What is Lumen efficiency(lumen/watt)?

Luminous eficacy basically describes how well a light source, such as an LED,radiats light.It can be calculated using the ratio between luminous flux to power, and hence is measured in lumen per watt as its SI unit.

What is Lumen Maintenance?

Lumen maintenance is defined as amount of luminous flux remaining in the light source during a time of working or operation.It used percentages to determine and compare teh luminxous flux when it is brand new to the luminous flux it will have in the future after constant use.If LEDs lose all of their light output over time, then they are not the value we think they are.

Lumen Maintenance is referred to as LM70, LM80 or LM 90.These are how many hours it will hold that light output,So a LM70 , 10K hours means it will keep at least 70% of the light for the first 10k hours. Top end manufactures go to greeat lengths to ensure LEDs have high lumen maintenance to ensure 20+ years of use.The new policy requires an LM90 of 36,000 hours, That 's a crazy high number to hit when you think about it .36000 hours will take more than 20 years formost fixtures and they can only lose 10% of the light in that time,That's how far the tech has come. 

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