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Revision History
This page describes the revisions and updates made to the Greenhouse Gas Equivalencies Calculator since it was originally posted on EPA’s website in February 2008.
April 25, 2013
- Passenger vehicles per year: Updated the assumptions for average fuel economy and vehicle miles traveled in 2010 to account for revisions made in December 2012 to the Federal Highway Agency's published statistics. Note that the emissions factor (4.8 metric tons of CO2E per vehicle per year) is not affected by these updates.
- Therms of natural gas: Unrounded the value given for CO2 emissions per therm of natural gas burned to be consistent with the value given in EPA's proposed rule for the Greenhouse Gas Reporting Program. The former value used by the calculator was 0.005 metric tons of CO2 per therm; the new value is 0.005306 metric tons of CO2 per therm.
October 17, 2012
- Starting points: Emissions of Hydroflurocarbon gases: Added five additional HFC blends (R-404A, R-407A, R-407C, R-410A, and R-507A) to the drop-down list of HFCs.
- Electricity reductions: Updated the CO2 emissions factor to reflect the updated eGRID 2012 version 1.0.
- Passenger vehicles per year: Updated assumptions for vehicle miles traveled and average fuel economy based on the most recent available sources.
- Home electricity use and Home energy use: Updated the electricity emission factor to reflect the updated eGRID 2012 version 1.0; updated average energy consumption figures based on the latest Residential Energy Consumption Survey data.
- Forestry equivalencies: The methodologies and sources used to calculate equivalencies for the number of acres of U.S. forests and the number of acres of U.S. forests preserved from conversion to cropland have been completely revised and updated.
- Railcars of coal: The average heat content and emission factors for coal have been updated to the most recent figures available.
- Tons of waste recycled: The conversion factor has been updated based on the emission factors in the current (2012) version of WARM.
- Coal-fired power plants: The number of coal-fired power plants and their CO2 emissions have been updated based on eGRID 2012.
November 1, 2011
- Home energy use: Corrected a typographical error in the final equation; the correct value for liquid propane is 0.34 metric tons CO2 (not 0.32 as previously shown), and the total emissions per household per year are 11.55 metric tons CO2 (not 11.53 as previously shown).
- Coal-fired power plant emissions for one year: Deleted the conversion to metric tons, which is not needed in the final equation and was inadvertently retained in the text from a previous version of the calculator. The result shown was correct and has not been changed.
May 20, 2011
- Electricity use, Home electricity use, Home energy use: Updated the CO2 emissions factor to reflect the updated eGRID2010Version 1.1.
April 29, 2011
- Electricity use: Modified the electricity use emissions factor to an unrounded value so it more closely matches the value given for the U.S. annual non-baseload CO2 output emission rate in eGRID2010 Version 1.0.
February 28, 2011
- Electricity use: Updated the electricity use calculation when converting reductions of kilowatt-hours into avoided units of carbon dioxide emissions: the Emissions & Generation Resource Integrated Database (eGRID) U.S. annual non-baseload CO2 output emission rate was updated from eGRID2007 Version 1.1 to eGRID2010 Version 1.0.
- Passenger vehicles per year: Updated the amount of carbon dioxide emitted per gallon of motor gasoline burned from 8.89 to 8.92*10-3 metric tons to reflect latest U.S. EPA Greenhouse Gas Inventory data. This gives a result of 5.1 metric tons of carbon dioxide equivalent per vehicle per year, consistent with EPA figures provided in the 2011-2016 light-duty fuel economy standards analysis.
- Gallons of gasoline consumed: Updated the amount of carbon dioxide emitted per gallon of motor gasoline burned from 8.89 to 8.92*10-3 metric tons to reflect latest U.S. EPA Greenhouse Gas Inventory data.
- Barrels of oil consumed: Updated the heat content and carbon coefficient of crude oil to reflect latest U.S. EPA Greenhouse Gas Inventory data. The conversion factor used in the calculator is unaffected by these updates and remains the same.
- Tanker trucks filled with gasoline: Updated the average heat content and carbon coefficient of motor gasoline to reflect latest U.S. EPA Greenhouse Gas Inventory data. These updates change the conversion factor from 74.89 to 75.82 metric tons of carbon dioxide per tanker truck.
- Home energy use: Updated the carbon coefficients for natural gas, distillate fuel oil, liquefied petroleum gases, and kerosene to match those in the latest U.S. EPA Greenhouse Gas Inventory data. These updates change the conversion factor from 11.75 to 11.77 metric tons of carbon dioxide per home per year.
- Acres of forest carbon preserved from avoided deforestation: Updated the average carbon density of U.S. forests to reflect the latest U.S. EPA Greenhouse Gas Inventory. The updates change the conversion factor from 105.38 to 100.94 metric tons of carbon dioxide per acre converted.
- Propane cylinders used for home barbecues: Changed the percentage of carbon in propane from 81.8% to 81.7% to reflect the latest U.S. EPA Greenhouse Gas Inventory. The conversion factor remains unchanged.
- Railcars of coal burned: Updated the average heat content of coal and the average carbon coefficient of coal to reflect the latest U.S. EPA Greenhouse Gas Inventory. These updates change the conversion factor from 191.5 to 183.65 metric tons of carbon dioxide per railcar.
