Modification of existing incandescent fixtures is a good source of savings because, for a given light output, they use more watts of energy than fluorescent lamps. Fluorescent lamps are over five times more efficient than incandescent lamps, as measured by the lumens of light emitted per watt of electricity used.
Some manufacturers have begun marketing fluorescent lamps that have a screw-in base that fits into the most common incandescent fixture sockets. These devices have an integral ballast that makes them a little larger than the incandescent bulbs they replace. This may be a problem in some applications where the lamps may project obtrusively from the fixture. Otherwise, some of the new lamps are very conventional in appearance and emit a uniform distribution of light.
Anyone contemplating a lighting-modification project should become familiar with the latest principles so that a zealous goal of reducing lighting electricity consumption does not result in lower-than-code light levels. This could have the unfortunate result of increased errors in the workplace, higher employee stress levels, and even an overall drop in performance. The best way to get a good feel for lighting is to purchase a light meter and to measure the footcandle levels at critical locations—at desktops, reception areas, and meeting rooms. Also, notice the high levels at windows on sunny days and at desks where task and area lighting contribute simultaneously.
Counsel people on their lighting needs. For example, show them the level at their desk and compare it to the recommended levels. Someone with a window office may even be more comfortable and relaxed when the lights are turned off on sunny days. Another person who performs detail work occasionally may find that using a task light at these times, to supplement the overhead lighting, may reduce errors and increase performance.
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Excerpt from Energy Conservation Projects.