by Erwin Schoitsch (AIT) and Georgios Mylonas (ISI, Athena Research and Innovation Center)

Smart city technologies have been proliferating at a rapid pace for some years now, and at the same time, the divide between the natural and digital worlds has lessened considerably. Multiple sensing endpoints located in our environment, offices, homes, devices, and even our body, produce continuous streams of sensor data. At the same time, the concept of the circular economy has entered the mainstream, and we are now seeing many communities and businesses adopt novel approaches based on circularity (e.g., in the European Green Cities Network). European policy (“Green Deal”) has reacted to the challenges of climate change and environmental footprint reduction, particularly in the context of large urban agglomeration. Smartness (intelligence) must address not only the immediate goals of human wellbeing, assisted living and comfort but, perhaps even more importantly, long-term sustainability, as defined by the 17 UN Sustainable Development Goals (see Figure 1).

Figure 1: The 17 UN Sustainable Development Goals (SDGs). Source:
Figure 1: The 17 UN Sustainable Development Goals (SDGs). Source:

In this environment, Smart Cities, AI and the IoT, together with sustainability and circular economy, form a significant part of the current research landscape. Several challenges have surfaced when designing and applying these systems in fields like energy, sustainability, smart transportation and digital twinning, especially when discussing their cross-section and a multidisciplinary approach. The fact that the implementation and deployment of such systems involves the participation of a large number of citizens has also opened a window for opportunities in fields such as citizen science and co-creation.

This special theme of ERCIM News reports on academic and industry research that addresses technology, systems, applications, and services in the Smart and Circular Cities domain. This section includes articles targeting important elements such as security and privacy, as well as the integration of technologies like Digital Twins and the Smart Grid, which are still evolving at a rapid pace. Experiences from deployments that use more conventional approaches from a technological standpoint offer us glimpses of the near future, while reports from smart city projects using novel methodologies and technologies give us a better sense of how smart city research will evolve to encompass new communities and tools.

Security and Privacy Issues
Kreutzer et al. discuss a framework for facilitating the transition from existing smart city services to smart governance, arguing that thus far research has focused more on technical aspects, leaving out of the equation more common ones, or even whole communities, e.g., in rural areas. They discuss five preventive measures that might help to mitigate cyber incidents towards smartification. When it comes to IT security in urban environments, Lämmel et al. discuss policies and recommendations towards the secure implementation and operation of urban infrastructure. In this context, the Urban Data Partnership (UDP) aims to accelerate the digital transformation of cities and communities, while considering data security. Moreover, Pustozerova and Mayer discuss aspects of using Federated Learning, an ML approach that is quickly gathering traction, for data security and privacy purposes in smart cities. They argue that although its adoption is growing, there are still challenges to overcome, and further investigation of defense mechanisms is needed. Furthermore, Klikovits et al. present an approach to integrating the plethora of constantly changing IoT devices and services within a smart city setting, based on the combination of an ID provider and the Arrowhead framework.

Resilient Cities: Digital Twin and Smart Grid
Moving on to novel technologies that are quickly becoming part of the smart city landscape, the Digital Twin is one such technology. Digital Twins are currently being introduced to help us on multiple fronts, including data security and privacy. The SecurityTwin project, presented in this issue by Eckhart et al., aims to develop the fundamental methods for employing the digital-twin concept to enhance the security of Cyber-Physical systems and provide the basis for implementing intrusion detection and response methods. Meanwhile, the Smart Grid is another field that has become a part of the research landscape, with its importance accentuated by the need to accelerate towards more sustainable cities. Efthymiopoulos et al. present the FLEXGRID project, which investigates the constraints of current smart grid architectures preventing integration of large-scale distributed energy resources into distribution networks and aiming to mitigate circularity and sustainability in modern smart grids. The project is currently developing a digital platform to offer digital energy services helping energy sector stakeholders to automate and optimise the planning, operation and management of systems and assets.

At the same time, energy communities have been forming throughout Europe to facilitate sustainable energy production in a decentralised manner. Norbu et al. discuss the Responsive Flexibility (ReFLEX) project, currently the UK’s largest smart energy demonstrator, focusing on an energy community at the Orkney Islands in Scotland comprising 200 households. They developed algorithms for the smart control of energy assets and redistribution mechanisms, achieving a fairer redistribution in the process. At a more localised scale, within home environments, Constantinou et al. (page 17) propose the IMCF+ framework to facilitate the smart consumption of energy at the time it is produced by e.g., photovoltaics on the roof of a building. Their strategy relies on an AI-inspired algorithm to schedule energy consumption of various devices, using a variety of strategies while at the same time meeting indoor comfort level requirements.

