Life Cycle Analysis
Let’s use the Energy Guide to perform a life-cycle analysis to help choose a water heater. Different models of water heaters with the same capacity can vary dramatically in the amount of electricity they use.
Instructions: Use the two EnergyGuide Labels for the different water heaters, to answer questions 1-8.
Click here to open a text description comparing the two Energy Guide Labels.
Compare the Two EnergyGuide Labels
Water Heater #1:
- Water heater: Electric
- Capacity (first hour rating): 58 gallons
- This model uses 4622 kwh/year
- Energy use range of all similar models (kwh/year): 4624 (uses least energy) - 5109 (uses most energy)
- This model's estimated yearly operating cost is $388
- Based on a 1994 U.S. Government national average cost of $0.0841 per kWh for electricity. Your actual operating cost will vary depending on your local utility rates and your use of the product.
- Sold for $380
Water Heater #2:
- Water heater: Electric
- Capacity (first hour rating): 58 gallons
- This model uses 4989kwh/year
- Energy use range of all similar models (kwh/year): 4624 (uses least energy) - 5109 (uses most energy)
- This model's estimated yearly operating cost is $419
- Based on a 1994 U.S. Government national average cost of $0.0841 per kWh for electricity. Your actual operating cost will vary depending on your local utility rates and your use of the product.
- Sold for $335
Compare the Two Models
Determine Savings
Determine the Pay Back Period
Still trying to figure out the payback period? The price difference between the two models was $45, and your annual monetary savings was $33.76. So after one year, you got back $33.76 out of the $45 extra you spent on the superior model. How much longer would it take you to get back the remaining $11.24? Since $11.24 is about a third of $33.76, it would take you about a third of a year. Thus, your payback period is 1.33 years.
Obviously, it pays to buy an energy-efficient water heater by saving $393.96. It also helps the environment by not using 4,771 kWh of electrical energy and thereby not emitting 9,652 lb of CO2, 21 lb of NOx, 75 lb of SO2 and 1 lb of CO and particulate matter each and into the environment. See the individual’s power!