1. Co-design in urban sustainability transformations

Co-design approaches in global change and sustainability research that are targeting at the collaboration between scientists and non-scientific actors range from jointly defined research questions and jointly developed projects (co-design), to ‘co-production of knowledge’ (Lang et al., Reference Lang, Wiek, Bergmann, Stauffacher, Martens, Moll, Swilling and Thomas2012; Moser, Reference Moser2016). It is particularly the aim to solve societal challenges that puts co-design and co-production more and more at the core of transdisciplinary research projects (Schuck-Zöller et al., Reference Schuck-Zöller, Cortekar and Jacob2017). Thereby, transdisciplinarity is understood as a joint effort of scientific and non-scientific actors for societal problem solving (Defila & Di Giulio, Reference Defila and Di Giulio2018). Knowledge co-production is considered a part of participatory and transdisciplinary research approaches, and is expected to result in greater sustainability outcomes (Norström et al., Reference Norström, Cvitanovic, Löf, West, Wyborn, Balvanera, Bednarek, Bennett, Biggs, de Bremond, Campbell, Canadell, Carpenter, Folke, Fulton, Gaffney, Gelcich, Jouffray, Leach and Österblom2020). Thus, a clear distinction between the different terms, such as co-design, co-creation, and co-production, is not always made (Moser, Reference Moser2016). But, overall, participatory activities and the exchange of knowledge are common elements that determine transdisciplinary research activities concerning actors' interaction in general.

One important initiative in research on sustainability transformations is the Future Earth program. Future Earth considers itself ‘a global network of scientists, researchers, and innovators, collaborating for a more sustainable planet’ and acts as an interdisciplinary umbrella network for research activities which investigate Global Environmental Change from different perspectives (Future Earth, 2020, para. 1). One main principle of Future Earth's ‘research for global sustainability’, which distinguishes it from other initiatives in global Change research, is the co-production of knowledge (van der Hel, Reference van der Hel2016). In Future Earth, co-design of knowledge addresses primarily the development of research agendas through stakeholders and academia collaboration (Beck, Reference Beck, Biermann and Lövbrand2019). Co-design is thereby considered as the initial step, followed by a co-production process (Mauser et al., Reference Mauser, Klepper, Rice, Schmalzbauer, Hackmann, Leemans and Moore2013), with outcome to both research as well as policy and practice (Webb et al., Reference Webb, Bai, Smith, Costanza, Griggs and Moglia2018). To give one example: In Australia, a Future Earth co-design process and its findings were considered as the starting point to develop a collaborative research agenda in the field of sustainable urban development, with the aim of not only informing Australian cities but to also contributing to international communities such as the Future Earth Urbanisation Knowledge Action Network (Webb et al., Reference Webb, Bai, Smith, Costanza, Griggs and Moglia2018).

This urban focus from the Australian example links to the recognition of cities as places with both a high need and the potential for sustainability transformations (Mc Cormick et al., Reference McCormick, Anderberg, Coenen and Neij2013; Rink et al., Reference Rink, Kabisch, Koch, Krellenberg, Kabisch, Koch, Gawel, Haase, Knapp, Krellenberg, Nivala and Zehnsdorf2018; WBGU, 2011). In the light of transformational change as targeted by the UN Agenda 2030 and its seventeen Sustainable Development Goals (SDGs), co-production is an essential part of the transformation towards sustainability (Iwaniec et al., Reference Iwaniec, Cook, Barbosa and Grimm2019), and requests ‘rigorous collaborative process[es]’ (ibid, p. 5). In this vain, transformative action at the local level is in demand (WBGU, 2011). Hence, obstacles occur when solutions of global issues are to be transferred to the local level (e.g. Nevens et al., Reference Nevens, Frantzeskaki, Gorissen and Loorbach2013); with complexity and context-specificity among the main obstacles. In order to unravel this complexity and to shed light on the context specificities of cities, we claim that co-design processes with co-production activities bear strong potential for actively shaving urban sustainability transformations. Given the complexity of cities, other scholars also argue that decision-making can benefit from relevant scientific knowledge (McPhearson et al., Reference McPhearson, Haase, Kabisch and Gren2016; Webb et al., Reference Webb, Bai, Smith, Costanza, Griggs and Moglia2018).

