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3 Key terms about LED lifespan

As an Australian owned and operated LED light supplier, we want all specifiers and building owners to be properly informed with facts so they can easily make objective choices when having to choose between differing LED products.

3 Must Know Terms That Will Make You an LED Lifespan Expert
(they will save you time & money)

It’s important that as an outsider you’re equipped with some basic understanding before forking out your hard earned dollars on what could potentially be an inferior product. Rest assured, I’m going to spell out how you can avoid disaster, save money, and save time by knowing these 3 simple terms about LED lifespan.

Here I’ll be spilling the beans about how manufacturers calculate LED lifespan and then report on those figures, so you can make a choice that will literally save you money now and in the future. What luminaire manufacturers do is publish a variety of different figures to prove the lifespan of their LED products, or their useful life at a prescribed light output – you will often see this in a products tech-specs as ’30,000 lamp hours’. They will often use terms like: ‘projected’, ‘theoretical’, ‘minimum lifetime’ or even ‘survivorship’ to describe that number, but how this number is calculated and reported by manufacturers is actually regulated by Australia’s Environmental Protection Authority and contains three key codes to keep in mind.


The first is ‘LM-80’, which is an international set of standards set out by IESNA (Illuminating Engineering Society of North America) defining how LED components can be tested to determine their performance over time.


The second is ‘TM-21’ which outlines a standard calculation method to predict future lumen (light brightness) depreciation using LM-80 data.

These standards ensure consistent reporting from LED manufacturers , enabling lighting professionals to make objective, informed analysis and therefore decisions when specifying luminaires.

Breaking Down the Technical Specifications

IESNA standards say that an LM-80 test period can be extrapolated using the TM-21 method which multiplies a test-period by a maximum of 6 times to calculate a particular LED’s lifespan. Typically, a test period lasts between 10k-12k hours, which extrapolates to a maximum useful lifespan projection of 60k-72k hours. LED manufacturers use the TM-21 method so they can claim a much greater lifespan than they are able to actually test for.

How do these terms fit into reality?

Theoretically, an LED being an electronic device with no moving parts could last forever – but there are three things that gradually diminish their effectiveness: heat, dirty power and moisture – and over time they will diminish an LED’s effectiveness to a point where they can no longer be used as a source of light. It is recognised that the human eye is only sensitive to lumen depreciation of 30% or more, so the industry as a whole has determined that an LED ceases to be a useful light source when lumen output reduces to 70% of its initial output – aptly termed L70.

How you can decipher the terms (it’s easy!):


Therefore L70 (an LED’s useful lifespan) = LM-80 data x TM-21 method. SO! Next time you see a product with a listed lifespan of 60,000 hours, you know it has been tested for at least 10,000 hours to achieve that IESNA recognised, EPA certified rating.

For example, let’s assume that a given LED lighting system operates for 12 hours per day, 5 days per week – this would translate into 3,120 hours per year – making 60,000 hours equivalent to a 19 year lifespan!

Based on those numbers the useful life of LED’s will far exceed the remodel cycle for many applications. Furthermore, the unceasing development of LED technology which occurs on average every 6-8 months means LED’s used today are inevitably going to be less efficient than those that will be deployed into the market in the coming months or years.

To Remember:

When specifying luminaires, it is essential to remember the difference between Reported and Calculated Lumen Maintenance data and how they relate to the projected lifespan of the LED. A luminaire with a Calculated Maintenance at 200,000 hours and a luminaire with a Reported Maintenance of 60,000 hours are different data points altogether and should not be compared as equal tests.

Now that you can differentiate between the key LED Lifespan insider terms: LM-80, TM-21 & L70 – you’re armed with some powerful information that’s going to give you an incredible edge when specifying or purchasing LED lighting products for your home or business. But if you still have questions, feel free to give one of our friendly consultants a call on 1300 650 625, or drop us a line at we’re always happy to help.

LED Lighting Solutions

Greenlux LED has been delivering quality lighting outcomes successfully to commercial sites nationally for the past 9 years.