Lighting Retrofit Considerations

There are many opportunities to improve the performance of existing lighting systems in which the power and energy use can be reduced while maintaining or improving the lighting quality. Too often, lighting retrofits do not meet their expectations because the decision malting criteria were base solely upon economics. Furthermore, some economic analysis are wanting because of the lack of comprehension of the performance of commonly used lighting equipment or are based upon the exaggerated claims of the manufacturers of energy saving and energy efficient lighting components. That is, some equipment is energy saving due to lowering light levels, however, there may be an improvement in efficiency due to thermal effects and not due to action of the equipment. This is detrimental in analysis when comparing different retrofit strategies when these factors are not understood. Often, we are convinced that occupants will not "notice the change in light level," however, even if the change does not invoke a response it is possible that productivity may be impacted, or the salability of the space may suffer. This report will attempt to address the above issues to assist the decision makers in reaching a sound decision with a lighting system that meets their needs. The considerations and information that follows will provide a guideline for evaluating and comparing different retrofit strategies.

We will confine ourselves to the consideration of retrofitting fluorescent systems in commercial or industrial spaces. Data presented represents performance data measured in our laboratory.

Published as "Retrofitting: Sure It Saves Money, But Does It Work?" in Electrical Systems Design, Vol. 69, No. 3, April 1989