Competencies of Sustainability Professionals: An Empirical Study on Key Competencies for Sustainability

Abstract

This paper presents an empirical study on key competencies for sustainable development. Over a period of two years, we collected empirical data on competencies of senior sustainability professionals by using an action research approach. Data collection took place in Belgium Flanders via an elaborate iterative action-reflection process including an interactive workshop, interviews, and an online survey. Our analysis provides strong empirical evidence for the existence of two complementary competency clusters, namely sustainability research competencies and sustainability intervention competencies. Together they enable the profound analysis and understanding of sustainability issues and ensure the ability to devise solutions and foster change towards sustainability. Furthermore, we shed a first light on the interaction of these competency clusters and their link with the practitioners’ topical knowledge and lived experience. This study bridges the divergence in literature between theoretically and empirically driven research and offers novel insights on sustainability competencies for the fields of sustainability science, human resource management, and higher education.

1. Introduction

At the beginning of the 21st century, global sustainability challenges are becoming paramount at an ever-increasing rate. Climate change, mass extinction of animals and plants, depletion of natural resources, poverty, malnutrition, child labor, and gender inequality are just some examples from a sheer endless list of urging sustainability issues. Pressure is rising for governments, public administration, business, and civil society to rethink and reinvent their norms, values, and practices towards sustainability. Fostering sustainable development, which has been defined as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs” [1] (p. 41) and contributing to sustainable development goals [2] requires collaboration across sector boundaries [3].

Today, practitioners from a wide array of fields and occupations devise and implement solutions to sustainability challenges [4]. For example, one might find architects, engineers, social workers, entrepreneurs, and public servants working together on climate change and sustainable urban housing. Collaboration for the purpose of sustainable development fosters situated learning [5] and situated knowledge development [6] in communities of practice [7]. It is becoming increasingly evident that we witness the rise of an entirely new profession [4,8,9] which is not yet described in formal job classification systems such as the International Standard Classification of Occupations (ISCO). Professional practitioners within the heterogeneous and complex field of sustainability have been labeled in the literature as ‘change agents’, ‘integrated catalysts’, ‘sustainability managers’, and ‘sustainability professionals’ amongst others (cf. [4,10,11,12]). We use the term ‘sustainability professional’ to refer to a professional practitioner who secures his/her livelihood by contributing to sustainable development and taking stewardship for the profession. Today, we know little about what enables sustainability professionals to co-create and implement solutions together with stakeholders, and how they become effective agents for transformation towards sustainability. We lack a detailed picture and sound understanding of key competencies which is particularly important in professions where an integration of different skills and knowledge domains is required [13]. Defining the concept of ‘competency’ often narrows down to two aspects, namely the integration of knowledge, skills, and attitudes plus a reference to a specific job context or situation [14]. Most of our understanding about competencies for sustainable development stems from higher education research [15,16,17,18] and the efforts of the United Nations to foster sustainability in education [19,20,21,22,23]. Drawing on a comprehensive literature review, Wiek, Withycombe, and Redman (2011) [18] synthesized a competency framework for the purpose of academic program development which gains increasing support in scientific community [24,25]. More recently, the field also started to research the empirical underpinnings of sustainability competencies by surveying students and graduates of newly developed sustainability programs [9,10,26]. However, empirical research on competencies of experienced practitioners who successfully operate in the field of sustainability is still scarce. The objective of this study is to identify and describe key competencies of sustainability professionals.

The research presented in this paper focusses on experienced practitioners at senior level, thereby going significantly beyond the perspective of students and young alumni. The participants of this study have on average 24 years of relevant work experience in the field of sustainability. Seeking insights into competencies of practitioners requires research to make them and their operating context the focal point of the analysis [13,27]. We use an elaborated action research approach to advance our understanding of key competencies for sustainable development. Action research enables us to draw on the lived experience and contextual embeddedness of the participants [28]. Thereby we respond to calls in higher education literature for more solution oriented research that investigates actions and practices in the field of sustainable development [12,29,30]. The insights presented in this study might help to prevent a division between the competencies gained in higher education and the competencies actually needed by professional practitioners in the field. Our empirical findings contribute to sustainability science, human resource management, and higher education literature. The terms sustainability and sustainable development are used interchangeably in this paper [31].

The remainder of this paper is structured as follows. First, we will briefly discuss recent literature on competencies for sustainable development. We will draw on insights from the field of sustainability science and higher education. Next, we will describe in detail all steps of the action research design that was used to collect empirical data in Belgium Flanders over a period of two years. We will outline the process of comprehensive triangulation which ensures analytical rigor and robustness of our findings. The section ‘Results’ will then present empirical evidence of two complementary competency clusters, namely ‘sustainability research competencies’ and ‘sustainability intervention competencies’. Furthermore, we lay out their relationship with topical knowledge and the lived experience of the professional practitioner. We discuss findings and limitations of our research and end this paper with conclusions.

