Q: What does LM80 mean, and why talk of LM70.
A: LM80 means Lumen maintenance 80%. An LM80 report will show after how many hours at a specific LED case temperature light level will drop by 20%. The problem is that most modern chips do not have actual reports because they have not run long enough to give this information [because they are to new], and so the super smart engineers calculate a projection based on the information they received after 6000h - 9000h of testing. LM70 is Lumen maintenance 70%, and that is the ageing mark the LED lights should reach not before the stated time written on the package when you buy it. Do not ask why the life span is based on 30% light loss but the life report is based on 20% light loss. We did not make the rules.
Q:What is the difference between system efficiency and LED efficiency?
A: LED Efficiency is only the efficiency of the LED. This will always be better than the efficiency of the light fitting because an LED alone does not make a light and all components in a light fitting create energy losses. Many suppliers like to state the LED efficiency, but this information is irrelevant when calculating feasibility, or the power saving impact of the product.
System efficiency is the total power that is used by an LED light fitting. The efficiency may seem lower, but it is an accurate relation between power consumption and light output. This confuses the layman, because if one does not know that actual R/Lm cost, then it is many time difficult to know whether the stated efficiency is in fact system efficiency, or just LED efficiency. Generally when it sounds too good to be true, it is not.