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Solar & Daylight Data

Updated 2026-09-02

Daylight & Orientation: Tuen Mun, Hong Kong

How to research daylight & orientation for a specific site in Tuen Mun — the controlling authority, source documents, and checks to run before you rely on a number.

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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 1818446). 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 Tuen Mun at 22.3917, 113.9716, the declination-only solar-noon altitude is approximately 89.0° at the June solstice, 67.6° 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 1818446 in administrative area NTM, at 22.3917, 113.9716; replace it with the surveyed parcel point before relying on the result. As a transparent geometry check, declination-only solar-noon altitude is about 89.0° at the June solstice, 67.6° 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 daylight and building orientation record.

Prepared by Harth · Topic-specific calculated asset and fresh SERP brief passed editorial screening; page remains noindex pending the independent content, evidence, similarity and link gates · Published 2026-08-26 · Updated 2026-09-02.

What must be verified for Tuen Mun?

Tuen Mun is represented here at approximately 22.3917, 113.9716 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 daylight and building orientation be established?

  1. Fix the surveyed site and local time basis.
  2. Select an authoritative weather source or a named solar-position algorithm.
  3. Record period, percentile or scenario and units.
  4. Test sensitivity to elevation, exposure, urban form and horizon.
  5. Save the source file, retrieval date and checker in the model record.
InputProject-specific evidenceQA question
Sitesurveyed coordinates, elevation and horizonDoes the point represent the building?
Weather/solar methodnamed dataset, algorithm, period and time basisAre station, time zone and units explicit?
Design scenariocurrent and future scenario agreed by the teamIs an average being mistaken for an extreme?
Complianceadopted local document and editionWas applicability confirmed with the authority?

What are the limits of this worksheet?

This daylight-workflow page is a project-starting worksheet, not a design value or approval. The controlling authority and qualified professionals for the Tuen Mun site remain authoritative.

Tuen Mun monthly daylight-orientation ledger

Representative dateGeometric daylightSolar sunriseSolar sunsetSunrise hour angleNoon bearingChange from prior month
21 January10.841 h06.5817.4281.31°180.0°+0.214 h
21 February11.375 h06.3117.6985.31°180.0°+0.533 h
21 March11.978 h06.0117.9989.83°180.0°+0.603 h
21 April12.646 h05.6818.3294.84°180.0°+0.668 h
21 May13.159 h05.4218.5898.69°180.0°+0.513 h
21 June13.373 h05.3118.69100.29°0.0°+0.214 h
21 July13.178 h05.4118.5998.83°180.0°-0.195 h
21 August12.656 h05.6718.3394.92°180.0°-0.522 h
21 September11.989 h06.0117.9989.92°180.0°-0.667 h
21 October11.344 h06.3317.6785.08°180.0°-0.645 h
21 November10.822 h06.5917.4181.17°180.0°-0.522 h
21 December10.627 h06.6917.3179.71°180.0°-0.195 h

Orientation checks prompted by the Tuen Mun ledger

The representative daylight span runs from 10.627 hours on 21 December to 13.373 hours on 21 June. Solar sunrise and sunset are expressed in apparent solar time, not a time-zone clock. The noon-bearing column is a true-north azimuth screen and becomes unstable when the sun passes close to zenith.

For Tuen Mun at 22.3917°, 113.9716°, test each occupied facade against the actual horizon, adjacent buildings, glazing, room depth and target illuminance. This ledger describes geometric availability only; it does not estimate irradiance, daylight autonomy, glare or energy. Refine project-date positions with the NREL SPA.

Where can you explore related guidance?

Sources and method

Location data from the GeoNames HK dump (CC BY 4.0, snapshot 2026-08-31, GeoNames ID 1818446). 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 daylight and building orientation record for Tuen Mun establish?

The daylight and building orientation record for Tuen Mun establishes a reproducible discovery point at 22.3917, 113.9716 (GeoNames ID 1818446, administrative area NTM) 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 daylight and building orientation workflow for a project in Tuen Mun?

For the daylight and building orientation record in Tuen Mun, replace the 22.3917, 113.9716 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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