2. Competencies for Sustainability

Empirical research on competencies of experienced practitioners who successfully operate in the field of sustainability is scarce today. The survey among the members of the International Society of Sustainability Professionals of Willard et al., (2010) [4] is among the first studies to explore competencies of sustainability professionals (79% of the respondents came from North America). The ability to communicate with stakeholders was outlined as the most important competency by far. Problem solving, inspiring and motivating others as well as strategic planning, systems-thinking, project management, and sustainability related knowledge were also identified [4]. Furthermore, findings stress the need for collaboration, facilitation, consensus building, and the ability to influence change within and outside the organization. This is in line with what Perez Salgado et al., (2018) [8] describe as intervention competency. Intervention competency enables the professional practitioner “to devise, in a process of consultation with relevant stakeholders, one or several solution(s) or decisions for a sustainability issue and subsequently successfully conduct the change process towards sustainability” [8] (p. 168). Mabon and Shih’s (2021) [32] comparative analysis of climate change adaptation initiatives in three different Asian countries underscore the significance of cross-sector collaboration as well as a “competency in getting things done and making interventions happen” (p. 11). A. MacDonald et al., (2020) [11] interviewed 26 sustainability managers employed by municipalities across Canada. Competencies to communicate with different stakeholders, to facilitate change, and to collaborate for intervention formulation and implementation were mentioned by more than 80% of the interviewees. Furthermore, an interpersonal competency (listening to stakeholders and incorporating their ideas into decision making) and strategic-thinking were frequently mentioned. Interestingly, competencies for futures-thinking, values-thinking, and systems-thinking were mentioned by less than half of the interviewees. Despite these first empirical insights, we still lack a coherent picture and overview of competencies for sustainability corroborated by experienced sustainability professionals.

L. MacDonald and Shriberg (2016) [33] revealed in a survey amongst early stage professionals, who recently graduated from sustainability leadership programs, that alumni report significant gaps between program outcomes and perceived needs in the workplace. The analyzed “programs tend to underemphasize negotiation, public speaking, facilitation, and coalition-building skills” (p. 60). Hesselbarth and Schaltegger (2014) [10] surveyed graduates of the worldwide first MBA program on sustainability management. Their findings underscore the importance of methodological, social, and personal competencies. Competencies for interpersonal collaboration, the ability to take the initiative, values-thinking, as well as information and media literacy were significantly higher for sustainability managers than for graduates who opted for a different occupational focus [10]. Salovaara and Soini (2021) [9] interviewed alumni of a sustainability focused master program and revealed that “interpersonal competence was most often mentioned with emphasis on collaboration” (p. 79). Furthermore, they stress the role of empathy as well as normative- and systems-thinking. Next to competencies, research with graduates of sustainability programs reveals the value of gaining sustainability related knowledge [9,10,33]. This ‘topical knowledge’ is specifically related to sustainability topics and strongly linked to competencies for sustainable development [24]. At present it is unclear which role topical knowledge and other forms of knowledge play for more seasoned practitioners in the field of sustainability.

De Haan (2006, 2010) [17,34] introduced the notion of ‘Gestaltungskompetenz’ (shaping competence) into higher education literature, which describes a comprehensive capacity to act and solve sustainability problems thereby changing and shaping economic, ecological and social behavior. Based on the idea of a comprehensive capacity under which several key competencies reside, Wiek et al., (2011) [18] synthesized a competency framework for the purpose of academic program development. Since then, systems-thinking, futures-thinking, values-thinking, strategic-thinking, implementation, integrated problem solving, interpersonal and basic academic competencies have become widely recognized by educational experts in the field of higher education as key competencies for sustainability [24]. These competences are increasingly used to empower students to become global citizens and enable them to foster transitions towards sustainability and achieve sustainable development goals (SDGs) [20,22]. Over the last years, the field examined the empirical underpinnings through expert evaluations [15,16,24], quantitate surveys [10,26,33,35,36], case studies [25,37,38,39,40], participatory research designs [41], and interview studies [9]. Emerging insights found their way into first handbooks and reports on education for sustainable development [2,21,22,23,42].

From the above, one can observe that sustainability competencies in higher education seem to differ from empirical research on sustainability professionals. Practitioners more strongly emphasize competencies that are relevant to devise and implement interventions together with stakeholders. These empirical observations substantiate the notion that some competencies well-established in higher education literature might be less relevant in real-world settings [33]. This study uses an action research approach to advance our understanding of key competencies for sustainability. We will address the following research questions: Which key competencies for sustainability can be identified and corroborated by senior sustainability professionals in the public domain of Belgium Flanders? To what extent do they differ from competencies used in higher education? How is topical knowledge linked to these competencies?

