This calculator gives payback time, and both the annual and life-time cost & savings figures for energy and maintenance.
It calculates Lighting Power Density from area of at least 500 square feet per fixture, and provides the maximum fixtures allowed from a target LPD. Check the DOE for your requirement.
Non-residential electric usually has additional cost if lower than 90% Power Factor.
Calculator will not perform properly if removed from this site.
ENSURE THAT LIGHTING REPLACEMENT HAS EQUIVALENT PERFORMANCE