The U.S. Department of Energy's CALiPER program has released Report 21.3, which is part of a series of investigations on linear LED lamps. Report 21.3 details a set of life-cycle cost simulations that compared a two-lamp troffer using LED lamps (38W total power draw) or fluorescent lamps (51W total power draw) over a 10-year study period. The LED lamps were assumed to produce similar light output and light distribution when mounted inside the troffers, an assumption that was reasonable for less than a third of the products tested for this series of reports, but that may be more widely achievable in the near future, as SSL products advance.

There are many factors to take into account in determining whether an LED system is cost-effective for a given site. This report focused only on the initial investment, energy use, and system lifetime/replacement needs. Variables included LED system cost (two lamps plus separate driver, if needed—totaling $40, $80, or $120), annual operating hours (2,000 hours or 4,000 hours), LED installation time (15 minutes or 30 minutes), and melded electricity rate ($0.06/kWh, $0.12/kWh, $0.18/kWh, or $0.24/kWh). Tables allow readers to look up combinations of factors that most closely match their own situation, and simple estimation between values can aid in making rough assessments of economic feasibility for projects.
 
In general, while their initial cost premium remains high, linear LED lamps are more likely to be cost-effective when electric utility rates are higher than average and hours of operation are long, and if their installation time is shorter.
 
Download the full report.