elevation, exposure, authority, and submission date must replace that city-centre reference before design use.
How should solar altitude and azimuth be established?
- Fix the surveyed site and local time basis.
- Select an authoritative weather source or a named solar-position algorithm.
- Record period, percentile or scenario and units.
- Test sensitivity to elevation, exposure, urban form and horizon.
- Save the source file, retrieval date and checker in the model record.
| Input | Project-specific evidence | QA question |
|---|---|---|
| Site | surveyed coordinates, elevation and horizon | Does the point represent the building? |
| Weather/solar method | named dataset, algorithm, period and time basis | Are station, time zone and units explicit? |
| Design scenario | current and future scenario agreed by the team | Is an average being mistaken for an extreme? |
| Compliance | adopted local document and edition | Was applicability confirmed with the authority? |
What are the limits of this worksheet?
This solar-angle-workflow page is a project-starting worksheet, not a design value or approval. The controlling authority and qualified professionals for the Choi Wan site remain authoritative.
Choi Wan monthly solar geometry check for solar altitude & azimuth
| Representative date | Declination | Solar-noon altitude | Geometric daylight | Noon shadow / height |
|---|---|---|---|---|
| 21 January | -20.14° | 47.53° | 10.845 h | 0.915 |
| 21 February | -11.23° | 56.44° | 11.376 h | 0.663 |
| 21 March | -0.40° | 67.26° | 11.978 h | 0.419 |
| 21 April | +11.58° | 79.25° | 12.644 h | 0.190 |
| 21 May | +20.14° | 87.80° | 13.155 h | 0.038 |
| 21 June | +23.45° | 88.88° | 13.369 h | 0.019 |
| 21 July | +20.44° | 88.11° | 13.174 h | 0.033 |
| 21 August | +11.75° | 79.42° | 12.654 h | 0.187 |
| 21 September | -0.20° | 67.46° | 11.989 h | 0.415 |
| 21 October | -11.75° | 55.91° | 11.346 h | 0.677 |
| 21 November | -20.44° | 47.22° | 10.826 h | 0.925 |
| 21 December | -23.45° | 44.22° | 10.631 h | 1.028 |
Choi Wan solar-geometry fingerprint at 22.3339, 114.2137
- Choi Wan, 21 January: declination -20.14°, noon altitude 47.53°, zenith 42.47°, geometric daylight 10.845 hours, and vertical-object noon shadow ratio 0.915.
- Choi Wan, 21 February: declination -11.23°, noon altitude 56.44°, zenith 33.56°, geometric daylight 11.376 hours, and vertical-object noon shadow ratio 0.663.
- Choi Wan, 21 March: declination -0.40°, noon altitude 67.26°, zenith 22.74°, geometric daylight 11.978 hours, and vertical-object noon shadow ratio 0.419.
- Choi Wan, 21 April: declination +11.58°, noon altitude 79.25°, zenith 10.75°, geometric daylight 12.644 hours, and vertical-object noon shadow ratio 0.190.
- Choi Wan, 21 May: declination +20.14°, noon altitude 87.80°, zenith 2.20°, geometric daylight 13.155 hours, and vertical-object noon shadow ratio 0.038.
- Choi Wan, 21 June: declination +23.45°, noon altitude 88.88°, zenith 1.12°, geometric daylight 13.369 hours, and vertical-object noon shadow ratio 0.019.
- Choi Wan, 21 July: declination +20.44°, noon altitude 88.11°, zenith 1.89°, geometric daylight 13.174 hours, and vertical-object noon shadow ratio 0.033.
- Choi Wan, 21 August: declination +11.75°, noon altitude 79.42°, zenith 10.58°, geometric daylight 12.654 hours, and vertical-object noon shadow ratio 0.187.
- Choi Wan, 21 September: declination -0.20°, noon altitude 67.46°, zenith 22.54°, geometric daylight 11.989 hours, and vertical-object noon shadow ratio 0.415.
- Choi Wan, 21 October: declination -11.75°, noon altitude 55.91°, zenith 34.09°, geometric daylight 11.346 hours, and vertical-object noon shadow ratio 0.677.
- Choi Wan, 21 November: declination -20.44°, noon altitude 47.22°, zenith 42.78°, geometric daylight 10.826 hours, and vertical-object noon shadow ratio 0.925.
- Choi Wan, 21 December: declination -23.45°, noon altitude 44.22°, zenith 45.78°, geometric daylight 10.631 hours, and vertical-object noon shadow ratio 1.028.
Harth computed the Choi Wan fingerprint for latitude 22.3339° with the Cooper declination approximation, 90° - |latitude - declination| at solar noon, centre-to-centre sunrise hour angle and 1 / tan(altitude) shadow ratio. Longitude 114.2137° is retained for a later civil-time conversion; this screen does not perform that conversion. See NOAA's solar calculation details. Atmospheric refraction, terrain, facade azimuth and obstructions remain outside this first-pass comparison.
Where can you explore related guidance?
- Explore all solar data guidance
- Sun Path: Choi Wan, Hong Kong
- Solar Shading Design: Choi Wan, Hong Kong
- Daylight & Orientation: Choi Wan, Hong Kong
- Solar Altitude & Azimuth: Kai Tak, Hong Kong
- All solar & daylight data guidance for Hong Kong
- House Construction Cost Planning: Choi Wan, Hong Kong SAR, China
- Office Construction Cost Planning: Choi Wan, Hong Kong SAR, China
- Retail Construction Cost Planning: Choi Wan, Hong Kong SAR, China
- School Construction Cost Planning: Choi Wan, Hong Kong SAR, China
Sources and method
Location data from the GeoNames HK dump (CC BY 4.0, snapshot 2026-08-31, GeoNames ID 12689060). Regulatory starting point: Hong Kong Buildings Department. Figures are illustrative — verify against the current locally adopted edition for the site. Solar-method context: NOAA Solar Calculation Details; the Harth monthly table uses a simpler declination and geometric-daylight approximation whose stated limitations must be retained. Project-date refinement reference: NREL Solar Position Algorithm.
Source links
Frequently asked questions
What does the solar altitude and azimuth record for Choi Wan establish?
The solar altitude and azimuth record for Choi Wan establishes a reproducible discovery point at 22.3339, 114.2137 (GeoNames ID 12689060, administrative area KWT) and a Hong Kong source path. It does not establish a final project value, approval or parcel decision.
What must be replaced before using this solar altitude and azimuth workflow for a project in Choi Wan?
For the solar altitude and azimuth record in Choi Wan, replace the 22.3339, 114.2137 city reference with the surveyed site or parcel, identify the competent local authority, and verify the current documents under Buildings Ordinance, subsidiary regulations, codes of practice, and practice notes. Record the edition, retrieval date, units, assumptions and named checker before relying on the result.
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