Information Technology — Software Carbon Intensity (SCI)

Key Takeaway

• SCI-specific carbon intensity is the rate at which software emits carbon related to energy consumption and hardware use.

• ISO 14064 provides a basis for quantification and verification of greenhouse gas emissions, including those from software and IT infrastructure.

• ISO/IEC 21031:2024 covers the calculation and management of carbon emissions related to software and introduces the Software Carbon Intensity score.

• The iSAQB GREEN Board follows GHG Protocol ISO 14064 in its effort to make software architecture greener by guiding the architect in reducing emissions related to software.

• Before any calculations of an SCI score, organizations have to define software scope, select a functional unit, monitor energy consumption, account for energy source carbon intensity, and optimize hardware efficiency.

What is SCI-specific carbon intensity?

Software Carbon Intensity (SCI) refers to the rate of carbon emission by a software system, considering energy consumption and hardware utilization. It is a metric that offers a structured method for assessing the environmental impact of software and helps developers make data-driven decisions in reducing emissions. Unlike the traditional carbon footprint studies, which look at the total emissions, SCI is a rate-based measurement. It calculates the CO₂ equivalent (CO₂e) per functional unit of software output; hence, it quantifies how much carbon is emitted to do one unit of work through the software.

How does it work out the SCI-specific carbon intensity?

In principle, the lower the SCI score is, the more a piece of software behaves according to the paradigm of sustainability. However, it is not possible to get a perfect score of zero since all software, by definition, uses some amount of energy and hardware.

Why is carbon intensity important for SCI specifically?

• Software Sustainability Transparency: This gives quite a good benchmark in making a comparison of different software systems regarding their impacts on the environment. 

• Encourages Carbon-Aware Development: Software teams are in a position to optimize their energy use by improving code efficiency, utilizing the cloud, and choosing low-carbon energy sources.

• Aligns with Global Climate Goals: SCI contributes to net-zero strategies through the quantification of emissions associated with software use that organizations implement.

• Standardization of Green Software: SCI forms part of the ISO/IEC 21031:2024 standard, hence guaranteed for its globally recognized measure of emissions within software.

Real-World Application of SCI-specific Carbon Intensity

Cloud computing services also use the measurement of SCI to identify which data centers have lower carbon emissions. The SCI score helps software engineers in writing power-efficient code, avoiding extra processing that is not necessary. Organizations use SCI calculators to assess and improve their carbon footprint by incorporating them into corporate sustainability reports.

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Related Resources:

ISO/IEC 21031:2024 Standard (https://www.iso.org)

Green Software Foundation – SCI Specification (https://sci.greensoftware.foundation)

What is the ISO Standard related to Carbon Emissions?

ISO 14064 is the international standard that underpins quantification, reporting, and verification of GHG emissions. It provides a formal framework through which organizations can accurately determine their carbon footprint and develop a strategy for reducing it. ISO 14064 was formulated with considerations necessary in transparency and credibility within reported emissions in relation to smooth accomplishment of corporate obedience with a wide number of climate policy as well as sustainable development-based legislations and sustainability challenges.

Key elements of ISO 14064

ISO 14064 consists of three main parts, which have to do with the following elements in carbon management: 

1- ISO 14064-1:2018 - Organizational-Level GHG Emissions Accounting

Guidance on the measurement and reporting of an organization's total carbon footprint.

Covers ISO 14064 Scope 1 2 3 emissions:

Scope 1: Direct emissions from owned or controlled sources (e.g., company vehicles, manufacturing).

Scope 2: Indirect emissions from purchased electricity or heat.

Scope 3: Indirect emissions from the supply chain (e.g., business travel, cloud computing).

2- ISO 14064-2:2019 - Carbon Reduction in Projects

Focuses on measuring carbon reduction from specific projects, such as switching to renewable energy or improving energy efficiency.

Ensures that emissions reductions are quantifiable and verifiable and represents permanent.

3- ISO 14064-3:2019 – Verification and Validation of GHG Emissions 

Sets requirements for independent third-party verification of carbon emissions reports.

Helps businesses and governments ensure the accuracy of carbon claims.

What is the ISO standard related to computer software?

ISO/IEC 21031:2024 lays down the method to measure and manage the carbon footprint of computer software. It introduces a SCI score that will help organizations understand the environmental impact of their software applications. This standard is critical for companies wanting to reduce emissions from software development, deployment, and operations. ISO/IEC 21031:2024 makes software sustainability more than an afterthought; it makes it measurable and manageable in a digital solution.

