Carbon References: Scope 3: Commuting and Travel

The table is subdivided into sections for CO2, CH4, and N2O.

Documentation for mobile sources for commuting
  Description Name Unit Source URL Calculations Notes
Commuting Faculty, staff, and student commuting Automobile kg CO2 / Mile

[1] Gasoline fleet emissions factor and

[2] U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics July 2013 (fuel efficiencies).

https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/n...

https://www.bts.gov/content/light-duty-vehicle-short-wheel-base-and-motorcycle-fuel-consumption-and-travel

(kg Co2/gal) / (miles/gal) Gasoline fleet CO2 emissions factor (kg CO2 / gal) divided by an average annual fuel economy. Average fuel efficiency is from Table 4-11 and includes passenger cars, light trucks and motorcycles.
Carpool kg CO2 / Mile Automobile commuting emissions factor (see above) n/a (Automobile kg CO2/mi) / (2 people per car) Assumed 2 people per car. Calculated as gasoline automobile emissions factor divided by 2.
Bus kg CO2 / Mile [1] Diesel fleet emissions factor (see above) and [2] U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics July 2013 (fuel efficiencies). https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/n... (kgCO2/gal) / (miles/gal) Diesel fleet CO2 emissions factor (kg CO2 / gal) divided by an average annual fuel economy. Average fuel efficiency is from Table 4-11 for buses.
Light Rail kg CO2 / Mile [1] US EPA. Emissions & Generation Resource Integrated Database (eGRID) 2014. and [2] U.S. Department of Energy Trasportation Energy Data Book, Edition 32 (July 31, 2013), Chapter 9 Tables 9.10-9.12 and Appendix A Tables A.14-A.16. https://www.epa.gov/energy/emissions-generation-resource-integrated-data..., http://cta.ornl.gov/data/index.shtml (kgCO2/kWh) / (passenger-mile/kWh) eGrid US average CO2 emissions factors per kWh used for light rail electricity. Divided by average fuel efficiency (passenger-mi per kWh). Electricity use for electricity use by commuter from Appendix A tables.  Passenger miles traveled from Chapter 9 tables.  
Commuter Rail kg CO2 / Mile [1] Diesel fleet emissions factor (see above), [2] US EPA. Emissions & Generation Resource Integrated Database (eGRID) 2014. and [3] U.S. Department of Energy Trasportation Energy Data Book, Edition 32 (July 31, 2013), Chapter 9 Tables 9.10-9.12 and Appendix A Tables A.14-A.16. https://www.epa.gov/energy/emissions-generation-resource-integrated-data..., http://cta.ornl.gov/data/index.shtml [ (electric kg CO2/kWh) / (passenger-mile/kWh) ] + [ (diesel kg CO2/gal) / (passenger-mile/gal) ] Sum of electricity use and diesel for commuter rail. Diesel emission factor from fleet vehicle calculation above. eGrid US average CO2 emissions factors per kWh used for commuter rail electricity. Divided by average fuel efficiency (passenger-mi per kWh). Electricity use for electricity use by commuter from Appendix A tables.  Passenger miles traveled from Chapter 9 tables.  
Directly financed outsourced travel Air travel Faculty / Staff kg CO2 / Mile [1] US EPA. 2014 National Emissions Inventory (NEI) Data (US total mobile aircraft CO2 emissions).
[2] US Bureau of Transportation Statistics. Table I-40: US Passenger-Miles (aircraft passenger-miles).
https://www.epa.gov/air-emissions-inventories/2014-national-emissions-in..., https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/n... [(ton CO2)*(2000 lb/ton)*(0.453592 kg/lb)] / (passenger-miles) Calculated CO2 emissions factor for years with US total CO2 aircraft emissions factors available from NEI (2008, 2011, 2014) and took an average. CO2 emissions including landing and take-off. Passenger miles include all air carrier, certified, domestic, and all services. Used average emission factor across all years.
Students kg CO2 / Mile Air travel emissions factor (see above) n/a n/a Assumed to be equal to air travel emissions factor
Other Train kg CO2 / Mile

