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 in a way, yes. But ultimately no.
Most of the time external labs are used. So, producing fake results is impossible.
To fake them you’d have to have control over the lab testing and the data produced. It’s only very large manufactures that have their own labs. And it’s down to their honesty to release accurate data. As these in-house labs have to be certified, and regularly recertified by external labs, it’s highly unlikely they’d take that risk.
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 is just supporting documentation to confirm the numbers used in a simulation are correct. But with that alone, you can’t choose which product is the best. It’s just a guarantee that someone is using the correct data to run a simulation.
LM80 depreciation values are obviously useful to consider too.
The best things to look at when you want to choose between products are the simulations themselves. That’s where you’ll always get the most useful data.