Emissions factors are released each year as versions. Each year's version includes the most up to date emissions factors available. You can select which version you would like to use on the calculation sources and methods form. And remember, Tier 1 users can always customize their emissions factors on the Data Entry tab.
List of references and table of emission factors for the 2021 version of emission factors. Check back soon for the 2022 version list of references
| Version | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 (Recommended) |
| Date released | November 2017 | April 2019 | February 2020 | January 2021 | February 2022 | March 2023 |
| Scope 1 | ||||||
| Stationary combustion | On-campus stationary changes, new NOx emissions factors | Unchanged from 2017 version |
Updated data to most recent year (Carbon Contents: 2017, Heating values: 2019) Updated methodology for CH4 from Wood Chips, Wood pellets, and Grass Pellets Error corrected for Incinerated Waste (reducing CO2 EF by around 70%) |
Updated data to most recent year (Carbon Contents: 2018, Heating values: 2019) Separated out biogenic emission factors Corrected biogenic % for residual and distillate heating (from 100% to 20%) |
Updated data to most recent year (Carbon Contents: 2019, Heating values: 2020) | Updated data to most recent year (Carbon Contents: 2021, Heating values: 2021) |
| Transport fuels | Unchanged from CCC, new NOx emissions factors | Unchanged from 2017 version |
Updated data to most recent year (Carbon Contents: 2017, Heating values: 2019, Average MPGs: 2016) CH4 and N2O update for gasoline and diesel vehicles (emission factors and fuel efficiency) Biogenic fuel % updated, and error corrected |
Updated data to most recent year (Carbon Contents: 2018, Heating values: 2019, Average MPGs: 2017) Updated biogenic % for E85 (from 85% to 74%) |
Updated data to most recent year (Carbon Contents: 2019, Heating values: 2020, Average MPGs: 2019) | Updated data to most recent year (Carbon Contents: 2021, Heating values: 2021, Average MPGs: 2020) |
| Fertilizer | Unchanged from CCC and NFT | Unchanged from 2017 version | Updated to the IPCC-recommended methodology for both Organic and Synthetic Fertilizer | Unchanged from 2019 version | Unchanged from 2020 version | Unchanged from 2021 version |
| Animals | Unchanged from CCC, n/a for NFT | Unchanged from 2017 version |
Updated data to most recent year (2017) Updated methodology for Beef Cows and Poultry |
Updated data to the most recent year (2018) | Updated data to the most recent year (2019) | Updated data to the most recent year (2020) |
| Refrigerants & chemicals | Unchanged from CCC, n/a for NFT | Unchanged from 2017 version |
Minor error corrections |
Minor naming corrections Added the option to view results using 20-year GWPs |
Unchanged from 2020 version | Unchanged from 2021 version |
| Scope 2 | ||||||
| Utility consumption | eGrid 2014 report (released 2016, factors updated through 2014), Custom fuel mix changes from CCC | eGrid 2016 report (released 2018, factors updated through 2016) |
eGrid 2018 report (released Feb 2020, factors updated through 2018) Note: The emission factors used in SIMAP were not affected by the 3/9/20 eGrid revision. |
eGrid 2018 report for location-based emission factors (unchanged from 2019 version of EFs) |
eGrid 2019 and eGrid 2020 report for location-based emission factors |
eGrid 2020 for location-based emission factors (unchanged from 2021 version) |
| Residuals for CO2 for 2015 by NERC region. | Residual emission factors for CO2 added for 2016 by NERC region. | Residual emission factors for CO2 in 2015, 2016, and 2017 by eGrid region. Residual emission factors were previously by NERC regions. | Residual emission factors for market-based approach updated through 2018 |
Green-e 2019 market-based residual emission factors added. Green-e 2020 market-based residual emission factors not yet available. |
Green-e 2020 market-based residual emission factors | |
| Scope 3 | ||||||
| Commuting | Unchanged from CCC, new NOx emissions factors | Unchanged from 2017 version |
