THE LIGHTING REFERENCE
LIGHTING · SCIENCE · PRACTICE

A lumen-maintenance projection is not a fixture lifetime.

Read source test data, projections and complete-system serviceability as different evidence.

Primary-source research · Original explanations · Reviewed October 4, 2026
01

What LM-80 measures

LM-80 measures maintenance of light-output characteristics of solid-state light sources such as LED packages, arrays and modules under controlled conditions. It is source-level evidence; it is not a test of every part of the final installed luminaire. [1]

02

What TM-21 projects

TM-21 projects long-term source flux maintenance from LM-80 data, subject to extrapolation limits. A projection is different from observing the entire stated period in a complete installed system. Request the underlying data, operating assumptions and reported projection conditions. [2]

03

What the owner must maintain

Our maintenance review includes optics, dirt, drivers, connections, controls, enclosure conditions and replacement access. A component-level flux projection does not answer whether a driver is replaceable, whether cleaning is feasible or whether spare parts will be available.

04

Plan for maintained performance

Record the light-loss assumptions used in design and how maintenance will support them. State what will be cleaned, inspected, replaced and rechecked. Do not apply an unexplained generic factor simply to make a calculation pass.

05

Preserve the configuration

After replacement, confirm output, optics, color characteristics and controls match the accepted design. Maintain an asset register with exact configurations and reports. A visually similar housing can contain a substantially different light engine or distribution.

PRIMARY SOURCES

Check the evidence.

Public definitions and catalog scope support the cited explanations. Full normative criteria remain in the applicable official document.

  1. 01
    Source recordANSI/IES LM-80-21 · Measuring Maintenance of Light Output Characteristics of Solid-State Light Sources ↗
  2. 02
    Source recordANSI/IES TM-21-21 · Projecting Long-Term Luminous, Photon, and Radiant Flux Maintenance of LED Light Sources ↗

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