Terms of Service

Last updated: October 7, 2026

The service

emission-factors.com ("the Service") provides a REST API that returns US electricity emission factors derived from EPA eGRID data, mapped to ZIP codes. The Service is operated by an independent developer and is not affiliated with, endorsed by, or operated by the US Environmental Protection Agency.

Data accuracy

Emission factors are sourced from EPA eGRID2023 Revision 2 (released June 12, 2025). We validate data integrity on every deployment by checking golden subregion values against EPA Table 1. However:

• The ZIP-to-subregion mapping is derived from Census ZCTA centroid analysis and may not match EPA's Power Profiler for every ZIP code.
• Data is provided as-is, without warranty of completeness or fitness for any particular regulatory or compliance purpose.
• You are responsible for verifying that the data meets your reporting requirements.

Acceptable use

• Do not attempt to circumvent the per-IP rate limits.
• Do not use the API for any unlawful purpose.
• Do not resell raw API access. You may use the data in your own products and services.

Rate limits

• The API is free and keyless: no signup, no API key, no paid tier. All endpoints included.
• Each IP address can make up to 2,000 requests per hour.

Exceeding the limit returns HTTP 429. The retryAfter field in the response body gives the number of seconds until your window resets.

Data sources and attribution

Responses are derived from third-party data. If you republish them, follow each source's terms:

• EPA eGRID2023, EPA GHG Emission Factors Hub 2025, EPA CAMD, EIA-861, EIA-930, US Census: US government works, public domain.
• eGRID2024 (Cornerstone) (?year=2024) and the GHG Emission Factors Hub 2026 (default Scope 1 factors), both from the Cornerstone Sustainability Data Initiative: CC-BY-4.0, attribution required.
• Green-e Residual Mix Emissions Rates (2025 edition, 2023 data, Center for Resource Solutions): cite the use of these rates in your GHG accounting.
• OpenEI Utility Rate Database (NREL) and GeoNames: CC-BY-4.0, attribution required.

Data freshness: eGRID and the residual mix are annual; EIA-861 retail rates lag about 2-3 months; EIA-930 hourly data lags about 24 hours; CAMD plant data is published by quarter, about 45+ days after each quarter ends. Details: Methodology.

Availability

We aim for high availability but do not offer a formal SLA. The Service may be temporarily unavailable during deployments or infrastructure maintenance. We are not liable for downtime, data loss, or any damages arising from use of the Service.

Termination

We may block IP addresses that violate these terms, and we may change or discontinue the Service at any time.

Limitation of liability

The Service is provided "as is" without warranties of any kind. In no event shall the operator be liable for any indirect, incidental, special, or consequential damages arising from use of the Service, including but not limited to incorrect emission calculations, regulatory penalties, or business losses.

Changes

We may update these terms. Continued use of the Service after changes constitutes acceptance.

Contact

[email protected]