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LEDs unable to replace large fluorescents "“ yet

US Department of Energy study concludes that LED-based replacements for 4-foot fluorescent lamps do not emit enough light.

“LED technology is not yet ready to displace linear fluorescent lamps as replacement light sources in recessed troffers for general interior lighting.”

That is the stark conclusion arrived at by the US Department of Energy (DOE), which has been testing the viability of replacing large, bright tubes with the solid-state technology.

Performed under the DOE s CALiPER (Commercially Available LED Product Evaluation and Reporting) program, the test results showed a “significant performance gap” between the two technologies.

It means that although some LED replacement lamps are marketed as one-for-one, or “drop-in” retrofits for fluorescents, many of them don t actually emit sufficient light to provide equivalent illumination.

“To maintain existing light levels, it would be necessary to install additional LED replacement lamps, thereby diminishing potential energy savings and requiring additional fixtures or fixture modifications,” said the DOE in a report just published on its web site.

Part of the problem is due to the troffers, the inverted metal troughs that are designed to reflect the omnidirectional light from the fluorescent lamps down towards the area intended to be illuminated.

Because light from LEDs is much more directional in nature, the fixtures do not distribute illumination nearly as effectively, but the main problem is that the solid-state technology does not produce as many lumens, limiting overall lamp performance.

The DOE highlighted other problems, too: of the four LED products that it tested in its most recent study, three needed to be directly connected to a line voltage circuit, rather than using the existing fluorescent ballast "“ meaning additional labor and expense during a retrofit.

Two of the four “replacement” LED lamps also produced a very cool white light "“ exceeding guidelines provided by American National Standards Institute (ANSI). “These non-compliant LED products would not integrate well with existing lighting systems,” said the DOE testers.

While the DOE says that LEDs are suitable for some niche applications where total lumen output is not at a premium "“ one of the key requirements is to ensure that luminaire designs can take advantage of LED directionality, and better accommodate thermal management.

Commenting on the report, Jim Brodrick, who heads up the DOE s solid-state lighting efforts, said: “My advice is to be wary of manufacturer performance claims. Do your homework and stay on top of technology advances.”

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