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LED T8 replacement lamps are proliferating in the lighting marketplace. How do these products compare to fluorescent T8 systems in terms of light output, distribution, color quality, and energy efficiency? What level of LED product performance should buyers specify for replacement applications?
Recessed “troffer” fixtures with four-foot fluorescent T8 lamps are commonly specified in commercial and institutional lighting applications, and represent a significant installed base of fluorescent fixtures. Are LED replacement lamps a “drop-in” equivalent to T8 fluorescent lamp-ballast systems, as claimed by many manufacturers? DOE’s CALiPER program has tested 12 different LED T8 replacement lamps to date, and finds that their performance falls short of fluorescent benchmarks. 1 Major findings (bare lamp and in a fixture) are summarized and compared with fluorescent benchmarks in Table 1.
Average initial bare lamp light output of the LED T8 replacements tested was about one-third the average for fluorescent T8s. On initial two-lamp system efficacy, two-lamp fixture output, luminaire efficacy, and CRI, the LED T8 replacement performance was significantly below that of the fluorescent T8s. Average fixture efficiency was higher with LED T8s because LEDs are directional, so less light is lost inside the fixture. This was not enough to compensate for the much lower light output however.
See CALiPER Round 5 and Round 9 summary reports for additional details: www.ssl.energy.gov
|CALiPER Test Results for 4-foot LED T8 Replacements with Fluorescent Benchmarks|
|LED T8 Replacements||Fluorescent Benchmarks|
(12 lamps tested)
(2 fixtures tested)
|Initial Lamp Light Output (lm)||345 – 1,579||1,111||2,778||3,091|
|Initial 2-Lamp System Efficacy (lm/W)||19 – 76||50||87||---|
|Initial 2-Lamp Fixture Light Output (lm)||597 – 2,038||1,563||3,577||4,064|
|Initial CRI||63 – 76||71||75 – 80||82|
|Fixture Efficiency (%)||74 – 86||83||74||66|
|Initial Luminaire Efficacy (lm/W)||17 – 57||41||64||57|
The bottom line is that to provide equivalent light to fluorescent T8s while keeping power input for these products at their current range (15-20 watts), LED T8s will have to become two to three times more efficacious than they currently are. Postings from Jim Brodrick email@example.com