At 4,000 annual operating hours, th

At 4,000 annual operating hours, the results were more favorable for the LED lamps. At $40 per two-lamp troffer, for an LED system consuming 38 W, simple payback occurred within the 10-year study period for all four electric rates, versus the alternative of a new high-efficiency fluorescent system. At $80 per two-lamp troffer, electric rates need to be at least $0.12/kWh to achieve a simple payback in year 7 or less. At $120 per two-lamp troffer, the electric rates must be at least $0.18/kWh to achieve a simple payback in year 8 or less.