LM-80 is a standard that defines how the lumen output and colour shift of LEDs should be measured over time and at different temperatures.
The full name of the latest version of this standard is “IES LM-80-20 Approved Method: Measuring Luminous Flux and Color Maintenance of LED Packages, Arrays and Modules”
BACKGROUND TO LM-80 – WHY WE NEED IT & WHAT IT COVERS
LM-80 is important to lighting designers, specifiers and manufacturers. It provides a standard method of testing LEDs and presenting the test results so that the data from different brands and models can be directly and objectively compared.
LM-80 is concerned with measuring two of the most important aspects of LED quality:
Lumen depreciation. Over time, the lumen output (sometimes known as the luminous flux) of all LEDs gradually decreases. In layman’s terms, they get dimmer. This is lumen depreciation. However, the rate of lumen depreciation varies from one make and model of LED to another and it varies according to temperature. At higher temperatures lumen depreciation takes place more rapidly than at lower temperatures.
Note that an LM-80 compliant test will not give any useful data related to absolute lumen output or energy efficiency. For these data a report from an LM-79 compliant photometric test is required.
Colour shift. Over time, the colour of light that an LED emits changes. In the LED and lighting industries this is called chromaticity shift. As they are used, white light LEDs might move towards the red or towards the blue end of the spectrum, and this change takes place more rapidly at higher temperatures
Note that an LM-80 compliant test will not give any useful data on the absolute quality of the light emitted by an LED. Data on the quality of light (such as its colour temperature, colour rendering index or spectral composition) can be found in a photometric test report. An LM-80 test is only concerned with quantifying the degree to which the colour of the light emitted by an LED changes over time.
Note that LM-80 is concerned only with LEDs, LED arrays and LED modules as individual components, not with LED lamps or LED fixtures. For this reason, LM-80 data is mostly used by lighting manufacturers when selecting the LEDs to use as components in a light fitting. For an end-user, specifier or installer to judge the relative merits of an LED lamp or an LED lighting fixture and LM-79 compliant photometric test report is recommended.