The cost of replacing incandescent bulbs can easily exceed the cost of the energy they consume in commercial and other buildings where maintenance personnel perform relamping.

According to National Lighting Bureau Director Cary S. Mendelsohn (Imperial Lighting Maintenance Company), who represents the interNational Association of Lighting Management Companies (INALMCO) on the Bureau’s board, “Switching from incandescent lamps to CFLs [compact-fluorescent lamps] can achieve significant labor savings that can go overlooked when people fail to consider all the time and motion associated with the replacement of just a single lamp.”

Mr. Mendelsohn elaborated on the time-and-motion issue: “The process starts when an employee notifies maintenance that a bulb needs to be replaced. Someone has to schedule the activity and then a worker has to implement it, often starting the process by walking to and examining the fixture involved to determine the kind of lamp that’s needed. The worker then walks to wherever the lamps are stored – and sometimes this can mean a trip to a hardware store – to retrieve the right lamp and, often, then walking to a separate area for a ladder. “When a ladder is required, the worker commonly has to move furniture for safe access to the fixture. The worker then goes up the ladder to remove the fixture’s shielding; down the ladder to put the shielding out of harm’s way; up the ladder to remove the old lamp and install the new one; down the ladder to pick up the shielding; up the ladder to reinstall it; and then down the ladder. Then the worker has to relocate any furniture that was moved, return the ladder, and discard the lamp. The worker may even have to fill out some paperwork. Although a half-hour is about average, sometimes it can take more than one hour to replace just one lamp, and sometimes the process involves two workers, for safety reasons.”

Mr. Mendelsohn noted that lamp replacement time and cost can be significantly impacted by the maintenance philosophy employed; i.e., spot relamping vs. group relamping. He explained, “With spot relamping, lamps are replaced as they burn out, resulting in a great deal of time and motion per replacement. With group relamping, all personnel, materials, and equipment are assembled to replace all the lamps at the same time, whether or not they’re burned out. While it may seem wasteful to replace a lamp that still operates, the value of the labor savings – about 80% to 90% – justifies the practice. Group relamping doesn’t eliminate the need for spot relamping, but it greatly reduces spot-relamping requirements when the lamps are long-lived, like CFLs. Especially when the number of incandescent lamps is relatively small – say, 100 sockets or less – few managers replace them on a group-relamping basis.”

Mr. Mendelsohn explained that group relamping typically occurs on three- or four-year cycles, assuming a facility uses fluorescent lamps for 3,000-4,000 hours each year. Incandescent lighting used to that extent would have to be replaced as many as nine to twelve times over the same period, explaining why it’s far easier and far more economical to integrate CFL replacement into an overall group-relamping schedule.

Mr. Mendelsohn used a hypothetical O&M-cost comparison to illustrate the differences between a 100-lamp incandescent installation and a 100-lamp CFL installation. Assuming an energy cost of $0.10 per kilowatt-hour (kWh) and a lamp-replacement labor rate of $20 per hour, the incandescent installation’s annual O&M costs could total $5,395, vs. $1,001 per year for the CFL installation; a CFL savings of $4.39 per lamp per year. If group relamping were used, the difference would fall to $2,522 per year, which is still significant; $3.32/incandescent lamp per year vs. less than $0.80 per CFL per year. “Realistically,” Mr. Mendelsohn said, “in most 100-lamp commercial installations, incandescent lamps would be replaced as they burn out while CFLs would be group-relamped. In that situation, an owner or manager might be paying O&M costs of, say, $5.40 per incandescent lamp per year vs. about $0.80 per CFL per year. Of course, all these numbers are hypothetical, and will vary principally based on the amount of energy actually used, the unit cost of the energy, and the cost of labor. Still, somewhat ironically, the least significant O&M cost factor is the annual cost of replacement lamps.”

Founded in 1976, the National Lighting Bureau provides information about and encourages reliance on High-Benefit Lighting®, that is, lighting that quickly pays for itself by improving productivity, reducing absenteeism, preventing accidents, enhancing security, and/or otherwise contributing important and valuable benefits – such as health benefits – while also minimizing energy waste.

More information about the National Lighting Bureau, its free publications, and a variety of research information are available at the National Lighting Bureau website (www.nlb.org) or by contacting the National Lighting Bureau Communications Office (8811 Colesville Road, Suite G106, Silver Spring, MD 20910; tel. 301-587-9572; fax 301-589-2017; e-mail [email protected]).