Part 1: Exploring an Electric Bill 

Link: Sample Electric Bill used for Sample Answers: 

  1. Reading a Bill
    • Customer Information: John J Customer; 123 Main St, Any Town, CT 00000;
      Account # 0000 000 0000
    • Billing Period: From MM/DD/YY to MM/DD/YY (31 days)
    • Electricity Usage (kWh): 697 kWh for the month
    • Supply (Generation) Charges: $96.12
    • Distribution (Delivery) Charges: $59.09
    • Transmission Charges: $28.67
    • Service Fees/Taxes/Other Charges: Public Benefits = $12.69
    • Total Amount Due: $196.57
  1. Generation vs. Distribution 
    • Question 1: The Supply section ($96.12) represents the cost of generating electricity at power plants.
    • Question 2: The Transmission ($28.67) and Local Delivery ($59.09) sections cover the costs of moving electricity through poles, wires, and substations. 
    • Question 3: The Local Delivery section ($59.09) has multiple line items (fixed monthly charge, improvements, local delivery, revenue adjustments, etc.), making it the most detailed and fee-heavy part.
  1. Calculating Cost per kWh
    1. Total Monthly Usage: 697 kWh
    2. Supply Charge: $96.12
    3. Supply Cost per kWh: $96.12 / 697 = $0.14 per kWh
    4. Total Bill Amount: $196.57
    5. Total Cost per kWh: $196.57 / 697 = $0.28 per kWh
    6. Difference: The total cost per kWh is about $0.14 more than, or double, the supply cost per kWh, because of transmission, delivery, and other fees.
  1. Reflection
    • Question 1: Answers will vary. (Example: Fuel prices for power plants may have increased, supply contract rates may have changed, or more electricity was needed due to higher demand.)
    • Question 2: Look at delivery charges, transmission fees, or public benefit charges – these may have increased even if usage didn’t.
    • Question 3: Answers will vary. (Example: To show transparency and promote customer understanding of what they are paying for. Customers can clearly see how much goes to power generation vs. maintaining and operating the electric grid.)

Part 2: Home Electricity Audit

  1. Make a Prediction
    Answers will vary.
  1. Practice Calculation 
    (Sample Response)
    • Appliance: Projector
    • From Label or Research: From label
    • Power (W): 300 W
    • Power (kW): 300 W / 1000 = 0.3 kW
    • Hours / day: 2 hr / day
    • kWh / day: 0.3 kW x 2 hr = 0.6 kWh / day
    • Cost per day @ $0.28 per kWh: 0.6 kWh x $0.28 = $0.17 per day
  1. Home Electricity Audit
    • Step 1: Cost($) per kWh
      From the Sample Electric Bill, this would be the same as the answer calculated in Part 1: Exploring an Electric Bill, Section C, Question 5: $0.28
    • Bonus Question: Answers will vary. (Sample Responses: Many devices like TVs, gaming systems, and chargers still draw electricity when “off.” Some appliances, like refrigerators, cycle “on” and “off” automatically, so my estimate of “hours in use” might not match the actual run-time. Heating, air conditioning, and fans use much more power during certain months, so my daily average might not reflect the real monthly variation. Some utilities charge different rates depending on time of day or other fees that aren’t tied directly to usage.

Part 3: Data Analysis

  1. Comparing Predictions to Results: Answers will vary. 
  2. Graphical Representation: Answers will vary.
  3. New Appliance Research: Sample Response: I chose to research a new refrigerator, since it was one of the biggest electricity users in my audit. The current refrigerator uses about 1000 kWh per year, which costs $280 per year (at $0.28 per kWh). A new Energy Star Refrigerator would use about 450 kWh per year. At the same rate, it would cost $126 per year. Annual savings would be $154 per year. 
    However, a new Energy Star refrigerator would cost around $650. That means it would take 4.2 years of savings to cover the price of the new refrigerator.