It’s important before beginning a major lighting retrofit project to first become familiar with the lighting environment of your business. Doing one or two of the less costly maintenance-type projects is an excellent way to understand lighting and to become familiar with the equipment and technology.
A strong incentive, other than simple energy savings, concerns the effect of lighting on performance, accuracy, visual comfort, and sometimes even morale and attitude. If your project is planned carefully and implemented correctly, there will be a reduction in energy usage, but also the working environment will be improved and an increase in productivity and job satisfaction will be realized.
The Illuminating Engineering Society (IES) has established guidelines for light levels. The older standards are represented by ranges of footcandles, according to the task being performed — detail work requiring higher light levels. The newer standards use a formula that is applied to these ranges to further pinpoint the necessary light level. The formula takes into account the age of occupants, the required accuracy of the work, and the contrast at the work surface.
Compact fluorescent lamps cost quite a bit more than incandescent bulbs, but they have ten times the expected lifetime. They are ideal for locations where the lights stay on for at least 3 hours every time they’re used. (Fluorescent lamps have a diminished lifetime when they’re cycled more often.)
An ideal installation for fluorescents (and HIDs) to consider is in places that are hard to reach, such as gymnasium ceilings, high on atrium walls, and other spots where a tall ladder or a scaffold must be used to access the fixtures. The labor expense saved, at having to change out lamps less often, is a tangible cost that can improve the new lamp payback considerably.
As an example, consider the labor cost of replacing an incandescent lamp with a lifetime of 2500 hours with a compact fluorescent unit having an expected 10,000-hour lifetime. The incandescent bulb will be replaced three times before a new fluorescent lamp is needed. Thus the cost of a single compact fluorescent should be compared with the cost of three incandescent bulbs plus maintenance labor. If it takes 15 min for each changeout, the total time will be 0.75 h. At $20 per hour, this is $15.
This example shows the importance of taking into consideration all aspects of a project. The fluorescent lamp may have an initial cost that is $18, versus $2.50 for the lamp it’s replacing. Factoring in labor and comparing them on the same terms (i.e., one fluorescent lasts as long as four incandescent), the cost is $7.50 plus $15.00 = $22.50 over the lifetime of the fluorescent. This figure does not yet include the savings in electricity use.
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Excerpt from Energy Conservation Projects.