A measurement of white light produced by each output watt.
A ratio expressing the luminous efficacy of a light source. Typical lamp efficacies:• Thomas Edison's first lamp — 1.4 lpW• Incandescent lamps — 10-40• Halogen incandescent lamps — 20-45• Fluorescent lamps — 35-105• Mercury lamps — 50-60• Metal halide lamps — 60-120• High-pressure sodium lamps — 60-140 Note: The values above for discharge lamps do not include the effect of the ballasts, which must be used with those lamps. Taking ballast losses into account reduces "system" or lamp-ballast efficacies typically by 10-20% depending upon the type of ballast used.
A measurement of the efficacy of a light source in terms of the light produces by the power consumed. For example a 100 watt lamp producing 1750 lumens give 17.5 lumens per watt.
The ratio of the amount of light provided to the energy (watts) used to produce the light; measurement of the bulb's efficacy.
A measure of the efficacy of a light source in terms of the light produced for the power consumed. For example, a 100-watt lamp producing 1750 lumens gives 17.5 lumens per watt. Examples: Edison's first lamp 1.4 lpw Incandescent lamps 10 - 40 lpw Fluorescent lamps 35 - 100 lpw Halogen lamps 20 - 45 lpw Mercury lamps 50 - 60 lpw Metal halide lamps 80 - 125 lpw High-pressure sodium lamps 100 - 140 lpw
Lumen (light) output divided by lamp watts consumed (i.e. amount of electricity used); also known as efficacy.