**1. Introduction**

Data centres are interior spaces that house electronic and electrical equipment that processes and stores digital data. The data centre industry (DCI) has evolved from zero in the 1980s into a global industry with 7.2 million sites [1] in 2021, annual electricity consumption is 200 TWh (i.e., 1% of global electricity consumption) [2,3] and carbon emissions are equivalent to those from the pre-Covid airline industry [4]; 60% of the global population are now connected via smart phones, laptops, and other computing equipment [5], and the sector currently processes around 4.2 trillion gigabytes of data per year. It is predicted that the DCI will grow by around 500%, by 2030, as more people and objects are connected via the Internet of Things (IoT) [6]. Reliance on digital communications technology and, therefore, the DCI has developed to the point where any systems failure will adversely affect major commercial, health, education, and other sectors and dependence has been highlighted during the Covid pandemic when there was a notable increase in data traffic in response to remote working, education, and communication. The sector has helped to transform all aspects of life and has already proved very beneficial to many of those who have access to digital technology.

The speed and scale at which data centre technology, and equipment, developed far exceeded that of recycling infrastructure which, in conjunction with the fact that products were not designed with any consideration for treatment at end-of-life (i.e., linear design)

**Citation:** Andrews, D.; Newton, E.J.; Adibi, N.; Chenadec, J.; Bienge, K. A Circular Economy for the Data Centre Industry: Using Design Methods to Address the Challenge of Whole System Sustainability in a Unique Industrial Sector. *Sustainability* **2021**, *13*, 6319. https://doi.org/10.3390/ su13116319

Academic Editor: Luis Jesús Belmonte-Ureña

Received: 30 March 2021 Accepted: 26 May 2021 Published: 2 June 2021

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and poor perception of second life products, means that the DCI is contributing to the increasing volume of e-waste that is generated every year. Critical Raw Materials are essential to DC and other electronic equipment and many are lost to landfill, and/or incineration, or cannot be accounted for at end-of-life. Consequently, unless there is a change in practice across all equipment life cycle stages, there is a threat to the supply chain for these and other materials, which will destabilise the market, the DCI, and all services that rely on it. Furthermore, current practice is environmentally and socially unsustainable.

There is an urgent need to transform the sector, but this is limited by various technical and behavioural barriers. The CEDaCI project is the first of its kind, and it was set up to instigate change and develop a Circular Economy for the Data Centre Industry by using a whole systems approach in a fragmented industry, comprised of 10 sub-sectors, that operate in individual silos. A whole systems approach is essential because decisions made, and actions taken, at each life cycle stage affect the sustainability of all other life cycle stages. Design thinking and design methods encourage holistic thinking, and, therefore, they were selected as models for CEDaCI; they underpin the structure and process to ensure that the project delivers what the sector needs. People/stakeholders and a 'hearts and minds' ethos are central to both methods; considering the history of and work practice across the DCI, however, there was a risk of failure if representatives did not engage with the various events and platforms. The project launched in October 2018, and in February 2021, a survey of DCI representatives was carried out to ascertain the extent to which the project structure and methods were working, to learn whether amendments or revisions were necessary to ensure success, and to assess the impact of the project to date.

This paper first describes the context of and barriers to a Circular Economy in more depth. It then describes the design methods and documents, the project structure, activities, and content, followed by details and results of a quantitative online survey and qualitative data gathered via semi-structured interviews. Participant numbers were limited to 44 (with 32 usable data sets) and 9 respectively. The response rate appears to be associated with the COVID-19 pandemic, which significantly increased data traffic, workloads and absence due to ill-health. The results were very positive and showed that the project methods and process were appropriate, although there were some shortcomings due to lack of representatives from two subsectors; the methods and process are raising awareness of the challenges and potential solutions in the DCI, and of circularity in general, as well as facilitating development of digital tools, business models, CE-fit designs and prototypes, and new recycling and CRM reclamation processes. Finally, these results endorse the project as an exemplar and the methodology could be adapted and applied in other industrial sectors facing similar challenges.
