Technology Spotlight: Induction lamps

What lamp has excellent white light, a lamp life of 100,000 hours and is commercially available now? No, it’s not an LED (light emitting diode). It’s an induction lamp—also known as electrodeless—a proven, available technology that risks being overshadowed by the media focus on the emerging technology of white LEDs. 

Light quality and performance

Induction lamps generate high-quality, white light (similar to fluorescent lamps), with an excellent color-rendering index (CRI) of 80-82.  They come in color temperatures of warm (2700K and 3000K), neutral (3500K), and cool (4100K)—measured in Kelvins (K). Some products are also available in the very cool 5000K. 

A high-frequency generator (similar to a ballast) provides energy to a power coupler in the lamp, which excites the phosphors and produces light. The power system has a rated life of 60,000 hours.

Induction lamps perform well in very cold temperatures (most will start at -40 degrees F). Their life is rated at 100,000 hours (twice as long as almost any other lamp on the market), so they may last 12 to 25 years under average-use conditions.  With their long life and good lumen maintenance (the rate at which light output declines), relamping can be infrequent—saving the relamping costs of labor, materials, equipment and disposal. Extra fixtures are not needed to counter lumen depreciation.

Applications

Good applications include areas that can be disruptive, dangerous or expensive to access, such as roadway tunnels, bridges and industrial high bays (although high-bay fluorescents may be more cost-effective there). Refrigerated warehouses may be another good application. Induction lamps are good where white light is desired after dark, such as outdoor retail and pedestrian areas. Color stability is not an issue (as it is with metal halide), and their long life and range of thermal environments surpasses metal halide and most fluorescent systems. Induction systems are much more compact than fluorescent ones.

Some drawbacks

Unfortunately, induction lamps may cost $200 more per fixture more than conventional metal halide lamps. They require special fixtures, making it difficult to use them for a retrofit. 

Induction lamps are not dimmable at this time and could be incompatible with nearby dimming or occupancy-sensor controls. The signal used to produce the light may also interfere with some electronics and radio gear (including but not limited to, pacemakers, computers, radios and cordless phones). It is important to confirm with the manufacturer that these will not be problems in your specific application.

Selecting a lighting technology

Lighting system selection must be based on more than just energy efficiency. Many customers focus only on getting the most “bang for the buck” while satisfying applicable codes. Energy codes restrict how much power is used, and lighting design guidelines specify how much light occupants need to see, leaving customers to hunt for lighting systems with high color quality and light output (measured in lumens), low maintenance and energy requirements and an affordable cost.

Recent studies indicate that perceived light levels are higher with very cool light (5000K+).  This could mean that fewer fixtures (or lower-wattage lamps) are required for a given space, reducing first cost, energy and maintenance.  Customers who look beyond first costs to life-cycle costs get a clearer picture of what a lighting system will really cost in the long run. Energy use and maintenance account for about 85 percent of the costs accrued, so a higher first cost may be an excellent investment if operation costs decline appreciably.

Ask your local vendor for data comparing the life-cycle cost of induction lamps with other alternatives. Most lamp types come in quite a range of performance characteristics, and lighting costs vary widely from supplier to supplier. Quantity purchases generally reduce the unit cost. If you need white light in a space with difficult access or cold temperatures, or for those who own their own building and hire lighting maintenance services, the induction lamp may be a very attractive choice.

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