Different pathways on how science can contribute to sustainable development in cities exist: for example, sharing knowledge practices, implementing transformative research projects, contributing to local capacity building or self-governing of research institutions towards sustainability (Bansard et al., Reference Bansard, Hickmann and Kern2019). All of these pathways require a close cooperation with actors outside of the academic world. Lessons from previous co-design activities emphasize the need to consider the differences between science and practice with regards to motivations, timelines as well as language (Binder et al., Reference Binder, Absenger-Helmli and Schilling2015), all of which underpins the ‘potentially bumpy road of transdisciplinarity’ (Scholz & Steiner, Reference Scholz and Steiner2015). This might be a reason why the proportion of transdisciplinary research that builds upon the joint work of science and society stakeholders has been described as ‘surprisingly low’ in comparison to more traditional forms of urban sustainability research (Wolfram & Frantzeskaki, Reference Wolfram and Frantzeskaki2016). Nowadays, there is evidence that transdisciplinary research approaches in urban sustainability research are increasing. ‘Urban Living Labs’ (Burch et al., Reference Burch, Hughes, Romero-Lankao, Schroeder, Elmqvist, Bai, Frantzeskaki, Griffith, Maddox and McPhearson2018; Voytenko et al., Reference Voytenko, McCormick, Evans and Schliwa2016) or ‘Real-World Laboratories’ (Wanner et al., Reference Wanner, Hilger, Westerkowski, Rose, Stelzer and Schäpke2018) are attracting considerable attention in sustainability science. Generally, those labs highlight the need for joint action of research and practice in a specific urban area and apply an experimental approach for a specific urban problem. The idea is foremost to first test possible activities that show the potential to foster sustainable development on a local level in a lab environment, and second, to upscale successful activities in a broader or different context. Some Urban Living Labs and Real-World Laboratories have already demonstrated that collaborative action of research and practices can lead to more sustainable practice on a local scale (Marvin et al., Reference Marvin, Bulkeley, Mai, McCormick and Voytenko Palgan2018; Menny et al., Reference Menny, Voytenko and McCormick2018).

While transdisciplinarity and co-design are increasingly accepted as a way of doing research on urban sustainability and lead to innovative contributions to science (Schneidewind et al., Reference Schneidewind, Augenstein, Stelzer and Wanner2018; von Wirth et al., Reference von Wirth, Fuenfschilling, Frantzeskaki and Coenen2019), there is still a lack of evidence concerning the ‘real’ needs of cities for processing towards urban sustainability transformations. On the one hand, there is only little evidence what city administrations and practitioners are struggling with and if and how science can support. Scientists, on the other hand, argue that the challenges of administrations and practitioners in terms of urban sustainability transformations range from a lack of political will and/or instruments, over obstacles to change existing behavioural patterns to economic forces (Naumann et al., Reference Naumann, Davis, Moore, McCormick, Elmqvist, Bai, Frantzeskaki, Griffith, Maddox and McPhearson2018; Romero-Lankao et al., Reference Romero-Lankao, Frantzeskaki, Griffith, Elmqvist, Bai, Frantzeskaki, Griffith, Maddox, McPhearson, Parnell, Romero-Lankao, Simon and Watkins2018b). Consequently, scientific work is often focusing on providing theoretical and conceptual knowledge, which reveals a particular discrepancy between theory and practice of urban transformations to sustainability (Koch et al., Reference Koch, Kabisch and Krellenberg2017).

Co-design approaches seem to be a promising tool to address this discrepancy. Given that urban transformations and the implementation of the SDGs require a holistic, cross-sector perspective, we argue that the focus of such a co-design approach needs to be broader than often pursued in Urban Living Labs and Real-World Laboratories: It is not a specific clearly identifiable urban problem but the process of urban transformations to sustainability as a whole which needs to be addressed in the co-design process.

