UNT is trying to replace 200 two hundred bulbs 100Watts inca

UNT is trying to replace 200 (two hundred bulbs!) 100-Watts incandescent light bulbs by 200 (two hundred bulbs!) 15-Watts LED bulbs. Assume that the incandescent bulbs operate 6 hours per day and need to be replaced every year at a cost of $1.50 each. The LED bulbs will last 8 years with initial cost of $15 each. The cost of electricity over this 8 year period is $0.10/kWh. Assume a discount rate of 9%. Calculate The payback period in years TLCC of 200 incandescent light bulbs in 8 years TLCC of 200 LED light bulbs in 8 years Level zed cost of Energy saving (LCOE), in the unit of $/kwh/year Show (or copy from EXCEL) detailed steps even if you used EXCEL for calculation.

Solution

1) Let payback year be x

therefore cost for 1 bulb = 1.5*(x-1) + 100*6*0.1*x*365/1000

cost of 1 led = 15 - 9*15/100 + 15*8*0.1*x*365/1000

equating both, we have , x= 0.7965

therefore payback year is 1 year

2) TLCC of 1bulb for 1 year = 1.5 + 100*6*0.1*365/1000 = $ 23.4

TLCC of 200 bulbs for 1 year = $200*23.4 = $ 4680

TLCC of 200 bulbs for 8 years = $ 4680*8 = $ 37440

3) TLCC of 1 LED for 8 years = 13.65 + 15*8*0.1*8*365/1000 =$ 48.69

TLCC for 200 LED for 8 years = 200*48.69 = $ 9738

4) Total energy consumed by bulb in 1 year = 100*6*0.1*365/1000= 21.9 $/kwh/year

Toatl energy consumed by led in 1 year = 15*8*0.1*365/1000 = 4.38 $/kwh/year

therefore total energy saved in 1 year = (21.9 - 4.38) = 17.52 $/kwh/year