Updated data to most recent year (Carbon Contents: 2017, Heating values: 2019, Average MPGs: 2016) CH4 and N2O update for gasoline and diesel vehicles (emission factors and fuel efficiency) Updated electricity mix (for light rail and commuter rail) using eGrid 2018 |
Updated data to most recent year (Carbon Contents: 2018, Heating values: 2019, Average MPGs: 2017) |
Updated data to most recent year (Carbon Contents: 2019, Heating values: 2020, Average MPGs: 2019) Added two new commuting modes: Electric vehicles and telecommuting Updated bus emission factor to use same ridership data source as the EPA factors. This significantly reduced the bus commuting emissions factor. |
Updated data to most recent year (Carbon Contents: 2021, Heating values: 2021, Average MPGs: 2020) |
| Business travel & study abroad | Air travel CO2, new NOx emissions factors | Unchanged from 2017 version |
Updated data to most recent year (Carbon Contents: 2017, Heating values: 2019, Average MPGs: 2016) CH4 and N2O update for gasoline and diesel vehicles (emission factors and fuel efficiency) |
Updated data to most recent year (Carbon Contents: 2018, Heating values: 2019, Average MPGs: 2017) | Updated data to most recent year (Carbon Contents: 2019, Heating values: 2020, Average MPGs: 2019) |
Updated data to most recent year (Carbon Contents: 2021, Heating values: 2021, Average MPGs: 2020) Air travel CO2 passenger-mile emission factors higher in 2020 and 2021 due to low ridership. 2022 set equal to 2019. Air travel CH4 emissions factors now 0 across all years |
| Student travel to/from home | Air travel CO2, new NOx emissions factors | Unchanged from 2017 version |
Updated data to most recent year (Carbon Contents: 2017, Heating values: 2019, Average MPGs: 2016) CH4 and N2O update for gasoline and diesel vehicles (emission factors and fuel efficiency) |
Updated data to most recent year (Carbon Contents: 2018, Heating values: 2019, Average MPGs: 2017) | Updated data to most recent year (Carbon Contents: 2019, Heating values: 2020, Average MPGs: 2019) |
Updated data to most recent year (Carbon Contents: 2021, Heating values: 2021, Average MPGs: 2020)
See notes above for air travel |
| Food | New to SIMAP with GHG emissions factors. Unchanged from NFT | Unchanged from 2017 version |
No changes |
No changes | No changes | Updated to new emission factor data set: Poore & Nemecek 2020. Expect food emissions to increase ~30% due to improved. methods and inclusion of food waste emissions. |
| Paper | Unchanged from CCC. N/A for NFT | Unchanged from 2017 version |
No changes |
No changes | No changes |
No changes Emission factors units updated from eCO2 to CO2 |
| Waste & wastewater | Unchanged from CCC, new nitrogen loss factors | Unchanged from 2017 version |
No changes |
Updated waste emission factors across time using the WARM Model. Previously, the same value was used across all years. Current through 2016. |
No changes to waste Updated wastewater method "Anaerobic Digestion" to "Aerobic + Anaerobic Digestion" Added new wastewater method "Anaerobic + Anaerobic Digestion" |
No changes |
| Purchasing Data | N/A | N/A | N/A | N/A | N/A | Added purchasing data entry across all scope 3 categories. Uses 2016 data from EPA EEIO database. |
| Sinks and offsets | ||||||
| Compost | Unchanged from CCC. Nitrogen update for average compost N content | Unchanged from 2017 version | No changes | No changes | No changes |
No changes Emission factors units updated from eCO2 to CO2 |
| Non-additional sequestration | Unchanged from CCC, new for nitrogen | Unchanged from 2017 version | No changes | No changes | No changes | No changes |
| Offsets | Unchanged from CCC, new for nitrogen | Unchanged from 2017 version | No changes | No changes | No changes | No changes |
Note: This table is specific to US emissions factors. The Canadian electricity emissions factors (regional and residuals) were also updated.
CCC = Campus Carbon Calculator, which was the Excel version of the campus carbon footprint tool
NFT = Nitrogen Footprint Tool, which was the original Excel version of the campus nitrogen footprint tool