WHAT’S THE DIFFERENCE BETWEEN DELIVERED AND CHIP LUMEN?
Well basically the initial chip lumen are what comes out of the LED in a raw test state, so not when built into a luminaire. They are a little bit like what lamp lumen are in conventional lamps, such as fluorescent, i.e. what the lamp outputs in a raw state. There is one major difference here though, conventional lamps typically have two major losses applied to them when installed in a light fitting – electrical (i.e. ballast losses) and light output, our luminaire losses (i.e. the light that gets trapped in the luminaire and doesn’t make it out). LED’s have one more major cause of losses – heat. The same LED chip placed on two difference heat sinks will result in two different sets of performance due to better or worse heat dissipation.
Therefore, a better engineered light fitting will typically have much improved performance, even if they both use the exact same LED chip/engine. Delivered lumen are the amount of lumen that make it out of the luminaire after all losses – heat, electrical and luminaire. They should be lumen that show in any luminaire photometric file, and are what we always strive to provide on our data sheets at Pierlite.
One general rule to follow is if a manufacturer doesn’t say if they are delivered lumen, then they probably aren’t. So when next comparing lumen to lumens, try and ensure you are comparing apples with apples (or delivered with delivered)!