Energy + Environment, LED + SSL

Are LEDs Ready to Retrofit the T8?

A recent article I wrote for Electrical Contractor talks about the push to replace linear fluorescent lamps with linear LED replacement lamps.

In a nutshell, linear LED replacement lamps are now being offered as direct drop-in replacements of 4-ft. T8 and T12 lamps. Even with the possibility of delamping due to higher fixture efficiency and the maintenance benefit of a service life up to 50,000 hours, at $45-$300 per lamp the payback is still not good enough to pass most corporate hurdle rates.

The biggest problem is that these lamps are typically not producing the promised light output, according to product testing by the U.S. Department of Energy’s CALiPER program. In fact, DOE found that manufacturers are often overstating performance.

CALiPER testing addressed a range of standard lighting measures, including power usage, luminous flux, photometric distribution, source and luminaire efficacy, correlated color temperature (CCT), and color-rendering index (CRI) for the lamps tested separately and in troffers.

Key findings:

• The comparatively low light output of LED linear replacement lamps could result in unacceptably low illumination levels in retrofit applications.
• LED linear replacements achieved higher fixture efficiencies than benchmark fluorescent configurations in CALiPER testing; however, low lumen output and efficacy limited their overall performance to levels significantly below those of fluorescent systems.
• CALiPER testing at this time shows that LED technology is not yet ready to displace linear fluorescent lamps as replacement light sources in recessed troffers for general interior lighting.

There are several lessons here, which are presented at the end of the article, but probably the most important is: Just because a lighting product is LED does not automatically mean it’s energy-efficient.

To read the complete article, visit Electrical Contractor here.

See the results of Round 5 of the DOE’s CALiPER testing here. A benchmark report has also just become available here.

  • Dave Inman February 10, 2009, 1:27 PM

    I have a issue with these LED T8’s, I have seen dozens of various flavors and as stated in this article they dont stack up.
    My biggest problem with them is this….
    Why are mfg’s creating products with the limitation of being in a linear tube? I see no reason they cannot simply use the medium bi-pin sockets to get power and have a 2×4 prismatic panel as the light source itself.

  • leo February 9, 2010, 9:34 PM

    Our company’s T8 linear LED tubes have been installed in hundreds of 2 x 4 recessed parabolic troffers with excellent results. Foot candle readings before and after have been very competitive between the base case fluorescent tubes and the post case LED tubes. Energy reduction results show about 50% and installations are as old as 10 months operating 18 hours per day.


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