Within this article, we aim to describe exemplarily how to realize such a process, reflecting our own experiences in that endeavour. Our established co-design process builds on the joint work of two activities, implemented within the German Future Earth network, and addressing both co-design as well as co-production activities. Insights on this process are given in Section 2. The urban practitioners who participated in the activities were informed beforehand about the scope of the process: Rather than developing solutions for the implementation of specific sustainability measures, the aim of the process was to identify co-productively research areas and methods, which support German cities in implementing the SDGs. The approach followed a pre-defined time table which was communicated to the participants. The main outcomes and results of this process are presented and discussed in Section 3. Section 4 highlights our findings concerning what city administration and urban practitioners actually require for SDG implementation from science. Finally, in Section 5, we take a step back and critically assess the potential and pitfalls of the co-design approach we designed in order to identify common principles which facilitate co-design processes on urban SDG implementation.

2. Organization and implementation of the co-design process

In order to identify what city administration and urban practitioners actually need from science in order to implement the SDGs in their respective cities, we were running two German Future Earth activities between the years 2017 and 2019: (a) the so-called Working Group on ‘Urban Sustainability Transformations’ and (b) the Co-design Group ‘SDGs and cities’. The German Future Earth Network (Deutsches Komittee für Nachhaltigkeitsforschung in Future Earth (DKN)) receives funding from the German Research Foundation (DFG), for activities such as conferences and lobbying for sustainability research within the wider German research landscape as well as for establishing Working and Co-design Groups. Between the years 2014 and 2019, the DKN network funded in total ten Working Groups on topics such as Sustainable Work or Social Innovations in energy policymaking, as well as two Co-design groups. Working Groups in the German Future Earth network are research community-driven, temporary, consist of nine members and aim at promoting research in the context of Future Earth topics. Co-design Groups in the German Future Earth Network are established to initiate dialogue between academia and non-academic actors, with the objective to identify the contributions of different actors to a specific sustainability topic in terms of a joint research agenda. This means that the co-design activities have a broader approach and can include different kinds of formats and structures, leading also to co-production activities.

Both groups were concerned with the challenges central for SDG implementation in cities. The Working Group ‘Urban Sustainability Transformations’ as well as the Co-design Group ‘SDGs and cities’ received funding for travelling, catering costs for all participants and the rent for rooms, limited in total to four meetings. In our case, the Co-design Group had only two organising members but the support of the German Future Earth community coordinator. Overall, around 60 participants from academia, municipal authorities, companies and ministries actively took part in the groups. Most of the participants work in Germany and represent therefore the specific German context of urban sustainability transformations.

When first established, the main aim of the Working Group ‘Urban Sustainability Transformations’ was to discuss how science can support the implementation of the SDGs by a new coalition of urban research expertise, bringing together the German urban research community. The work of the group was framed by two questions:

• ■ How can the SDGs be implemented in German cities, and thus contribute to successful transformations towards sustainability?

• ■ What obstacles have to be overcome on the way of German cities towards urban sustainability transformations?

The Co-design Group ‘SDGs and Cities’, on the other hand, first of all aimed at analysing challenges, experiences, success factors and obstacles of previous efforts of sustainable urban development in German cities by bringing voice to the urban actors, and considering science as ‘one voice among others’ (cf. Scholz, Reference Scholz2017, p. 11). This was followed up in order to reveal the current needs of SDG implementation in cities, by learning from the past. The research questions guiding the work of the co-design process are:

• ■ What is the role of science in urban sustainability transformation processes?

• ■ What are possible constraints, but also the potentials of transformative urban research?

The questions of both groups are highly interlinked. This way, the conducted activities and answers to the questions are informing each other and both need an academic and a non-academic perspective. We therefore decided to see the work of both DKN Future Earth groups as a joint effort in pooling resources, capacities, and most of all, co-producing knowledge.

The co-design process we organized hence consisted of different activities, interlinking the findings of the DKN Working and Co-design Group (see Figure 1). Temporally speaking, the DKN Future Earth Working Group started half a year before the Co-design Group, in summer 2017. During the first meeting of the Working Group and based on a survey that was sent to the group members beforehand, an overview of ongoing research activities with relation to urban research on SDGs in Germany was elaborated. What came apparent is that investigations on SDG implementation in cities and the challenges cities are facing in this context are still scarce in Germany. Therefore, during the first meeting, it was decided to focus the work of the group on the challenges of SDG implementation in German cities.

