University-Sponsored Travel at the University of Michigan

Abstract

MethodsWe utilized two methods for our university travel GHG emissions accounting, both of which utilize emission factors, Great Circle Distances (GCDs), and ground vehicle miles. The first method (EPA method) relied on CO2, CH4, and N2O emission factors from the EPA. 3 Ground vehicle emission factors were based on data from the EPA's Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2015 and the Federal Highway Administration Highway Statistics 2015. Car and bus emission factors were standardized to vehicle miles while train emission factors were standardized to passenger-miles. Air travel emission factors, standardized to passenger-miles, were based on 2017 Guidelines to Defra/DECC's GHG Conversion Factors for Company Reporting. These air travel emission factors were segmented based on travel distance, with different factors for trips <300 miles, trips between 300 and 2,300 miles, and trips >2,300 miles. Additionally, the most recent global warming potentials (GWPs) were used to convert all emissions to GHG units of tCO2e. The second method (SIMAP method) relied on CO2, CH4, and N2O emission factors from SIMAP. 4 SIMAP is a GHG accounting tool designed by the University of New Hampshire and commonly used by other organizations. Its ground vehicle emission factors, standardized to vehicle miles, are based on U.S. Department of Transportation fleet emission factors and fuel economies. Its air travel emission factors, standardized to passenger-miles, were calculated using the EPA's National Emission Inventory for combustion factors and passenger-mile data from the U.S. Bureau of Transportation Statistics.

Quantifying the climate benefits of a virtual versus an in-person format for an international conference

“…For those residing in the U.S., their home ZIP code was used. We assumed the threshold between a registrant flying versus driving was 300 miles (a commonly used distance threshold in similar travel emissions analyses) [ 11 ]. An embedded formula for Google Maps driving directions was utilized to determine driving distance [ 12 ].…”