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.
ISO-accredited and endorsed by leading technology organisations
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.
Software's environmental impact is invisible but significant — and growing exponentially with AI and digital transformation.
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 standardised 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 organisations, including AVEVA, Microsoft, NTT DATA, and UBS, are already using SCI to transform how they build and deploy software.
Drive Cost Efficiency - Software optimised 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
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 organisations optimise 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 optimisations could prevent millions of tons of carbon emissions annually.
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.
Financial institutions, consultancies, and technology companies worldwide are implementing SCI to measure and reduce software carbon emissions.
Accenture applied SCI to calculate and track carbon emissions for an internal reference application, establishing a practical baseline methodology that includes embodied 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.
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.
A practical guide to measuring carbon emissions of serverless applications using the SCI specification, with step-by-step methodology for event-driven architectures.
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.
“SCI specification provided a practical methodology to baseline carbon emissions of the application, including embodied emissions and reducing the same.”
The SCI specification is the only ISO-accredited carbon measurement standard for software, referenced in 15+ peer-reviewed research and implemented by leading technology organisations worldwide.
Microsoft integrated SCI into Azure's official sustainability framework.
Read Documentation →Global implementation guide for calculating software carbon intensity.
Read Guide →The Sunk Carbon Fallacy: Rethinking Carbon Footprint Metrics for Effective Carbon-Aware Scheduling.
Read Paper →Current focus: The specification is actively developing, and experts, operators, and sustainability practitioners are invited to refine and validate it.
Vision Launched
v1.0 Published
ISO Accreditation Achieved
v1.1 Released
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