 IES Indoor Report Zonal Lumens

Zonal lumens are computed by taking the average luminous intensity (candelas) at the center of the zone then multiplying by the Zonal Constant to arrive at the Zonal Lumen value. Photometric Toolbox uses the candela information and angles provided in the photometric file to calculate the average candlepower within each zone. Zonal lumens are computed by Photometric Toolbox for ten degree zones then compiled to create a composite zonal lumen summary.

% Lamp

A percentage of total rated lamp lumens emitted. Example: A luminaire contains one lamp rated 3150 lumens. If the 0-30 degree zone contains 618 lumens then the % Lamp figure would be 618/3150=.196 or 19.6%.

% Fixture

A percentage of total luminaire (fixture) lumens emitted. Example: A luminaire contains one lamp rated 3150 lumens. The total efficiency of the luminaire is 73.7%. The total fixture lumens is then 3150 x (.737) or 2322 lumens. If the 0-30 degree zone contains 618 lumens then the % Fixture in this zone would be 618/2322 = 0.266 or 26.6%.