When looking at the life-cycle cost of lighting, it pays to parse all the pieces: not just the prices for fixtures, lamps, and ballasts, but also the costs for power to run them, the labor to maintain them, and services to dispose of them. Savings are possible that could cut the overall cost of illumination by 5 to 15 percent.
Most estimates are that 80 percent of the cost to operate a fixture is energy, with the remainder distributed between labor and parts. But such charts may not include the initial cost of the fixture, lamp/ballast disposal, and other charges. Fortunately, options exist to minimize these and other factors, including energy.
For the purpose of looking at the lifetime costs of lighting, and opportunities to contain and reduce them, the following examples use a typical recessed 3-lamp, 4-foot linear fluorescent fixture with standard T8 lamps and an electronic ballast. All costs are in today's dollars, without escalations.
Most spaces are illuminated to achieve tasks such as work, instruction, or sales. Each has an appropriate lighting level, but finding such excessive levels is common. Some corridors are lit as brightly as offices or classrooms, despite the fact that a much lower level may be satisfactory. The same may be true when a task changes. One college library space was converted to a cafeteria, with no adjustment to lighting levels. Many offices now filled with LCD screens are still lit as though typewriters were in use. The end result in all three cases is roughly double the necessary light level, which then doubles the operating and maintenance costs.
Whenever the main task in a space changes, consider ways to adjust lighting levels. In cases where localized tasks (or occupants) require a higher level of light, consider adding task lighting using compact fluorescent or LED sources instead of raising the ambient level of an entire space.
If corridors and lobbies are as bright as offices (e.g., 50 foot-candles), adjusting their level to about 20 to 25 foot-candles cuts the lighting cost of such common areas of the building (perhaps 10 percent of the floor area) roughly in half. That's about a 5 percent savings for the whole building, achievable merely by removing half the lamps in non-emergency fixtures. When done as part of a standard group relamping, no extra labor is involved. If that method is not acceptable, a variety of low-wattage lamps and ballasts are available that cut light and power levels while maintaining a "fully lit" appearance.
What you choose to install is what you are choosing to later maintain. Specifying designer fixtures may look great in demo spaces, but may prove to be more expensive to sustain than standard units, once the full installation is in use. Remember that "cutting edge" does not always equal "cutting cost."
Custom-designed fixtures may have parts not readily available except through the designer or the original manufacturer. Think twice before allowing specification of something that will be difficult or expensive to replace or repair during the fixture's lifetime. While a fancy fixture may cost over $500, the installed cost of the typical unit being used as our example is $250.
Allowing specification of any type of lamp or ballast may mean stocking many more lamp and ballast types, or paying a lighting maintenance firm extra to do so. Some lamps and ballasts are also much more expensive than others. Consider economizing during the design phase by specifying lamp types already common to a facility, or standardizing on several basic new types.
Think carefully about any new lighting controls being considered. Who will commission and maintain them, and at what cost? While wall-mounted occupancy sensors are great for cutting energy waste, for example, they can be vandalized or otherwise disabled.
Ensuring that such controls are allowed to do their job may entail some internal corporate/institutional communication and training. Involving employees and occupants in the process often results in greater savings for both energy and maintenance. Merely emphasizing the "green" aspects of efficiency may do the trick. The cost of such efforts is miniscule compared to the potential loss in energy savings if controls are disabled.
Unless a building has been specifically designed to utilize a significant level of natural light while minimizing glare, very careful consideration is required before specifying automatic dimming or daylighting controls. While such controls are not yet common, complaints about them are. "Because of such problems, we've had calls to decommission them," says Phil Kielkucki, vice president of Sales for Knight Electrical Services. Remember this general axiom: Don't specify anything too complex for the people who must maintain it.
Examine Use Requirements and Design Before Choosing Lighting Fixtures
Consider Energy and Maintenance Costs in Lighting Life-cycle Assessments
