# Carbon Emission Methodology

## Scope 2 emissions: market-based vs location-based

Scope 2 emissions are indirect greenhouse gas emissions from the generation of purchased electricity consumed by an organization. The GHG Protocol defines two methods for Scope 2 accounting:

### Market-based method

Uses emission factors from contractual instruments that convey attributes of the electricity consumed, such as:
- Renewable Energy Certificates (RECs) or Guarantees of Origin (GOs)
- Power Purchase Agreements (PPAs) with specific generators
- Supplier-specific emission factors published by utilities

Effect: when a cloud provider purchases RECs or PPAs covering 100% of their electricity use in a region, the market-based Scope 2 emission factor for that region approaches zero. This is why hyperscaler-reported Scope 2 figures are often significantly lower than location-based figures.

Default in this skill: **market-based**, because it reflects the cloud provider's actual contractual commitments and is the value reported in vendor sustainability disclosures.

### Location-based method

Uses average emission factors for the electricity grid(s) where consumption occurs, regardless of contractual instruments. These factors are typically published by grid operators or national energy agencies (e.g., EPA eGRID for US, AIB residual mixes for Europe).

The location-based figure represents what emissions would have been if the electricity came from the average mix of sources on the local grid.

Both methods may be required for CSRD (ESRS E1) and GHG Protocol dual-reporting.

## Data lag

Provider carbon data typically lags the billing period by 60-90 days or more:

- AWS Customer Carbon Footprint Tool: approximately 3 months lag.
- Microsoft Emissions Impact Dashboard: approximately 2-3 months lag.
- Google Cloud Carbon Footprint: approximately 2 months lag.
- Third-party (Electricity Maps historical): 24-hour lag for the previous day; monthly averages available sooner.

Implication for disclosure: carbon estimates produced for a quarter's cloud spend will be based on emission factors from the same or a prior quarter. Always state the data period when citing vendor-published factors.

## How to label uncertainty

Every kgCO2e output must carry one of three confidence labels with the stated basis:

| Label | When to use | What to state |
|---|---|---|
| `vendor-published` | Provider's own sustainability API or dashboard data was retrieved | Source URL, data period (e.g., "Q3 2025"), fetch timestamp |
| `third-party` | Electricity Maps or Cloud Carbon Footprint data was used | Source URL, date of data, which grid zone was used |
| `estimated` | Regional or national grid average used as fallback | Emission factor (kgCO2eq/kWh), source (e.g., IEA 2023), year of data |

Do not present a kgCO2e figure without one of these labels. If a value cannot be computed with any of the three approaches, state that a carbon estimate is not available for this region or service category and explain why.

## Conversion from $/spend to kgCO2e

When only a dollar spend value is provided (not resource quantity), a spend-based emission factor is required. These are less precise than activity-based factors (kgCO2e per kWh or per vCPU-hour) because price varies by region, service type, and over time.

If the provider publishes a spend-normalized factor (kgCO2e/$) for the relevant service or region, use it and label as `vendor-published`.

If no spend-normalized factor is available, prefer an activity-based route:
1. Estimate the resource quantity from the spend (e.g., divide by on-demand price per vCPU-hour to get vCPU-hours).
2. Multiply vCPU-hours by the energy use per vCPU-hour (typical: 0.0025 kWh for a modern data center instance).
3. Multiply energy use by the regional emission factor (kgCO2eq/kWh).

State each step and label the result `estimated` unless the emission factor was fetched from a vendor or third-party source.

## Scope 1 emissions (note)

Scope 1 emissions (direct on-site combustion) from cloud data centers — backup generators, on-site equipment — are typically immaterial compared to Scope 2 and are not separately published by cloud providers per customer. Unless the caller specifically requests Scope 1, this skill produces Scope 2 only.

## Regulatory framing

| Framework | Requirement relevant to cloud |
|---|---|
| CSRD / ESRS E1 | Gross Scope 1, 2, and 3 by category; both market-based and location-based Scope 2; alignment with GHG Protocol |
| SEC Climate Rule | Material Scope 1 and 2; Scope 3 if material or targeted; large accelerated filers required to include |
| GHG Protocol Corporate Standard | Both market-based and location-based Scope 2 recommended; Scope 3 Category 1 (purchased goods/services) may include cloud |

Cloud emissions typically appear in:
- Scope 2 (electricity) for compute, storage, and networking in data centers
- Scope 3 Category 1 (purchased goods and services) for cloud spend treated as a supply chain input

This skill computes Scope 2 (electricity) only unless the caller specifies otherwise.

# Carbon Data Sources

## Provider sustainability data (vendor-published)

### AWS — Customer Carbon Footprint Tool

| Resource | URL |
|---|---|
| Tool overview | https://aws.amazon.com/aws-cost-management/aws-customer-carbon-footprint-tool/ |
| Documentation | https://docs.aws.amazon.com/cur/latest/userguide/ccft-overview.html |
| Methodology | https://docs.aws.amazon.com/cur/latest/userguide/ccft-methodology.html |

AWS Customer Carbon Footprint Tool provides estimated carbon emissions for AWS usage in metric tons of CO2 equivalent (MTCO2e) broken down by service, region, and time period. Data is available through the AWS console and the AWS Cost Explorer API.

