Luminaire efficacy

According to BRE’s The essential guide to retail lighting:

A luminaire is a ‘Light fixture or fitting; an electrical device used to create artificial light and / or illumination, by use of an electric lamp.’

Luminaire efficacy is the ‘Light output of an entire luminaire divided by the total power consumed by the lamps and ballasts. Equal to the lamp efficacy multiplied by the light output ratio of the luminaire.’

It is expressed in lumens per Watt (lm/W).

Ballast or control gear, is ‘Part of the control equipment of fluorescent or discharge lamps, used to stabilise the current. The older, traditional main-frequency ballast can consume up to 20-25% of the total lamp current. A modern electronic ballast working at high frequency consumes about 30% less current, and can be used to regulate or dim the lamp output.’

--BRE Group

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