Breaking Silos: A Systemic Portfolio Approach and Digital Tool for Collaborative Urban Decarbonisation

Abstract

Urban decarbonisation requires governance models that overcome the fragmentation and rigidity of traditional urban planning. This article presents a systemic and digital framework for managing urban decarbonisation portfolios aligned with the EU Mission for Climate-Neutral and Smart Cities. Grounded in systems thinking and portfolio theory, this study develops an analytical taxonomy and an interactive digital tool to support strategic coordination, multistakeholder collaboration, and adaptive decision-making. The framework is empirically validated through the case of Madrid’s Climate City Contract, demonstrating its functionality and transferability. Using a mixed-method approach—combining co-creation workshops, interviews, document analysis, and iterative prototyping—this research maps interdependencies among projects, actors, and levers of change. The digital tool enables real-time visualisation of collaboration patterns, gaps, and synergies, enhancing strategic foresight and coordination capacity. Findings reveal that 75% of initiatives in Madrid’s CCC address climate adaptation, 80.36% are linked to knowledge generation, and key anchor projects serve as integrative hubs within the portfolio. This study concludes that the portfolio approach strengthens systemic innovation and reflexive governance by integrating digital infrastructures with collaborative planning processes. While challenges persist—including data integration, institutional capacity, and political dynamics—this research offers a replicable methodology for embedding mission-oriented strategies into urban governance. The digital portfolio emerges as a complementary governance tool that enhances transparency, organisational learning, and alignment across governance levels.

1. Introduction

Operationalising Mission-oriented innovation [1,2] and governing the transition towards urban decarbonisation present an unprecedented and complex challenge overall for local governments [3,4], which are often constrained by rigid administrative structures grounded in sectoral hierarchies and fragmented governance stemming from the fact that responsibility for climate action is distributed across several municipal departments, each operating under different mandates, priorities, and procedures—thereby making coordination and decision-making particularly difficult [2].

While urban climate governance has produced high-level policy recommendations, few contributions have provided tactical frameworks capable of integrating these efforts into operational systemic strategies [5,6]. In addition, recent studies highlight that focusing solely on carbon reduction targets can obscure deeper systemic impacts—such as distributional equity, procedural justice, health, or ecological regeneration—central to building resilient, inclusive, and legitimate urban futures [7,8,9,10]. Therefore, overcoming this complexity requires going beyond traditional urban planning instruments by embracing collaborative and learning-based approaches with digital tools that could offer opportunities to accelerate coordination, enhance integration, and support more adaptive decision-making [11,12].

In response to this growing demand for innovative planning models and practical management tools to support resilient, just, and low-carbon cities, the European Union (EU) launched the European Mission for Climate-Neutral and Smart Cities by 2030 in 2021 as a flagship programme to place innovation at the heart of cities’ green and digital transition [1,13]. Through the Climate City Contract (CCC)—the central process and document of the Cities Mission—participating cities develop a city agreement aimed at collaboratively advancing transformative action towards climate neutrality [1]. Each city has drafted its CCC following a common structure intended to standardise the principal projects, actions, and efforts undertaken by the cities [1,13]. Despite this effort, internal coordination remains a challenge—both among municipal departments and between city-level organisations—as does inter-city collaboration within the Mission. These gaps hinder the development of a shared learning community with the capacity to accelerate the transition towards just and carbon-neutral cities.

To address this challenge, this research is guided by the following question: How can a systemic portfolio-based digital tool enhance the strategic coordination and collaborative governance of climate actions in complex urban ecosystems? In doing so, this research aims to contribute to the operationalisation of mission-oriented innovation by developing and empirically testing a framework that integrates systems thinking, portfolio management theory, and digital planning tools. Although portfolio approaches have been examined by many organisations at the level of conceptual frameworks or thematic groupings, this study takes a tactical–operational step forward. It generates and translates a taxonomy into an interactive systemic mapping tool and tests it on a real case—the Madrid CCC—allowing us to visualise interdependencies, identify gaps and synergies, and foster cross-sector coordination.

By applying systems thinking to a portfolio-based approach, this research proposes an alternative “second operating system” [14] that could complement and enhance conventional urban planning by enabling local governments to coordinate diverse projects under a shared strategic vision, foster collaborative practices, and activate public capabilities for transformative urban futures.

This research adopts a mixed-method, case study methodology [15,16], and action-oriented approach [17,18,19], combining a state-of-the-art review on portfolio-based approaches in climate innovation projects with the development of an analytical taxonomy tailored explicitly to the EU Cities Mission. The taxonomy contributes to the establishment of a common framework by identifying and systematising key variables extracted from actions and projects documented in technical materials and strategic plans from both municipal and non-municipal sources, thereby supporting a structured approach to systemic portfolio management. Building on this foundation, a digital tool is created to operationalise and test the proposed operational framework. As an empirical application, the digital tool was implemented in Madrid’s CCC [20], serving as a case study to assess its functionality and practical relevance. The digital tool is designed to be transferable to other cities participating in the EU Cities Mission, providing a replicable framework for integrating the portfolio approach into local climate planning and governance processes.

Compared to existing portfolio-based frameworks, this study contributes three specific advances: (1) it develops a refined systemic taxonomy tailored to the governance structures of EU CCCs, which includes dimensions such as levers of change, experimentation areas, and actor ecosystems; (2) it translates this taxonomy into a digital, interactive, open-source tool, enabling real-time mapping of portfolio interdependencies; and (3) it empirically validates this operationalisation through iterative testing and co-creation with Madrid city officials and organisations involved in the EU Mission. This represents a methodological and practical step forward in supporting municipal governments to implement dynamic, learning-oriented, and mission-driven planning.

This research is structured as follows: after the introduction, Section 2 depicts the theoretical foundations of the portfolio approach and its relevance for managing complexity, collaboration, and systemic innovation in urban decarbonisation. Section 3 presents the materials and methods, including the case study of Madrid’s CCC and the methodological process for developing the systemic taxonomy and the digital tool. Section 4 describes the results of operationalising the systemic portfolio through the digital tool, detailing its architecture, variables, application to Madrid’s portfolio, and the collaboration patterns identified. Section 5 critically discusses the emerging benefits, limitations, and collaboration dynamics revealed by the tool and reflects on their implications for governance and policy. Finally, Section 6 presents the main conclusions and suggests directions for future research and practice.

