Light Emitting Diodes or LEDs are the new kings of the bulb world. When an LED is switched on, electrons and electron holes come together, which results in the release of energy in the form of light.
An LED bulb will use a fraction of the wattage that is required to power bright incandescent bulbs. LEDs are then highly cost effective over the course of time.
LEDs are also said to last tens of thousands of hours, which is decades of use. This is one of the reasons that so many people have found LEDs to be attractive.
According to Energy Star and the Illuminating Engineering Society or IES, which is the independent organization that created the testing procedures to rate LED lights, these bulbs can really last you for decades. LED bulbs have only been available for a few years so the longevity claims are still to be seen.
With that being said, LED testing is pretty transparent so we are able to understand them better.
LED lights do not burn out the way that incandescent do; instead they go through lumen depreciation, which means they gradually grow dimmer over time.
The IES tests the longevity of a bulb with the LM80 test and it calculates how long it will take for an LED to fade to a noticeable level. This test is ran over the course of 9 months in order to get an accurate read and so that they can calculate when the light will fade to 70% of its original brightness. This point is the L70 and used as the standard for LED longevity. If you have an LED that says it will last for 25 000 hours then it means it will take the LED bulb 25 000 hours to fade to 70% brightness.
LEDs though do fail, but LED bulbs now come with multiyear warranties if they fail mechanically.
The average life expectancy of an LED is 20 000 hours and come in wattages between 4W and 22W.
When you are buying an LED make sure that it has the Energy Star label.