Scope 3: Commuting/Travel Abroad/Travel to and from home 



Mode 
Name 
Unit 
Source 
URL 
Calculations 
Notes 
Commuting 
Faculty, staff, and student commuting 
Automobile 
kg NOx / 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 NOx/gal) / (miles/gal) 
Gasoline fleet NOx emissions factor (kg NOx / gal) divided by an average annual fuel economy. Average fuel efficiency is from Table 411 and includes passenger cars, light trucks and motorcycles. 
Carpool 
kg NOx / Mile 
Automobile commuting emissions factor (see above) 
n/a 
(Automobile kg NOx/mi) / (2 people per car) 
Assumed 2 people per car. Calculated as gasoline automobile emissions factor divided by 2. 
Bus 
kg NOx / 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 NOx/gal) / (miles/gal) 
Diesel fleet NOx emissions factor (kg NOx / gal) divided by an average annual fuel economy. Average fuel efficiency is from Table 411 for buses. 
Light Rail 
kg NOx / 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 9.109.12 and Appendix A Tables A.14A.16. 
https://www.epa.gov/energy/emissionsgenerationresourceintegrateddata..., http://cta.ornl.gov/data/index.shtml 
(kg NOx/kWh) / (passengermile/kWh) 
eGrid US average NOx emissions factors per kWh used for light rail electricity. Divided by average fuel efficiency (passengermi per kWh). Electricity use for electricity use by commuter from Appendix A tables. Passenger miles traveled from Chapter 9 tables. 
Commuter Rail 
kg NOx / 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 9.109.12 and Appendix A Tables A.14A.16. 
https://www.epa.gov/energy/emissionsgenerationresourceintegrateddata..., http://cta.ornl.gov/data/index.shtml 
[ (electric kg NOx/kWh) / (passengermile/kWh) ] + [ (diesel kg NOx/gal) / (passengermile/gal) ] 
Sum of electricity use and diesel for commuter rail. Diesel emission factor from fleet vehicle calculation above. eGrid US average NOx emissions factors per kWh used for commuter rail electricity. Divided by average fuel efficiency (passengermi 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 NOx / Mile 
[1] US EPA. 2014 National Emissions Inventory (NEI) Data (US total mobile aircraft NOx emissions). [2] US Bureau of Transportation Statistics. Table I40: US PassengerMiles (aircraft passengermiles). 
https://www.epa.gov/airemissionsinventories/2014nationalemissionsin..., https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/n... 
[(ton NOx)*(2000 lb/ton)*(0.453592 kg/lb)] / (passengermiles) 
Calculated NOx emissions factor for years with US total NOx aircraft emissions factors available from NEI (2008, 2011, 2014) and took an average. NOx emissions including landing and takeoff. Passenger miles include all air carrier, certified, domestic, and all services. Used average emission factor across all years. 
Students 
kg NOx / Mile 
Air travel emissions factor (see above) 
n/a 
n/a 
Assumed to be equal to air travel emissions factor 
Other 
Train 
kg NOx / Mile 
[1] Diesel fleet emissions factor (see above), [2] Distillate oil heating value (see CCC), [3] Train fuel efficiency (see CCC) 
n/a 
(kg NOx/gal) / (MMBtu/gal) * (MMBtu/mi) 
Diesel fleet emissions factor (kg NOx/gal) was converted to kg NOx/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 NOx / Mile 
Automobile commuting emissions factor (see above) 
n/a 
(Automobile kg NOx/mi) 
Assumed to be equal to automobile commuting emissions factor 
Public Bus 
kg NOx / Mile 
Diesel bus commuting emissions factor (see above) 
n/a 
(Bus kg NOx/mi) 
Assumed to be equal to diesel bus commuting emissions factor 
Charter bus  Diesel 
kg NOx / Mile 




Charter bus  CNG 
kg NOx / Mile 




Charter bus  Other 
kg NOx / Mile 
n/a 
n/a 
n/a 
Customized by users. No data entry here. 
Alternative Fuel Bus 
kg NOx / Mile 
n/a 
n/a 
n/a 
Assumed to be 0. 
Personal Mileage Reimbursement 
kg NOx / Mile 
Automobile commuting emissions factor (see above) 
n/a 
(Automobile kg NOx/mi) 
Assumed to be equal to automobile commuting emissions factor 
Study abroad 
Air travel 
Air Travel 
kg NOx / Mile 
Air travel emissions factor (see above) 
n/a 
n/a 
Assumed to be equal to air travel emissions factor 