There are many opportunities to improve the performance of existing lightingssystems in which the power and energy use can be reduced while maintaining orsimproving the lighting quality. Too often, lighting retrofits do not meet theirsexpectations because the decision malting criteria were base solely upon economics.sFurthermore, some economic analysis are wanting because of the lack ofscomprehension of the performance of commonly used lighting equipment or aresbased upon the exaggerated claims of the manufacturers of energy saving and energysefficient lighting components. That is, some equipment is energy saving due toslowering light levels, however, there may be an improvement in efficiency due tosthermal effects and not due to action of the equipment. This is detrimental insanalysis when comparing different retrofit strategies when these factors are notsunderstood. Often, we are convinced that occupants will not notice the change inslight level, however, even if the change does not invoke a response it is possible thatsproductivity may be impacted, or the salability of the space may suffer. This reportswill attempt to address the above issues to assist the decision makers in reaching assound decision with a lighting system that meets their needs. The considerations andsinformation that follows will provide a guideline for evaluating and comparingsdifferent retrofit strategies.

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