How ISO/IEC 21031:2024 Works

ISO/IEC 21031 defines a structured method to calculate the carbon emissions rate of software systems. The standard covers:

1- Software Carbon Intensity Calculation

Specifies how the energy consumption and hardware impact of a software system are measured.

Uses the SCI formula 

2- Defining the Software Boundary to be Measured

Specifies what part of the software system should be analyzed, for example, backend, frontend, or the whole application.

3- Energy and Hardware Optimization Guidelines

Recommends ways to reduce energy consumption, and to use low-carbon infrastructure, such as renewable-powered cloud providers. 

4- SCI reporting and transparency 

Standardizes how organizations should document and share their software carbon footprint.

Connection of iSAQB GREEN Board to ISO 14064

The GREEN Board, the new department set up at iSAQB-a truly worldwide International Software Architecture Qualification Board-engages itself on a constant front to popularize SSA, aiming primarily to design for efficiency by developing energy efficiency within it through Carbon-Ware Development towards greening in Computing/Architecture. Since the software system is among the biggest contributors to carbon emissions globally, GREEN Board has joined the initiative on international carbon reduction such as ISO 14064 to lay down clear guidelines on sustainability for software architects.

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How iSAQB-certified architects can apply SCI-specific carbon intensity metrics.

iSAQB-certified software architects are indispensable in the design of energy-efficient and low-carbon software systems. Embedding SCI-specific carbon intensity will enable them to make informed architectural decisions:

Assess the Carbon Impact of Software Systems

• Quantify the emission from software applications and infrastructure using the SCI scores

• Analyze hardware, energy consumption, and cloud resource efficiency. 

Optimize Software for Lower Energy Use 

• Implement best practices to ensure code operates efficiently with no superfluous computations.

• Emphasize hardware-aware software development capable of balancing processing loads with energy-efficient infrastructure. 

Implement ISO 14064 Carbon Accounting into Software Development 

• Align the software lifecycle assessment with ISO 14064-1 for corporate sustainability reporting.

• Calculate emissions from software deployment and cloud usage using ISO-compliant methodologies. 

Advocate for Sustainable Software Policies 

• Promote carbon-conscious software engineering in organizations. 

• Lead organizations in net-zero software development with ISO 14064-aligned strategies. 

Key Considerations before Calculating Your SCI Score in Green Software

Before calculating Software Carbon Intensity (SCI), it’s important to define clear boundaries, measure energy use accurately, and consider hardware efficiency. Here are the key factors to keep in mind:

1. Define the Software Scope

Identify what areas of your software system you want to measure.

Example: Are you calculating the emissions for the backend, frontend, or the entire system?

2. Choose a Functional Unit

SCI is measured per unit of work. Choose an appropriate metric.

Examples may include API calls, transactions, data processed, and user sessions.

3. Energy Consumption Monitoring

Leverage real-time energy data from cloud providers, hardware monitoring tools, or profiling software.

Example: AWS, Azure, and Google Cloud provide carbon footprint insights for applications running in these environments.

4. Look After Carbon Intensity of Energies

SCI is based on whether your software runs on renewable energy or fossil fuels. 

Example: A solar-powered data center would have lower emissions compared to a coal-powered one.

5. Hardware Efficiency Optimization

Powerful processors, virtualization, and efficient cooling systems make these solutions much less power consuming. 

Example: ARM-based servers, including AWS Graviton, are less power-consuming than traditional x86 machines. 

Meanwhile, the SCI score methodically helps software teams in measuring and reducing their carbon footprint. Well-defined scoping, monitoring of energy consumption, and efficient infrastructure reduce the emission and align with sustainability goals.

Conclusion

SCI-specific carbon intensity allows tracking of energy use to help reduce software-related emissions. ISO 14064 and ISO/IEC 21031 are standards for accurate carbon measurement. The iSAQB GREEN Board advances sustainable software architecture by embedding SCI metrics and ISO standards into the development culture. It guides architects in the design of low-carbon software systems. To build a greener future, developers and organizations should adopt SCI measurement. Start by tracking energy use, optimizing code efficiency, and choosing low-carbon infrastructure. Small steps can lead to significant impact.