Luminous Efficacy

Energy efficiency of light sources is typically measured in lumens per watt (lm/W), meaning the amount of light produced for each watt of electricity consumed by the light source. This is known as luminous efficacy.

The efficacy of LEDs is improving all the time and have recently exceeded more traditional types of lamps. For a rough comparison, the range of luminous efficacies for traditional and LED sources, including ballast and driver losses as applicable, are shown below.

Light Source                                                 Typical Luminous Efficacy Range in lm/W
Incandescent (no ballast)                              10-18
Halogen (no ballast)                                     15-20
Compact fluorescent (CFL) (including ballast)   35-60
Linear fluorescent (incl. ballast)                      50-100
Metal halide (including ballast)                       50-90
Cool white LED 5000K (including driver)            80-100
Warm white LED 3300K (including driver)          75-95

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