2. From Scarcity to Abundance: A Systemic Portfolio Approach to Urban Decarbonisation

2.1. Abundance Management as a Driver of Climate Innovation in Cities

In the current context of innovation and technological development, the way societies and cities address climate challenges is increasingly linked to the abundance of knowledge and resources rather than the scarcity agendas that dominated economic paradigms for much of the twentieth century [21]. Open access to vast information networks has created a promising scenario where cities can develop and scale urban solutions, fostering more resilient and adaptive governance models [2,3]. Technology and connectivity play a pivotal role in facilitating access to these abundant resources, accelerating innovation and maximising its transformative potential [4]. This setting challenges traditional scarcity-centred paradigms and highlights the need to manage abundance as both an efficiency strategy and a key driver of innovation [18,19].

Abundance management refers to the strategic organisation, allocation, and optimisation of existing resources to generate systemic value [22,23]. It entails adopting a new perspective on human, knowledge-based, ecological, and technical resources and managing them more efficiently and collectively [22]. Unlike traditional resource management—focused primarily on scarcity and cost-efficiency—abundance management prioritises connectivity, innovation, and redistribution as mechanisms to foster creativity, entrepreneurship, and collaboration [3,24,25]. Such an approach reinforces calls for more justice-sensitive urban climate governance, in which abundance is not only about efficiency or innovation but about revealing and redistributing socio-ecological resources—often marginalised in carbon-centric metrics—to support health, accessibility, social cohesion, and ecological integrity at the neighbourhood scale [7,8,9,10]. Therefore, abundance management opens up a promising opportunity to address global challenges by enabling individuals and organisations to concentrate on shared goals, optimise resource use, and capitalise on collective knowledge, thereby fostering an environment conducive to inclusive and sustainable innovation [24].

Despite its potential, abundance management faces significant institutional barriers. The prevailing paradigm—centred on scarcity—is reflected in public management models prioritising stability, procedural adherence, and regulatory compliance over innovation [2]. Public administration remains rigid and fragmented, with responsibilities dispersed across sectoral hierarchies and multiple departments operating under distinct mandates, priorities, and procedures [2]. While such structures ensure consistency and accountability, they are also resistant to change, creating an inherent tension between the need for standardisation and the innovation potential [26]. This fragmentation limits the capacity of local governments to explore complementary strategies that could accelerate innovation efforts. As regulations proliferate and governance structures become increasingly compartmentalised and hierarchical, the room for municipal staff to innovate within city management processes and proposals becomes progressively constrained [27,28].

European policy agendas have acknowledged this structural weakness in public management, which advocates for the concept of the “entrepreneurial state” [29]. This perspective has led to a growing implementation of urban experimentation initiatives across Europe, exemplified by strategies and actions such as Copenhagen’s Climate Resilient Neighbourhoods, Vienna’s ‘Wien 2030’ strategy, and Helsinki’s urban labs, among others. However, such experimental approaches often remain confined to a “niche” and face considerable challenges in achieving mainstream adoption—mainly due to their multidisciplinary nature [30,31], the difficulties of scaling without being co-opted [32,33], and the demands of deep multistakeholder collaboration [34]. In this regard, Charles Handy introduces the concept of the “second curve” [14], representing an alternative operating system to the dominant paradigm. This approach suggests that to avoid stagnation and obsolescence, organisations must adopt complementary strategies that enable them to evolve towards higher levels of complexity, supporting a transition towards more resilient and adaptive models [14]. In this sense, complementary strategies are needed to foster more decentralised and coordinated management approaches capable of integrating diverse actors and initiatives, facilitating cross-sectoral collaboration, and enabling adaptive, systemic responses to complex urban challenges.

2.2. A Systemic Portfolio Framework for Climate Action and Sustainable Urban Transformation

The concept of the portfolio as an organisational and management approach originated in the mid-20th century [35]. It was initially rooted in finance as a theory designed to balance risk and return through asset diversification and later gained prominence in the business sector as a strategy for optimising resource allocation and coordinating multiple projects [35,36,37]. As the portfolio approach has evolved, it has given rise to increasingly dynamic and adaptive models capable of responding to complex challenges and structural transformations [25].

The portfolio approach in the field of climate systems innovation has been increasingly implemented as a strategic framework to manage interconnected initiatives that simultaneously address climate challenges [38,39]. It serves as an integrative, multistakeholder, and multilevel mechanism to coordinate diverse climate actions and projects under shared objectives [25,40,41]. This approach has been embraced by several international organisations, which have developed various applications of the portfolio approach. For example, EIT Climate-KIC applies it to organise and manage its funded projects [42], itdUPM and Dark Matter Labs have implemented it through the Madrid Deep Demonstration initiative [43], Vinnova and Viable Cities have adopted the approach to support the implementation of European Missions in Sweden [44], the UNDP applies it in systemic transformation projects [45], and ICLEI applies it in a sectoral manner within the EU Mission [46]. These examples highlight its emphasis on climate action experimentations supporting the exploration of novel and uncertain pathways within multistakeholder ecosystems, fostering continuous learning and enhancing adaptive capacity in the face of climate uncertainty [44,47,48,49,50,51]. In contrast to conventional sectoral approaches, the portfolio approach adopts a systemic perspective, enabling the identification of synergies across projects and emerging insights [45,52] and the activation of multiple levers of change [49].

Multistakeholder and multidisciplinary collaboration is central to the portfolio approach, fostering the creation of dynamic ecosystems where continuous learning reinforces collective knowledge and a shared sense of purpose [53,54,55,56]. By distributing responsibilities and risks among diverse actors [37,48,49], the collaborative ecosystem also facilitates the establishment of governance mechanisms that promote coherence and consistency in implementing public policies [52].

Nevertheless, the portfolio approach is not without challenges. Diverging interests, power asymmetries, and coordination difficulties may hinder its effectiveness, particularly in multistakeholder contexts where actors operate under different mandates, incentives, and accountability structures [34,37,48,49,53]. Institutional inertia and bureaucratic rigidity can further constrain the adoption of systemic approaches, while power imbalances risk undermining equitable participation and collaborative decision-making [29,56]. Addressing these challenges requires designing governance structures that foster inclusivity, transparency, and trust [34,50]. Facilitation mechanisms are essential to mediate interests, bridge institutional silos, and sustain cross-sector collaboration [57,58]. Conflict-resolution strategies must also be embedded to navigate disagreements and ensure the meaningful integration of diverse perspectives into portfolio management processes [34].

The portfolio approach, therefore, holds strong potential to complement—rather than replace—traditional public management tools. It could act as a “second operating system”, offering a systemic view that enhances cities’ ability to navigate complexity and harness abundant available resources and knowledge.

