I’ve been reading the “Summary of Results: Round 9 of Product Testing,”(warning – this link opens a PDF file) by the US Department of Energy’s Solid-State Lighting CALiPER Program. If you are interested in the current state of LED lighting products, it makes for some fascinating reading. One big concern I have had both testing and installing LED tube lights from various manufacturers as well as looking at lots of product information from a wide range of vendors, is that there is definitely huge variation in quality, and it is clear that some products don’t live up to the vendor descriptions.
The Department of Energy (DOE) created the CALiPER program to attempt to help address some of the quality and consistency issues that purchasers of LED lighting continue to encounter. CALiPER is an acronym for the Commercially Available LED Product Evaluation and Reporting Program. The program was established in 2006 to investigate the performance of luminaires and replacement lamps that use LEDs. To help users better compare LED products with conventional lighting technologies, CALiPER also has performed benchmark research and testing of traditional (i.e., non-LED) lamps and fixtures.
The DOE has performed tests of a wide range of LED lighting products, and overall they have found that with each successive generation of testing, performance has improved significantly. One of the key areas they looked at in round 9 was what they describe as use of solid state lighting (or LED lighting) technology to replace fluorescent troffers. “Troffer” is a term used to describe a recessed luminaire that is installed in the plenum with the opening flush with the ceiling. Typically rectangular or square in shape, as in a 2-foot-by-4-foot luminaire. Fluorescent and LED tube lights are often installed in troffers. The CALiPER Round 9 testing tested examples from two different approaches to using LED technology to replace fluorescent troffers. In products that are designed to replace 2’x2’ troffers, LED products tested were integral luminaires, meaning that they are complete fixtures rather than replacement lamps for existing troffers. In products designed to be used in 2’x 4’ troffers, LED lighting products tested were linear replacement lamps (LED tube lights), marketed to replace the 4’ T8 or T12 fluorescent tube lamps in existing troffers.
Example of Integral 2' by 2' LED Lighting Panel
Some of these LED tube lights that were tested are designed to function using the same ballast as fluorescent lamps, so their installation does not require removing the ballast from the troffer. However, this testing found that lamps designed to use the fluorescent ballast have lower overall efficacy than those designed to use their own drivers (in CALiPER testing, losses were 10-20% higher for LED lamps using the fluorescent ballast). Most of the LED tube lights require that the ballast in existing troffers be bypassed (as discussed in detail in an earlier post on installing LED tube lights), using their own driver; an approach which enables somewhat more efficacious designs.
In a nutshell. what the CALiPER testing found was that the LED tube lights did not yet match the fluorescent lights they are marketed to replace. What’s more, the CALiPER researchers found that the majority of manufacturers of LED tube lights that they tested provide incorrect data—some promising as much as 50% more lumens than their products deliver. Similarly the lumens per Watt documented by the manufacturers ran between 30 and 50% higher than the products measured. CRIs in general were also lower—most promised 80 or higher, when in fact, a few had CRIs in the mid-70s and half were in the mid-60s.
The CALiPER testers did find that several of the 2′x2′ LED panels that they tested met or exceeded the performance levels of the fluorescent lights they were designed to replace.
So, does this mean that we should give up on fluorescent tube lights? I don’t think so. Performance continues to improve, and the best of the products tested are beginning to approach the performance levels of equivalent fluorescent tubes. As the CALiPER report notes, fluorescent troffers can be among the most efficacious lighting applications available today. By using high-performance lamps, high-performance troffer designs, and judicious choices in ballasts, these fixtures can provide extremely economical and efficient lighting. Therefore, this is one of the most challenging lighting application areas for LED when it comes to providing similar levels of energy efficiency. Given the targeted high efficacies and light outputs required by troffer applications, optimal LED product design will be needed to be competitive. The best products available today provide great solutions when used in the right applications. The reduced energy consumption and extremely long performance life of even these products can overcome other limitations.
