Solar & Daylight Data

Updated 2026-08-31

Sun Path: Cardiff, UK

How to research sun path for a specific site in Cardiff — the controlling authority, source documents, and checks to run before you rely on a number.

Last updated August 31, 2026 · Location data from the [GeoNames GB dump](https://download.geonames.org/export/dump/GB.zip) (CC BY 4.0, snapshot 2026-08-31, GeoNames ID 2653822). Regulatory starting point: [UK and devolved building-control authorities](https://www.gov.uk/government/collections/approved-documents). 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.

Direct answer

For Cardiff at 51.4800, -3.1800, the declination-only solar-noon altitude is approximately 62.0° at the June solstice, 38.5° at an equinox and 15.1° 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 2653822 in administrative area WLS, at 51.4800, -3.1800; replace it with the surveyed parcel point before relying on the result. As a transparent geometry check, declination-only solar-noon altitude is about 62.0° at the June solstice, 38.5° at an equinox and 15.1° at the December solstice. Representative 21st-day geometry ranges from about 7.6 hours in December to 16.4 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 sun path record.

Prepared by Harth · Prepared from the cited location and country sources; local project inputs remain unreviewed · Published 2026-08-26 · Updated 2026-08-31.

What must be verified for Cardiff?

Cardiff is represented here at approximately 51.4800, -3.1800 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 sun path 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 sun-path-workflow page is a project-starting worksheet, not a design value or approval. The controlling authority and qualified professionals for the Cardiff site remain authoritative.

This primary route consolidates the location evidence needed for Sun Path, Solar Altitude & Azimuth, Solar Shading Design, Daylight & Orientation. A narrower route should be released only when it adds a materially different official source, calculation, process, threshold or worked example.

Cardiff monthly solar geometry check for sun path

Representative dateDeclinationSolar-noon altitudeGeometric daylightNoon shadow / height
21 January-20.14°18.38°8.343 h3.009
21 February-11.23°27.29°10.075 h1.938
21 March-0.40°38.12°11.932 h1.275
21 April+11.58°50.10°13.989 h0.836
21 May+20.14°58.66°15.657 h0.609
21 June+23.45°61.97°16.403 h0.532
21 July+20.44°58.96°15.723 h0.602
21 August+11.75°50.27°14.020 h0.831
21 September-0.20°38.32°11.966 h1.265
21 October-11.75°26.77°9.980 h1.983
21 November-20.44°18.08°8.277 h3.063
21 December-23.45°15.07°7.597 h3.714

Cardiff solar-geometry fingerprint at 51.4800, -3.1800

  • Cardiff, 21 January: declination -20.14°, noon altitude 18.38°, zenith 71.62°, geometric daylight 8.343 hours, and vertical-object noon shadow ratio 3.009.
  • Cardiff, 21 February: declination -11.23°, noon altitude 27.29°, zenith 62.71°, geometric daylight 10.075 hours, and vertical-object noon shadow ratio 1.938.
  • Cardiff, 21 March: declination -0.40°, noon altitude 38.12°, zenith 51.88°, geometric daylight 11.932 hours, and vertical-object noon shadow ratio 1.275.
  • Cardiff, 21 April: declination +11.58°, noon altitude 50.10°, zenith 39.90°, geometric daylight 13.989 hours, and vertical-object noon shadow ratio 0.836.
  • Cardiff, 21 May: declination +20.14°, noon altitude 58.66°, zenith 31.34°, geometric daylight 15.657 hours, and vertical-object noon shadow ratio 0.609.
  • Cardiff, 21 June: declination +23.45°, noon altitude 61.97°, zenith 28.03°, geometric daylight 16.403 hours, and vertical-object noon shadow ratio 0.532.
  • Cardiff, 21 July: declination +20.44°, noon altitude 58.96°, zenith 31.04°, geometric daylight 15.723 hours, and vertical-object noon shadow ratio 0.602.
  • Cardiff, 21 August: declination +11.75°, noon altitude 50.27°, zenith 39.73°, geometric daylight 14.020 hours, and vertical-object noon shadow ratio 0.831.
  • Cardiff, 21 September: declination -0.20°, noon altitude 38.32°, zenith 51.68°, geometric daylight 11.966 hours, and vertical-object noon shadow ratio 1.265.
  • Cardiff, 21 October: declination -11.75°, noon altitude 26.77°, zenith 63.23°, geometric daylight 9.980 hours, and vertical-object noon shadow ratio 1.983.
  • Cardiff, 21 November: declination -20.44°, noon altitude 18.08°, zenith 71.92°, geometric daylight 8.277 hours, and vertical-object noon shadow ratio 3.063.
  • Cardiff, 21 December: declination -23.45°, noon altitude 15.07°, zenith 74.93°, geometric daylight 7.597 hours, and vertical-object noon shadow ratio 3.714.

Harth computed the Cardiff fingerprint for latitude 51.4800° with the Cooper declination approximation, 90° - |latitude - declination| at solar noon, centre-to-centre sunrise hour angle and 1 / tan(altitude) shadow ratio. Longitude -3.1800° 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.

Sources and method

Location data from the GeoNames GB dump (CC BY 4.0, snapshot 2026-08-31, GeoNames ID 2653822). Regulatory starting point: UK and devolved building-control authorities. 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.

Frequently asked questions

What does the sun path record for Cardiff establish?

The sun path record for Cardiff establishes a reproducible discovery point at 51.4800, -3.1800 (GeoNames ID 2653822, administrative area WLS) and a United Kingdom source path. It does not establish a final project value, approval or parcel decision.

What must be replaced before using this sun path workflow for a project in Cardiff?

For the sun path record in Cardiff, replace the 51.4800, -3.1800 city reference with the surveyed site or parcel, identify the competent local authority, and verify the current documents under Building Regulations and nation-specific Approved Documents or technical handbooks. Record the edition, retrieval date, units, assumptions and named checker before relying on the result.

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