quotient of the sum of the areas of the working plane and the plane of the luminaires and the sum of the area of the walls bounded by the working plane and the plane of the luminaires, used in the calculation of the utilization factor or utilance
Note 1 to entry: The room index is expressed by the formula
Note 3 to entry: The room index has unit one.
Note 4 to entry: This entry was numbered 845-09-55 in IEC 60050-845:1987.
Note 5 to entry: This entry was numbered 17-1121 and 17-587 in CIE S 017:2011.