[1] Diesel fleet emissions factor (see above),

[2] Distillate oil heating value (see CCC), [3] Train fuel efficiency (see CCC)

n/a (kg CO2/gal) / (MMBtu/gal) * (MMBtu/mi) Diesel fleet emissions factor (kg CO2/gal) was converted to kg CO2/mi using distillate oil heating value from CCC (MMBtu/gal from EF_Heating values tab) and fuel efficiency for trains from CCC (MMBtu/mi from EF_Transportation tab).
Taxi / Ferry / Rental Car kg CO2 / Mile Automobile commuting emissions factor (see above) n/a (Automobile kg CO2/mi) Assumed to be equal to automobile commuting emissions factor
Public Bus kg CO2 / Mile Diesel bus commuting emissions factor (see above) n/a (Bus kg CO2/mi) Assumed to be equal to diesel bus commuting emissions factor
Charter bus - Diesel kg CO2 / Mile        
Charter bus - CNG kg CO2 / Mile        
Charter bus - Other kg CO2 / Mile n/a n/a n/a Customized by users. No data entry here.
Alternative Fuel Bus kg CO2 / Mile n/a n/a n/a Assumed to be 0.
Personal Mileage Reimbursement kg CO2 / Mile Automobile commuting emissions factor (see above) n/a (Automobile kg CO2/mi) Assumed to be equal to automobile commuting emissions factor
Study abroad Air travel Air Travel kg CO2 / Mile Air travel emissions factor (see above) n/a n/a Assumed to be equal to air travel emissions factor
CH4 Description Name Emission Factors Source URL Calculation Notes
Commuting Faculty, staff, and student commuting Automobile kg CH4 / Mile [1] Gasoline fleet emissions factor (see above) and [2] U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics July 2013 (fuel efficiencies). https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/n... (kg CH4/gal) / (miles/gal) Gasoline fleet CH4 emissions factor (kg CH4 / gal) divided by an average annual fuel economy. Average fuel efficiency is from Table 4-11 and includes passenger cars, light trucks and motorcycles.
Carpool kg CH4 / Mile Automobile commuting emissions factor (see above) n/a (Automobile kg CH4/mi) / (2 people per car) Assumed 2 people per car. Calculated as gasoline automobile emissions factor divided by 2.
Bus kg CH4 / Mile [1] Diesel fleet emissions factor (see above) and [2] U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics July 2013 (fuel efficiencies). https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/n... (kg CH4/gal) / (miles/gal) Diesel fleet CH4 emissions factor (kg CH4 / gal) divided by an average annual fuel economy. Average fuel efficiency is from Table 4-11 for buses.
Light Rail kg CH4 / Mile [1] US EPA. Emissions & Generation Resource Integrated Database (eGRID) 2014. and [2] U.S. Department of Energy Trasportation Energy Data Book, Edition 32 (July 31, 2013), Chapter 9 Tables 9.10-9.12 and Appendix A Tables A.14-A.16. https://www.epa.gov/energy/emissions-generation-resource-integrated-data..., http://cta.ornl.gov/data/index.shtml (kg CH4/kWh) / (passenger-mile/kWh) eGrid US average CH4 emissions factors per kWh used for light rail electricity. Divided by average fuel efficiency (passenger-mi per kWh). Electricity use for electricity use by commuter from Appendix A tables.  Passenger miles traveled from Chapter 9 tables.  
