Green coding: What is it and why is it important?

Green coding is a relatively new practice that seeks to minimise the energy intensity involved in processing lines of code. As the telecoms industry works towards its net zero goals, green coding could play an important role.

What is green coding?

Green coding is term that has been coined, relatively recently, to refer to programming code that has been produced and written in a way that minimises the energy consumption of software, thereby limiting the potential environmental impact.

The principles of green coding should not be considered in opposition to existing practices. Rather, they should be incorporated into the principles of software engineers to consider when writing and designing code in order to balance functionality and with energy usage.

Background: why is green coding applicable to the telecoms industry?

The telecoms and ICT industry more generally is a significant contributor to carbon emissions globally. These emissions originate from a variety of sources, including the energy required to power telcos’ mobile networks, the manufacturing and distribution of handsets, and the emissions associated with the processing of other digital applications and technologies. These CO2 emissions will continue to rise as the use of digital technologies proliferate. For example, the proportion of GHG emissions globally that are linked to digital technologies has grown by 1.2% since 2013, up from 2.5%, and the energy demand from data centres has grown by four times in the same period.

Telecoms operators and other ICT companies have made ambitious commitments towards their net-zero agendas, particularly in Europe, where a significant number of telcos have announced a 2030 target. However, reaching this goal will not be possible without a concerted effort across all domains: including more energy efficient hardware and software.

The role of green coding in reducing emissions

There are many levers the telecoms industry can, and must, pull in order to meet net zero emissions, including the use of greater automation to reduce the need for (carbon intensive) human intervention in the way of site visits, or greater use of renewable energy.

However, it is also important to consider methods of reducing the amount of energy required to power operations in the first place. This is where green coding comes in. Software applications and programs are instructed by lines of code that have been written by developers. As each line of code is parsed, the device that processes this code gives rise to carbon emissions. The more code to process, the higher the level of emissions.

Approximately 90% of software developments leverage open-source code which is not tailored for specific uses and applications. It therefore contains redundant sections of code, using up more processing power and giving rise to unnecessary carbon emissions.

Green coding principles can be adopted to encourage lean coding practices, where only the minimal amount of processing is required to deliver the same application or result.

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Green coding principles

Although green coding will not solve all of the industry’s problems (the distribution, use of, and end of life management of device handsets, for example) it can be an important lever for reducing energy consumption. Furthermore, incorporating green coding principles can further enhance the move towards greater sustainability by enabling the following::

Enabling greater use of renewables through workload orchestration

Green coding can enable the use of intelligent orchestration of workloads, for example by moving telco cloud workloads to data centres based on the availability of renewable energy sources, e.g. solar or wind power at any given time. This can help to reduce true emission (the location-based emissions) which are increasingly being reported against as well as ‘accounting’ emissions (using market-based emissions).

Reducing granular energy consumption through silicon-aware coding

Modern chipsets come with inherent energy management capabilities that can be exploited to reduce energy use. For example, multi-core processors can be coded such that some of the cores have directly addressable ‘sleep modes’ that bypass default energy management (that might take several seconds to move cores into sleep mode). Instead, the application code can directly instruct cores to shut down and re-start within microseconds. If developers fully leverage these capabilities when writing code for highly variable workloads such as in the RAN, this can have a significant impact on energy.

Cloud caching can help to reduce energy intensity

CDNs improve customer experience by caching content locally to the user. This improves the user experience as it minimises buffering and also means fewer workload requests are routed to the central cloud which in turn reduces the amount of energy being used for transport. CDNs themselves can be further optimised for energy use through green coding. This is just one example of how applications and workloads can be coded in ways that reduce overall energy consumption.

What are the next steps for organisations looking to leverage green coding principles?

  • Offer training on green coding to new and existing IT engineers within the business to raise awareness of the importance of this practice and encourage the adoption of these principles on an ongoing basis. Ensure to minimise the amount of superfluous lines of code, as each one gives rise to carbon emissions and even minimal reductions will have a large overall impact when realised on a global scale.
  • Incentivise software engineers within the organisation to leverage green coding, thereby encouraging innovation and skills development.
  • Embed a mentality and culture of efficiency across the business, making it part of an organisation’s DNA to incorporate sustainability by design across business units. A successful sustainability strategy recognises its multi-faceted nature: sustainability is not the responsibility of only one team.
Grace Donnelly


Grace Donnelly

Senior Consultant

Grace works across the spectrum of consulting engagements at STL Partners, including edge computing, private networks and 5G. Grace is the co-lead of STL’s sustainability practice and is focuses on driving sustainability within the telecoms industry and beyond. Prior to joining STL, she worked for KPMG, helping clients to solve business critical issues. Grace holds a BA in Human, Social and Political Sciences from the University of Cambridge.

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