LED warranties are essential. But if they are to mean anything, they must be supported by recognised performance standards and backed by an established business.
We use LM80, essentially a US stress test conducted over a minimum of 6,000 hours with a formula (TM21) to extrapolate the results to predict lifetime performance.
The LM80 standard originated in 2008 and has been accepted in the industry. Any LED luminaire manufacturer that claims to be credible should be prepared to use this standard and publish the results.