50 years ago yesterday, Nick Holonyak Jr. demonstrated the first LED to General Electric suits. Back then, while the only existing LED emitted crimson infrared light, Holonyak predicted his invention would replace standard household incandescent light bulbs. Today LED manufacturers haven’t stopped being idealistic.
Since LEDs have only been around for half a century, the 20, 25, 30 year expiration dates on the brand new technology might be difficult to believe. Honestly, LEDs have barely been around long enough to find a niche in the market, let alone undergo 20, 25, 30 years of definitive testing. The claims and the benefits of LEDs are impressive, but how can we make sure they’re not a farce?
Enter the U.S. Department of Energy and their new Lighting Facts program, created to help you navigate the teeming sea of new lighting technology. The program addressed this issue of LED luminaire depreciation in depth, to help people like you and me know what we’re getting into.
How do manufacturers come up with these numbers?
Instead of traditional testing, where a large sample of lamps are operated until 50% burn out, developers must determine an LED’s rated life a different way. Since the LED doesn’t burn out, but dims gradually, the rated life comes from the estimated lumen depreciation, not accounting for other causes of decline.
What causes LED failure?
Other factors besides age that might increase the rate of gradual dimming include:
- Exposure to extreme temperatures
- Contact with moisture and humidity
- Voltage and current fluctuations
- Driver or other electrical component failure
- Damage to material encapsulating the LEDs
- Damage to any wire bonds connecting the LED to the fixture
- Degradation of phosphors
Since very few of us live in sterile, mellow, laboratory-like houses, the entire light bulb’s rated life will not live up to the life span of its LED. Continue reading »