Summary
Details
- Global
Any organisation that develops, deploys, maintains, or procures software applications can adopt ISO/IEC 21031 to measure and manage software-related emissions and support internal sustainability programmes or external reporting.
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Introduction
ISO/IEC 21031:2024 was published in March 2024 as an International Standard under ISO/IEC JTC 1 (Information technology). It defines the SCI specification, a method to calculate the carbon emission rate of a software system per unit of work—its SCI score. This score is intended to provide transparency on software sustainability credentials and enable decisions that can ultimately reduce emissions.
The SCI score allows organisations to define targets and track progress over time, making software sustainability measurable and actionable in development and operational workflows.
What ISO/IEC 21031:2024 asks
ISO/IEC 21031 expects organizations that apply it to:
Define boundaries – Set clear software and infrastructure boundaries for the system being assessed (e.g., service, API, batch job).
Choose a functional unit (R) – Select a relevant “unit of work”, such as per user, per request, per transaction, or per job.
Quantify key inputs – Measure:
energy use (E) by the software and underlying hardware,
carbon intensity (I) of the electricity mix over time and location, and
embodied emissions (M) associated with manufacturing and refreshing the hardware that runs the software.
Calculate and use the SCI score – Compute and track the SCI score over time (a rate of emissions per unit of work) and use it to guide practical design, deployment, and optimization decisions, such as architecture choices, workload placement, and scaling strategies.
The standard’s focus is not on certifying organizations, but on providing a consistent, comparable way to express software-related emissions so teams can reduce them.
Current status
ISO/IEC 21031 was published in March 2024 as the first international standard for software carbon intensity, under ISO/IEC JTC 1. It formalizes the Green Software Foundation’s SCI specification and is expected to be adopted alongside ESG reporting and IT-service standards in sustainability programs. Early uptake is visible among cloud providers, digital consultancies, and green-IT initiatives. As tools, benchmarks, and sector guidance mature, future revisions may clarify data rules, emission factors, and how SCI aligns with global net-zero and product regulations. For now, the standard remains voluntary but influential in shaping green-software practice.
Resources
ISO/IEC 21031:2024 – Preview & publication details (ANSI Webstore).
Tailpipe.ai: A software that measures emissions from cloud computing using an ISO 21031-based methodology.
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