3. Materials and Methods

3.1. Materials: Case Study of the Madrid CCC

In September 2021, the European Commission launched the Climate-Neutral and Smart Cities Mission (Cities Mission), one of the EU’s key instruments for advancing cities’ green and digital transition through innovation [13]. The Cities Mission seeks to transform cities into hubs of experimentation and innovation for decarbonisation by engaging administrations, businesses, researchers, investors, and citizens [59]. In April 2022, 112 cities were selected to begin this process by drafting their CCCs—a city agreement and governance innovation tool designed to drive transformative action towards climate neutrality collaboratively. Each CCC comprises three components: (1) political and multistakeholder commitments, (2) the Climate Action Plan (CAP), and (3) the Climate Investment Plan (CIP) [59]. Together, these components are intended to provide a shared analytical framework that enables all Mission Cities to structure their climate strategies in a coherent, comparable, and coordinated manner, aligning political will, action pathways, and financial planning [1,40].

By May 2025, 102 cities had submitted their CCCs, with 92 receiving the EU Mission Label, recognising their commitment and the quality of their proposed actions [60]. The label aims to attract investment for CAP implementation and foster multistakeholder collaboration, promoting coordinated efforts across sectors and governance levels. Within this framework, the CAPs represent an opportunity to align actors, organisations, projects, and resources under a systemic vision that transcends traditional sectoral approaches.

Madrid reflects this approach in its CCC through the “Citizens of the Future” experimentation area, aimed at fostering a climate culture across its 250 public schools and 6.5 km² of public university campuses [20,61,62]. This experimentation area integrates complementary urban strategies and policies, including Madrid + Natural [63], the Roadmap to Climate Neutrality 2050 [62], Madrid 360 [64], the IV Plan for Children and Adolescents [65], the Sustainable Mobility Ordinance [66], and the city’s school environment strategy [67]. In the same line, in October 2024 Madrid City Council and three public universities signed bilateral agreements to transform university campuses into platforms for urban experimentation [68,69,70]. These agreements foster interdisciplinary research on climate adaptation and mitigation, facilitate knowledge transfer, and engage the university community and citizens. Research focuses on climate shelters, energy efficiency in buildings, identifying opportunity areas within campuses, health protection under climate change, urban landscape management, and carbon sequestration. Together, these efforts integrate academia and society, linking research to broader social and environmental challenges in the fight against climate change [68,69,70].

Madrid’s CCC includes 14 municipal projects, such as STARS, which promotes active commuting among students; CLEVER Cities, which creates several green corridors; LIFE PACT, which naturalises playgrounds with community participation; and URBREATH, which develops digital tools to promote participatory urban processes (Appendix A: List of the projects of the Climate City Contract of Madrid). Collectively, these projects address climate and social challenges by integrating innovative, collaborative, and adaptive solutions in school and university environments.

3.2. Methods

The case study was adopted as the main methodological approach of this research, given its value for analysing complex social phenomena where cause-and-effect relationships are not readily observable and are strongly shaped by context [15,16]. The case study is considered particularly suitable for theory-building in emerging fields, as it identifies and articulates relevant variables and mechanisms based on empirical observation [71].

This research combines qualitative data to inform both the development of a systemic taxonomy and the design of a digital portfolio tool. The process followed an iterative cycle of empirical data collection, conceptual modelling, and tool prototyping, ensuring alignment with real-world governance contexts and practitioner insights. Qualitative data were gathered through semi-structured interviews, workshops that served as feedback focus groups, and a review of relevant documents. A total of 11 semi-structured interviews were carried out with public officials from Madrid City Council directly involved in the CCC process, with a member of the Spanish national platform supporting Cities Mission implementation, and with a representative of the European NetZeroCities project (NZC). These interviews explored governance dynamics, technical challenges, and expectations surrounding digital tools for interdepartmental and inter-city coordination. Additionally, a co-design workshop was held with 22 municipal technicians through the Official School for City officials of the Madrid City Council (Escuela de Formación Continua del Ayuntamiento de Madrid), where the initial taxonomy and tool interface were tested, discussed, and refined. Over 20 documentary sources—including CCC drafts, project fiches, funding calls, and internal policy reports—were reviewed to extract structural features, strategic priorities, and emerging patterns across climate portfolios. The documentary review enabled the construction of a relational database, classifying more than 100 projects and associated actors according to the dimensions of the taxonomy. This facilitated a structural mapping of systemic levers, experimentation domains, actor roles, and governance arrangements.

Triangulation was achieved through iterative integration of the different data sources: (i) interview insights helped interpret gaps in the documentary analysis and identify unarticulated connections; (ii) workshop feedback informed modifications to the taxonomy; and (iii) the modelling uncovered structural patterns that shaped the tool’s visualisation and filtering logic. This methodological approach ensured that both the taxonomy and the digital interface were not preconfigured abstractions but emerged from grounded institutional knowledge and multilevel practitioner engagement.

The choice to conduct the analysis on a single case study does not undermine its validity, because the framework and digital tool were validated through a multi-level process: first, at the local level, with Madrid municipal officers, and at the European level, through feedback from NZC experts. These interactions helped refine and adapt the taxonomy and tool, ensuring their usability and transferability beyond Madrid.

This study was conducted by three researchers, including one who directly participated in drafting the Madrid CCC and in the design and implementation of the Collaborative Platform for Climate Neutrality in Spanish Cities in the framework of the Cities Mission. The municipal technical team responsible for the Madrid CCC reviewed the results, discussion, and conclusions, enriching the analysis and enhancing its practical relevance [71]. This collaboration contributed to ensuring the applicability of the portfolio approach within municipal planning tools and offered valuable insights into its integration within local governance processes.

