Luminous efficacy is a measure of how efficiently a light source produces visible light. It quantifies the amount of visible light emitted per unit of power consumed by the source.

Common examples of related units of measurements include lumens, which measure the total amount of visible light output by a source, and watts, which measure the power consumed by the source.

• Luminous efficacy is crucial in determining the energy efficiency of lighting systems.
• It helps in comparing different light sources to choose the most efficient option.
• Luminous efficacy is also important in the design and development of lighting technologies to improve energy conservation.