Carbon Footprint Calculator Assumptions

General Information

  1. Typical PG&E Residential Customer—Monthly Household Energy Use1
    • Electricity Usage: 538 kilowatt-hours (kWh)
    • Natural Gas Usage: 33.75 therms
  2. ClimateSmart Rates2
    • Electricity: $0.00254 per kWh
    • Natural Gas: $0.06528 per therm
  3. PG&E Carbon Dioxide (CO2) Emissions Rates for the ClimateSmart Program3
    • Electricity: 0.524 lbs CO2 per kWh
    • Natural Gas: 13.446 lbs CO2 per therm
  4. PG&E Carbon Dioxide (CO2) Emissions Rates
    • Electricity (2009): 0.575 lbs CO2 per kWh4
    • Natural Gas (all years): 11.7 lbs CO2 per therm5

Minimizing Your Carbon Footprint –
Estimated Avoided CO2 Emissions

  1. Switch to Compact Fluorescent Light Bulbs
    • Compares a 100-watt incandescent bulb to a 23-watt compact fluorescent
    • Lighting used 2.34 hours per day6
    • PG&E emissions rate (electric): 0.575 lbs CO2 per kWh
  2. Install an Energy-Efficient Clothes Washer
    • Based on California Energy Commission-rated Tier 3, 2.65 cubic feet clothes washer supplied by a gas water heater—savings will vary greatly depending upon number of loads and size of washer, whether front- or top-loading, and whether electricity or natural gas is used for water heating
    • PG&E emissions rate (natural gas): 11.7 lbs CO2 per therm
    • PG&E emissions rate (electric): 0.575 lbs CO2 per kWh
  3. Purchase an Energy-Efficient Water Heater
    • 30 to 50 gallon 0.63 Energy Factor (EF) natural gas water heater—EF is a measure of energy efficiency
    • PG&E emissions rate (natural gas): 11.7 lbs CO2 per therm
  4. Install High Efficiency Central Furnace
    • Based on installation of a more efficient furnace (94% AFUE) to replace a less efficient unit (70% AFUE) of the same size (67.611 kBtuh rating) — AFUE stands for Annual Fuel Utilization Efficiency and is a measure of heating efficiency on an annual basis
    • PG&E emissions rate (natural gas): 11.7 lbs CO2 per therm
  5. Install Solar Electric Panels
    • Typical residential system is 3-5 kW
    • 18% capacity factor
    • Operating 8,760 hours per year
    • PG&E emissions rate (electric): 0.575 lbs CO2 per kWh
  6. Switch to Hybrid-Electric Vehicle
    • 12,000 miles per year for average automobile7
    • Compares hybrid-electric subcompact with comparable vehicle: 2010 Toyota Prius (50 miles per gallon average fuel efficiency) and (non-hybrid) 2010 Honda Civic 5-speed automatic (29 miles per gallon average fuel efficiency)8
    • Burning 1 gallon of gasoline produces 19.4 lbs CO29

Average Per Capita CO2 Emissions
(Energy and Vehicle Use)

  1. Average Californian
    • 2009 California Average Monthly Household Electricity Use: 589 kWh10
    • 2009 California Average Monthly Household Natural Gas Use: 32 therms11
    • California Emissions Rate for Delivered Electricity: 0.681 lbs CO2 per kWh12
    • Emissions Rate for Natural Gas: 11.7 lbs CO2 per therm5
    • 12,000 miles per year and 21 miles per gallon for average passenger vehicle13
    • Burning 1 gallon of gasoline produces 19.4 lbs CO29
  2. Average American
    • 2009 U.S. Average Monthly Household Electricity Use: 963 kWh14
    • 2009 U.S. Average Monthly Household Natural Gas Use: 35 therms15
    • United States Emissions Rate for Delivered Electricity: 1,300 lbs CO2 per kWh16
    • Emissions Rate for Natural Gas: 11.7 lbs CO2 per therm5
    • 2008 United States Per Capita Vehicle Usage: 522 gallons per vehicle17
    • Burning 1 gallon of gasoline produces 19.4 lbs CO29
  3. Average Global Person
    • 9479.78 lbs CO2 per person18

Sources

  1. PG&E's 2009 Residential Appliance Saturation Survey (RASS)
  2. PG&E's ClimateSmart program, authorized by the California Public Utilities Commission in Decision 06-12-032.
  3. PG&E's ClimateSmart program, authorized by the California Public Utilities Commission in Decision 06-12-032. The most accurate measure of emissions from electricity generation involves calculating the emissions from each plant in a utility's portfolio for each hour of the day and year, which can vary considerably by time of day, year, and with seasonal variations in weather.

    A simpler approach is to use an average emissions rate such as the California Public Utilities Commission (CPUC)-approved ClimateSmart electric emissions rate of 0.524 lbs CO2 per kWh. This reasonable approximation is based on the average emissions rate for PG&E's electric portfolio, consistent with the emissions rates that were independently verified and registered with the California Climate Action Registry (see www.climateregistry.org). The CPUC-approved ClimateSmart natural gas emissions rate is 13.446 lbs CO2 per therm.
  4. PG&E's 2009 The Climate Registry (TCR) Electric Power Sector (EPS) Report To find the emissions rate:
    • Select "Standard Reports"
    • Select "Entity Emissions Details (Public)"
    • On drop-down menus, select "Pacific Gas & Electric Corporation", "2009", "National-US", and "PDF"
    • Select "Detailed Information"
    • Scroll down to "Entity Documents"
    • Click on "2009 EPS Report PG&E"
    • Click on "Additional Optional Information" tab
  5. U.S. Energy Information Administration, Voluntary Reporting of Greenhouse Gases Program
  6. Database for Energy Efficient Resources, California Public Utilities Commission and California Energy Commission
  7. Emission Factors (EMFAC) Model 2007 Version 2.3, Average Annual Mileage from Air Basins in PG&E Service Territory
  8. U.S. Environmental Protection Agency, 2010 Estimated New EPA Miles-Per-Gallon
  9. U.S. Environmental Protection Agency, Overview: Pollutants and Programs Average Carbon Dioxide Emissions Resulting from Gasoline
  10. Based on the following information:
  11. Based on the following information:
  12. U.S. Environmental Protection Agency, eGRID2010 Version 1.0, which contains year 2007 information configured to reflect the electric power industry's current structure as of December 31, 2010
  13. Emission Factors (EMFAC) Model 2007 Version 2.3
  14. Based on the following information:
  15. Based on the following information:
  16. U.S. Environmental Protection Agency, eGRID2010 Version 1.0, which contains year 2007 information configured to reflect the electric power industry's current structure as of December 31, 2010
  17. U.S. Energy Information Administration, 2008 Motor Vehicle Mileage, Fuel Consumption, and Fuel Economy, Passenger Cars
  18. World Resources Institute, Climate Analysis Indicators Tool CAIT) Version 8.0. (Washington, DC: World Resources Institute, 2011), based on the following selections:
    • Year: 2007
    • Region: World
    • Emissions Source: Energy Use
    • GHGs: CO2
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