From T5 lamps to white LEDs and digital ballasts, the lighting industry has seen a decade of significant technological advances. Here is a recap.

By Craig DiLouie

One sometimes hears designers say about the lighting industry's product offerings around this time of year, 'Not much new!' And yet when one looks back over a decade, all the baby steps add up to big leaps in technology and changes in design practice. Below is a sampling of seven innovations, listed in no particular order, that either have had a significant impact on lighting design or represent a significant technological advancement over the past decade.

1. T5 & T5HO Lamps

Many innovations in the lighting industry seem to start with new light sources, followed by new ballasts and fixtures. T5 and their high-output versions, T5HO lamps, appeared in North America in 1996 and 1998 respectively, and today are popular in lighting fixtures such as linear fluorescent, direct/indirect, recessed baskets, soffits, valences, cove, wall-mount and high-bay fixtures. Thinner in diameter than T8 and T12 lamps and with high lumen packages available, T5 lamps enabled more compact fixtures, continuing a trend in lighting towards a smaller profile. 'T5 lamps currently comprise less than 10 percent of the linear fluorescent lamp market, but they are the fastest growing lamp in the linear fluorescent family,' says Ted Simpson, senior manager of field marketing for the Professional Lighting Organization of Philips.

2. White LEDs

In the mid 1990s, the first true white light LED was offered, achieved through the use of blue indium gallium nitride (InGaN) material with a phosphor. The phosphor converted some of the light emission into yellow, resulting in a cool bluish-white light. This opened the door for LEDs into a much broader range of architectural lighting applications and has gotten energy experts excited over the potential of this light source as a future competitor to fluorescent, halogen and HID lighting in general applications. Some predict that this goal will be accomplished in five to ten years. Why are energy experts excited? Theoretically LEDs have the potential to more than double the efficiency of general lighting systems, thereby saving enough energy over the next 20 years to power the states of Arizona, Colorado and Mississippi and reducing the nation's electric bill by $98 billion, according to the U.S. Department of Energy.

According to market research firm Strategies Unlimited, white LEDs accounted for half of the total 2004 world market for LEDs, which the company estimates at $3.7 billion. Strategies Unlimited has forecasted the world market for LEDs to be more than $7 billion in four years—more than half of what the Economic Census considers the entire U.S. lighting fixtures market to be today.

3. Explosive Growth in T8s

T8 lamps have a remarkable history. About 10 years ago, T12 lamps held about 95 percent of the linear fluorescent market; T8 lamps had made a small penetration of about 5 percent, and T5 lamps weren't even on the radar screen, according to lamp manufacturer Osram Sylvania. Today, according to the National Electrical Manufacturers Association, T12 lamps now make up about 65 percent, while T8 lamps have 33 percent and T5 and T5HO lamps now comprise the remaining 2 percent. This market share can only be expected to grow, as currently more than 30 states have begun complying with a U.S. Department of Energy requirement to adopt energy codes at least as stringent as ASHRAE/IES 90.1-1999, which is twice as restrictive as the 1989 version.

As T8 lamps become more popular, manufacturers are now offering new energy-saving and high-output models, including 28W, 30W, and 'Super T8' lamps. Super T8 lamps produce more than 3100 lumens compared to standard T8 lamps (which provide 2800 to 2900 lumens), and have a slightly higher lumen maintenance. This means Super T8 lamps can be used to provide higher light levels or to reach required light levels with potentially fewer fixtures (estimated 16 percent energy savings). T8s can also be specified in combination with low-output electronic ballasts to maximize energy savings (about 14 percent) with the same number of fixtures that would be used with a standard T8 system.

4. Meso-Optics

Ledalite's MesoOptics technology was first introduced in 2001, when it won the best new product award at Lightfair. It has since been applied to a growing number of the company's products, most recently its PureFX line of recessed systems.

MesoOptics, produced in a manner similar to the holograms that appear on most credit cards, is based on tiny microstructures no greater than five microns in size, which are applied to a common fixture material such as acrylic, polycarbonate, or glass. According to the company, the first inspiration for MesoOptics came from observing how the multicolored wings of butterflies become pure white at certain angles. With MesoOptics acting as a medium between the light source and the viewer, the fixture material gains extraordinary capability to control light.