Figure 1. Co-design process.

It was consensus that a merit would be to identify the gaps between the practical needs in cities, existing and usually applied research modes, and research funding options. The necessity to intensively exchange with non-academic actors from urban development practice and planning was highlighted. In accordance, the decision was made that the main work of the group should consist in developing a position paper on the challenges related to SDG implementation in cities and that the hypotheses of this position paper should be validated and further developed by urban practitioners.

This envisaged approach was positively enhanced by the successful application at the German Future Earth Network for a Co-design Group. This opened the possibility to start the foreseen exchange on SDG implementation with non-academic actors and to validate the so far elaborated hypotheses with those actors. Until this moment, a first version of the position paper was already developed, but the hypotheses mainly reflected a scientific view on the challenges, although one of the nine working group members represented the practice-side.

As the first action of the Co-design Group, a stakeholder mapping was conducted to identify relevant actors from multiple levels that have a role to play for SDG implementation in German cities. One of the results of this mapping was that a lot of research as well as work in administration and politics deals with sustainable urban development in general, but only few actors and networks explicitly use an SDG-oriented perspective. We contacted some practitioners working with the SDGs in cities and invited them to join the process, which marked the starting point of the co-design activity.

At the same time, intensive exchange with the city of Bonn took part in order to organize two activities as side events of the 23rd Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC), the COP 23, in Bonn in 2017. We considered this a good opportunity to bring different actors together and to reach a wider audience. The activities we organized were (1) a panel discussion on the challenges of SDG implementation in German cities, and (2) a workshop along experiences of SDG implementation and the kind of urban research needed to support the implementation. This happened in collaboration with the Future Earth Secretariat in Paris, in particular the Urban Knowledge-Action Network (KAN), and opened an international perspective on the topic.

The panel session discussion at the COP 23 was organized with mayors and deputy mayors from the Cities of Bonn, Stuttgart and Augsburg, as well as a representative from the German Institute of Urban Affairs (DIFU). Input was given by a member of the Cities Alliance. All panellists already dealt in different ways with the SDGs and had a broad experience in urban sustainable development in general. The public event was filmed, the presentations translated to English and uploaded on the Youtube Channel of the Future Earth SecretariatFootnote ¹.

The position paper with the hypotheses developed by the Working Group was central to the discussion of the workshop, which took place after the panel discussion. Representatives from German cities and municipalities, planning authorities, ministries, research and planning companies participated. As the workshop's topic was thematically open to all fields of urban transformations, the invited participants represented different areas of expertise including urban and regional water management, community organization, project development, climate adaptation and spatial planning. The participants were mostly working as head of departments or team leaders in their respective work environment. This way, we could ensure that different perspectives were included and the participants had the necessary knowledge of specific processes but at the same time also a strategic perspective. The overall aim of the workshop was to develop jointly ideas on future collaboration foci to support the implementation of the SDGs as part of overall urban sustainability transformations (start of the co-production activity).

The final activity of both DKN Future Earth groups was the so-called Rundgespräch. This Rundgespräch marked the official completion of the two-year work of both groups, and was designed as an open dialogue between academia and different actors concerned with the implementation of SDGs in cities: representatives of municipal administrations and politics, associations, civil society, intermediaries and funding agencies. We invited the latter to the two-half-day meeting of the Rundgespräch, as to discuss funding opportunities and formats to support SDG implementation in cities in a joint effort of academic and non-academic actors. In contrast to the previous activities, the aim of the Rundgespräch was broader: Besides presenting examples of how cities together with academia work in SDG implementation, also issues of funding for urban sustainability transformations research were discussed. During the Rundgespräch, presentations, panel discussions and a world café were organized, bringing in total about 40 people with different backgrounds together (co-production activity). The position paper in its revised state served as the main basis for the discussions. In addition, and in response to a beforehand spread open call for running urban collaboration projects between scientific and non-scientific actors on SDGs in cities, selected representatives from science and practice presented on the strengths and challenges of those projects. The overall limited response rate to the open call for contributions, although intensively advertised through different channels, underpins that concrete projects targeting explicitly on SDG implementation in German cities are still only partial.

