Embodied Carbon Disclosure Base Specification v1 (OCP/iCA Carbon Disclosure Workstream), effective July 2025

Overview

The specification is designed to address inconsistent and inefficient embodied carbon reporting across the data centre supply chain. It defines a standard format for how vendors prepare and submit embodied carbon disclosures and supporting data (methods used, referenced publications, emission factors) to customers, tackling disparate data requests, high reporting overhead for suppliers and difficulty aggregating and comparing data. It covers data centre ICT equipment, mechanical, electrical and plumbing (MEP) equipment and building materials. Data collected by the operator is not compiled or published by OCP, the iMasons Climate Accord or their partners.

Scope and definitions are narrow and explicit. Embodied carbon is cradle-to-gate (A1-A3: raw material supply, transport, manufacturing) greenhouse gas emissions per ISO 21930:2017, ISO 14044:2006 or the ILCD Handbook, excluding use and end of life. The value is normalised to a functional unit; examples are 5.1 kg CO2e per metre of cable and 700 kg CO2e per 500 kW UPS. Permitted methods include life cycle assessment (LCA), environmental product declaration (EPD, typically ISO 14025), product carbon footprint (PCF; ISO 14067, GHG Protocol, WBCSD Pathfinder), CIBSE TM65 and environmentally extended input-output (EEIO; spend-based, USEEIO and DEFRA factors), as long as the method is disclosed.

The functional requirements fall into four sections. The first asks for respondent identification (company name, respondent name and title, email). The second asks for product identification: type of equipment or material, product category, name, description and part number. The third asks for the embodied carbon footprint per functional unit in kg CO2e, confirmation that it covers only A1-A3, and a link to the assessment. The fourth asks for the measurement methodology and method-specific details: for LCA/EPD, third-party verification status (not required but called the highest quality), software, database and product category rule; for PCF the framework; for TM65 basic or mid-level calculation; for EEIO the emission factors.

The specification standardises format and content, not tools or channels. The operator requests data by referencing the specification in procurement documents, the vendor calculates with its own tools and may send the data packet by email, supplier portal or a future API. The compliance checklist includes: data available to the prospective customer within 120 days of the request (pending any required NDAs), required fields completed, unavailable data explained, the method and its details stated, and defined terms used as intended. Compliance is self-certified; OCP runs no separate testing or validation process.

The limits are plain. The specification is not a data collection tool, database or measurement guide; the pilot phase showed that varied readiness and a standards gap made a single disclosure tool premature. Because methods are left flexible, values calculated by different methods may not be directly comparable, which is why method information is mandatory. The submitter is responsible for accuracy and by submitting attests validity to the best of its knowledge. Appendix A is an approval checklist, Appendix B recommended databases and tools (Ecoinvent, GaBi and Sphera, openLCA, EIO-LCA, Pathfinder) and Appendix C a specification-compliant template. The document is licensed CC BY-SA 4.0.

Key points

1. Embodied carbon is cradle-to-gate (A1-A3: raw material supply, transport, manufacturing) greenhouse gas emission per ISO 21930:2017, ISO 14044:2006 or the ILCD Handbook.
2. The value is normalised to a functional unit; examples are 5.1 kg CO2e per metre of cable and 700 kg CO2e per 500 kW UPS.
3. Permitted vendor methods are LCA, EPD (ISO 14025), product carbon footprint (PCF), CIBSE TM65 and EEIO spend-based models (USEEIO, DEFRA), as long as disclosed.
4. The disclosure packet has four sections: respondent identification, product identification, the A1-A3 footprint (with scope confirmation and assessment link) and measurement methodology.
5. For LCA/EPD third-party verification is not required but is considered the highest quality; software, database and product category rule (PCR) are reported.
6. For TM65 a basic or mid-level calculation is stated; for EEIO the emission factors (USEEIO, DEFRA); for PCF the framework.
7. The specification standardises only format and content, not tools or transmission channels (email, supplier portals, APIs).
8. Compliance checklist: data within 120 days of the request, required fields completed, missing data explained, method and details stated, defined terms used.
9. Compliance is self-certified; OCP has no separate test or validation process, and the submitter attests to accuracy.
10. The example disclosure (fictional 500 kW UPS module): 750 kg CO2e per 500 kW module, A1-A3 only, LCA/EPD method, third-party verified.

Using it in design

• Give catalogue items (UPS, generators, switchgear, cable, CDUs, racks, concrete) an embodied-carbon block: A1-A3 kg CO2e, functional unit, method (EPD/LCA/TM65/EEIO), verification status and emission factor source, matching this disclosure template.
• Have the embodied carbon calculator scale by functional unit (per metre of cable, per kW of UPS) and flag lower-confidence EEIO-based figures.
• In procurement exports reference this specification when requesting vendor data, and reflect the 120-day provision period in the bid timetable.
• Check the method field before summing or comparing values calculated by different methods; the value covers only A1-A3, so use and end of life must be calculated separately.
• Ask suppliers for an explanation of each missing field and store it in the record, since the specification requires any unavailable data to be explained.

Who should read it

Engineers and sustainability specialists in data centre design and procurement who collect embodied carbon data, give suppliers a template, or design catalogues and calculators.

Document contents

1. License
2. Compliance with OCP Tenets
3. Overview
4. Definitions
5. Base Specifications
6. Description
7. Goals and Vision
8. User Requirements/User Stories
9. Solution Architecture
10. Functional Requirements (Specification Content Definition)
11. Example Disclosure
12. Constraints
13. Test and Validation Requirements
14. Compliance
15. Additional References
16. Appendix A - Checklist for IC approval of this Specification
17. Appendix B - Recommended Databases and Tools to conduct Embodied Carbon Emission Calculation Studies
18. Appendix C - OCP Base Specification Compliant Template

Related standards

• ISO 14044
• ISO 21930
• ISO 14025
• CIBSE TM65
• GHG Protocol Product Standard
• EN 15978

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Publication details

Authors

Open Compute Project Foundation

Publisher

Open Compute Project Foundation

Year

2025

Document number

v1

Document language

English

Source type

Industry body

Access

Open licence — downloadable

Licence

CC BY-SA 4.0 — share with attribution under the same licence

Licence evidence

www.opencompute.org

Citation