Important notes:
- Data typically lags approximately 3 months (90 days).
- Figures reflect AWS's own renewable energy purchases (market-based Scope 2).
- Location-based figures are also available in the methodology documentation.
- The tool does not expose a public unauthenticated API; for live fetch, use WebFetch against the public documentation and methodology pages, which publish the aggregate emission factors and regional renewable energy percentages.

For unauthenticated access to AWS carbon methodology data, fetch from:
- https://docs.aws.amazon.com/cur/latest/userguide/ccft-methodology.html
- https://sustainability.aboutamazon.com/

### Microsoft — Cloud for Sustainability Emissions API

| Resource | URL |
|---|---|
| Industry sustainability hub | https://learn.microsoft.com/en-us/industry/sustainability/ |
| Emissions Impact Dashboard | https://www.microsoft.com/en-us/sustainability/emissions-impact-dashboard |
| Microsoft Sustainability Manager docs | https://learn.microsoft.com/en-us/industry/sustainability/sustainability-manager-overview |

Microsoft publishes carbon data through the Emissions Impact Dashboard (Power BI report, not unauthenticated API) and the Microsoft Cloud for Sustainability APIs. For unauthenticated reference data, use:
- https://www.microsoft.com/en-us/sustainability/reports (annual sustainability report with regional energy data)
- https://learn.microsoft.com/en-us/azure/carbon-optimization/ (Azure carbon optimization documentation)

Data lag: typically 2-3 months behind current billing.

### Google Cloud — Carbon Footprint Export

| Resource | URL |
|---|---|
| Documentation | https://cloud.google.com/carbon-footprint/docs |
| Methodology | https://cloud.google.com/carbon-footprint/docs/methodology |
| Region carbon data | https://cloud.google.com/sustainability/region-carbon |

Google Cloud Carbon Footprint provides gross and net carbon emissions per product and region. The regional carbon data page publishes the carbon-free energy percentage per region, which can be combined with regional grid intensity to estimate net Scope 2 emissions.

For unauthenticated reference:
- https://cloud.google.com/sustainability/region-carbon — carbon-free energy percentages per region; fetch this page with WebFetch.
- https://cloud.google.com/carbon-footprint/docs/methodology — describes the market-based and location-based calculation approach.

### OCI — Sustainability Dashboard

| Resource | URL |
|---|---|
| OCI Sustainability overview | https://www.oracle.com/sustainability/ |
| Oracle sustainability report | https://www.oracle.com/corporate/citizenship/ |

OCI does not publish a per-region unauthenticated carbon API equivalent to AWS CCFT or Google Cloud Carbon Footprint. For OCI carbon estimates, fall back to the Electricity Maps regional data for the grid serving the OCI data center, or use the Cloud Carbon Footprint project's OCI emission factors.

## Third-party sources

### Electricity Maps

| Resource | URL |
|---|---|
| Global carbon intensity map | https://www.electricitymaps.com/ |
| API documentation | https://static.electricitymaps.com/api/docs/index.html |
| Open data | https://github.com/electricitymaps/electricitymaps-contrib |

Electricity Maps publishes real-time and historical grid carbon intensity (gCO2eq/kWh) for electricity grids worldwide. This is suitable for location-based Scope 2 calculations. The public API requires an API key for live data; the open data repository on GitHub contains historical zone data accessible without authentication.

For unauthenticated WebFetch, use the public zone data from the GitHub repository.

### Cloud Carbon Footprint Project

| Resource | URL |
|---|---|
| Project site | https://www.cloudcarbonfootprint.org/ |
| Emission factors repository | https://github.com/cloud-carbon-footprint/cloud-carbon-footprint |
| Coefficient data | https://github.com/cloud-carbon-footprint/cloud-carbon-footprint/blob/trunk/packages/gcp/src/domain/GcpFootprintEstimationConstants.ts |

The Cloud Carbon Footprint project publishes open-source emission coefficients for AWS, Azure, and GCP including per-region grid intensity and average embodied carbon for common instance types. These are community-maintained, not vendor-published, and should be labeled `third-party`.

## IEA and national grid averages (fallback)

If neither vendor nor third-party data is available for a region:

| Source | URL |
|---|---|
| IEA CO2 emissions from electricity data | https://www.iea.org/data-and-statistics/data-product/emissions-factors-2023 |
| EPA eGRID (US) | https://www.epa.gov/egrid |

Use the regional or national grid average in kgCO2eq/kWh and multiply by the estimated kWh consumed. Label as `estimated` and state the factor and its source year.

## Source selection priority

When multiple sources are available, use the highest-confidence source available:

1. Vendor-published (provider sustainability API or dashboard documentation for the specific region)
2. Third-party (Electricity Maps or Cloud Carbon Footprint for the specific grid region)
3. Estimated (IEA or EPA national/regional average, clearly labeled)