U.S. Department of Energy 

### PAYBACK S TS

The median payback period for product classes and design options analyzed are listed in the table below. The output from the payback period analysis is a distribution of paybacks which can sometimes contain negative values. Occasionally, there can be some very large negative values (for cathode cutout analyses) which cause instability and distort the mean payback period value. For this reason, we have chosen to present the median payback period, which we feel is a more meaningful value. Therefore, for the 10,000 cases analyzed for each lamp/ballast combination, 5000 have payback periods below and 5,000 have payback periods above the median values shown in the table. It is possible for the median payback period to be negative if the first cost of the ballast plus lamp is lower for the more efficient technology than for the baseline. We interpret short negative or positive payback periods (e.g., for 3 lamp non tandem, T8 ERS and 4 lamp T8 ERS) as essentially immediate paybacks. The probability distributions of payback periods for all design options can be found in the Life Cycle Cost Results section on this website.

# ~N**~&-7** 

# u.s. Department ofEnergy April 1999 PAYBACKRESULTS
The medianpaybackperiod for product classes and design options analyzed are listed in the table below. The output from the paybackperiod analysis is a distribution ofpaybacks which can sometimes contain negative values. Occasionally, there can be some very large negative values (for cathode cutout analyses) which cause instability and distort the meanpaybackperiod value. For this reason, we have chosen to present the median payback period, which we feel is a more meaningful value. Therefore, for the 10,000 cases analyzed for each lamplballast combination, 5000 have paybackperiods below and 5,000 have payback periods above the median values shown in the table. Itispossible for the median payback period to be negative ifthe first cost of the ballastplus lamp is lower for the more efficient technology than for thebaseline. We interpret short negative orpositive payback periods (e.g., for 3 lamp non tandem, T8 ERS and 4 lamp T8 ERS) as essentially immediatepaybacks. The probability distributions ofpayback periods for all design options can be found in the Life Cycle Cost Results section onthis website.

### U.S. Department of Energy April 1999
Summary of Payback Periods
Product Class Design Option Sector Median Payback Period (yrs)
1F40 T12 CC Commercial 24.6 T12 ERS Commercial 6.5 T8 ERS Commercial 2.7 2F40 T12 CC Commercial 10.8 T12 ERS Commercial 5.4 T8 ERS Commercial 2.5 3F40 Tandem-Wired TI2 CC Commercial 8.9 T12 ERS Commercial 7.1 T8 ERS Commercial 2.4 Not Tandem-Wired T12 CC Commercial 10.8 T12 ERS Commercial 3.0 T8 ERS Commercial -0.1 4F40 T12 CC Commercial 8.1 T12 ERS Commercial 4.5 T8 ERS Commercial 0.3 2F96 T12 EIS Commercial 5.8 T12 EIS Industrial 7.1 2F96HO T12 CC Commercial 2.3 T12 ERS Commercial 2.6 T12 CC Industrial 3.7 T12 ERS Industrial 3.1 U.S. Department ofEnergy

Product Class

IF40

2F40

3F40 Tandem-Wired

2F96

2F96HO 

### Summary ofPaybackPeriods Design Option Sector

T12CC T12ERS T8 ERS
T12CC T12ERS

T12CC T12ERS Commercial T8 ERS Commercial
T12 EIS Commercial T12EIS Industrial
T12CC Commercial T12ERS T12CC T12ERS Median Payback Period (yrs)

2.5
8.9 7.1

8.1 4.5 0.3
5.8 7.1 April 1999