Solar & Daylight Data

Updated 2026-08-31

Sun Path: Ludhiana, India

How to research sun path for a specific site in Ludhiana — 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 IN dump](https://download.geonames.org/export/dump/IN.zip) (CC BY 4.0, snapshot 2026-08-31, GeoNames ID 1264728). Regulatory starting point: [Bureau of Indian Standards and the applicable state or urban local body](https://www.services.bis.gov.in/php/BIS_2.0/bisconnect/knowyourstandards/Indian_standards/isdetails/). 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 Ludhiana at 30.9120, 75.8538, the declination-only solar-noon altitude is approximately 82.5° at the June solstice, 59.1° at an equinox and 35.7° 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 1264728 in administrative area 23, at 30.9120, 75.8538; replace it with the surveyed parcel point before relying on the result. As a transparent geometry check, declination-only solar-noon altitude is about 82.5° at the June solstice, 59.1° at an equinox and 35.7° at the December solstice. Representative 21st-day geometry ranges from about 10.0 hours in December to 14.0 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 Ludhiana?

Ludhiana is represented here at approximately 30.9120, 75.8538 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 Ludhiana 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.

Ludhiana monthly solar geometry check for sun path

Representative dateDeclinationSolar-noon altitudeGeometric daylight
21 January-20.14°38.9°10.3 h
21 February-11.23°47.9°11.1 h
21 March-0.40°58.7°12.0 h
21 April+11.58°70.7°12.9 h
21 May+20.14°79.2°13.7 h
21 June+23.45°82.5°14.0 h
21 July+20.44°79.5°13.7 h
21 August+11.75°70.8°13.0 h
21 September-0.20°58.9°12.0 h
21 October-11.75°47.3°11.0 h
21 November-20.44°38.6°10.3 h
21 December-23.45°35.6°10.0 h

Month-by-month geometry interpretation

  • 21 January: approximate solar-noon altitude 38.9° (zenith angle 51.1°) and 10.3 hours of geometric daylight. That is 0.3 hours longer than the preceding representative date in this annual sequence.
  • 21 February: approximate solar-noon altitude 47.9° (zenith angle 42.1°) and 11.1 hours of geometric daylight. That is 0.8 hours longer than the preceding representative date in this annual sequence.
  • 21 March: approximate solar-noon altitude 58.7° (zenith angle 31.3°) and 12.0 hours of geometric daylight. That is 0.9 hours longer than the preceding representative date in this annual sequence.
  • 21 April: approximate solar-noon altitude 70.7° (zenith angle 19.3°) and 12.9 hours of geometric daylight. That is 1.0 hours longer than the preceding representative date in this annual sequence.
  • 21 May: approximate solar-noon altitude 79.2° (zenith angle 10.8°) and 13.7 hours of geometric daylight. That is 0.8 hours longer than the preceding representative date in this annual sequence.
  • 21 June: approximate solar-noon altitude 82.5° (zenith angle 7.5°) and 14.0 hours of geometric daylight. That is 0.3 hours longer than the preceding representative date in this annual sequence.
  • 21 July: approximate solar-noon altitude 79.5° (zenith angle 10.5°) and 13.7 hours of geometric daylight. That is 0.3 hours shorter than the preceding representative date in this annual sequence.
  • 21 August: approximate solar-noon altitude 70.8° (zenith angle 19.2°) and 13.0 hours of geometric daylight. That is 0.8 hours shorter than the preceding representative date in this annual sequence.
  • 21 September: approximate solar-noon altitude 58.9° (zenith angle 31.1°) and 12.0 hours of geometric daylight. That is 1.0 hours shorter than the preceding representative date in this annual sequence.
  • 21 October: approximate solar-noon altitude 47.3° (zenith angle 42.7°) and 11.0 hours of geometric daylight. That is 0.9 hours shorter than the preceding representative date in this annual sequence.
  • 21 November: approximate solar-noon altitude 38.6° (zenith angle 51.4°) and 10.3 hours of geometric daylight. That is 0.8 hours shorter than the preceding representative date in this annual sequence.
  • 21 December: approximate solar-noon altitude 35.6° (zenith angle 54.4°) and 10.0 hours of geometric daylight. That is 0.3 hours shorter than the preceding representative date in this annual sequence.

Harth calculation for latitude 30.9120°: Cooper declination approximation, 90° - |latitude - declination| at solar noon, and centre-to-centre sunrise hour angle. See NOAA's solar calculation details for fuller method context. This screening table excludes equation-of-time/civil-time conversion, atmospheric refraction, terrain, facade azimuth and obstructions; it is not an hourly shading result.

Sources and method

Location data from the GeoNames IN dump (CC BY 4.0, snapshot 2026-08-31, GeoNames ID 1264728). Regulatory starting point: Bureau of Indian Standards and the applicable state or urban local body. 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 Ludhiana establish?

The sun path record for Ludhiana establishes a reproducible discovery point at 30.9120, 75.8538 (GeoNames ID 1264728, administrative area 23) and a India 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 Ludhiana?

For the sun path record in Ludhiana, replace the 30.9120, 75.8538 city reference with the surveyed site or parcel, identify the competent local authority, and verify the current documents under National Building Code of India plus state and urban-local-body rules. Record the edition, retrieval date, units, assumptions and named checker before relying on the result.

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