When listening to a symphony orchestra, one might get the impression that the many musicians on stage merge into a single unit as soon as the piece begins. In addition to the harmonies, the musicians’ shared dynamics are also striking. All musicians must contribute equally to influence the tempo or volume of the music. This coordination is handled by one person: the conductor.
In a sense, the image of a symphony orchestra can be applied to modern software systems, because distributed system components also perform individual tasks but must be perceived as a single unit. In addition, cloud systems offer flexibility and coordination capabilities. This allows for control over when and where an IT-supported process step should take place. This helps, for example, with load balancing within the system.
If we imagine that we can also integrate sustainability aspects into process control, we arrive at the basic idea of Carbon Aware Computing. In Carbon Aware Computing, the metric of carbon intensity is used to control the operation of an IT system. Sustainability thus becomes the conductor of the system.

How the Carbon Intensity of the Electric Grid Fluctuates

Depending on the time and place at which electrical energy or electricity is consumed, different levels of pollutant emissions are associated with it. This is because not all electricity is generated in the same way. The combustion of fossil fuels to generate electricity produces more emissions than energy generation from renewable sources. In addition to greenhouse gases—which are standardized using the metric of carbon dioxide equivalents—other substances harmful to the environment or human health can also be released into the environment. For the sake of clarity, this blog post focuses on carbon dioxide equivalent emissions and excludes other pollutants.
Carbon intensity describes how many carbon dioxide equivalents are emitted per kilowatt-hour of electricity consumed. Put simply, this metric helps assess the sustainability of an electricity grid. Carbon intensity is always specific to a particular location and time.
The location-specific nature stems from the fact that electricity generation varies by region. As a result, carbon intensity is naturally lower in regions with extensive renewable energy deployment than in regions where fossil fuels are increasingly used to generate electricity. To get an idea of how carbon intensity varies around the world, you can use the online tool Electricity Maps, which provides current and historical data on carbon intensity and electricity generation.
Furthermore, carbon intensity is a time-specific value, as electricity generation is not static. Consumer energy demand and the availability of renewable energy sources are subject to fluctuations. Energy demand rises in the evening, for example, when many people use household and kitchen appliances, while solar energy generation decreases because the sun is no longer shining as intensely. As a result, energy producers continuously generate electricity from fossil fuels to keep the power grid stable. Fossil fuels are used for this purpose because they are dispatchable—meaning the amount of electricity generated can be easily controlled. Consequently, carbon intensity also fluctuates depending on the time of day. An effective measure to counteract these time-dependent fluctuations is the installation of energy storage systems.

What Is Meant by “Carbon-Aware Computing”?

Carbon-Aware Computing addresses this issue. To do so, IT systems are controlled automatically to dynamically adjust energy consumption based on the carbon intensity of the power grid being used. The goal is to reduce carbon-equivalent emissions during software operation. In the field of Carbon-Aware Computing, four patterns have emerged that help manage energy consumption in a sustainable manner:

Location Shifting: A resource is deployed in a geographic region with low carbon intensity to reduce carbon emissions, or a resource is provided in close geographic proximity to the user to shorten the data transmission path.

Temporal Shifting: An IT-supported process is carried out during a period of low carbon intensity in order to reduce carbon emissions.

Peak Shaving: An IT system controls the number of requests processed to avoid peak loads. Peak loads can lead to an exponential increase in energy consumption. This principle can be implemented, for example, by placing requests in a queue.

Demand Shaping: An application reduces its own output when carbon intensity is high in order to lower its own energy consumption.

These four patterns can also be used in combination to maximize the benefits of carbon-aware computing. However, they must be implemented in a way that is consistent with the software’s other quality requirements. For example, the use of location shifting requires that the software be permitted to run in other geographic regions and that security requirements do not prohibit this.

The Impact of Carbon-Aware Computing

• Location shifting and temporal shifting are great ways to reduce CO2 emissions; for example, Poland vs. Scandinavia
• It also increases a system’s resilience, since it does not rely on fixed locations or times and can be used flexibly
• Peak shaving and demand shaping have a positive effect on load behavior and system stability, but may affect the fulfillment of tasks and must therefore be consistent with customer expectations
• Dynamic Pricing: Green electricity is cheaper to generate and could be sold at a lower price
• Relieving the strain on the power grid during periods of high demand caused by other consumers

How Carbon Aware Computing Helps Meet Sustainability Goals

• A great way to make unavoidable resource consumption more sustainable
• It is still important to reduce resource consumption

In his animated films, Japanese filmmaker Hayao Miyazaki often explores the relationship between humans and nature. In the 1997 film *Princess Mononoke*, for example, the main character stands up against the destruction of nature by humans. Through his films, Miyazaki seeks to illustrate that we exist within the context of our environment—indeed, that we are dependent on it.
As software architects, we know that our software operates within a context and is subject to influencing factors. The connection to nature is not immediately obvious here. It is no coincidence that technology-based science fiction works are usually set in megacities or in space. Yet the IT industry does have a connection to nature: Green IT.
In this blog series, we provide insight into the challenges and opportunities of Green IT and aim to show that Green IT is about more than just environmental protection. In this first article, we explore the various facets of sustainable software systems, explain the underlying motivation, and present selected Green IT measures.

