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Measure What Matters: Software's Carbon Impact

The global standard for calculating and reducing the carbon emissions of your software

Every software application has a carbon footprint through the energy it consumes and the hardware it requires. The Software Carbon Intensity (SCI) specification provides the first ISO-accredited methodology to measure this impact as a score. Unlike carbon offsets, SCI focuses on actual emission reductions—empowering developers, architects, and organizations to make informed decisions that create real environmental change.

ISO-accredited and endorsed by leading technology organizations

Accenture Cisco Google NTT DATA Siemens UBS ACIS Almaviva Almaviva S.p.A. - LF Amadeus Aveva Bloomberg Boavizta Chalmers University of Technology ClimateAction.tech Cloud Sustainability Watch Code from Finland Concordia University Digital Emissions DXC EDSP ECO Electricity Maps Energy Web Envite German Informatics Society GitHub GitLab Globant Goldman Sachs GovTech Singapore Green Software Foundation GrUSP HARC IBM Indian Institute of Management Mumbai Infocomm Media Development Authority Interfima International Institute of Information Technology Leaders for Climate Action Linnaeus University Manchester Metropolitan University Mastercard Metropolitan Police Microsoft mondragon.edu Nomura Research Institute, Ltd OpenUK Renewable Energy Laboratory (NREL) Responsible AI Schneider Electric Sentry Shell Sustainable Digital Infrastructure Alliance Texas State University The Explorers The Green Web Foundation Thoughtworks Time for the Planet Trust.ai UCL Universidad Politécnica de Madrid Università degli Studi dell'Aquila University of Amsterdam University of Bristol University of Edinburgh University of Huddersfield University of Limerick University of Salento Virtasant WattTime ZutaCore ZutaCore
Accenture Cisco Google NTT DATA Siemens UBS ACIS Almaviva Almaviva S.p.A. - LF Amadeus Aveva Bloomberg Boavizta Chalmers University of Technology ClimateAction.tech Cloud Sustainability Watch Code from Finland Concordia University Digital Emissions DXC EDSP ECO Electricity Maps Energy Web Envite German Informatics Society GitHub GitLab Globant Goldman Sachs GovTech Singapore Green Software Foundation GrUSP HARC IBM Indian Institute of Management Mumbai Infocomm Media Development Authority Interfima International Institute of Information Technology Leaders for Climate Action Linnaeus University Manchester Metropolitan University Mastercard Metropolitan Police Microsoft mondragon.edu Nomura Research Institute, Ltd OpenUK Renewable Energy Laboratory (NREL) Responsible AI Schneider Electric Sentry Shell Sustainable Digital Infrastructure Alliance Texas State University The Explorers The Green Web Foundation Thoughtworks Time for the Planet Trust.ai UCL Universidad Politécnica de Madrid Università degli Studi dell'Aquila University of Amsterdam University of Bristol University of Edinburgh University of Huddersfield University of Limerick University of Salento Virtasant WattTime ZutaCore ZutaCore

What is Software Carbon Intensity?

The Software Carbon Intensity (SCI) specification is an ISO-accredited standard (ISO/IEC 21031:2024) for measuring the carbon emissions of software applications. It provides a clear, consistent methodology that transforms complex environmental data into a single actionable score—making it possible to compare different software solutions, track improvements over time, and make evidence-based decisions about technology choices.

Unlike traditional carbon accounting that focuses on totals and offsets, SCI calculates a rate—carbon emissions per functional unit of your software, whether that's per user, per transaction, or per API call. This approach reveals the true efficiency of your software and guides you toward meaningful reductions through better code, smarter infrastructure choices, and carbon-aware computing strategies.

Referenced in 15+ peer-reviewed papers | Globally adopted | ISO/IEC 21031:2024 certified | Referenced in 15+ peer-reviewed papers | Globally adopted | ISO/IEC 21031:2024 certified |

Why SCI Matters

Software's environmental impact is invisible but significant—and growing exponentially with AI and digital transformation.

Industry Impact

Every line of code, every server, every user interaction contributes to the software's growing carbon footprint. The SCI specification makes this invisible impact visible and actionable. By providing a standardized measurement protocol, it enables the entire industry to work from the same playbook—creating transparency, driving innovation, and accelerating the transition to truly sustainable technology. Major organizations, including AVEVA, Microsoft, NTT DATA, and UBS, are already using SCI to transform how they build and deploy software.

