Energy Efficiency Questions and Answers

Monthly Electricity Consumption and Cost for High-Intensity Discharge Lights and Ballasts

1. There are 20 lights and ballasts that consume 440W (400W high Intensity discharge (HID) bulbs with a ballast that consumes 40W). The cost of electricity is $0.10/kWh and $7/kW-month demand and the lights are on 24 hours a day, seven days a week. How much electricity do the HID lights and ballasts consume monthly? What is the estimated cost of operating the 20 HID lights and ballast monthly? 

2. For the same lights in Question 1, you are able to install a timer of the lights and Instead of operating 24 hours a day, they operate 8 hours a day. How much electricity do the HID lights and ballast consume monthly? What is the new estimated cost of operating the 20 HID lights and ballasts monthly? 

3. For the same lights in question 1, you are able to install the same timer as Question 6, reducing daily operating hours from 24 hours to 8 hours. However, you are also able to replace the 400W lights and 40W ballasts with LED luminaires that consume 150W of power each. How much electricity do the LED luminaires consume monthly? What is the new estimated cost of operating the 20 LED luminaires monthly? 

4. An energy efficiency protect is expected to save 10,000 kWh annually and 2 kW of demand. The cost of electricity is $0.10/kWh and $7/kW nfonth of demand. The energy efficiency project is expected to cost $5000 to rnplement and will last lot 15 years. What is the simple payback of the project? 

5. For the same project in Quest en 4, what Is the net present value of project at a 10% discount rate (see page 168 of your textbook for compould interest factors). Be sure to include a basic cash flowdiagram. 

6. Research some of the most common new construction or green bulding labels (ex. LEER. ENERGY STAR Now Home). Compare and contest these common labels. Which label on labels do you thrk is most helpful in encouragffig tailders to adopt energy efficient building practices. Defend your assertion. 

7. A premium effidency pump in an industrial facility wall cost S40,000 installed, and will consume $9,500 per year of energy and require $1,500 per year worth of maintenance for a lifetime of 12 years. A standard-efficiency piny will cost S27.000 and will consume $13,000 per year of energy and will require $800 per year worth of maintenance for the same Nen me If your company uses a MARR of 101f, would you invest in the energy fficient pump? Justify you- answer. 

8. A property company who will also operate the building is deciding whether to build a standard efficiency office building or a high efficiency office building. The office building is 8,000 m2 and its energy is supplied 100% by electricity. The standard efficiency office tower will consume approximately 140 kWh / m2 /y. The high efficiency office tower will consume approximately 100 kWh / m2 /y. The incremental cost (i.e. the cost between the standard efficiency and high efficiency office tower) is $40 per m2 and the building systems are expected to last 25 years. Assume electricity price is at $0.10 per kWh. 

a. What is the estimated annual energy cost savings per year for the high efficiency building compared to the standard efficiency building?

b. Does it make sense for the property company to invest in the high efficiency office building? Defend your answer.