Commuter Rail kg CH4 / Mile [1] Diesel fleet emissions factor (see above), [2] US EPA. Emissions & Generation Resource Integrated Database (eGRID) 2014. and [3] U.S. Department of Energy Trasportation Energy Data Book, Edition 32 (July 31, 2013), Chapter 9 Tables 9.10-9.12 and Appendix A Tables A.14-A.16. https://www.epa.gov/energy/emissions-generation-resource-integrated-data..., http://cta.ornl.gov/data/index.shtml    
Directly financed outsourced travel Air travel Faculty / Staff kg CH4 / Mile [1] US EPA. 2014 National Emissions Inventory (NEI) Data (US total mobile aircraft CH4 emissions). [2] US Bureau of Transportation Statistics. Table I-40: US Passenger-Miles (aircraft passenger-miles). https://www.epa.gov/air-emissions-inventories/2014-national-emissions-in..., https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/n... [(ton CH4)*(2000 lb/ton)*(0.453592 kg/lb)] / (passenger-miles) Calculated CH4 emissions factor for years with US total CH4 aircraft emissions factors available from NEI (2008, 2011, 2014) and took an average. NOx emissions including landing and take-off. Passenger miles include all air carrier, certified, domestic, and all services. Used average emission factor across all years.
Students kg CH4 / Mile Air travel emissions factor (see above) n/a n/a Assumed to be equal to air travel emissions factor
Other Train kg CH4 / Mile [1] Diesel fleet emissions factor (see above), [2] Distillate oil heating value (see CCC), [3] Train fuel efficiency (see CCC) n/a (kg CH4/gal) / (MMBtu/gal) * (MMBtu/mi) Diesel fleet emissions factor (kg CH4/gal) was converted to kg CH4/mi using distillate oil heating value from CCC (MMBtu/gal from EF_Heating values tab) and fuel efficiency for trains from CCC (MMBtu/mi from EF_Transportation tab).
Taxi / Ferry / Rental Car kg CH4 / Mile Automobile commuting emissions factor (see above) n/a (Automobile kg CH4/mi) Assumed to be equal to automobile commuting emissions factor
Public Bus kg CH4 / Mile Diesel bus commuting emissions factor (see above) n/a (Bus kg CH4/mi) Assumed to be equal to diesel bus commuting emissions factor
Charter bus - Diesel kg CH4 / Mile        
Charter bus - CNG kg CH4 / Mile        
Charter bus - Other kg CH4 / Mile n/a n/a n/a Customized by users. No data entry here.
Alternative Fuel Bus kg CH4 / Mile n/a n/a n/a Assumed to be 0.
Personal Mileage Reimbursement kg CH4 / Mile Automobile commuting emissions factor (see above) n/a (Automobile kg CH4/mi) Assumed to be equal to automobile commuting emissions factor
Study abroad Air travel Air Travel kg CH4 / Mile Air travel emissions factor (see above) n/a n/a Assumed to be equal to air travel emissions factor
N2O Description Name Emission Factors Source URL Calculation Notes
Commuting Faculty, staff, and student commuting Automobile kg N2O / Mile