Building on these premises, the methodological process of this research was structured into three interconnected phases aimed at exploring, operationalising, and evaluating a systemic, portfolio-based digital tool, as illustrated in Figure 1 and detailed below:

• Phase 1|Analytic taxonomy: This first phase aimed to develop a robust taxonomy capable of enabling a systemic analysis of CCCs. The materials used included a comprehensive review of the academic literature on portfolio management, systems thinking, and mission-oriented innovation policies, as well as technical documents, strategic plans, institutional reports, and other documentation related to the structure of CCCs. The process involved extracting key concepts and attributes from these sources to identify the relevant components in unpacking urban decarbonisation projects. Importantly, the analytical taxonomy builds-in some variables already embedded within the CCC structure, particularly in the CAP. This analysis was complemented by focus group sessions with 22 municipal technicians from various departments of Madrid City Council (Appendix B: List of officials participating in the workshop on taxonomy and digital tools), allowing the taxonomy to be validated and refined through practitioner insights. As a result, a taxonomy was developed to classify projects into categories according to a defined set of variables.
• Phase 2|Digital tool design: The objective of the second phase was to translate the analytical taxonomy into an operational, interactive digital tool that could support local governments in coordinating and managing the project portfolios within their CCCs. The process involved coding the taxonomy—developed in Phase 1—into a digital tool using an open-source platform, enabling the visualisation, classification, and mapping of projects based on their systemic attributes (Appendix C: Programming code of the digital tool). Throughout the design process, iterative validation was carried out through interviews and co-creation sessions with municipal staff and other organisations involved in the Cities Mission (Appendix D: List of interviewees for feedback on the digital tool), ensuring that the tool’s functionalities, interface, and data structure aligned with the operational needs and governance challenges identified by practitioners. The result was a digital tool that provides a user-friendly interface for navigating the portfolio, offering real-time visualisations and relational maps.
• Phase 3|Madrid CCC case study: The objective of the third phase was to apply the digital tool to the portfolio of projects included in Madrid’s CCC to test its functionality and evaluate its practical utility in a real governance context. The materials used in this phase consisted of the full dataset of projects and initiatives comprising Madrid’s CCC, complemented by feedback and documentation from the municipal staff (Appendix A: List of the projects of the Climate City Contract of Madrid). The process involved loading the CCC portfolio data into the digital tool, configuring it according to the taxonomy, and conducting iterative testing to refine its outputs. Additional feedback was gathered through co-creation and validation sessions with municipal technical staff to assess the tool’s capacity to facilitate coordination, improve information integration, and support decision-making. This process was carried out in six steps.

  (1)

  Identification of CCC Initiatives|CCC initiatives were identified and selected, covering both municipal and collaborative projects at various stages of development.

  (2)

  Definition of tabular structure|A tabular structure was defined to clearly distinguish between components, subcomponents, and responsible organisations, assigning a unique label and entity type to each entry.

  (3)

  Manual coding using the taxonomy|Each initiative was manually coded based on the previously developed taxonomy, including experimentation area, associated umbrella project, development stage, involved sectors, activated systemic levers, and strategic orientation.

  (4)

  Integration of relational data|Relational data was incorporated by linking each project and actor to other elements through connections, enabling the identification of collaboration patterns, overlaps, and synergies.

  (5)

  Validation through triangulation|The resulting matrix was reviewed and validated through triangulation with official CCC documents, interviews with public officials, and co-creation workshops with municipal staff.

  (6)

  Upload to digital tool|The matrix is uploaded into the digital tool, which already integrates the necessary code for data processing and visualisation.

The result was a tested systemic portfolio within a collaborative digital tool, validated by practitioners, which enabled the mapping of the Madrid CCC portfolio, the identification of synergies and gaps, and the visualisation of connections between projects, actors, and strategies.

4. Results

This section presents the results of operationalising the systemic portfolio approach through the digital tool based on the analytical taxonomy and its application to the Madrid CCC. The taxonomy serves as the conceptual backbone of the tool, providing a structured framework. Once the programming code based on the taxonomy is established, the digital tool enables interactive portfolio exploration, allowing users to visualise relationships, identify synergies, and analyse connections between projects and actors.

4.1. Operationalising the Systemic Portfolio Through a Digital Tool

The digital tool was designed as an interactive, collaborative digital platform to facilitate the participation and inclusion of diverse actors across the urban system (https://embed.kumu.io/8f3d5c4648af530e990531ff0f4fdeb9, accessed on 30 May 2025). It was developed using KUMU (kumu.io), an open-source platform that enables the creation of dynamic, visually engaging connection maps, categorising elements, and embedding descriptive content within network nodes and connections (Appendix C: Programming code of the digital tool).

The visualisation interface of the digital tool is organised into two main sections, as illustrated in Figure 2. On the left, fact sheets provide detailed information about each element and connection, including their attributes (based on the analytical taxonomy), objectives, progress status, and the actors involved. On the right, the interactive portfolio map displays relationships across the five rings, dynamically processing data on components, subcomponents, and actors. In systems thinking, these relationships are understood through multiple theoretical lenses that describe their directionality and relational dynamics, which were subsequently integrated into the design of the digital tool. Complex systems theory [72] and hierarchical systems theory [73] differentiate between unidirectional and bidirectional interactions. Unidirectional connections indicate that one element influences another without feedback, while bidirectional connections represent mutual exchange and reciprocity. Interdependence theory [74] further classifies interactions as sequential (unidirectional), reciprocal (bidirectional), or group interactions (feedback loops). Additionally, frameworks of collaborative value creation [75,76] propose a “collaboration continuum”, where relationships evolve from transactional (low-commitment, limited resource-sharing, primarily functional value) to transformational (high-commitment interactions involving deep resource-sharing and co-creation), fostering innovation and systemic change both within and across organisations [75].

The taxonomy developed in the research underpinning the visual logic of the interface is structured around five concentric rings that represent the systemic organisation of the portfolio (Figure 3). Each ring corresponds to a distinct analytical variable—ranging from the ecosystem of actors to specific climate actions—enabling a multidimensional understanding of the interactions among projects, stakeholders, and strategic levers across different levels. The rings are described as follows:

