Chapter 09 · Sustainability & AISustainability & AI
Software carbon intensity (SCI)
Definition
A specification for scoring a software system's carbon emissions per unit of work — such as per user, request or transaction — enabling like-for-like comparison and target setting.
References
This source provides part of the technical or institutional basis for the definition.
This source supports the explanation of how the term is applied, measured or governed in practice.
Overview
What it means
Developed by the Green Software Foundation and published as ISO/IEC 21031:2024, SCI combines the software's energy use, the carbon intensity of the electricity supplying it, and an allocation of embodied hardware emissions, divided by a chosen functional unit.
How it is used
Teams compute SCI scores during development and operation to compare design options, track reductions over time and communicate software sustainability performance. It underpins carbon-aware computing practices and green-software procurement discussions.
Why it matters
SCI gives software what fuel-economy ratings give vehicles: a comparable, improvable number. That makes software emissions — including AI services — manageable through engineering rather than estimation alone.