[1] Gasoline fleet emissions factor (see above) and

[2] U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics July 2013 (fuel efficiencies).

https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/n... (kg N2O/gal) / (miles/gal) Gasoline fleet N2O emissions factor (kg N2O / gal) divided by an average annual fuel economy. Average fuel efficiency is from Table 4-11 and includes passenger cars, light trucks and motorcycles.
Carpool kg N2O / Mile Automobile commuting emissions factor (see above) n/a (Automobile kg N2O/mi) / (2 people per car) Assumed 2 people per car. Calculated as gasoline automobile emissions factor divided by 2.
Bus kg N2O / Mile

[1] Diesel fleet emissions factor (see above) and

[2] U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics July 2013 (fuel efficiencies).

https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/n... (kg N2O/gal) / (miles/gal) Diesel fleet N2O emissions factor (kg N2O / gal) divided by an average annual fuel economy. Average fuel efficiency is from Table 4-11 for buses.
Light Rail kg N2O / Mile

[1] US EPA. Emissions & Generation Resource Integrated Database (eGRID) 2014. and

[2] U.S. Department of Energy Trasportation Energy Data Book, Edition 32 (July 31, 2013), Chapter 9 Tables 9.10-9.12 and Appendix A Tables A.14-A.16.

https://www.epa.gov/energy/emissions-generation-resource-integrated-data..., http://cta.ornl.gov/data/index.shtml (kg N2O/kWh) / (passenger-mile/kWh) eGrid US average N2O emissions factors per kWh used for light rail electricity. Divided by average fuel efficiency (passenger-mi per kWh). Electricity use for electricity use by commuter from Appendix A tables.  Passenger miles traveled from Chapter 9 tables.  
Commuter Rail kg N2O / Mile

[1] Diesel fleet emissions factor (see above),

[2] US EPA. Emissions & Generation Resource Integrated Database (eGRID) 2014. and [3] U.S. Department of Energy Trasportation Energy Data Book, Edition 32 (July 31, 2013), Chapter 9 Tables 9.10-9.12 and Appendix A Tables A.14-A.16.

https://www.epa.gov/energy/emissions-generation-resource-integrated-data..., http://cta.ornl.gov/data/index.shtml [ (electric kg N2O/kWh) / (passenger-mile/kWh) ] + [ (diesel kg NOx/gal) / (passenger-mile/gal) ] Sum of electricity use and diesel for commuter rail. Diesel emission factor from fleet vehicle calculation above. eGrid US average N2O emissions factors per kWh used for commuter rail electricity. Divided by average fuel efficiency (passenger-mi per kWh). Electricity use for electricity use by commuter from Appendix A tables.  Passenger miles traveled from Chapter 9 tables.  
Directly financed outsourced travel Air travel Faculty / Staff kg N2O / Mile

[1] US EPA. 2014 National Emissions Inventory (NEI) Data (US total mobile aircraft N2O emissions).

[2] US Bureau of Transportation Statistics. Table I-40: US Passenger-Miles (aircraft passenger-miles).

https://www.epa.gov/air-emissions-inventories/2014-national-emissions-in..., https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/n... [(ton N2O)*(2000 lb/ton)*(0.453592 kg/lb)] / (passenger-miles) Calculated N2O emissions factor for years with US total N2O aircraft emissions factors available from NEI (2008, 2011, 2014) and took an average. N2O emissions including landing and take-off. Passenger miles include all air carrier, certified, domestic, and all services. Used average emission factor across all years.
Students kg N2O / Mile Air travel emissions factor (see above) n/a n/a Assumed to be equal to air travel emissions factor
Other Train kg N2O / Mile

[1] Diesel fleet emissions factor (see above),

[2] Distillate oil heating value (see CCC), [3] Train fuel efficiency (see CCC)

n/a (kg N2O/gal) / (MMBtu/gal) * (MMBtu/mi) Diesel fleet emissions factor (kg N2O/gal) was converted to kg N2O/mi using distillate oil heating value from CCC (MMBtu/gal from EF_Heating values tab) and fuel efficiency for trains from CCC (MMBtu/mi from EF_Transportation tab).
Taxi / Ferry / Rental Car kg N2O / Mile Automobile commuting emissions factor (see above) n/a (Automobile kg N2O/mi) Assumed to be equal to automobile commuting emissions factor
Public Bus kg N2O / Mile Diesel bus commuting emissions factor (see above) n/a (Bus kg N2O/mi) Assumed to be equal to diesel bus commuting emissions factor
Charter bus - Diesel kg N2O / Mile        
Charter bus - CNG kg N2O / Mile        
Charter bus - Other kg N2O / Mile n/a n/a n/a Customized by users. No data entry here.
Alternative Fuel Bus kg N2O / Mile n/a n/a n/a Assumed to be 0.
Personal Mileage Reimbursement kg N2O / Mile Automobile commuting emissions factor (see above) n/a (Automobile kg N2O/mi) Assumed to be equal to automobile commuting emissions factor
Study abroad Air travel Air Travel kg N2O / Mile Air travel emissions factor (see above) n/a n/a Assumed to be equal to air travel emissions factor