• 1st ring|Ecosystem: These are all the portfolio’s stakeholders working on climate actions and projects. The Quintuple Helix Innovation model is a feasible theoretical framework for this field [53,56]. This model proposes the exchange of knowledge between actors in the multistakeholder ecosystem divided into five systems: the political system (governments, city councils, ministries, etc.), the economic system (companies, startups, corporations, etc.), the academic system (schools, universities, technology centres, etc.), the media-based and culture-based system (civil society, citizens, media, artists, etc.) and the environmental system [53,56,77]. This framework is a transdisciplinary model where all five helixes feedback into continuous flows of knowledge inputs and outputs [53,56].
• 2nd ring|Levers of change: This is a framework for designing, monitoring and understanding interventions in complex systems [78,79]. This concept stems from the theory of “leverage points” developed by Donella Meadows, which defines them as places in a complex system where a small change can produce significant changes in the whole [79]. This concept allows for analysis beyond thematic or sectorial lines. In the Cities Mission context, levers of change are the cross-cutting axes of the city needed to trigger profound changes in a multisectoral manner to reduce CO₂ emissions. To this end, the Cities Mission integrates technology and infrastructure, governance and policy, social innovation, participation and democracy, financing, and learning as levers for change [80]. While this grouping interweaves different socio-technical axes, its anthropocentric character (human-centred) still dominates the analysis. It is therefore important to integrate more eco-centric approaches (ecosystem-centred) that refocus attention on the many examples of abundance. In this sense, urban commons serve as an analytical framework, a collective resource governance strategy, and an organisational model based on collaboration [81,82], aligning with levers of change. Their relevance has grown amid the climate crisis, revealing the deep link between ecological issues and dominant social structures [82]. In the portfolio approach, the urban commons can be integrated as systemic levers, opening up a broad spectrum of possibilities from an anthropocentric to a complementary eco-centric approach. Hence, the research proposes a binary analysis system characterised by both visions, defining seven systemic levers: economy (monetary and non-monetary), ecology (human-centred and non-human-centred), infrastructures (material and social; technological and natural), knowledge (formal and experiential), location (based on territorial conditions, and based on social conditions), social status (based on the narrative of the upper/cosmopolitan classes, and based on the narrative of the middle and working classes), and governance (top-down, and bottom-up).
• 3rd ring|Experimentation areas: These are the specific strategies in which the portfolio is implemented to explore and understand how innovation can facilitate transformation processes. These experimentation areas allow for identifying the most suitable contexts for designing, testing, and implementing projects or experiments, providing key information on their feasibility, impact, and scalability [83]. The problem owner—represented by local authorities responsible for designing strategies and public policies that reflect societal needs [48,50]—should define the scope and boundaries of these experimentation areas [38,83]. Rather than adopting a hierarchical or top-down approach, these areas should be co-designed through collaborative, multistakeholder processes grounded in observational data collection and ethnographic analysis [44,50]. The experimentation areas integrate a series of urban experiments that allow different actors to creatively and iteratively test sustainable solutions within various domains (from technical solutions, tools, and services to innovations in public policies), allowing them to induce change in a controlled manner, evaluate, communicate, and learn [12,83,84,85].
• 4th and 5th rings|Components: The fourth ring comprises the projects, while the fifth ring contains the climate actions embedded within those projects, representing the portfolio’s core components. The “climate action” constitutes the minimum unit of analysis within the portfolio. Both projects and actions are explicitly designed to align with the levers of change and experimentation areas, embedding these attributes as intrinsic characteristics that guide their function, connection, and contribution within the systemic portfolio. In addition to these attributes, the components also exhibit the following key variables:
  • Level of development: The portfolio should depict and facilitate the analysis of the evolution over time of the city’s climate actions. Therefore, it should not only be composed of projects under-development but also integrate knowledge from previous experiences and projects under-study. In this way, the portfolio can create continuous knowledge flows based on the abundance of the city’s knowledge [77]. The portfolio should also integrate projects identified as necessary for the city but not yet being studied or developed by the ecosystem of actors. These projects would allow the ecosystem to identify new themes of interest and redirect the actions of existing projects towards them.
  • Sectors: The sectoral character of the portfolio components—in the context of the Cities Mission—is shaped by their CO₂ abatement potential. NZC designed and implemented an economic model for decarbonisation integrated into the CAP [86]. This economic model stands out for its ability to quantify scope 1 and 2 CO₂ emissions and analyse the emission reduction potential of the five sectors—transport, buildings, energy, waste, and industry—which account for more than 90% of emissions [86]. The division of European Missions between mitigation (Cities Mission) and adaptation (Adaptation Mission) has led this tool to exclude adaptation measures in the accounting of the economic model. However, cities have incorporated adaptation projects and actions in their respective CCCs, so this research integrates actions linked to climate change adaptation as a key sector of the portfolio.
  • Orientation: The portfolio addresses complex urban challenges that require clear direction to drive systemic change [38,83]. This orientation should guide the ecosystem toward achieving the shared mission while simultaneously fostering continuous improvement, anticipation of emerging challenges, and the creation of spaces for reflection and adaptation in uncertain contexts. To support this approach, the OECD offers a balanced categorisation for orienting urban innovation [50,51], recognising the need for initiatives that are not only relevant in the short term but also contribute to long-term resilience and adaptive capacity in the face of future challenges [50]. In this sense, four categories of orientation are identified: (1) improvement-oriented, focused on enhancing current conditions by optimising resources, reducing costs, connecting knowledge, and integrating infrastructures and skills [84]; (2) adaptive, geared toward responding to rapid changes or crises through flexible organisational structures, decentralised governance, and environments that enable experimentation, reflection, and continuous learning [44,46]; (3) Mission-driven, focused on tackling grand societal and environmental challenges beyond the reach of traditional policy and governance systems [44], such as achieving climate neutrality by 2030 and fostering inclusivity [21]; and (4) anticipatory, aimed at embracing complexity and uncertainty by anticipating and acting on emerging futures, implemented through foresight practices that translate future visions into actionable strategies and evaluation mechanisms [84,87,88].

Based on the taxonomy, the digital tool incorporates a series of interactive controls located at the top-left of the interface, enabling users to explore and filter connections between the portfolio’s variables (Figure 4a–g). It also includes a keyword search function to facilitate targeted navigation of the portfolio (Figure 4h). Additionally, the tool allows users to trace first-level (direct), second-level (via an intermediate node), and third-level (via two intermediate nodes) connections, making it possible to identify indirect links and hidden relational pathways within the portfolio (Figure 5a–c). This layered connectivity model offers a powerful analytical advantage by revealing not only the explicit structure of interactions, but also the underlying patterns of influence and mediation that shape the functioning of the portfolio. Figure 5a displays the first-level connections of a selected component—typically a tractor project or core initiative—highlighting its immediate ties to relevant actors (positioned in the first ring), the levers of change it activates (second ring), and the experimentation areas it contributes to (third ring). This view outlines the direct ecosystem of design and implementation, facilitating the identification of lead organisations, operative alliances, and the strategic intent of each project. Figure 5b expands this perspective by tracing second-level connections, uncovering how an initiative is indirectly linked to other variables of the portfolio through shared intermediaries. For example, a project may be indirectly connected to a sector or actor it does not interact with directly but that is reached through a common lever of change or experimentation area. This intermediate layer reveals the functional redundancies and interdependencies between initiatives, helping detect clusters of influence and opportunities for cross-learning. Figure 5c further deepens the analysis by including third-level connections, which visualise extended pathways of association across the portfolio through two or more intermediaries. This enables users to detect latent linkages that may otherwise remain invisible, and to anticipate the systemic ripple effects of changes introduced in a particular initiative.

