Right Down the Line: Linear Fluorescents

Significant innovation in linear fluorescent lighting is being spurred on by commercial building energy codes, sustainability initiatives, new legislation and regulations, customer demands and competition from other light sources, such as light-emitting diodes (LEDs).

Commercial building energy codes are growing more restrictive and increasingly mandate lighting controls. The American Society of Heating, Refrigerating, and Air Conditioning Engineers/Illuminating Engineering Society (ASHRAE/IES) 90.1 2004 became the national energy standard in late 2009, with most states now in compliance. ASHRAE 90.1 2010 explicitly covers lamp plus ballast retrofits and new construction.

The growing green building market has been a bright spot in construction. Today, one third of all new nonresidential construction is green—a $54 billion market—according to McGraw-Hill. In the next 5 years, the green building market is expected to grow to $120–145 billion in new construction, or 40–48 percent of the nonresidential building market, and $14–18 billion in major retrofit and renovation projects. About seven out of 10 green projects are registered with the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) rating system. A significant number of jurisdictions require LEED registration for certain buildings, such as public construction, which has received significant support from federal stimulus spending.

Meanwhile, as new construction has sagged, retrofits have increased, driven largely by legislation, rebates and a desire to increase profitability by reducing energy costs. In 2010, 46 percent of fluorescent ballast shipments were sold to the retrofit/replacement market, according to sales figures reported by National Electrical Manufacturers Association (NEMA) member companies; historically, this market has garnered about a 30 percent share.

Government intervention is the most powerful driver in the existing buildings market. Recent legislation eliminated most magnetic ballasts for T12 lamps, while upcoming Department of Energy (DOE) regulations will eliminate the most common T12 lamps starting in July 2012. DOE fluorescent ballast rules, expected to be published this month, would likely cover T12, T8, T5 and T5HO ballasts and become effective July 1, 2014. In a nutshell, the lowest cost and least-efficient options are being eliminated, compelling owners to replace existing systems.

On the lamp side, T8 continues to dominate the 4-foot linear lamp market, with most T12 lamps sold to service existing installations (see Figure 1).

In 2010, market share for T5 and T8 increased at the expense of T12, sales for which declined about 7 percent. T5 lamp sales increased nearly 31 percent in 2010, according to NEMA, driven by the green building market and high-bay retrofits (see Figure 2). As a result, we’re seeing much innovation in not only in the premium T8 category, but also T5 and T5HO offerings.

The $788 million linear ballast market tells its own story (see Figure 3). Programmed-start T8 sales increased in 2010, driven by adoption of occupancy sensors and owner interest in longer lamp life. T5 sales increased 26 percent in 2010 for the reasons above. Daylight harvesting in green building projects drove demand for dimming ballasts, which increased by 35.5 percent in 2010. Meanwhile, the fluorescent magnetic ballast continues its decline due to the Energy Policy Act of 2005, with customers shifting to T8 systems or electronic T12 ballasts.

In a short, lighting technology and design are steadily becoming more energy-efficient and controllable using automatic switching and dimming controls. And due to owner interest in reducing maintenance costs—and with strong competition from LED sources in this area—today’s fluorescent linear lighting offers dramatic extensions of service life.

Energy efficient
Energy efficiency is perhaps the most important driver in product innovation in linear fluorescent technology.

When all T8 electronic ballasts are basically efficient—compared to the magnetic ballast, the previous standard—how do we know which ones are high efficiency? NEMA Premium label for ballasts operating 4-foot T8 lamps answers that question. The ballasts operate between 90 and 95 percent, providing 2–5 watts (W) per ballast savings compared to standard systems. They are the best not only in efficiency but also in added performance features. Most T8 ballast innovation is occurring in this segment.

However, the program does not cover T5 and T5HO ballasts, but manufacturers may promote them as “high efficiency,” usually meaning 90 percent or higher.

On the lamp side, the big efficiency story is T5. The major lamp manufacturers continue to bring to market new energy-efficient T5HO lamps, increasing efficacy to as high as 102 lumens per watt. Some products involve a reduction in light output, some offer the same performance for less wattage. Examples include Philips Energy Advantage 49W (same light output), GE T5HO Watt Miser 51W (same light output), Sylvania Pentron SuperSaver Ecologic 51W (same light output), GE T5HO Watt Miser Plus 47W (4 percent lower output) and Sylvania Pentron HO SuperSaver 47W (8 percent lower output).
Manufacturers are also beginning to introduce complimentary alternatives to other T5 and T5HO lamps, which save energy while operating on the same ballast. Examples include Philips’ 25W direct replacement for 28W T5 lamps and Sylvania’s 2-foot, 20W and 3-foot, 35W T5HO lamps, targeting 24W and 39W lamps, respectively.

Lamps and ballasts also are enabling more efficient designs through flexibility in several ways. First is a broader selection of lamp choices with different lumen packages, enabling light output to be tuned to application need. For example, Sylvania recently introduced a 4-foot, 23W T8 lamp that produces about 30 percent less light output for 28 percent energy savings, suitable for coves, corridors and overlighted existing office spaces.

