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The ENERGY STAR TM-21 Calculator is based on the Illuminating Engineering Society’s TM-21-11: Projecting Long Term Lumen Maintenance of LED Light Sources, referenced in the ENERGY STAR Luminaires V1.1 specification and in Draft 1 of the ENERGY STAR Lamps V1.0 specification. The Calculator is available for download on www.energystar.gov/TM-21calculator.