4.2. Mapping and Analysing the Madrid CCC Portfolio: Insights from the Digital Tool

The analysis of Madrid’s CCC portfolio, conducted through the digital tool, identified 14 core components (projects) and 42 sub-components (actions) implemented by a network of 47 actors (32 organisations and 15 teams belonging to 5 organisations). The ecosystem is distributed as follows: 8.51% from the political system, 17.02% from the economic system, 44.68% from the media and culture-based system, and 29.79% from the academic system. Although the political system exhibits the lowest percentage of actor representation, it plays a pivotal role in connectivity: the Madrid City Council (political system) emerges as the central node, establishing 37 direct connections with components and sub-components, followed by itdUPM (academic system), with 35 connections. Together, these two institutions are linked to over 76% of the total initiatives in the portfolio, underscoring their strategic importance in interlinking governance, knowledge, and implementation. These findings highlight which organisations act as key knowledge brokers and intermediaries, facilitating the flow of information, collaboration, and alignment across initiatives and stakeholders [89,90,91].

In terms of level of development, the portfolio reveals that 30.36% of components and sub-components are under development, and 19.64% are under study. Focusing only on active projects, 39.29% are under study, while 60.71% are actively under development. Additionally, the portfolio includes 27 initiatives already implemented (48.21%), while only 1.79% are classified as necessary but not yet initiated. This indicates a relatively low implementation gap and a high rate of activation within the proposed actions. A sectoral analysis shows that 75% of initiatives address climate change adaptation, followed by 58.93% linked to buildings, 42.86% to energy, 37.5% to transport, 30.36% to waste management, and 26.79% to industry. On average, each initiative engages with at least 3.7 sectors. This distribution reflects a portfolio strongly oriented towards climate adaptation, while maintaining cross-sectoral coverage in mitigation-related sectors. When mapped against levers of change, 80.36% of initiatives focus on knowledge generation, 41.07% on governance, 39.29% on infrastructure, 35.71% on economy and ecology, and 33.93% on social status. Knowledge thus emerges as the dominant lever, being present in over four-fifths of the initiatives, which suggests a deliberate emphasis on capacity-building, institutional learning, and evidence-based planning.

Regarding orientation, 57.14% of initiatives aim to improve current conditions (improvement-oriented), 59.93% align with the mission-driven objective of climate neutrality, 26.79% are anticipatory-oriented, and 21.43% are adaptive-oriented. Notably, more than half of the initiatives combine improvement and mission-orientation, demonstrating a hybrid approach that blends incremental change with transformative ambition. Finally, two initiatives stand out for their high connectivity within the experimentation area dimension: LIFE PACT (23 connections) and University–City Binomial (16 connections). Their strong relational embeddedness highlights their potential as anchor projects for experimentation. These projects not only act as hubs within the network, but also embody integrative logics by combining spatial interventions, social co-creation, and policy alignment. Understanding their organisational structures, funding models, and governance mechanisms offers valuable insights for scaling or replicating their integrative capacity across other initiatives.

5. Discussion

5.1. From Static to Dynamic: Emerging Benefits and Challenges

The digital tool is not a static representation of the urban system, but a dynamic platform that captures multiple perspectives and variables of urban transformation. Sustaining this dynamism requires collaborative spaces that foster decentralised participation and continuous interaction. This section reflects on the practical implications, emerging benefits, and potential challenges of operationalising the systemic portfolio approach through a digital tool. Below, we outline the potential benefits identified through the application of the digital tool:

• It enhances strategic and anticipatory decision-making in complex, multistakeholder governance contexts by equipping city managers with improved foresight and scenario-planning capabilities. This anticipatory capacity helps stakeholders proactively address uncertainties, ensuring that short-term actions remain aligned with long-term climate neutrality goals, such as the 2030 target envisioned by the Cities Mission.
• The digital tool integrates the knowledge of diverse stakeholders by bridging municipal silos and connecting across wider societal systems that have historically hindered collaborative climate action. By serving as a shared platform, it facilitates cross-sectoral collaboration and joint planning.
• The digital tool is inherently learning-oriented as it encourages organisational reflection and knowledge transfer by capturing project insights and lessons learned and facilitating peer learning across departments. This emphasis on continual learning fosters adaptive planning, allowing strategies to be iteratively refined based on feedback and evolving conditions.
• The digital tool aids in identifying synergies and gaps across the entire portfolio. Mapping and analysing interdependencies, it reveals where initiatives can reinforce one another and where critical interventions are missing, thereby enabling more coherent, targeted, and systemic interventions.
• The digital tool identifies connections and overlaps, i.e., when two components complement each other or when they operate in isolation despite sharing similar characteristics and actions. The connections enable the transfer of knowledge, skills, and resources unidirectionally or bidirectionally. In the case of overlapping components, it allows for greater resources (financial and human) to be made available for project implementation, amplifying the scope and scale of the intervention. Another possible scenario is the redirection of resources towards dedicated portfolio management. This scenario requires providing public administrations with more flexible and complementary management instruments.
• The visualisation and systemic structuring enabled by the taxonomy and digital tool support strategic understanding at multiple scales. Thanks to its fractal capacity, the portfolio approach is applicable at local, national, and supranational levels (Figure 6), allowing actors to analyse, compare, and coordinate actions across governance tiers. This scalability fosters shared learning, capacity-building, and access to funding for cities pursuing aligned climate objectives, thereby contributing to the emergence of a multilevel ecosystem of urban transformation. For example, in Madrid, the strategic orientation of its CCC—centred on climate adaptation infrastructure—is reflected in the portfolio’s structure: 75% of initiatives address adaptation, while 80.36% relate to knowledge generation. This local portfolio aligns with other city-level strategies within the EU Cities Mission. For instance, Barcelona’s Escoles Refugi programme uses nature-based solutions to convert heat-exposed schools into climate shelters, echoing Madrid’s educational renaturalisation agenda [92]. Heidelberg’s CCC prioritises energy efficiency and thermal comfort in school buildings to advance climate neutrality goals [93], while Malmö’s CCC integrates neighbourhood-scale participatory processes to enhance resilience and equity [94]. These synergies demonstrate the practical utility of the portfolio approach and highlight its transferability, contingent on governance capacities, regulatory frameworks, and civic engagement. Therefore, the integration of city portfolios could strengthen collective knowledge and reinforce strategic approaches developed across diverse urban contexts, particularly in relation to shared priority areas.