Another way to tune light output is the specification of ballast factor. In review, ballast factor (BF) is expressed as the fraction of rated lamp output that is emitted when the ballast and lamp operate together as a system. Traditionally, ballasts were offered in low (0.74–0.78 BF, typically 0.77 or 0.78) and normal (0.85–0.90 BF, typically 0.87 or 0.88) BF. High BF (greater than 1.0 BF, typically 1.15–1.18) became offered for high-bay and other applications where more light was needed.

Now, nonstandard BFs are becoming available, such as 0.50, 0.70 and so on, to satisfy precise load calculations for a space for projects meeting tough green building or energy code requirements. A recent Sylvania T8 electronic ballast has a BF of 1.0, offering about 14 percent higher light output than a typical normal BF ballast. GE’s feature-rich UltraStart T8 electronic ballast is specifiable with 0.6, 0.71, 0.89 and 1.15 BFs. And the Lutron H Series of ballasts, which recently expanded to include new 347V options and a universal-voltage three-lamp version for 32W T8 lamps, provides customizable ballast factor from 0.5 BF up to the maximum published value (1.0 or 1.17 BF) in 0.01 increments.

Demand for maximum flexibility and energy savings in green building projects, coupled with mandatory requirements in the latest commercial building energy codes, is creating demand for easily controllable lighting systems.

Almost all energy codes require that lighting be automatically turned off when it is not in use, with occupancy sensors mandated in a growing list of applications. Frequent switching can reduce the operating cycle, which also can reduce rated lamp life. Sylvania responded by increasing rated life for its XP, SS and XPS lamps at shorter operating cycles—up to 31,000 hours at 15 minutes per start. The Octron 800XP/SL family of T8 lamps, for example, is rated at 55,000 hours at 12 hours per start on programmed-start ballasts and 44,000 hours at 30 minutes per start.

Another way to compensate for shorter lamp life caused by occupancy sensors is to use programmed-start ballasts. However, as rapid-start ballasts, they can take up to a second or longer to achieve full brightness, which may be a problem where fast-moving lift trucks are common, such as warehouses. In response, start times are getting shorter. Universal Lighting Technologies’ Ultim8 high-efficiency ballast, for example, starts the lamp in about half of a second. GE makes a similar claim for its UltraStart T8 ballast.

A related innovation between NEMA Premium (4-foot T8) and high-efficiency T5HO programmed-start ballasts is parallel lamp operation. This provides independent lamp operation within a fixture (see Figure 4). When one lamp reaches its end of life, the remaining lamp(s) on the ballast stay lit. As a result, fewer lamps are replaced. It reduces the urgency of relamping and preserves light levels, uniformity and appearance of the system. Examples for T8 lamp operation include the Universal Ultim8, Sylvania ProStart and Philips Optanium. Examples for T5HO lamp operation (four lamps, with two lamps operated in series and two in parallel) include GE HE UltraStart, Sylvania Quicktronic ProStart and Philips Optanium.

The ultimate in flexibility and controllability is dimming. There are essentially three types of dimming—step dimming with no fade transition, step dimming with a fade transition, and continuous dimming. Examples of the first include Sylvania’s Quickstep Bilevel T8 Switching ballast (dims to 50 percent lamp power) and GE’s UltraMax T8 hi/lo instant-start switching ballast (60 percent). An example of step dimming with a fade transition is the GE UltraMax T8 load-shedding variable instant-start dimming ballast, which dims to 60 percent, which is well suited to applications desiring the efficiency of instant-start operation and additional savings of dimming without the cost of full-range dimming.

Continuous dimming is the next step up, with dimmable ballasts available from most manufacturers. A notable example is Philips’ EssentiaLine 0–10V dimming high-efficiency ballast. Dimming ballasts are also becoming increasingly available for T5 lighting. The Sylvania Quicktronic QHE DALI ballast offers both high-efficiency operation and dimming of T5 lamps using the DALI protocol.

Another aspect of dimming is whether the lamps are easily dimmable. Linear amalgam lamps, for example, are now being offered to produce greater than 90 percent of rated light output over a broader temperature range, suitable for high-bay applications, and yet these lamps may not be recommended for dimming by their manufacturer. Until recently, energy-saving 4-foot T8 lamps—25W, 28W, 30W—were not rated as dimmable. Now they are. For example, Sylvania recently announced that its 23–30W T8 lamps are dimmable. On the ballast side, Lutron recently introduced the EcoSystem reduced-wattage digital dimming ballast specifically to dim these lamps reliably to as low as 1 percent.

Long life
As a final linear fluorescent lighting trend, special extended-life T8 and T5 lamps are being offered with longer rated life for green projects and maintenance-sensitive applications.

For T8, 4-foot lamps, labeled XL, XLL and SXL, offer rated life up to 50,000 hours and longer at 12 hours per start on an instant-start ballast (industry average is 24,000 hours) and 55,000 hours on a programmed-start ballast (industry average is 30,000 hours).

More recently, T5HO lamps are enter the market offering rated life up to 60,000 hours at 12 hours per start.

DILOUIE, L.C., a lighting industry journalist, analyst and marketing consultant, is principal of ZING Communications. He can be reached at www.zinginc.com.

About the Author

Craig DiLouie

Lighting Columnist
Craig DiLouie, L.C., is a journalist and educator specializing in the lighting industry. Learn more at ZINGinc.com and LightNOWblog.com .​

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