Frequently asked questions

Cornerstone launched in August 2025 to bring USEEIO and CEDA together into one open, comprehensive dataset of Scope 3 spend-based emission factors. Cornerstone EEIO 2026 is the first release of that combined model. It is the continuation of both USEEIO v1.4 and CEDA 2025. Today Cornerstone is the home of 3 additional datasets: eGRID, the GHG EF Hub and Orbae. Learn more at cornerstonedata.org, and see the release candidate note for what is in this release.

Three groups of changes:

1. A more current US economy that accounts for imports. US tables are rebuilt for every year from 2017 to 2024, manufacturing uses facility-reported emissions, and imports are modeled where they are made.

2. Newer data for Europe, the UK and China, and better gap-filling for other countries.

3. A validation process that feeds back into the model. Third-party benchmarks review the sectors behind about 50% of global emissions.

Examples with numbers are in What changed in the release candidate note. The full list is in the Change log. Side-by-side summaries are in Summary of changes vs. USEEIO and Summary of changes vs. CEDA.

Both. Data updates reflect real-world change, such as new economic, trade and emissions data. Methodology changes reflect modeling improvements, such as modeling US imports by origin and the auto-balanced structural reflection (ABSR) method. See the Change log and, for the size of each driver, What drives the change for CEDA users and What drives the change for USEEIO users.

2026 is the first time CEDA and USEEIO are combined in one model, and the first time a time series is released. The two-phase release gives companies time to assess the impact on their most recent year of measurements while the time series is under development. The release candidate (2026-rc.1) is published on October 27, 2026. The full release (2026-v1), with the 2017–2026 time series and the model matrices, follows in early December 2026. See 2026-rc.1 (Release Candidate).

We don’t foresee significant changes, but some sector–country combinations could move because of improvements made while developing the time series. If you need numbers for reporting or rebaselining, wait for the final version. See 2026-rc.1 (Release Candidate) for what to expect from the time series.

Releases are published every October so companies can plan for them. The next, Cornerstone EEIO 2027, will be released in October 2027. Cornerstone EEIO 2026 will stay methodologically stable for at least five years, so you have a consistent basis to rebaseline and set targets. See Release details and Update cadence.

Yes, slightly. Cornerstone EEIO uses 405 sectors, based on the BEA input-output commodity codes. When the USEEIO and CEDA teams reconciled their US models, they resolved the differences in sector definitions as follows.

Changes compared to USEEIO

• Electric utilities are aggregated into one sector (221100). USEEIO split them across three.

• Government and private transit are aggregated into one sector. USEEIO kept them separate.

Changes compared to CEDA

• Waste is split into seven sectors. CEDA had a single waste sector.

• Aluminum is split into primary and secondary sectors. CEDA merged them.

• Home appliances are one sector, as in the BEA tables. CEDA had four.

See the model reconciliation section of the change log for all 18 differences.

Yes. The new release is different from open CEDA and from the USEEIO v1.4. See What's in a release for more details.

It depends on which sectors and countries your spend falls in.

• Coming from CEDA 2025: global production-weighted factors fall by 23.3%. In a sample of 400 corporate footprints, the median company sees a 14% decrease.

• Coming from USEEIO v1.4: US factors change by −0.8% overall. In the same sample, the median company sees a 1.3% decrease.

A small median can hide large moves in individual sectors, in both directions. See How do the emission factors change?, Summary of changes vs. CEDA and Summary of changes vs. USEEIO.

We do expect the majority of companies to be above the SBTi rebaselining threshold, but every company will have a different experience and ultimately whether to restate is a decision under your own company’s policy and your target framework. This year, the release of the time series is designed for exactly this purpose. Because every year from 2017 to 2026 is built with one methodology, you can recalculate prior years on a consistent basis and compare them. See 2026-rc.1 (Release Candidate) for what to expect from the time series, and Summary of changes vs. CEDA and Summary of changes vs. USEEIO for how much your factors may move.

We recommend using Cornerstone EEIO 2026 for 2026 measurements, since it supersedes both. If you have a reason to stay on a previous version, apply a price index to it, and explain the choice to your verifier. See Summary of changes vs. CEDA and Summary of changes vs. USEEIO for what changed.

State the source (Cornerstone EEIO 2026) and the years you are applying the model to.

Suggested wording: “The changes this year are due to adopting Cornerstone EEIO 2026. The Cornerstone model combines CEDA’s global coverage with USEEIO’s detailed US data into a single model that supersedes them both. This model was adopted as an improvement in data quality, as it provides a more current picture of the global economy.”