These benefits collectively contribute to operationalising a mission-oriented, integrated, and adaptive strategy. However, their implementation also entails multiple emerging challenges, which may serve as potential lines for future research:

• Constructing this tool requires extensive data collection, analysis, and systematisation. For effective implementation, each organisation within the urban ecosystem has to actively interpret and contextualise the taxonomy according to its own language and operational framework. While the taxonomy is designed for direct application to the CCCs, failing to fully understand its attributes may lead to distortions in how the portfolio is configured and analysed. Therefore, portfolio managers have a critical role in ensuring that all actors share a common understanding of the taxonomy, promoting coherent interpretation, analysis, and evaluation across the system. Capacity-building initiatives, tailored training, and collaborative workshops with public administrations and organisations involved can address these challenges, fostering co-ownership and enhancing adoption.
• Concerns regarding data ownership, consent, and accountability are relevant in multi-actor ecosystems. However, it is important to reinforce that the digital tool primarily draws from information that is already publicly available, including documentation from Open Data Portal of the City (in the case study Madrid’s Open Data Portal) and CCC itself. The objective of the tool is not to generate new sensitive datasets, but to translate and organise existing information to enhance strategic coordination.
• Adopting a dedicated portfolio management framework may increase administrative overhead and necessitate reallocating funds from other programmes, which could generate stakeholder tensions. Where institutional capacity is limited, such trade-offs become more pronounced.
• Data integration from multiple stakeholders can be particularly complex, calling for standardised formats or bridging applications to ensure interoperability. User interface design must be tested iteratively to minimise complexity and facilitate widespread adoption among diverse actors. The implementation of digital tools in public governance also raises ethical and data-governance concerns that require critical reflection. The relational mapping of actors and initiatives may reproduce or amplify existing power asymmetries, particularly if less-institutionalised stakeholders (e.g., grassroots or neighbourhood groups) are underrepresented in the source data. To mitigate this, it is essential to adopt inclusive data protocols and encourage participatory mapping practices that update and validate ecosystem representations over time.
• Cybersecurity risks should also be addressed, especially concerning sensitive public investment and stakeholder data. While the tool has been developed as an open-source platform to promote transparency and replicability, the application of cybersecurity standards—and the definition of appropriate levels of openness—must be determined by the institutional and technological context of each local government. Risks such as unauthorised access, data manipulation, or service disruption should be addressed as part of the broader governance framework of the tool through risk assessments, tiered access controls, and adherence to municipal or national IT security regulations. In some cases, deploying the tool in closed-code formats may be necessary, depending on the risk profile, capacity of the implementing institution, and the context of each city.
• In evaluating the long-term impacts of portfolio-based governance on decarbonisation outcomes, equity considerations, and urban resilience, developing integrated evaluation frameworks and metrics to assess systemic change, including unintended consequences, will be critical for advancement in this field. Additionally, exploring integrating artificial intelligence, predictive analytics, or participatory sensing into portfolio tools could further enhance their capacity to support anticipatory governance and real-time decision-making.

Despite these challenges, the transformative potential of the tool is not diminished; rather, it highlights the importance of embedding it within ethical frameworks, participatory governance structures, and ongoing deliberative practices. Digital infrastructures must complement—not replace—public decision-making, ensuring that technology strengthens transparency, inclusion, and collective agency in urban climate governance [95,96].

5.2. Beyond Carbon: Social Co-Benefits, Ecocentric Levers, and Climate Justice

While the portfolio approach is designed to support climate neutrality pathways, its structure and digital representation allow it to go beyond carbon metrics by addressing deeper systemic variables that influence equity, well-being, and ecological integrity.

The portfolio is not only organised around technocratic categories. It is made up of seven systemic levers—including economy, ecology, infrastructure, knowledge, governance, location, and social status [82]—that adopt both anthropocentric and ecocentric perspectives. This dual framing enables decision-makers to visualise dimensions often excluded from traditional planning, such as non-monetary economies (e.g., time banks), urban biodiversity (e.g., seed libraries), and localised forms of ecological care (e.g., community-managed green spaces). By activating these levers, the tool amplifies visibility over underutilised or emergent sources of value and resources [81,82].

The experimentation areas embedded in the portfolio act as place-based entry points for addressing multiple co-benefits simultaneously. These include public health improvements (e.g., thermal comfort in schools), enhanced educational equity, psychological well-being through greening, and community cohesion [81]. The systemic taxonomy links each experimental context to its potential for social and ecological regeneration, encouraging a relational and territorialised understanding of impact.

The digital tool enables the identification of distributional disparities within the collaborative ecosystem. By analysing network density and actor centrality, users can explore who participates, who is underrepresented, and how decision-making power circulates across public, private, academic, and civil society domains [21,53,54,56]. For instance, while the Madrid City Council act as hub, other sectors—such as neighbourhood associations or youth groups—may be weakly connected. This insight opens a pathway for reflexive governance, reinforcing inclusion and just transition [81,96,97].

Finally, by linking co-benefits, actor representation, and eco-centric resource mapping, the portfolio approach contributes to ongoing debates on urban climate justice [1,98]. It makes visible not only emissions and investments, but also disparities in exposure, participation, and access to benefits, thus allowing cities to integrate procedural and distributive justice into their transformation strategies.

5.3. Collaboration Patterns Identified Using the Digital Tool

Application of the digital tool to the Madrid CCC revealed several patterns of collaboration between the municipal administration and other actors within the urban ecosystem. Identifying these patterns provides valuable lessons for other cities seeking to adopt this systemic, portfolio-based approach. By understanding how collaborations materialise, where connections are concentrated or lacking, and which actors serve as intermediaries, local governments can better design governance mechanisms with strategic stakeholders that enhance coordination, facilitate the inclusion of new agents and projects, and foster systemic impact across the city. Therefore, this research proposes 3 models for collaborative portfolio management between the city council and facilitators/portfolio managers (called Actor X) (Figure 7):

• Model (A): Actor X leads portfolio management, which exchanges knowledge and capabilities with the City Council. Throughout the process, Actor X delegates competencies over portfolio management to the City Council, which gradually assumes leadership until the point of convergence is reached, where Actor X hands over full control of portfolio management to the City Council.
• Model (B): Actor X leads portfolio management, which exchanges knowledge and capabilities with the City Council. Throughout the process, Actor X does not delegate competence over portfolio management to the City Council. The City Council assumes eventual leadership at the convergence points without taking full control of the portfolio.
• Model (C): Actor X leads portfolio management, which exchanges knowledge and capabilities with the City Council. Throughout the process, Actor X delegates competencies over portfolio management to the City Council, which gradually assumes leadership until reaching the point of convergence, where Actor X and the City Council co-manage the portfolio in continuous knowledge exchange and learning feedback loops.

