Workiva Carbon’s EPA EEIO factor generation method & steps to reproduce

EPA EEIO v1.3

This section outlines the modifications made to the official Supply Chain Greenhouse Gas Emission Factors v1.3 (developed by the U.S. EPA) in order to generate BEA industry summary–level GHG emission factors instead of the default NAICS-6 commodity-level outputs.

These changes allow internal users and auditors to easily reproduce, verify, or extend the generation of summary-level factors aligned to the USEEIOv2.2.22-GHG model using 2022 GHG data and 2022 USD.

Step-by-Step Instructions to reproduce

1. Download the v1.3 supply chain factors code

GitHub: https://github.com/USEPA/supply-chain-factors/releases

2. Modify the model specification

Open model-specs/USEEIOv2.2.22-GHG.yml and apply the following changes:

Parameter	Change
BaseIOLevel	"Summary" ← was "Detail"
CommodityorIndustryType	"Industry" ← was "Commodity"

3. Modify CalculateEmissionFactors.Rmd

Edit supply-chain-factors-1.3.0/CalculateEmissionFactors.Rmd as follows:

Line	Change
24	# checkModelIOYear(modelname)➔ Commented out, since IOYear = 2017 is valid for v1.3 & matches the IOyear used to generate the EPA-published factors
56	# table <- mapto2017NAICS(...)➔ Commented out to skip NAICS mapping, which is not applicable for BEA industry summary outputs
94 & 111	*Adjust export filename suffixes: Rename: _NAICS_CO2e_USD → _BEA-IS_CO2e_USD Rename: _NAICS_byGHG_USD → _BEA-IS_byGHG_USD

*These changes clarify that the exported files contain BEA summary industry–level factors, not NAICS-level. They only change the file name of the export files, not any of the results or data.

4. Run the model

After applying the above changes, run the RMarkdown file: CalculateEmissionFactors.Rmd

This will generate the GHG emissions factors in both CO2e and by individual GHG gas.

Output files

File	Description
SupplyChainGHGEmissionFactors_v1.3.0_BEA-IS_CO2e_USD2022.csv	GHG emission factors in CO2e per BEA industry (with and without margins)
SupplyChainGHGEmissionFactors_v1.3.0_BEA-IS_byGHG_USD2022.csv	Emission factors broken out by gas (e.g., CH₄, N₂O, CO₂) per BEA industry

View output file:

SupplyChainGHGEmissionFactors_v1.3.0_BEA-IS_CO2e_USD2022.csv

Notes

GHG Year:2022

IO Year:2017 (from BEA benchmark Make and Use tables)

Price Year:2022 USD (purchaser prices)

Sector schema: BEA summary industry sectors (not NAICS-6)

Methodological alignment:All modifications follow the official v1.3 release documentation and USEEIO modeling conventions

EPA EEIO v1.2.3

This section outlines the modifications made to the official Supply Chain Greenhouse Gas Emission Factors v1.2.3 (developed by the U.S. EPA) in order to generate BEA industry summary-level GHG emission factors instead of the default NAICS-6 commodity-level outputs.

These changes allow internal users and auditors to easily reproduce, verify, or extend the generation of summary-level factors aligned to the USEEIOv2.1.19-GHG model using 2019 GHG data, 2022 USD, and 2019 IO data.

Step-by-Step Instructions to reproduce

1. Download the v1.2.3 supply chain factors code

GitHub: https://github.com/USEPA/supply-chain-factors/releases

2. Modify the model specification

Open model-specs/USEEIOv2.1.19-GHG.yml and apply the following changes:

Parameter	Change
BaseIOLevel	"Summary" ← was "Detail"
CommodityorIndustryType	"Industry" ← was "Commodity"
IOYear	2019 ← was 2012
DisaggregationSpecs	null ← Removed (not used in summary models)

3. Modify CalculateEmissionFactors.Rmd

Edit supply-chain-factors-1.2.3/CalculateEmissionFactors.Rmd as follows:

Line	Change
68	# table <- mapto2017NAICS(...) → Commented out to skip NAICS mapping, which is not applicable for BEA industry summary outputs
98 & 115	*Adjust export filename suffixes: Rename: _NAICS_CO2e_USD → _BEA-IS_CO2e_USD Rename: _NAICS_byGHG_USD → _BEA-IS_byGHG_USD

*These changes clarify that the exported files contain BEA summary industry–level factors, not NAICS-level. They only change the file name of the export files, not any of the results or data.

4. Run the model

After applying the above changes, run the RMarkdown file: CalculateEmissionFactors.Rmd

This will generate the GHG emissions factors in both CO2e and by individual GHG gas.

Output files

File	Description
SupplyChainGHGEmissionFactors_v1.2.3_BEA-IS_CO2e_USD2021.csv	GHG emission factors in CO2e per BEA industry
SupplyChainGHGEmissionFactors_v1.2.3_BEA-IS_byGHG_USD2021.csv	Emission factors broken out by gas per BEA industry

View output file:

SupplyChainGHGEmissionFactors_v1.2.3_BEA-IS_CO2e_USD2021.csv

Notes

GHG Year:2019

      used instead of EPA's default IOYear 2012 to avoid model errors and improve alignment with the GHG year (2019) and relevant economic period of interest (2016–2021)

IO Year:2017 (from BEA benchmark Make and Use tables)

Price Year:2022 USD (purchaser prices)

Sector schema: BEA summary industry sectors (not NAICS-6)

These steps enable teams to generate BEA-level factors using v1.2.3 in a reproducible, transparent way that better aligns with historical purchase data (2016–2021) and ensures audit-ability of calculations.