3. Methodology

The context in which professional practitioners operate shape the development of their competences [27]. Consequently, it would be hard to imagine how theoretical considerations or quantitative surveys could reflect the distinctive qualitative structure of competencies within a profession [13]. A qualitative discursive research approach that allows for interaction, dialogue, and probing seems more adequate to explore competencies of sustainability professionals, especially at an early research stage [8]. We choose an action research approach which has established itself next to other qualitative methodologies such as grounded theory or case studies research [43]. The notion action research (AR) was initially introduced by Kurt Lewin (1946) [44] as a novel research approach where researcher and research subject directly interact in a collaborative manner. It draws on critical theory, constructivism, and an interpretivist philosophy [45,46,47,48,49]. Action research can be defined as collective, self-reflective inquiry undertaken by participants in social situations in order to improve the rationality and justice of their own social practices as well as the understanding of these practices and the situations in which these practices are carried out [50]. At the heart of action research lies the so-called ‘self-reflective spiral’ [47,50] which is a cyclical process with the elements of planning, acting, observing, and reflecting [51,52]. However, action research is not a rigid mechanical sequence of prescribed strategies, but an adaptive process [46,53]. Variables are neither predetermined nor controlled, but arise from iterations between action and reflection [47,50,51]. Since there is no prescribed design, action researchers need to “enact a process based on declared-in-advance methodology…in such a way that the process is recoverable by anyone interested in subjecting the research to critical scrutiny” [54] (p. 18). We deliberately chose to use established principles to plan and apply action-reflection cycles with participants [52,54]. Findings are based on comprehensive triangulation [55,56] and well-established techniques for data analysis [43,57,58] to ensure academic integrity, rigor, and reliability [59,60,61]. Our action research process consists of four stages, namely the identification and selection of participants, an interactive workshop, semi-structured interviews, and an online survey.

3.1. First Stage—Identification and Selection of Action Research Participants

We assembled a multidisciplinary research team to enhance opportunities for theoretical, methodological, and analytical triangulation [55,56]. Next, we identified practitioners based on predefined selection criteria which limit extraneous variation and help to asses possibilities to compare and generalize findings [62,63]. Fixed selection criteria are of special importance in this study, since we could not draw on formal job classification standards for the purpose of participant selection. Currently, formal classification standards in Belgium Flanders do neither recognize sustainability professionals as a single group nor provide a list of occupations linked to sustainability. Therefore, we set the following three selection criteria. First, all practitioners would have to qualify as sustainability professionals as defined earlier. Second, practitioners needed to operate at senior level and have more than 10 years of work experience out of which at least 5 years in the field of sustainability. Third, all practitioners needed to have a proven track record corroborated by reliable impact measurement. This is regularly the case for sustainability projects within the public domain of Belgium Flanders. Since these projects are reported publicly by the Flemish supervisory authorities and municipalities, we were able to identify 60 professionals who fulfilled all three selection criteria. We randomly contacted them by phone and e-mail until we reached the maximum capacity of participants. In total, 20 sustainability professionals took part in an interactive workshop, and another 5 were interviewed at a later stage. All professionals spearheaded multiple sustainability initiatives throughout their careers and had on average 24 years of relevant work experience (see

Table 1. Characteristics of the 25 participating sustainability professionals from Belgium Flanders.

Characteristics		Number (Percentage)
Gender	Female Male	5 (20%) 20 (80%)
Education	None High School/Secondary School Bachelor Master PhD	1 (4%) 7 (28%) 8 (32%) 8 (32%) 1 (4%)
Work Experience as Sustainability Professional	6–10 years 10–20 years 20–30 years 30+ years	3 (12%) 6 (24%) 8 (32%) 8 (32%)
Average	24 years of work experience as sustainability professional
Affiliation	Local municipality Educational institution Nature conservation center State authority NGO or temporary Campaign	5 (20%) 5 (20%) 6 (24%) 5 (20%) 4 (16%)

). Based on the International Standard Classification of Occupations (ISCO-8) these professionals can be identified as biologists, botanists, zoologists and related professionals (2131), environmental protection professionals (2133), environmental engineers (2143), teaching professionals (2359), and regulatory government associate professionals (3359). However, due to their long careers some have more than one occupation and others have switched occupations through the years (e.g., a chef who is now the director of a sustainable food academy). They all identify themselves as sustainability professionals.

