The Department of Energy estimates there are 360 million fluorescent troffers installed across the US, but market data show that shipments of linear fluorescent lamps have been tanking since 2014. Tubular LEDs (TLEDs) are taking over. Like other LED replacement lamps, TLEDs are penetrating both the maintenance market for replacing conventional-lamp burnouts and the system-wide retrofit market, where utilities drive change and push for persistent savings. Multiple paths to achieving that energy savings, plus tremendous diversity in product quality and attributes, are leading the rapid market expansion.
“The high dollar value (compared to the cost of the material) of utility incentives coupled with the low first material cost leading to favorable economics and the low labor costs are the reasons why we’ve seen such a large uptake in TLED shipments and installations in the last 15 months,” says Michael Myer, research analyst at Pacific Northwest National Laboratory, referring specifically to Type A, plug-and-play TLEDs. According to the National Electrical Manufacturers Association, shipments of all types of TLEDs rose from a 6.9 percent share in Q1 2016, their first appearance on the market penetration chart, to 12.8 percent just 6 months later. In Q1 2017 TLEDs accounted for 15.3 percent of florescent lamp shipments. As volume rises, prices fall, and utility rebates for TLEDs are dropping, too.
Even large manufacturers are producing products at different levels of quality, seeking out the sweet spots for different market sectors. These products move quickly through generations of technology. Often, multiple new lamp models are debuted over the course of a year. A manufacturer may list only certain models on the DesignLights Consortium’s Qualified Products List (DLC QPL).
A listing in the QPL provides customers and utilities with some assurance of product quality and energy savings, including standardized comparisons of lifetime and photometrics. DLC is providing leadership here, evolving its specification to include multiple types of TLEDs, including T5s. The latest specification requires a minimum 110 LPW for a 4 ft lamp.
Myer believes the array of products from first- and second-tier manufacturers (according to volume) will meet the needs of most customers. He advises customers to ask if the company has been in business longer than its current warranty. Do they have deep experience in the lighting business? Even with significant lighting experience, there have been large recalls of TLED products from major players like Cree and Sylvania.
Paths to payback
TLEDs are increasingly represented in utility rebate programs, according to Myer. He said he has seen rebates vary from as little as $1 per 4 ft lamp to as high as $15 per lamp (a 2016 program). “When you have a fluorescent system that’s maybe drawing 29W per fluorescent lamp, and I can replace that fluorescent lamp with a TLED that may only be drawing 14W to 18W, and it only costs $15 or $18, and you can get a $3 to $6 incentive from the utility program – you can make it cost-effective very quickly.”
In cases where today’s TLEDs are replacing an old T12 installation, energy use is easily cut in half. But even where fluorescent T8s are running up around 95 LPW, a convincing energy savings argument can be made. Manufacturers are choosing to produce TLEDs in multiple lumen packages. “Many people installing TLEDs – not everybody, but definitely some – are not matching lumen for lumen,” said Myer.
Fluorescent lamps are 360 degree emitters and nearly always rely on fixture optics to deliver light to where it’s needed. Optics always produce light losses: around 25 percent in parabolic troffers. The LED emitters inside TLEDs are more unidirectional, so there can be far less losses inside the fixture. The goal is to improve “useful lumens” or “delivered lumens” and achieve similar illumination. The reverse can also be true: a TLED that is not compatible with the optics of a fixture may prove grossly inefficient.
Highly directional TLEDs can cause glare or spotty illumination, so evaluation on-site is warranted. Look for TLEDs with frosted lenses or wide beampatterns to soften contrasts inside “darker” troffers. In some cases, striations across a troffer lens may be undesirable. Poor compatibility may create dark areas on upper walls or poor uniformity, i.e., contrasting areas of high and low illuminance across the space. Sharp or multiple shadows on a floor or work area can be dangerous. Note that these kinds of issues may apply not at all to certain highly shielded retrofits or TLED conversion of a high-bay product.
A space could be perceived as being overlighted, according to current trends and practices. In these cases, an owner could choose to swap out three fluorescent lamps for two TLEDs; though using three TLEDs with smaller lumen packages may offer improved aesthetics. Too often, according to Myer, there is overemphasis on the quick payback, to the detriment of light levels or lighting quality.
TLEDs look to the future
Emergency lighting is an issue here and now. Type As require a compatible emergency lighting ballast with battery backup. A Type B TLED (where the fixture is rewired to deliver line voltage to the lamp) would require the installation of a microinverter for designated fixtures. Although at least one manufacturer, Energy Focus, offers a Type B TLED with an integrated battery. A Type C TLED (using an LED driver) could utilize a microinverter or a specialized emergency driver.
Besides fluorescent options, TLEDs are competing with new LED troffers and retrofit kits that use an array of LEDs (no conventional sockets). “Though these latter options have higher costs, they also offer additional energy savings potential through more advanced controls,” wrote Teren Abear, technology area lead for Advanced Lighting & Controls, Emerging Products Group at Southern California Edison in an email. “Having advanced control capabilities allows a whole-system approach, which can integrate electric lighting, daylighting and even other building energy uses for not just energy savings but for demand reductions as well.” Utility incentives, generally, are moving toward integrated lighting controls that take advantage of granular energy savings.
It seems unlikely, however, that individual TLEDs would require on-board sensors or wireless receivers. Even with a value proposition, there would be significant engineering and cost challenges to consolidating additional electronics inside the tube. The exception might be tunable white, or circadian lighting. It is possible that a dynamic shift in CCT could one day be required in schools or healthcare settings.
The cost of TLEDs has plummeted since 2014, though Myer predicts that both pricing and efficacy will level off soon. Because of the required electronics, he expects prices can only fall to around $10 for a quality lamp (traditional fluorescent lamps range from $2 to $6). TLEDs are the highest-efficacy replacement lamps listed on the QPL, and Myer expects they could eventually rise into the 170 LPW range.
“There are more standardized test procedures that are being used as a metric for product listings,” Abear wrote. “Regarding reliability, time will tell.”
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