Paolo, What are LM79 and LM80?
Before the introduction of LM79 and LM80, there were no standard ways to meaningfully compare manufactures’ data on their luminaires. This was because they were free to publish data based on their own different types of tests.
This was resolved when the Illuminating Engineering Society of North America (IESNA) introduced these two standard methodologies.
LM79 measures a luminaire’s performance as a whole and covers things such as output/flux, colour characteristics, light distribution, power use, and overall effectiveness. The European equivalent of LM79 is the EN 13032-4:2015.
LM80 just covers an LED’s lighting depreciation and can be used to determine the lifetime of a product.
How accurate are they at predicting performance in the field?
LM79 data gives the exact figure of what a luminaire is emitting down to one lumen. So, it’s as accurate as you can get. Of course, there’s always going to be a small difference between each luminaire produced and its flux. This is so small though it’s insignificant.
LM80 data is based on large sample tests of LEDs over a long time. So, it’s pretty accurate.
Are these values easy to fake?
No, and perhaps in some cases, yes. However, ultimately, the chances of producing fake results are highly unlikely. This is because most of the time, external labs are involved in the testing process. To falsify the results, one would need to have control over the lab testing and the data produced. Only very large manufacturers have their own labs, and it is their honesty that determines the accuracy of the data they release. Moreover, these in-house labs need to be certified and regularly recertified by external labs, further minimizing the risk of any deception.
Can we compare one luminaire’s value to another?
Yes. You can compare these results on paper. But the best comparison is always the lighting simulation data.
What should the end-user consider when looking at these values?
LM79 serves as supporting documentation to validate the accuracy of numbers used in simulations. However, it alone cannot determine the superiority of a product. It simply assures that the correct data is being utilized for running simulations. Additionally, considering LM80 depreciation values is of obvious importance. When making choices between products, the simulations themselves are the most valuable source of information. That's where you'll always find the most insightful data.