luminance coefficient, LC

[] The ratio of average wall luminance or ceiling cavity luminance to the quotient of the total lamp flux (lumens) divided by the floor area. This requires the luminance in the nonstandard units of footlamberts and floor area in square feet. (See exitance coefficient, EC for current terminology.)


  1. Luminance coefficient is an obsolete term.  It is retained for reference purposes only.
  2. Ref.: IESNA Calculation Procedures Committee. Recommended procedure for calculating coefficients of utilization, wall exitance coefficients, and ceiling cavity exitance coefficients. J Illuminating Engineering Society. Oct 1982;12:3.
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