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.
Current testing on luminaire reliability shows some LEDs maintaining output for impressive amounts of time, others dropping off quickly, and some even changing color over time.
For now, manufacturers are still working to determine definitive lamp lifetime stats.
Can we trust LEDs?
With this information, you might be thinking, LEDs are some of the most expensive light sources around, is it really worth it to gamble on something so new?
Well, Lighting Facts has some advice for you. LEDs have many benefits, they’ll save you tons of energy and let you light your home, office, or wherever else in new, exciting ways. If you stay informed and proactive about purchasing quality LEDs, you’ll be making a good investment. Here are some guidelines the next time you’re in the market for a new light bulb:
- Use high quality LEDs from manufacturers who are transparent about their product’s reliability.
- Keep an eye out for a luminaire warranty that’s at least comparable to traditional luminaires used for the same purpose.
- Find a product that has been independently tested.
- Look for temperature data for the LED in question; how the conditions of where it’s meant to operate affect the expected life.
- Investigate any testing done on the long term performance of the LED (including DOE CALiPER testing, manufacturer in-house testing, or field tests done by the DOE, utilities, or others).
Where can we find all this information?
Those guidelines seem a little overwhelming, no? Luckily, hundreds of LED manufacturers have opted to include a Lighting Facts label with their products, which organizes all that information into one small, convenient table. If your product doesn’t include a Lighting Facts label, you can look it up at LightingFacts.com.