Business Benefits

Drive Cost Efficiency - Software optimized for lower SCI scores uses less energy and hardware, directly reducing operational costs

Meet Sustainability Goals - Demonstrate measurable progress toward net-zero commitments with ISO-certified methodology

Gain Competitive Advantage - Differentiate your products with verified sustainability credentials that customers increasingly demand

Future-Proof Operations - Stay ahead of emerging regulations and reporting requirements with established measurement practices

Environmental Impact

Every point reduction in your SCI score represents real carbon that never enters the atmosphere. This isn't about purchasing offsets or making claims - it's about fundamental changes in how software is designed, developed, and deployed. When organizations optimize for SCI, they naturally adopt practices that reduce energy consumption, extend hardware lifecycles, and shift computing to cleaner energy sources. The cumulative effect of thousands of development teams making these optimizations could prevent millions of tons of carbon emissions annually.

A New Way to Think About Software

The SCI score combines three essential factors that determine software's carbon footprint: the energy your software consumes (E), the carbon intensity of that energy based on location and time (I), and the embodied emissions from manufacturing the hardware (M). These are calculated per functional unit (R) - creating a rate that reveals true efficiency.

SCI = (E × I + M) per R

This simple equation transforms how teams approach software development. Instead of guessing at environmental impact, you can measure it. Instead of generic best practices, you have specific targets. Instead of greenwashing, you have genuine reductions.

Organizations Leading with SCI

Financial institutions, consultancies, and technology companies worldwide are implementing SCI to measure and reduce software carbon emissions.

Accenture

Implementing SCI to Track Software Emissions

Accenture applied SCI to calculate and track carbon emissions for an internal reference application, establishing a practical baseline methodology that includes embodied emissions.

Read Case Study
UBS

Baselining Software Carbon Emissions

UBS demonstrates applying SCI to baseline carbon emissions for two enterprise applications in investment banking and asset management, identifying available data sources and calculation methodologies.

Read Case Study
CAST Software

Decarbonizing Software with SCI

CAST integrated SCI with CAST Highlight to decarbonize an enterprise application, achieving an estimated 400 kg annual CO2 reduction and 5% improvement in execution duration.

Read Case Study
NTT Data

Calculating Carbon Footprint for Serverless Apps

A practical guide to measuring carbon emissions of serverless applications using the SCI specification, with step-by-step methodology for event-driven architectures.

Read Guide
UBS & Microsoft

Carbon-Aware Computing at UBS

UBS and Microsoft implemented the first enterprise-scale carbon-aware computing system, using SCI and the Carbon Aware SDK to reduce emissions in their core risk platform workloads.

Read Whitepaper
"SCI specification provided a practical methodology to baseline carbon emissions of the application, including embodied emissions and reducing the same."
Navveen Balani Managing Director, Chief Technologist Accenture

Validated by Academia and Industry

The SCI specification is the only ISO-accredited carbon measurement standard for software, referenced in 15+ peer-reviewed research and implemented by leading technology organizations worldwide.

ISO/IEC International Standard 21031:2024
15+ Peer-Reviewed Research since 2022
ACM FAccT & SoCC Published in Top Venues

Microsoft Azure Sustainability Framework

Microsoft integrated SCI into Azure's official sustainability framework.

Read Documentation →

ACM FAccT 2022 Research

"Measuring the Carbon Intensity of AI in Cloud Instances"

Read Paper →

ThoughtWorks Implementation Guide

Global implementation guide for calculating software carbon intensity.

Read Guide →

ACM Symposium on Cloud Computing (SoCC '24)

The Sunk Carbon Fallacy: Rethinking Carbon Footprint Metrics for Effective Carbon-Aware Scheduling.

Read Guide →

Built for Every Role in Software

Everything You Need to Get Started

The SCI Specification

Access the complete ISO/IEC 21031:2024 standard with technical methodology and implementation guidance

SCI Guidance

Explore various approaches on how to understand the different methodologies that are available for calculating the core components of the SCI.

Ask Questions

Connect with the SCI community, get implementation help, and share your experiences

Journey to Transformation

Current focus: The specification is actively developing, and experts, operators, and sustainability practitioners are invited to refine and validate it.

  1. June 2021

    Vision Launched

  2. March 2022

    v1.0 Published

  3. April 2024

    ISO Accreditation Achieved

  4. October 2024

    v1.1 Released

  5. 2026

    Current

Project Leadership

Part of the Software Standards Working Group

Navveen Balani

Software Standards Working Group Chair

@Accenture

Henry Richardson

Software Standards Working Group Chair

@WattTime

About the Green Software Foundation

The SCI specification is developed and maintained by the Green Software Foundation (GSF), a nonprofit consortium under the Linux Foundation dedicated to building a future where software has zero harmful environmental impact. With steering members including Accenture, Avanade, BCG X, Cisco, Google, Microsoft, NTT Data, Siemens, and UBS, GSF creates trusted standards, tools, and education for sustainable software development.

Beyond the SCI specification, the foundation develops open-source tools like the Impact Framework and Carbon Aware SDK, and has trained over 130,000 practitioners in green software principles worldwide.