Technology drives our daily lives, but it comes with an environmental cost. The software we use — whether mobile apps, websites, or cloud services — consumes energy and contributes to carbon emissions. To create a sustainable digital future, it’s essential to measure and reduce this impact.

Metrics like Software Carbon Intensity (SCI) and tools designed to monitor and optimize software sustainability can help organizations take meaningful action.

What is Software Carbon Intensity (SCI)?

SCI measures the environmental impact of software during its operational phase. It combines:

• Energy Consumption: The total energy the software consumes during use.
• Carbon Intensity: The type of energy (renewable vs. fossil fuels) powering the software.
• Usage Patterns: How much and how often the software is used.

Formula:

SCI = Energy Consumed (kWh) × Carbon Intensity (kg CO2 e/kWh) / Useful Output

For example, a video streaming platform might analyze the energy per hour of video streamed and adjust its operations to use renewable energy during peak times.

Why Measure SCI and Other Indicators?

Metrics like SCI help businesses:

• Reduce Environmental Impact: SCI highlights inefficiencies, enabling targeted optimizations.
• Save Costs: Optimized software often reduces energy use, cutting operational expenses.
• Comply with Regulations: Governments increasingly require reporting on carbon emissions.
• Enhance Transparency: Demonstrating sustainability builds trust with users and stakeholders.
• Foster Innovation: SCI drives the creation of efficient algorithms and greener architectures.

Other Sustainability Metrics

SCI isn’t the only measure of software’s environmental impact. Here are some others and how they differ:

Power Usage Effectiveness (PUE):

• Focuses on data center efficiency, measuring how much energy is used for IT equipment versus cooling and other overhead.
• Useful for data center operations but doesn’t extend to the software layer.

Carbon Usage Effectiveness (CUE):

• Measures carbon emissions per unit of IT energy consumed, providing insight into the cleanliness of energy sources.

Digital Carbon Footprint:

• Examines the total emissions from a software system across its lifecycle, from development to end-user interaction.

Embodied Carbon:

• It looks at emissions from producing the hardware supporting the software (servers, devices, etc.), offering a broader lifecycle perspective.

These indicators complement SCI, giving a holistic view of software sustainability.

Practical Tools to Measure and Optimize

Several SDKs and libraries can help developers measure and reduce software’s environmental impact:

Carbon Aware SDK:

• Purpose: Schedules software tasks during periods of cleaner energy availability.
• Use Case: Ideal for cloud-based services like batch processing or AI training.

PowerAPI:

• Purpose: Tracks energy consumption at the process level, identifying inefficient components.
• Use Case: Useful for optimizing high-performance computing applications.

pyJoules:

• Purpose: Measures energy consumption of specific code snippets.
• Use Case: Helps optimize Python applications for energy efficiency.

Kepler:

• Purpose: Monitors energy usage in Kubernetes workloads using machine learning models.
• Use Case: Best for cloud-native apps running in containerized environments.

Scaphandre:

• Purpose: Collects and exports energy usage data for servers, integrating with monitoring tools.
• Use Case: Suited for IT and DevOps teams managing infrastructure.

How to Measure and Optimize Software Sustainability

The journey to sustainable software starts with measurement. Here’s how you can get started:

Step 1: Assess Energy Usage

Use tools to monitor energy consumption at various levels:

• PowerAPI: Tracks energy usage of specific software processes (e.g., CPU or memory).
• pyJoules: Measures energy consumption of individual code snippets to optimize algorithms.

Step 2: Measure Carbon Emissions

Calculate the carbon footprint of software by considering energy consumption and the energy source:

• Carbon Aware SDK: This SDK integrates with software to make carbon-conscious decisions, such as scheduling tasks during periods of renewable energy availability.
• Kepler: Monitors Kubernetes workloads and estimates their energy consumption.

Step 3: Optimize Software and Infrastructure

Focus on reducing energy consumption and emissions:

• Optimize Code: Refactor code to reduce unnecessary processing or data transfers. Tools like pyJoules can pinpoint inefficient code.
• Leverage Green Hosting: Choose data centers powered by renewable energy to lower carbon intensity.
• Use Scalable Architectures: Adopt serverless or containerized systems to scale efficiently and reduce idle resource usage.

Step 4: Track and Report Progress

Implement monitoring systems to measure sustainability continuously:

• Scaphandre: Collects power usage data for servers and integrates with monitoring tools like Prometheus or Grafana.
• CUE and PUE Metrics: Use these indicators to monitor the efficiency of data center operations.

Step 5: Educate Teams and Users

• Train developers on writing efficient code and using energy-aware tools.
• Encourage users to adopt energy-saving behaviors when interacting with your software.

The Way Forward

Building sustainable software doesn’t require drastic changes. Start with small, actionable steps:

• Measure: Use tools like SCI to understand your software’s environmental impact.
• Optimize: Make informed changes to reduce energy usage and emissions.
• Monitor: Continuously track progress and adapt.

By integrating sustainability into software development and operations, businesses can reduce costs, stay compliant, and contribute to a healthier planet.

Sustainability in software development is no longer optional — it’s essential. By understanding metrics like SCI, leveraging tools, and following actionable steps, developers and organizations can reduce energy consumption, save costs, and contribute to a greener planet.