Figure 7. Collaborative models for portfolio management based on stakeholders, level of leadership, requirements, and time. (a) Model (A), (b) Model (B), and (c) Model (C).

Figure 7. Collaborative models for portfolio management based on stakeholders, level of leadership, requirements, and time. (a) Model (A), (b) Model (B), and (c) Model (C).

These models allow the identification of Actor X based on a multilevel approach. Models (A) and (C) could be enabled through local portfolios, with Actor X represented by the academic system, particularly the University, as a neutral organisation interacting with the different social systems [57,58]. These models can be channelled through national or European projects with defined timing. The difference between both scenarios is the type of relationships established between the two actors where in the first case (A), there is a gradual exit of Actor X and, in the other (C), a continuous accompaniment throughout the management process. Collaborative management between these two actors will work if they have trusted relationships and constantly exchange knowledge and capabilities [57,98]. On the other hand, models (A) and (B) could be enabled in national or supranational portfolios. Actor X is represented by the structures that articulate the collaboration in the framework of the Cities Mission. The difference between scenarios (A) and (B) lies in the degree of local political support for the Mission and the legitimacy of its interlocutors or facilitators to promote it within the multistakeholder ecosystem.

6. Conclusions

This research has explored the question: How can a systemic, portfolio-based digital tool enhance the strategic coordination and collaborative governance of climate actions in complex urban ecosystems? Through the development and application of an analytical taxonomy and an interactive digital platform, this study offers empirical and conceptual insights into operationalising the portfolio approach within the governance structures of a major European city participating in the EU Mission.

A critical contribution of this study lies in demonstrating the capacity of the portfolio tool to bridge the gap between fragmented institutional arrangements and the systemic ambition of climate-neutrality missions. By consolidating diverse projects and actors within a coherent relational map, the tool provides municipal decision-makers with an integrated overview of ongoing initiatives, revealing otherwise invisible connections and overlaps across organisational silos.

Technically, the digital tool functions as a shared repository and interactive space that enables cross-sectoral dialogue, knowledge exchange, and joint planning. Strategically, it opens up possibilities for more transparent and inclusive governance by making visible the roles, contributions, and relationships among stakeholders. The empirical findings show that while the digital tool can map existing collaborations, its capacity to foster new alliances or redistribute decision-making authority remains contingent on political will and organisational culture. However, digital tools alone cannot resolve governance fragmentation, instead, they must be embedded within broader institutional reforms and capacity-building strategies that foster trust, legitimacy, and shared ownership among actors’ ecosystems.

By enabling continuous monitoring and visualisation of the portfolio’s evolution, the tool facilitates reflective practices that allow local governments to adjust strategies in response to feedback, emerging challenges, or shifting priorities. This learning-oriented function aligns with the principles of mission-oriented innovation, emphasising experimentation, iteration, and adaptive capacity as essential to achieving transformative outcomes. Nevertheless, without mechanisms to translate portfolio insights into actionable changes, there is a risk that the tool becomes a symbolic exercise rather than a catalyst for transformation.

The mapping function of the digital tool enables municipal planners to identify redundancies, misalignments, and underexplored areas across projects, facilitating a more strategic allocation of resources and interventions. This insight supports the pursuit of co-benefits between mitigation, adaptation, and social objectives, enhancing the potential for integrated urban regeneration. However, the focus on interdependencies also reveals that not all synergies are administratively actionable. Some of these require negotiation of competing values, trade-offs, or political conflicts that exceed the remit of technical tools. Consequently, the digital portfolio tool should be seen as a support mechanism that informs and aids the decision-making, rather than replacing the analogue and real-world networks built through listening, dialogue, and collaboration across the multifactor and multilevel ecosystem.

While the taxonomy and platform were designed for replication in other cities participating in the EU Cities Mission, their effective adoption depends on each context’s institutional capacity, data availability, and governance cultures. Cities with less developed data infrastructures, lower technical capacity, or weaker multistakeholder ecosystems may struggle to operationalise the tool without significant adaptation and investment. In addition, the scalability and replicability of these findings depend on the sociopolitical environment into which they are introduced, especially when dealing with non-stable or non-democratic contexts. Although the digital tool has shown promise at local, national, and supranational levels, they are predicated mainly on stable democratic circumstances. In settings marked by political volatility or limited institutional capacity, further adaptations may be required to establish legitimacy, foster trust, and maintain continuous feedback loops.

From a scientific standpoint, this study advances the theoretical debate on portfolio-based governance by empirically operationalising concepts drawn from systems thinking and mission-oriented innovation in a local–global context. Specifically, the article contributes to the literature in four keyways:

• Operationalising systemic portfolio theory in urban governance: While prior studies have conceptualised portfolio approaches in climate action, this research translates those concepts into a practical digital tool based on an analytical taxonomy tailored to European CCCs. This advances portfolio theory by demonstrating its applicability to multilevel approaches through an interactive, data-driven framework.
• Integrating systems thinking into local decision-making: Building on the foundational principles of systems theory, the digital tool enables urban actors to visualise interdependencies, feedback loops, and leverage points across projects, thus embedding systemic analysis within urban planning processes. This marks a shift from fragmented governance to a holistic view of urban decarbonisation planning.
• Strengthening mission-oriented innovation through dynamic coordination mechanisms: Mission-oriented frameworks call for adaptive governance structures capable of managing complexity. This study demonstrates how digital tools can serve as catalysts for a ‘second operating system’ grounded in experimental, learning-oriented, and collaborative approaches to urban planning.
• Bridging collaborative governance and digital planning: This study expands the collaborative planning literature by showing how digital infrastructures can institutionalise multistakeholder engagement, knowledge sharing, and reflexive learning—moving beyond ad hoc and unilateral collaborations to sustained ecosystem coordination.

Finally, urban planning for climate neutrality in the twenty-first century requires not only better tools but also new governance paradigms capable of navigating complexity and abundance, fostering collaboration, and embracing uncertainty as an inherent condition of systemic transformation. The digital portfolio tool presented in this research offers a promising response to the challenges of governing urban decarbonisation in complex, multi-actor contexts. Therefore, it should be understood as part of an ongoing process and iterative refinement. Its strength lies in its ability to reveal systemic interdependencies, gaps, and synergies across urban initiatives, thereby offering a platform for coordination, learning, and strategic alignment. However, realising this potential requires broader institutional commitments, participatory governance structures, and continuous reflexive practices, all oriented towards progressive institutional innovation—where impact emerges from the redefinition of the State’s role as facilitator, mediator, and learner.