- Tons of waste recycled instead of landfilled: Updated the net emission reduction from recycling mixed recyclables to 0.78 from 0.81 metric tons of carbon equivalent per short ton to reflect figures given in the latest U.S. EPA WARM. This update changes the conversion factor from 2.97 to 2.87 metric tons of carbon dioxide equivalent per ton of waste recycled instead of landfilled.
- Coal-fired power plant emissions for one year: Updated the number of power plants using coal and their carbon dioxide emissions to reflect the latest eGRID data for 2007. These updates change the conversion factor from 3,850,479 to 4,023,304 metric tons of carbon dioxide per power plant.
March 8, 2010
- Home electricity use: Corrected CO2 emissions factor from 7.70 metric tons CO2/home to 8.24 metric tons CO2/home to account for emissions associated with transmission and distribution losses. The figure of 7.70 metric tons is for electricity generated at the plant; the figure of 8.24 metric tons is for delivered electricity.
- Home energy use: Based on the correction described above, increased the annual CO2 emissions per home from 11.21 metric tons to 11.75 metric tons.
- Propane cylinders used for home barbecues: The conversion from pounds to kilograms was inadvertently omitted from the calculation; this was corrected and the result changed from 0.054 metric tons CO2 per cylinder to 0.024 metric tons CO2 per cylinder.
November 20, 2009
- Passenger vehicles per year: Updated fuel economy and vehicle miles traveled figures to reflect 2007 data; previous figures were for 2005. Also adjusted the ratio of carbon dioxide emissions to total emissions based on 2007 data. Result is now slightly lower (5.23 metric tons CO2 equivalent per vehicle per year, compared with 5.46 previously).
- Gallons of gasoline consumed: Revised the methodology used to calculate emissions per gallon of gasoline; the new methodology yields a slightly different result (8.89*10-3 metric tons CO2/gallon compared with 8.81*10-3 metric tons CO2/gallon previously).
- Tanker trucks filled with gasoline: Corrected the result from 74.88 to 74.89 metric tons CO2/tanker truck.
- Home electricity use: Updated electricity use per home and the number of homes to reflect 2008 Residential Energy Consumption Survey (RECS) data. The changes result in a slightly higher level of annual CO2 emissions per home (7.70 metric tons based on 2008 RECS data versus 7.21 metric tons based on 2003 RECS data).
- Home energy use: Updated energy use per home and the number of homes to reflect 2008 Residential Energy Consumption Survey (RECS) data. The changes result in a higher level of annual CO2 emissions per home (11.21 metric tons based on 2008 RECS versus 10.99 metric tons based on 2003 RECS data).
- Number of tree seedlings grown for 10 years: Revised the caveats to the assumptions.
- Acres of pine or fir forests storing carbon for one year: Revised and updated the calculations; the new result is slightly higher than before (4.69 metric tons of CO2 per acre of pine or fir forests, compared with 4.4 previously).
- Acres of forest preserved from deforestation: Updated to reflect data from the 2009 U.S. Greenhouse Gas Inventory. The new result is lower than before (105.38 metric tons of CO2 per acre converted, compared with 143.37 previously).
- Propane cylinders used for home barbeques: Revised the calculation methodology to account for the fact that pure propane (rather than LPG) is used in propane tanks. The previous calculation mistakenly assumed that LPG is used in these tanks. The new result is higher than before (0.054 metric tons CO2/cylinder, compared with 0.024 previously)
- Tons of waste recycled instead of landfilled: Updated this calculation to reflect data from the 2009 version of WARM. The new result is slightly higher than before (2.97 metric tons CO2E per ton of waste recycled, compared with 2.90 previously).
- Coal-fired power plant emissions for one year: Changed the data source to eGRID from the Clean Air Markets Division. The new result is lower than before (3,850,479 metric tons CO2 per power plant, compared with 4,643,734 previously).
February 17, 2009
- Electricity Use: Updated the electricity use calculation when converting reductions of kilowatt-hours into avoided units of carbon dioxide emissions: the Emissions & Generation Resource Integrated Database (eGRID) year 2005 U.S. annual non-baseload CO2 output emission rate updated from eGRID2007 Version 1.0 to eGRID2007 Version 1.1.
- Home Electricity Use: Updated the home electricity use calculation when converting units of avoided CO2 emissions into annual electricity use of number of homes: the eGRID U.S. annual CO2 output emissions rate was updated from eGRID2006 Version 2.1 (year 2004 data) to eGRID2007 Version 1.1 (year 2005 data).
- Home Energy Use: Updated the home energy use calculation when converting units of avoided CO2 emissions into annual energy use of number of homes: the eGRID U.S. annual CO2 output emissions rate was updated from eGRID2006 Version 2.1 (year 2004 data) to eGRID2007 Version 1.1 (year 2005 data).
December 8, 2008
- Electricity Use: Updated the electricity use calculation when converting reductions of kilowatt-hours into avoided units of carbon dioxide emissions: the eGRID non-baseload national average emissions rate was updated from eGRID2006 Version 2.1 (year 2004 data) to eGRID2007 Version 1.0 (year 2005 data).