Optimising the use of established methods and tools
Several projects utilise more established tools and technologies in the circular and smart city domain – for example, electric bikes and cars are rapidly becoming part of the urban transport landscape. Gunner et al. discuss results obtained by fitting monitoring equipment to a fleet of electric bikes that were deployed as part of the H2020 Lighthouse Project REPLICATE in Bristol, UK. This has produced a dataset that could help us better understand aspects such as route selection by e-bike users or identify city areas where cycling infrastructure would be most beneficial. Smart water metering is another quickly evolving domain, following electric power metering. Amaxilatis et al. describe Tethys, a large-scale water metering deployment in Thessaloniki, Greece, using water consumption data to identify patterns, behaviours and anomalies. Such data can lead to indirect observations, e.g., indoor activity levels during the COVID-19 pandemic. Moreover, the circular economy is entering our daily lives. Gentimis et al. present a digital platform that aims to encourage citizens to recycle used cooking oil in West Macedonia, Greece. The goal is for the platform to be adopted by 10,000 households across 13 municipalities in this area.

Novel technologies and methods
Going back to major issues at the heart of smart and circular cities, traffic monitoring, air quality and pollution monitoring, as well as sustainable water resource management immediately spring to mind. Over recent years, the research community has attempted to tackle them using rather conventional approaches. However, we are beginning to see more innovative approaches adopted, utilising novel methodologies. In the context of real-time traffic monitoring, Litzenberger et al. use fiber optic acoustic sensing and the existing telecom fiber cable infrastructure in a prototype study in Graz, Austria. Initial results suggest that it is feasible to derive real-time traffic estimation using this approach. Ruston McAleer et al. discuss the emerging concept of city-scale Digital Twins and present the DUET project. The pilots developed in the project across three cities are expected to go live in autumn 2021, tackling mobility and air quality, city planning and public decision-making. Bruno et al. discuss the use of plants, specifically strawberries, as biosensors to monitor air quality. They report on a large-scale deployment across Spain in the “Vigilantes del Aire” project, utilising samples from 205 municipalities and 26 Spanish provinces. Malamis et al. address sustainable water resource management as investigated by the HYDROUSA project, which uses innovative nature-based solutions (NBS) to manage a variety of water streams. The project promotes decentralised on-site water, materials and energy conservation, treatment and reuse. It has established large-scale demonstrators in three Greek islands, while its solutions are being evaluated in 25 early-adopter cases in other Mediterranean coastal areas.

Sustainability projects in specific contexts
Finally, there is the issue of focusing on specific communities and co-creation to deliver for smart and circular cities. Ruston McAleer et al. present the COMPAIR project, scheduled to begin in November 2021, which brings social and emotional intelligence into the decision-making process within cities. H. Lelligou presents the ASSET project, which focused on the educational community, an important community for the transition to smart and circular cities. The project produced more than 25 training programmes on energy transition, evaluated through pilot studies. Ganos et al. present their experiences from several smart city initiatives in the city of Patras, Greece, and argue that even small communities with limited resources can make a difference and facilitate change. Thomay et al. tackle the issue of sustainable tourism in smart cities, and how digital tourism can provide new ways to share cities’ cultural heritage. Furthermore, Abbas Petersen and Geirbo discuss the Learning Flexibility project, focusing on waste management and circularity in regions such as small islands. The project takes a bottom-up approach, in contrast to the more conventional top-bottom approach adopted by many related projects, aiming to identify innovative and sustainable solutions.

Overall, research on smart and circular cities in Europe appears to be moving towards using innovative technologies and approaches, reaching to novel application domains, as well as encompassing communities in a more active and engaging manner.

Please contact:
Erwin Schoitsch  
Austrian Institute of Technology, Austria
This email address is being protected from spambots. You need JavaScript enabled to view it.  

Georgios Mylonas   
ISI, Athena Research and Innovation Center, Greece
This email address is being protected from spambots. You need JavaScript enabled to view it.

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