Overview

The Software Carbon Intensity (SCI) technical specification describes how to calculate the carbon intensity of a software application or service. It provides a methodology for measuring total carbon emissions and translating them into a rate—a metric that enables practical, measurable reductions in real-world software operations.

Electricity has a carbon intensity that varies by location and time. An intensity is a rate with a numerator and denominator. By expressing software carbon as a rate (rather than absolute emissions), SCI enables fair comparisons across applications of different scales and helps organizations make informed decisions about how to design, develop, and deploy software more sustainably.

Status: Published (v1.1) — This is the foundational GSF standard. View the full specification.

Getting Started

1. Understand the Standard

• Read the SCI specification for detailed methodology and guidance
• Review the repository for technical documentation and examples
• Explore reference implementations to see how others have applied the standard

2. Define Your Functional Unit

• Choose what you'll measure against: users, API requests, transactions, data processed, or time
• Document your choice clearly for transparency and reproducibility
• This selection shapes how you'll calculate and compare your SCI score

3. Gather Data & Calculate

• Measure energy consumption (from cloud providers, monitoring tools, or estimates)
• Estimate embodied carbon of hardware (use published factors or models)
• Include Scope 3 emissions if applicable to your use case
• Calculate your baseline SCI score

4. Set Targets & Optimize

• Compare your score against similar applications or industry benchmarks
• Identify optimization opportunities (efficiency, renewable energy, hardware selection)
• Recalculate and track progress regularly

Resources

• Specification: sci.greensoftware.foundation
• Repository: github.com/Green-Software-Foundation/sci
• Mailing List: [email protected]
• Related Standards:

Get Involved

Subscribe & Participate

1. Complete GSF Registration if you haven't already
2. Subscribe to the project to access the mailing list and meetings

Contributing

• GitHub: We work in the open via the sci repository. Issues, pull requests, and discussions are welcome.
• Meetings: Join the Software Standards Working Group meetings (details sent to subscribers)
• Email: Reach out to the project mailing list ([email protected]) with questions or contribution ideas

How to Help

• Apply SCI to your own software and share lessons learned
• Contribute case studies, implementation guides, or reference tools
• Help develop domain-specific adaptations (similar to SCI AI or SCI Data Center)
• Participate in discussions about methodology improvements or new use cases