In particular, MesoOptics removes striations and hot spots from light sources, allows 95 percent of the light that enters to pass through, and can constrain and disperse light for optimum control and uniformity—allowing for the creation of highly controlled beam patterns and the ability to redirect light into desired angles.

MesoOptics offers potential for daylighting, translucent wall and other architectural elements, roadway and exterior floodlighting, and theatrical and film lighting.

5. Pulse-Start Lamps

Low-wattage pulse-start lamps first appeared on the lighting scene in the 1980s, with medium-wattage lamps introduced around 1996. In recent years, they have expanded into very low wattages (down to 20W) and high wattages (up to 1000W). Today, pulse-start lamps have gained significant share of the metal halide lamp market (about 25 percent, according to one estimate), a trend that will grow as manufacturers continue to add wattages and new lamp and ballasting options.

Pulse-start systems can provide higher lumen maintenance, efficiency, longer service life, and faster warmup and restrike times than standard metal halide systems in new construction projects. The economics can also make pulse-start systems practical for retrofit in a range of situations, from replacement of existing standard metal halide systems in high-bay applications to replacement of halogen and incandescent track heads and downlights.

'Pulse-start systems represent superior technology and are not just a trend, they're here for the long term,' says John Cummings, director of HID product management for Advance. Pulse-start systems are currently popular in applications such as warehouses, gas station canopies, industrial and manufacturing spaces, parking lots and facilities, big box and smaller retail, grocery stores, and public spaces.

Ceramic metal halide lamps were first introduced in 1994 after Philips engineers essentially borrowed a ceramic arc tube from a sodium lamp and put it in a metal halide lamp to create something entirely new. The final result was a lamp that produces a crisp, white light and provides superior color appearance and color control qualities than standard metal halide lamps. These qualities have made ceramic lamps ideal for color critical areas in commercial applications where a high-efficiency, long-life alternative to incandescent and halogen lamps is desired.

6. HID Electronic Dimming Ballasts

Electronic dimming ballasts for HID lamps are now available in new fixtures to achieve continuous dimming. In addition to dimming, these ballasts are designed to operate at a higher efficacy, improved color control, less stroboscopic effect, and harmonic distortion under 20 percent.

While generally not cost-effective for retrofit, electronic HID ballasts can yield significant energy savings in a new fixture. They are interoperable with occupancy sensors, photocells and time-programmable systems. The signal can be transmitted along the power circuit or low-voltage wires. Ideal applications include anywhere it is advantageous to adapt the lighting system to a wide range of light levels to meet various space uses, such as airports, lobbies, classrooms, industrial facilities, sporting arenas, gymnasiums and auditoriums. With the exception of industrial buildings, metal halide lamps are typically used for most of these types of applications. Continuous dimming is also ideal for daylight harvesting by enabling the HID lamp output to be tuned to maintain a constant light level in the space.

'The big trend is more control,' says A. J. Glaser, president of HUNT Dimming. 'Sophistication in job design necessitates having the ability to vary the environment in precise increments. Continuous, variable control down to 50 percent provides this.'

7. Digital Ballasts

Traditional dimming ballasts are analog ballasts that operate using a three-wire, 0-10VDC, two-wire, or wireless method. Digital ballasts offer a greater variety of capabilities. In essence, they enable users to connect all of the fixtures in a room, zone, or a building to a centralized point of control. From there, users can program individual fixtures or groups of fixtures to dim or shut off according to a schedule or based on external input, such as occupant preferences or available daylight. The communication path is two-way, meaning not only can users send commands to fixtures, but they can receive information back from the fixtures upon request that is useful for energy management and maintenance.

The advantage of this type of system is that it offers a high degree of granularity of control capability, enables feedback from ballasts, allows users control of a wide variety of zones and scenes, and can easily accommodate changes over time. These advantages boil down to two primary desirable benefits: Digital lighting systems are flexible for current and future lighting needs, and offer an effective energy management tool.

Craig DiLouie, principal of ZING Communications, Inc. (, is a consultant, analyst and reporter specializing in the lighting and electrical industries.