What Green IT Means

To better define the term “Green IT,” let’s first take a look at the broader concept of “sustainability.” The principles of sustainable development trace back to the 1987 report *Our Common Future* by the United Nations World Commission on Environment and Development. Today, this report is better known as the “Brundtland Report.” In this report, sustainable development is described as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”
Building on the Brundtland Report, the Enquete Commission of the German Bundestag presented a report in 1998 in which the concept of sustainability is specified within a three-pillar model:
Ecological sustainability: Our economic activities are guided by the limits of naturally renewable resources.
Economic sustainability: Our economic activities aim to remain viable in the long term.
Social sustainability: Our social actions aim to include all people and prevent social tensions.
The Green IT sector focuses on the ecological sustainability aspects of IT systems, without neglecting social and economic factors. Thus, ecologically sustainable practices are often accompanied by cost savings. The goal of Green IT measures is always to reduce resource consumption and the associated greenhouse gas emissions, which have been proven to drive climate change.

Why We Should Pay Attention to Green IT

In our blog series on Green IT, we highlight Green IT measures and their impact on the energy and resource consumption of software systems. However, we also believe it is important to highlight the motivation behind these measures, which goes beyond environmental protection. To illustrate the benefits of Green IT here, we draw on the Japanese Sanpo-Yoshi model. It originates from the guild of traveling merchants who built infrastructure in the provinces to establish long-term relationships with their customers. Sanpo-Yoshi is a centuries-old business principle that evaluates a business model based on whether it is good for the seller, the buyer, and society.
Green IT is good for the software manufacturer (seller) because the development of sustainable software is faster and its operation is more cost-efficient. Sustainable software is leaner, and DevOps processes are executed more quickly. Furthermore, a commitment to sustainability has a positive impact on brand image and employer attractiveness.
Green IT is good for the software user (buyer) because sustainable software performs better and consumes less power on the user’s system. Furthermore, sustainable software is compatible with older hardware, allowing it to be used for longer.
Green IT is good for society because it reduces resource consumption and the resulting greenhouse gas emissions. It is also an exciting field of research where jobs can be created.
This analysis illustrates that Green IT offers numerous benefits for various stakeholders. When discussing measures for developing sustainable software systems, we highlight these benefits to demonstrate why these measures are worthwhile.

What Needs to Be Done in the Area of Green IT

In this section, we would like to share ideas on what Green IT measures are possible. Here, we focus on potential actions in the development of software systems. While software users can also realize savings through efficient use, these savings are minimal compared to scalable optimization measures implemented by software manufacturers.
The simplest measure to reduce resource consumption in a software company is to shut down unused services (so-called “zombie services”). In particular, decommissioning cloud resources can also lead to significant cost reductions. In a 2025 report, Barry Runyon described how the American healthcare organization Trinity Health succeeded in achieving an annual reduction in IT operating costs of $68 million by identifying and shutting down unused IT services. While this report focuses exclusively on the financial aspect, the ecological resource savings are directly linked to it.
Additionally, systems that are only needed for a limited time can be started up and shut down as needed. These include, for example, test and reporting systems. This measure is not only simple but also extremely effective. The resource consumption of a test system can be reduced by nearly 60% if it only needs to be operated during core working hours.
An effective measure in the field of software development is caching. Caching prevents the need to perform the same work multiple times to generate identical content. In this way, caching improves a process’s runtime performance and also reduces its resource consumption. Depending on the architecture, caching can also lead to a reduction in the volume of network communication.
With this blog post, we aim to lay the groundwork for an entire blog series on Green IT. We look forward to presenting you with numerous measures, models, and methods for efficiently designing your IT landscape. In the next blog post, we’ll dive right into the topic and discuss the carbon intensity of electricity and the principle of “Carbon Aware Computing.”
If you are interested in resource-efficient software architecture, we recommend taking a look at our training offerings, which include our iSAQB® “Green Software” training course.