Can LEDs live forever? The long and short of it

June 24, 2016
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One of the major advantages of LED lighting is its long lifetime when compared with traditional fixtures. But how much longer will LEDs last? And are there differences from one LED fixture to the next? Do they burn out all at once or fade slowly over time? Below, we’ve detailed the answers to these questions and more.


Burn Hours


The most important thing to understand when it comes to measuring the lifetime of light fixtures is that they are rated in terms of “burn hours,” or the number of hours they can be turned on before significantly degrading. So how do you figure out how long an LED light will last for you?


The calculation is pretty simple. Just take the number of hours you expect to leave the light on and multiply it by 365 (which assumes you leave the lights on during weekends, otherwise multiply by 260). This will give you your annual burn hours. Then take the rated lifetime of your LED lamp and divide it by this number.


The lifetime of many Cree LEDs is roughly 50,000 hours. This means that:


  • If you leave your lights on 24-7, your LEDs will last 5.71 years
  • If you leave your lights on 12 hours per day and 7 days per week, your LEDs will last 11.42 years
  • If you leave your lights on 8 hours per day and 7 days per week, your LEDs will last 17.12 years

There are a few conclusions that follow from this calculation. First, you will not get a straight answer on the lifetime of your LED luminaires without knowing a thing or two about your own lighting usage. Second, the overall lifetime can be greatly affected by small changes in daily usage, so it helps to plan out an updated (read, shorter) lighting schedule along with your LED upgrade. Third, it helps to be honest, really honest,  about your lighting usage if you want to have an accurate estimate of your LED system’s lifetime.


It’s also worth noting that the lifetime of most LEDs far surpasses that of traditional forms of lighting, and can be as much as 25 times longer. Below are a few estimates of the average lifetime for other forms of lighting, for the sake of comparison:


  • Incandescent lighting: 1,800 hours
  • Compact fluorescent lighting (CFLs): 12,000 hours
  • Metal halide lighting: 15,000 hours
  • High pressure sodium lighting: 24,000 hours

The above means that no matter how often you use your lights, you will have to replace other forms of lighting at least twice as often as LED lighting. This is worth keeping in mind when comparing the upfront costs of each lighting type. Often, annualized costs are a better estimate of your true lighting investment than looking at the sticker price alone.


The L70


With LED lighting, your fixtures are less likely to suddenly burn out than they are to appear dimmer or shift in color. So how do you measure the lifetime of a fixture that doesn’t burn out all at once?


An important term to remember here is the L70. The L70 is the number of hours after which the LED will most likely output 70% or less of its maximum number of lumens. When a light has reached its L70, it’s ready to be replaced, even if the fixture still gives off light.


The L70 is unique to LEDs, but even between LED brands, the L70 can vary significantly, so it’s worth comparing for every type of light you hope to replace.


Which begs the question, when can you tell when your light output has significantly decreased? Until you have reached the L70, it’s likely that you will not notice a difference in output at all. This happens because LEDs don’t degrade in a linear fashion, but instead degrade quickly at the end of their lifetime.


Catastrophic Failure


Another related term, “catastrophic failure,” sounds alarming, but is actually another way of describing the lifetime of an entire system, whether of LEDs or another type of lighting.


What it really means is that 50% of your LED lights are operating at 70% of their possible output. For other forms of lighting, this means that 50% of the lights have burnt out, which sounds a little more “catastrophic.” Although some building owners may delay replacing lights even despite catastrophic failure, we strongly recommend that you undergo a lighting retrofit before your lighting system reaches this point.


Warrantied Lifetime


But what does all of this matter, as long as your lights are under warranty?


At the end of the day, the warrantied lifetime is more important than any other measure of longevity, because it determines when you will have to pay out-of-pocket to replace your lighting. The trick with warranties is to make sure that they cover every part of the fixture that is likely to contribute to its failure.


Ask your dealer or installer who you will call if your lights fail, both out-of-the-box and later on. If they have a different answer depending on the LED component, or it otherwise isn’t clear how warranty claims are processed, this could be a red flag.


And by the way, if you’re a Joule Energy client, you should reach out to us for any problem with your fixtures, and we will deal with the warranty paperwork as well as any needed fixture repair or replacement. We deal directly with Cree and other manufacturers, so your repair is as quick and seamless as possible.


Changing out lights can be a pain, not to mention expensive. So when it comes to undergoing a lighting retrofit, make sure you consider the lifetime of your system and how it can be affected by leaving the lights on just a little bit longer.

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