Encyclopedia of Color Science and Technology

Living Edition
| Editors: Ronnier Luo

Coefficient of Utilization, Lumen Method

  • Peter Thorns
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27851-8_117-2


The lumen method is an indoor lighting calculation methodology that allows a quick assessment of the number of luminaires necessary to achieve a given average illuminance level or alternatively the average illuminance level that will be achieved for a given number of luminaires. It is valid for empty rectangular rooms with simple three-surface diffuse reflectances for ceiling, wall, and floor.


When an electric lamp is turned on, it emits light and it is possible to quantify the amount of light by measuring it, the result being given in the units of lumens. In itself this is a useful piece of information, but what would be more useful would be to have a method of converting this into a measure of the amount of light that would be received onto a desk from one or more luminaires or alternatively the number of luminaires necessary to achieve a given quantity of light on the desk. This calculation is known as the lumen method.

Light falling onto a surface is called...


Task Plane Utilization Factor Maintenance Cycle Maintenance Factor Illuminance Level 
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  1. 1.
    CIE Publication 40: Calculations for interior lighting – basic method (1978)Google Scholar
  2. 2.
    CIE Publication 52: Calculations for interior lighting – applied method (1982)Google Scholar
  3. 3.
    CIE Publication 97: Guide on the maintenance of indoor electric lighting systems (2005)Google Scholar
  4. 4.
    ISO 8995-1:2002(E)/CIE S 008/E: 2001: lighting of work places part 1: indoorGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  1. 1.Strategic Lighting Applications, Thorn Lighting LtdSpennymoorUK