What is TM-21?

TM-21 is a technical standard developed by the Illuminating Engineering Society of North America (IESNA) that provides a recommended method for projecting the long-term lumen maintenance (brightness) of LED light sources based on measured data. It uses data collected according to another standard called LM-80, which involves testing the lumen depreciation of LED packages, arrays, or modules for a period—usually 6,000 to 10,000 hours. TM-21 then mathematically extrapolates this data to predict how long the LED will maintain a certain level of light output, for example 70% of its initial brightness, often referred to as L70.

TM-21 is important because LED chips don't have a traditional failure point (like a filament burning out) but instead gradually lose brightness over time. This standard gives manufacturers, suppliers, and end users a reliable way to estimate the useful lifetime of an LED based on solid test data rather than guesswork. It also accounts for effects such as operating temperature, which influences LED degradation rate.

In the lighting industry, looking for TM-21 reports helps verify the expected longevity and performance of LED products, ensuring better quality and reliability in lighting designs and installations. Without such projections, it's harder to compare products or guarantee long-term lighting effectiveness.

In brief: TM-21 predicts how long LED light sources will maintain usable brightness based on LM-80 test data, making it crucial for evaluating LED product lifespan and performance.

Contact us for a free consultation to check.