At the German Future Earth Conference in 2018, the hypotheses as an important result of the entire process of both DKN Groups were finally presented in order to connect with the broader German and International science community (Schmalzbauer & Visbeck, Reference Schmalzbauer and Visbeck2018). In addition, we authored a report of the COP23 co-design event and published a summary for the newsletter of the KAN Urban in order to inform the international audience on the process and connect with other initiatives from outside Germany.

3. Outcomes of the different activities of the co-design process

As all activities conducted during the co-design process informed each other and led to a step-wise improvement of the hypotheses and the position paper, the outcomes are also step-wise described in the following.

The panel discussion at the COP 23 that was organized with mayors and deputy mayors on the challenges of SDG implementation in German cities revealed that, although considerable progress has been made in the respective cities towards sustainable development (e.g. the transformation of municipalities' public transport system on e-mobility), obstacles still exist. Those obstacles often relate to behavioural inertia of administrations and citizens. One of the issues mentioned is that many citizens oppose measures to reduce individual car traffic especially in a city where car industry companies are major employers. This makes it difficult for politicians to implement such measures. As missing support for transformative political measures is not a new problem at all, the participants of the discussion also drew parallels between the SDGs and the Local Agenda 21. In this context, lessons learned from the challenges and processes of implementing the Local Agenda 21 were considered as helpful: for example, the involvement and engagement of civil society actors and the possibility to deliberate also the economic potential of sustainability measures.

Overall, there was consensus that small-scale measures, with only limited immediate effect, may trigger a broader shift towards more profound sustainability in cities (e.g. in the mobility sector or the increasing use of renewable energy in the housing sector). The panel participants further agreed that the SDGs and the Paris Agreement can help to attract political attention to sustainability. However, SDGs are perceived more as a general framework or guideline than as a concrete action program for cities. Nevertheless, they bear the potential to foster urban sustainability transformations as they address several dimensions of sustainability at the same time. This allows concerted action and simultaneous transformations which can potentially lead to synergy effects. In addition, the participants of the discussion emphasized the importance of city networks. Those networks can play a crucial role in sustainability transformations, because they facilitate the knowledge transfer between cities and help to strengthen cities' roles within the global sustainability discourse.

In the subsequent workshop with eleven representatives from German cities and municipalities, planning authorities, ministries, research and planning companies, the participants were asked to highlight factors driving SDG implementation in cities based on their practical experiences. They mentioned an array of different, partly interrelated factors from which the following three stand out:

1. (1) political will,

2. (2) adequate municipal administration structure which allows integration or action across departments, and

3. (3) engagement of local communities in concrete sustainability projects.

The participants expressed different opinions about the need for changes when it comes to organizational structures of city administration. Some argued that the sectoral structure of German city administrations handicap SDG implementation because integrated actions towards sustainability are hardly possible within these silos. This implies a transformation of the administrative structure in order to achieve local SDG implementation. Other participants were less pessimistic and highlighted the progress made in SDG implementation and sustainability action, which was already realized within and through the existing administrative bodies of the respective cities or communities. In addition, the participants also emphasized the need to differentiate between SDG implementation in smaller and bigger cities. The organizational structure of bigger cities often consists of administrative units specifically dedicated to and responsible for sustainability and environmental issues. In contrast, smaller cities often do not have comparable structures and much of the work on sustainability is done in part-time or in voluntary work. Therefore, especially smaller cities have difficulties to capture the complexity of the SDGs and to assign responsibility to administrative units for leading the process of SDG implementation.

Both the panel discussion and the workshop helped to ‘practice check’ the hypotheses developed by the DKN Working Group. This ‘practice check’ underpinned that the emerging challenges of SDG implementation at the local level can only be informed by and addressed through intensive discussion and insights from urban practice. Thus, the final decision is a political one. Based on the insights from the co-design activities, the Working Group revised the original hypotheses and discussed them during the next group meeting.