For numbers you can cite, see What changed in the release candidate note, Summary of changes vs. CEDA and Summary of changes vs. USEEIO.

The producer price is what the producer receives. The purchaser price adds trade and transport margins, and is what you pay for a ready-to-buy product. If you’re unsure, use producer prices, which are more conservative. If you’re confident your spend includes typical margins, for example buying off-the-shelf goods at retail, use purchaser prices. See Choose between purchaser and producer price.

Choose the country where the product was produced. If you don’t know it, use this order, from most to least relevant:

1. Country of manufacture

2. Country of the supplier

3. Country of purchase

4. Country of your company’s headquarters

If a country has no factors of its own, use its regional average. The Locations tab shows which of the 249 locations have their own country factors (148 do) and which region each belongs to. See Step 2: Choose the country.

Use the factor for the region it belongs to, or the global average if the region isn’t clear. See the Locations tab, Methods by country and Step 2: Choose the country.

The factors cover upstream emissions up to the point of purchase, so they apply to the upstream categories: purchased goods and services (1), capital goods (2), upstream transportation and distribution (4), waste generated in operations (5), business travel (6), and upstream leased assets (8), as well as the upstream part of category 3. They don’t cover downstream emissions (categories 9–15). See User guidance.

Three reasons: the emissions intensity of each country (for example its electricity grid), the economic structure of the sector in that country, and the trade structure, meaning where its inputs are imported from. Factors for a sector in countries with detailed data differ for real reasons, but see the tier question below for countries with less data. For worked examples, see New data for China and New data for Europe.

Yes. Cornerstone factors are designed for spend-based Scope 3 calculations under the GHG Protocol Corporate Value Chain (Scope 3) Standard, and they follow its minimum boundary conditions: a cradle-to-gate boundary that covers all upstream emissions up to the point of purchase, all seven GHGs reported in CO₂e with IPCC AR6 100-year global warming potentials, and no downstream emissions. See User guidance and The GHG extension: overview.

Yes. The factors cover all upstream emissions, from raw material extraction up to the point of purchase. Downstream use and end-of-life emissions are not included. See User guidance.

The factors do not account for direct land use change, but they do include land management emissions. Farming emissions are counted in the farm sectors, including methane from livestock and rice, N₂O from agricultural soils, and CO₂ from liming and urea. Land use, land-use change and forestry (LULUCF), including carbon removals, is not counted. See What is and isn’t counted.

No. All seven GHGs are included. The release reports each gas separately, alongside the total, in kg CO₂e per USD. See Gases and global warming potentials and Producer and purchaser price tabs.

No, biogenic emissions are not included.

IPCC AR6, 100-year time horizon. Sources that report in AR5 CO₂-equivalents are converted to AR6 gas by gas. Prior versions of USEEIO used earlier GWPs, so a share of the change versus those models comes from the GWP update. Cornerstone EEIO 2026 also fixes a double application of the AR5-to-AR6 conversion. See Gases and global warming potentials, the GWP tab described in Auxiliary tabs and the bug fixes in the Change log.

Start with Methods by country, which lists the data and methods behind every country. The IO model and GHG extension pages describe the method step by step, and the Change log lists what changed against USEEIO and CEDA. Methodology decisions are discussed openly on GitHub. Benchmark results are in Why we benchmark.

Cite the version and the release date. For example the Cornerstone EEIO 2026-rc.1 released on October 27th, 2026. See Cover and Release details.

The factors are published by the Cornerstone Sustainability Data Initiative under a Creative Commons Attribution 4.0 International (CC BY 4.0) license. You can use and redistribute them, including commercially, as long as you give credit and indicate any changes. Please attribute the factors to Cornerstone EEIO. See Cover.

Countries are grouped in four tiers by the input-output data available for them. Tier 0 (US) has detailed annual tables, Tier 1 (China, Japan, South Korea, UK) uses detailed national tables, Tier 2 (60 countries) uses coarser multi-regional tables from FIGARO or ICIO, and Tier 3 (83 countries) has no usable table and uses a template built from other countries. Factors for Tier 3 countries carry more uncertainty. See IO sources by country tier for the IO data, GHG data by country tier for the emissions data and Methods by country.

For more detail, or custom support on how the changes affect your footprint, you can sign up for a demo of the enterprise product here.

Open an issue on GitHub. Please include the sector code, the country, the year and the tab (PRO or PUR), so we can reproduce it. For additional support, enquire about the enterprise product here.