US tests show credibility gap in LED fixtures
The output and efficacy of commercial solid-state lighting fixtures is close to claimed performance in only two out of twelve cases, suggest the latest tests performed by the US Department of Energy.
The DOE s second round of product testing found that all other products overstated efficacy by 25 to 35 percent and light output by 30 to 95 percent, according to its August report.
“While a few manufacturers are publishing credible values for luminaire output and efficacy, many are still making wild and misleading claims,” the report says.
Possible reasons for the discrepancies put forth by the DOE include fixture makers publishing LED performance values instead of luminaire values without saying so, performing luminaire testing using different methods, or even inflating values to exaggerate performance.
However, despite the general failure of solid-state lights to live up their billing, some shone much more brightly than the rest, according to the report. “The DOE s testing has revealed both excellent and dismal performances,” it says.
In DOE tests between March and May 2007, downlight luminaires and directional replacement lamps produced light output comparable to incandescent and CFL downlights, with much higher efficacy.
By contrast, non-directional replacement lamps in particular did not produce enough light to replace any existing products.
Off-state power consumption, known as “vampire loading”, also concerned the DOE. Testing was only performed on devices with on-off switches, which constituted two LED-based desk-lamps, one consuming 1 W and the other consuming 2.5 W in the off-state. A comparable halogen lamp consumed only 0.16 W whilst off.
The desk lamp which consumed 2.5 W while off is claimed to use 70 percent less energy than a comparable incandescent unit and produce more light that a halogen bulb.
When tested against a halogen bulb, it used 65 percent less energy in the on-state, but provided less than half the light output, making it dimmer and, because of “vampire loading”, less energy efficient overall.
“Poorly performing products are seen when SSL technology is introduced without sufficient attention toward treating it as an integrated system,” the report says.
“Designers need to consider thermal management, drivers, optics, the LED souces and their directionality as an integrated system, and performance measurements need to assess the integrated system.”
