As the climate crisis intensifies, the energy consumption of the IT sector is drawing increasing attention. According to the Intergovernmental Panel on Climate Change (IPCC), severe impacts can only be mitigated through immediate emission reductions. IT plays a dual role: on the one hand, digitalization can help reduce emissions in other sectors (green by IT). On the other hand, the industry itself must become more sustainable (green in IT).

Software is at the center of this transformation—because sustainable software is efficient software. Every inefficient line of code creates not only technical but also ecological debt. Like technical debt, it can impair long-term maintainability and efficiency—but with the added impact on real resources like electricity and CO₂. The good news: no radical changes are needed—what matters most is a sharpened awareness and a few targeted adjustments. This article presents practical Green Coding Patterns that are easy to integrate into everyday development.

Small Levers, Big Impact

Sustainable development doesn’t have to start with a complete overhaul. Often, small everyday changes—a different format here, a more conscious decision there—can lead to measurable effects. These adjustments act like levers: small in effort but large in impact. Many small decisions can significantly reduce energy consumption across multiple levels.

Changing behaviors step by step leads to a new awareness. What feels like an extra effort today can soon become the new normal. The following examples highlight such small levers with big impact—immediately applicable and effective for both the environment and system performance.

Efficiency Through Reduced Computation

One of the first levers lies in the code itself: the less computational power an application requires, the less energy it consumes. Avoiding unnecessary calculations is a key lever—just as a fuel-efficient car uses less gas, efficient code uses less electricity. It’s not about perfection, but about setting clear priorities for resource use.

  • Avoid unnecessary processes: Does every click really need to trigger a new query? Does the entire DOM need to re-render? Smart event handling and caching can prevent excess computation.
  • Prefer simple data types: Integer operations often use less energy than floating-point ones. Small changes in data handling can make a big difference.
  • Use precompiled resources: Bundle and optimize scripts and assets before delivery to reduce computation on end devices.

Transferring Data Efficiently

Data traffic also consumes energy—on end devices, in networks, and in data centers. The rule: the less, the better.

  • Transfer only necessary data: Keep API responses and database queries focused on essentials.
  • Compress files: Text and image files can often be reduced significantly in size without losing quality.
  • Use caching effectively: Repeated data retrievals can be avoided by storing static content locally or on the server.

Energy-Efficient Interfaces and UX

The design of an application directly influences its energy demand. User-friendliness and resource efficiency are not mutually exclusive—they go hand in hand.

  • Use images efficiently: Lean formats like WebP and properly scaled media reduce file size and energy consumption.
  • Reduce animations: Visual effects increase GPU usage, especially on mobile devices. Less is more.
  • Offer dark mode: On OLED screens, a dark interface saves energy and improves accessibility.
  • Optimize loading times: Faster loading not only saves energy but also improves user experience.

Using Resources More Wisely

The infrastructure behind an application also holds potential for optimization. The goal is to scale resources to actual needs.

  • Scale based on demand: Systems should automatically adapt to load and scale down during off-peak times.
  • Shut down unnecessary environments: Development and test environments don’t need to run 24/7.
  • Use serverless and containers: These technologies help use hardware more efficiently.

Carbon-Aware Coding

Not all electricity is equally green. CO₂ emissions per kilowatt-hour vary depending on the time of day and grid load—depending on whether renewable sources like wind and solar are feeding the grid or whether fossil fuels dominate. This is called carbon intensity, describing how much carbon dioxide is emitted per kilowatt-hour of electricity. Carbon-aware coding takes these variations into account.

  • Schedule intelligently: Batch jobs or analyses can be timed to run during periods of low grid load or lower CO₂ intensity—for instance, when renewables are abundant. Tools like the Carbon Aware SDK or apps like StromGedacht help identify particularly green times in the grid mix.
  • Adapt to device states: Applications should detect whether a device is in energy-saving mode and adjust their behavior accordingly.

Measuring and Improving

Sustainability needs metrics. Only what is measured can be improved. A realistic overview of energy usage is the foundation for meaningful change.

  • Measure energy consumption: There are various ways to track how much energy an application uses—through runtime profiling or indirect indicators like CPU load, runtime, or memory usage. While these proxies aren’t precise, they offer helpful insights. More detailed analysis can be done with specialized tools.
  • Use benchmarks: Standardized metrics like the Software Carbon Intensity (SCI) make progress measurable. A practical example is available in the previous article on energy analysis with Powermetrics.

Low Hanging Fruits: Saving Energy on Devices

Not all optimization happens in code or infrastructure—devices themselves offer opportunities for simple yet effective actions:

  • Activate dark mode: Especially on OLED screens, this can significantly reduce power usage.
  • Reduce screen brightness: One of the simplest ways to save energy.
  • Shut down devices after hours: Turning off monitors, laptops, and peripherals avoids unnecessary standby power.
  • Enable energy-saving modes: Many operating systems and IDEs offer these features—they’re often just unused.
  • Close unused tabs and applications: Less load on the CPU means less energy consumed.

These small, easy-to-implement actions complement structural improvements and make Green Coding a holistic approach.

One major advantage: Many of these actions can be implemented individually, without team consensus or lengthy discussions. Anyone adjusting local power settings or activating energy-saving features can have an immediate impact. A portion of the responsibility—and freedom to act—lies in one’s own hands.

Conclusion: Small Steps, Big Difference

Green Coding doesn’t have to be complex. Many practices are simple to implement and deliver real impact. Efficient code, reduced data transfer, and thoughtful interfaces help lower energy consumption while making software more performant and reliable.

Developers have the power to make software more sustainable—one line at a time.

Want more? You can find strategic background and further insights in the article “Green Software, Green Future”.