The US Environmental Protection Agency (EPA) has made available the Energy Star TM-21 calculator, which is based on the IES’s (Illuminating Engineering Society’s) Technical Memorandum, TM-21. The calculator is available for download at www.energystar.gov/TM-21calculator.
TM-21 is used to project for lumen degradation of an LED package, array or module based on data collected according to LM-80. For instance, if 6000 hours of testing of an LED package has been performed according to LM-80 criteria, that data can be extrapolated to give an estimate of lumen degradation at 36,000 hours. TM-21 is referenced in the Energy Star Luminaires V1.1 specification and in Draft 1 of the Energy Star Lamps V1.0 specification.
The calculator has been developed specifically to simplify lumen maintenance projection calculations for manufacturers designing lighting products for Energy Star qualification, and to ensure consistent results across all EPA-recognized Certification Bodies and Laboratories. Calculated results have been validated by the US National Institute of Standards and Technology (NIST). Users are encouraged to download a new blank worksheet for each product, and to save individual product results on a local drive. The calculator includes user instructions and contact information for questions.
Users are encouraged to request LM-80 data sets from LED vendors and then perform calculations using the new calculator. For instance, if LM-80 data is available at two test temperatures such as 55°C and 85°C, users can interpolate for 75°C lumen depreciation values.
