The LED industry is certainly still struggling with how to establish accurate life claims. The most common practice is to use the standard IES LM 80 life test results of the specific LEDs designed into a given luminaire or bulb. This testing is based on the concept of “lumen maintenance.” An LED chip does lose its ability to emit light over a period of time. Through this 6000 hour test, it is determined how fast that happens and it is projected when the LED product is expected to reach its end of useful life. The standard industry definition of end of life is when the product no longer puts out at least 70% of its original level of lumens, a value representing the total amount of light emitted. In establishing these life claims, however, manufacturers are commonly not testing the LEDs “in-situ”, meaning within the specific luminaire or bulb, and in the type of environment that it will be actually used.
It is really not known how those particular LEDs used in a luminaire will perform over time, only that the LED package on own has has some projected life on a standard test. It also may not take into account the expectations of other parts of the “system.” For example, when a company claims that their LED luminaire lasts 50,000 hours based on the LEDs LM80 tests, it is likely that this number does not account for the shorter life of other components, such as the driver, for example. Since most quality drivers last between 30,000 to 40,000 hours, how can the manufacturer of an LED luminaire claim that their product lasts 50,000 hours? Should not the life claim be based on the life of whatever component is expected to fail first, especially if it is not easily replaced and has a high replacement cost?
The industry has been very effective in developing a wide variety of standards for LED lighting, including testing protocols, and has an excellent quality control discipline through the Energy Star and Lighting Facts Label programs. Unfortunately, the life claim is one topic that has not been addressed. As an industry, we should at least clarify to the buyer in some standard way that these life claims only relate to the performance of the LEDs, and not the entire product. Ideally, we would communicate the true expected life of the whole luminaire, having connected the appropriate testing to support the claim.