1. A company is doing an energy audit for incandescent light bulbs on campus and needs to assess the energy savings associated with replacing them with CFL or LED light bulbs. At present, the company has 75W incandescent light bulbs that run for ~11 hours per day averaged over the month and have a life of ~3 months. The Facilities and Administration (F&A) department has calculated that the labor cost of replacing a single light bulb is approximately $10 and that an average light bulb costs $0.60. If electricity costs at the company are $15 per MW-hr, draw a cash flow diagram for an incandescent light bulb that includes capital, labor, and electricity costs and calculate the equivalent annual uniform cost per month.
Assume:
1. Nominal interest/discount rate of 5%
2. Monthly compounding
2. Continuation of question above... A 75W incandescent light bulb produces about 700 lumens (lumen=a measure of the total quantity of visible light emitted). If a 20W compact fluorescent lamp (CFL) bulb costs $4, produces the same amount of lumens, and lasts for four times that of an incandescent light bulb, what is the equivalent annual uniform cost per month for a CFL bulb? In the paper copy, draw a cash flow diagram.
3. Continuation of question above... A 9W LED light bulb produces ~700 lumens, costs $20, and lasts for 10 years. What is the equivalent annual uniform cost per month for an LED bulb? In the paper copy, draw a cash flow diagram.