Unified Glare Rating

from Wikipedia, the free encyclopedia

The Unified Glare Rating ( UGR ; German standardized glare rating ) was developed by the International Commission on Illumination CIE (Commission International de l'Eclairage). It is a procedure that aims to standardize the assessment of glare worldwide. The lower the UGR value, the lower the psychological glare.

The UGR formula is a further development of the formula for calculating the CIE Glare Index .


In contrast to previous methods in which the glare was assessed by the luminance of a single luminaire, the UGR method calculates the glare of the entire lighting system for a defined observer position .

DIN EN 12464-1 specifies the UGR reference value for a standard room. Modern light planning programs enable an exact calculation of the UGR value for a defined observer position in the room. The elevation angle 65 °, 75 ° or 85 ° for luminance <1,000 candela / square meter (ratio of light intensity / area) is also specified . This is the critical angle above which the luminaire has a luminance of 1,000 candela / square meter all around.


According to DIN EN 12464-1, different UGR values ​​must be observed depending on the difficulty of various visual tasks:

  • Technical drawing : UGR ≤ 16
  • Reading, writing, classrooms, computer work, control work : UGR ≤ 19
  • Work in industry and trade, reception : UGR ≤ 22
  • Rough work, stairs : UGR ≤ 25
  • Corridors : UGR ≤ 28

In rooms with computer screens and office workplaces , the UGR value must not be greater than 19, regardless of the lighting level. Luminaire manufacturers offer corresponding UGR tables.


The UGR calculation was developed in order to apply it to light sources that have a small, but homogeneously radiating surface, e.g. B. Unshielded fluorescent lamps, or lights with diffusers. Large areas, such as B. luminous ceilings with backlit stretch films, small inhomogeneous light sources such as spotlights or certain downlights result in a value in the calculation process that no longer correlates with the perceived glare. LED light sources, which often consist of a large number of individual light points, are particularly affected by this deficiency.

Various studies suggest that the UGR calculation, like most other glare calculations, show a low correlation to the perceived glare.

From Takahashi et al. Changes were proposed to improve the calculation of glare. So far, however, there are no corresponding standards in sight that enable an improved glare assessment. The effort involved in introducing such a system in the lighting industry must also be assessed as great, since the common light calculation software, such as B. DIALux or Relux only use EULUMDAT information for the calculation and this data is insufficient for the description of inhomogeneous luminance levels at light sources.


Individual evidence

  1. Publications of the CIE Division 3 ( Memento of the original dated February 21, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / www.cie.co.at
  2. DIN EN 12464-1.
  3. Presentation on UGR and GI of the TU Berlin PDF file.
  4. ZVEI guidelines for DIN EN 12464-1 ( Memento from September 30, 2013 in the Internet Archive ) (PDF; 522 kB) ZVEI guidelines for planning with DIN EN 12464-1, accessed on September 8, 2011.
  5. http://alexandria.tue.nl/extra2/afstversl/tm/Geerdinck_2012.pdf (PDF; 1997 kB; 2.0 MB) Leonie Geerdinck: Glare perception in terms of acceptance and comfort. August 2012, Graduation Report to: Faculty Industrial Engineering & Innovation Sciences, Technische Universiteit Eindhoven.
  6. http://lrt.sagepub.com/content/early/2012/04/17/1477153512444527.abstract ( Memento of the original from March 5, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Robert D Clear: Discomfort glare: What do we actually know? In: Lighting Research and Technology. April 2013 vol. 45 no. 2 141-158 doi : 10.1177 / 1477153512444527 . @1@ 2Template: Webachiv / IABot / lrt.sagepub.com
  7. https://www.jstage.jst.go.jp/article/jlve/31/3/31_3_128/_article (PDF; 698 kB) Hiroshi TAKAHASHI, Yoshinori KOBAYASHI, Shou ONDA, Takashi IRIKURA: Position Index for the Matrix Light Source. In: Journal of Light & Visual Environment. Vol. 31 (2007) No. 3 pp. 128-133.