As a result of these discussions, the group adjusted the position paper and identified four main hypotheses, which are presented here in their final wording (whereas hypothesis 4, as presented here, includes some additional explanation) agreed on:

1. (1) Sustainability as a cross-cutting issue in cities and communities calls for additional resources in order to fulfil the necessary integration and coordination.

2. (2) The participation process of different actors is among the major challenges, and it is crucial to find the right level and mechanism of participation to steer decision processes effectively.

3. (3) Local and practical framings need to be accepted, which calls for continuous and binding collaboration with urban stakeholders, and the importance to define the merit of the collaboration clearly.

4. (4) If adequate research funding programs are in place, science can support cities in their efforts to implement the SDGs. Here, Urban Living Labs or Real-World Laboratories are offering the possibility for experimenting and testing. Nevertheless, those Labs can only serve to support co-design and co-production for implementing the SDGs towards urban sustainability transformations but do not presenting a goal themselves.

From the final Rundgespräch, it became again clear that public participation is very crucial for SDG implementation in cities, even though the simultaneous involvement of all population groups can complicate implementation processes. It was stressed in the discussions that to foster synergies and to facilitate the implementation of the SDGs, collaboration with existing sustainability activities at the urban level should be followed up, such as climate protection or the still ongoing Local Agenda 21 processes. Networks to exchange ideas and best practices on urban sustainability are crucial as well. Although sustainability as a topic and target was considered to be of high importance for all institutions involved in the workshop discussion, only a few represented cities yet directly refer to the SDGs. The majority of the participants indicated that they defined their own, independent sustainability targets.

Participants of the Rundgespräch differed in their opinion concerning the kind of knowledge needed to successfully implement the SDGs. While some participants flagged specific research gaps (e.g. the degree of sealed surfaces in cities), others felt that there is no longer any thematic research gap in terms of how to address sustainability issues, and which would call for scientific analyses. Thus, overall, the discussion revealed that more knowledge on the process of implementing the SDGs is required, as well as more specifically, knowledge on evaluation mechanisms, the interdependencies between different sustainability targets and associated to this, on the interlinked processes. Here, academics can play an important role in working on the issues. It was also pointed out that so far scientific research on the urban dimension of the SDGs predominantly focuses on bigger cities. However, the German settlement structure mainly consists of small to middle-sized towns, which means that the specifics of these smaller-scale urban areas should also be considered in urban SDG research.

This way, the various discussions of the Rundgespräch again validated the hypotheses developed so far and brought further insights to the challenges of SDG implementation in cities: the process itself, the intensity of participation, indicators and data. From city representatives' point of view, it is particularly the high requirement to deal with cross-cutting issues, such as sustainability, that challenges administrations; nevertheless, it is politics that is often lacking behind administration. Already strong cities are gaining currency, which leads to an increase of disparities between cities. Here, as discussed as part of the co-production activity, adequate funding opportunities might be of help, if developed in a way that they also support the exchange between cities, at national and international level. Overall, different stakeholders stressed that new governance structures already reveal around power, lobbyism and the role of economic enterprises in SDG implementation. Thus, SDGs are rather seen as an opportunity than a threat and there is consensus that the newly evolving dynamics for sustainability should be taken up.

5. Lessons learnt? Potentials and pitfalls of co-design processes

Based on the experiences with the co-design process organized by the German Future Earth Working Group and the Co-design Group, we conclude by critically looking at the process as well as its outcomes and achievements. One of the specifics of our co-design approach was its wide scope. Instead of a clearly identifiable urban development problem, the topic of the co-design process was more fuzzy, asking about SDG implementation and the role of science, based on the needs and challenges identified by practitioners. With the following subsections, we aim at contributing to the evaluation of challenges and benefits of co-design processes, particularly looking at factors which facilitate a successful implementation of co-design processes with a wider scope. Organizational, structural as well as content- and impact-related issues of the conducted process are reflected.