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    Lumens, Lux & Efficacy

    lumen-output.jpg



    LED chips typically consume 80% less power than a halogen of equivalent brightness.





    What are lumens?

    The total light output from a light source, regardless of the direction the light travels, is specified as lumens (lm), where 1 lumen is defined as equivalent to the light output from 1 candle. This figure is used to describe and compare lamp brightness.

    What is efficacy?

    Efficacy (lm/w) is the total light output in lumens per watt of power consumed. The higher the lumens per watt, the more efficient a light source is. The efficacy specification is simple to calculate. For example, a LED globe that produces 720 lumens from 10 watts has an efficacy of 72 lumens per watt (720 lumens/10 watts).

    How efficient are LED lights?

    The following table shows the power consumption of a LED light is typically 80% less than a halogen of equivalent brightness:


    A Comparison of Light Types

    PowerOutputEfficacy
    Incandecent60 watts770 lm13 lm/w
    Halogen50 watts750 lm15 lm/w
    CFL11 watts740 lm65 lm/w
    LED10 watts720 lm72 lm/w



    What is lux?

    Lux (lx), is defined as the level of brightness at a particular distance from the light source. 1 lux is equivalent to 1 lumen per square meter, so if you measured 800 lux at 1.5m height using a lux meter, then there is 800 lumens of light per square meter at 1.5m.







    What lux levels are required for various tasks?