The Usefulness of Near-Field Goniophotometry Data to Assess Illuminances and Discomfort Glare in Indoor Lighting

ABSTRACT

In lighting simulations, a luminaire is usually modeled using a luminous intensity distribution emitted by a single-point source. This so-called far-field approach is valid as long as the dimensions of the luminaire are much smaller than the distance to the calculation surface. This assumption is generally not met in standard indoor lighting and may lead to significant errors in the prediction of illuminances and discomfort glare. This work describes a practical near-field approach based on splitting the luminaire into N point sources. The errors in relation to the near field (infinite value of N) are evaluated as a function of N. This approach generates a more accurate assessment of the Unified Glare Rating in the case of luminaires with non-uniform emission.

KEYWORDS:

• Discomfort glare
• near-field goniophotometry
• indoor lighting
• lighting simulation
• photometry

Acknowledgments

We would like to thank Dr Pierre Boulenguez for fruitful discussions on near-field photometry and for his enthusiasm, which the authors share, to promote this approach in lighting design.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors report no funding for the preparation of this manuscript. Samuel Carré and Christophe Martinsons contributed to this work through the Health and Comfort Research Program SEC 2.1 of the Centre Scientifique et Technique du Bâtiment.