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The fact that the IT sector has a carbon footprint equivalent to that of Germany should be reason enough to consider what potential in terms of reducing greenhouse gas emissions have remained untapped so far. This is where digital sustainability comes in to play as a way to make our digital infrastructure more sustainable – from applications and networks to hardware.

As I write this, the ICT sector is responsible for between two and six per cent of global greenhouse emissions; this figure also includes the production of the necessary hardware. Researchers estimate that in the worst case scenario, this could increase to 23 per cent of all global greenhouse gas emissions by 2030. In my previous blog post you can read how the three dimensions of sustainability relate to digital products and services. In this blog post, however, we will be looking at the use of energy and resources by software with the aim of reducing CO2 emissions.

How digital technologies are used has an impact on sustainability, as this blog post shows. It is incumbent on users as well as manufacturers and operators to use technology responsibly. Consumers are not the only ones who expect responsible environmental management. Investors, employees and business partners are also making it increasingly clear that companies need to have a coherent sustainability strategy. There is simply no way around this. They understand that it is not just about protecting the environment as an end in itself. It’s also about preserving the foundation of business and life in general going forward. Another driver of digital sustainability is regulation, especially the new EU taxonomy and CSRD. That’s because managers are now realising for the first time just how much of an impact IT actually has on their carbon footprint.

What role does efficiency play?

When speaking with others, you hear that highly efficient software, with efficiency in this context meaning the ratio of power consumed to computing power, is often seen as the solution for digital sustainability. The easily accomplished improvements have often already been made to mobile systems and as part of search engine optimisation, however. And in hardware development, they have a decades-long head start anyway, since hardware has historically been trimmed much more for efficiency. It is therefore important to weigh up whether the available funds should be invested in increasing efficiency, or whether other approaches such as carbon awareness – more on this below – promise to deliver greater improvements in sustainability. Minor improvements that are difficult to implement make sense in cases where software components are frequently used, such as with popular open source software. At the end of the day, the efficiency of developers must always be weighed against the efficiency of the machines. Here are a few everyday tips to improve the efficiency of software:

  • Optimise cache validity period
  • Provide images in the correct resolution
  • Use system fonts instead of external fonts
  • Server-side rendering of content

The bullet points listed above are only a small selection of the many improvements that are possible. You can learn more about this in the following blog post.

Is green hosting the solution?

Automatic adaptation of system behaviour, taking into account the current power source, is referred to in the literature as carbon awareness. Systems use energy market or weather data to determine how many grams of CO2 are emitted per kilowatt hour of electricity consumed, also referred to as the electricity’s CO2 intensity, which can already be forecasted with a higher degree of precision using machine learning. Due to variations in wind and solar power, the renewable energy sources feed different amounts of electricity into the grids at any given time. The amount of electricity consumed that cannot be met by renewable power or via energy storage systems is offset by fossil-fuel energy sources. Due to this interplay of fossil-fuel and renewable energy, the CO2 intensity in the grid varies constantly.

Time shifting

In the case of time shifting, systems can take advantage of this volatility in CO2 intensity. Resource-intensive processes, such as creating backups or sending newsletters, do not always have to be carried out ad hoc. Instead, they can be performed when a lot of renewable electricity is being fed into the grid.

Location shifting – follow the sun/wind

Location shifting is based on the same principles. However, resource-intensive processes are not postponed but instead offloaded to other data centres. If a data centre is currently being supplied with large amounts of renewable electricity, it may make sense to transfer computing processes there due to the lower expected CO2 emissions. Offloading these processes is a worthwhile option if the energy costs associated with transmitting data to the data centre do not exceed the amount of CO2 saved. It is the perfect option for the transmission and processing of simple data. With complex data such as videos and images, you would first need to do in-depth assessment of whether offloading the process really makes sense.

Peak loads

In addition to time and location shifting, peak load avoidance should also be implemented since every time there is a load peak in the grid, the additional demand is met by fossil-fuel energy sources or energy storage systems. Simple measures to avoid peak loads include not running processes such as cron jobs on the hour, as other processes are also often scheduled to run at this time.

Green hosting

Green cloud or hosting services are another way to increase sustainability. Although the data centres generally consume the same electricity as every other data centre in the region, the energy providers back the expansion of renewables or environmental protection projects through a surcharge levied on green electricity or via power purchase agreements. Data centres in Switzerland, Iceland or Scandinavia, which are powered exclusively by renewable electricity, are some of the few counterexamples. These can be a real alternative if the information being sent is not very complex and does not require a lot of power from the network infrastructure during transmission.

Do we really have to conserve power?

Wasteful use of computing power

Along with efficiency and the source of electricity, avoiding waste when it comes to software and hardware is the third key aspect of environmentally sustainable software. Sensors that take ultra-precise measurements several times a second, for example, consume an unnecessarily large amount of power if this level of precision is not absolutely required by the application. The same also applies to the provision of resources. Every application does not need to be available around the clock or provide maximum computing power at all times. Responsible use of digital resources, which entails avoiding unnecessary resource consumption, is an important building block of digital sustainability – and it is often the easiest step to take.

Role of hardware

Beyond power consumption, hardware continues to play a central role in digital sustainability. That’s because the production of hardware, be it laptops, smartphones or the equipment used in data centres, also consumes resources. Over the lifetime of a typical web application, it makes up roughly 19 per cent of the footprint of the hardware based on its share of use. For that reason, Blue Angel, the ecolabel for resource and energy-efficient software, requires software to be backward compatible for at least five years. This can reduce the need to purchase new, more powerful hardware on a regular basis. However, even these measures cannot be implemented without trade-offs. For example, a generic system that is developed for many chip architectures consumes more power than would be the case if low-level code were to be developed specifically for the chip being used.

How sustainable is my software?

Official standards for assessing digital sustainability do not exist yet. However, general frameworks for evaluating the sustainability of products, services and companies are broad enough to be applied to digital solutions. There are also a small number of frameworks for the targeted analysis of digital solutions available. Prime examples include ISO 14040:44 and the GHG Protocol. A framework for the assessment of digital sustainability is currently being developed based on the Software Carbon Intensity Standard. Tools such as the Website Carbon Calculator or the Green Web Checker can also help with the initial classification.


A coherent sustainability strategy should always include an assessment of digital sustainability. Sustainable software does not necessarily have to be more expensive; in fact, most companies already see it as an opportunity more than anything. Many of the sustainable software solutions presented here can also be implemented with little effort, and they can help reduce operating costs by lowering the amount of electricity consumed or computing power purchased. Best practices such as caching and image compression have also long been part of the repertoire of most developers – they only need to be optimised in practical application.

On our website, we’ll show you what goals we at adesso have set for ourselves with regard to sustainability, what measures we want to implement and what the associated opportunities and challenges are for our company.

You will find more exciting topics from the adesso world in our latest blog posts.

Picture Yelle Lieder

Author Yelle Lieder

Yelle Lieder is Green IT Lead at adesso. As part of the CIO Advisory Competence Centre, he focuses on strategies for measuring and reducing the environmental impact of IT systems and on the use of technology to achieve sustainability goals.

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