Due to the seniority of the professionals and the public display of their projects, all participants are highly recognizable at local, national, and some even at international level. After careful deliberation with the participants, we ensured to keep all names, specifics of projects, and details about affiliations anonymous to enable open communication and free interaction. This helped to build mutual trust and long-term commitment which are of tremendous importance in action research [53,56]. The professionals worked on sustainability issues such as recycling and upcycling, renewable energy, sustainability education, climate change, urban development, sustainable water and food consumption, sustainable agriculture, biodiversity, nature conservation, ocean and coastal protection, substance abuse, and fair trade.

3.2. Second Stage—Interactive Workshop

We started this stage with a homework assignment that was e-mailed to the professionals two weeks before the workshop. The assignment assisted them in recalling important events and experiences (including obstacles and bottlenecks) and requested to elaborate on all aspects of their competencies (knowledge, skills, and attitudes). These insights were input for an interactive workshop in February 2019. The workshop was designed as a hermeneutic process of divergence and convergence for joint knowledge construction between participants [8]. It lasted 4.5 h and was structured in four major phases. (1) Introduction phase: welcome; presentation of research aim and methodology; clarification of rules, roles, and responsibilities; asking consent with this research and the publication of findings. (2) Divergence phase (in groups of three to five people): sharing important events and experiences (including obstacles and bottlenecks); Elaboration on knowledge, skills, and attitudes; summarizing insights on flip-over charts. (3) Convergence phase (plenary): presentation of flip-over charts; Q & A for clarification. (4) Plenary discussion about the most important and most relevant competencies for sustainable development; Drawing preliminary conclusions (end of convergence phase); Outlook and next steps. The research team took field notes and photographed all output (flip-over charts). Both were later codified in form of transcripts to increase reliability of the following analyses [56]. We used open, axial, and selective coding procedures to derive theoretical concepts from raw data [64,65] which is a common approach in action research [57,58]. A total of 356 empirical observations were coded by two researchers independently and supported by a software application to increase reliability. Afterwards similarities and differences were discussed and agreement on a joint coding scheme was reached. The outcome was a preliminary collection of competencies which was shared with the participants via email. Based on their feedback and critical evaluation we developed interview questions for the next stage.

3.3. Third Stage—Semi-Structured Interviews

We conducted five semi-structured interviews to triangulate findings from the workshop. Interviewees meet the same selection criteria as the workshop participants and additionally have expertise in sustainability competencies. Amongst other things, our interviewees have published articles, reports, and books about sustainability issues, worked as board-level executives at educational institutions concerned with sustainability, and have taken roles such as lecturer, trainer, and consultant in the field of sustainability (see

Table A1. Sample description interviews.

Number	Length Interview	Background Description Interviewees	Work Experience
Interview 1	33:56 min.	Director anthroposophical educational institution, teacher biology and sustainability	40 years
Interview 2	Continued in writing due to technical issues	Sustainability official (public institution), Editor-in-chief of a non-scientific sustainability journal, executive board member of an international NGO for environmental education, author	32 years
Interview 3	1:07:00 min.	Director sustainable food academy, chef, speaker, author	21 years
Interview 4	49:35 min.	Lecturer in sustainability philosophy, trainer for teachers in biology and sustainability, author	16 years
Interview 5	29:48 min.	Director vocational educational institution (sustainable agriculture), consultant and coach	30 years

in the Appendix A for details). Interviews lasted between 30–67 min and were audio-recorded. Recordings were codified (word-by-word transcripts) and analyzed with the same coding procedures as outlined in the second stage. Overall, outcomes provided an improved understanding of the workshop results and delivered additional insights on several aspects of competencies. In these situations Lennie (2006) [56] recommends to improve data assessment by applying coding procedures based on relevant theory which allows for methodological triangulation. We reviewed higher education and sustainability literature to develop a theory based a-priori coding scheme [62] to reassess the workshop data. Afterwards, outcomes of the different coding procedures were compared. 80% of all codes were consistent between coding procedures which underscores the overall robustness of the analysis. Only 3% of the codes showed major discrepancies. Closer inspection of the raw data revealed that participants described personality factors and general abilities which could not be attributed to specific sustainability competencies. Furthermore, adding another layer of coding provided a more fine-grained picture of competencies. Closer inspection of minor discrepancies between the coding procedures revealed that for 9% of all codes the a-priori coding described the raw data more accurately and that for 8% of all codes the open codes were a better fit. After comparing and discussing outcomes of both coding procedures the research team agreed on a final coding scheme which included 48 distinct codes that were clustered into 18 categories. The findings were summarized in a preliminary competency set.

3.4. Fourth Stage—Online Survey

Based on the evolving insights we constructed an online survey to validate findings. The survey presented a competency set based on the outcomes of the previous action-reflection iterations. We provided clear definitions of all competencies and descriptions of underlying relationships. The survey used open and closed questions to critically evaluate the competencies and the overall competency set. The survey was created with a software application (LimeSurvey) and administered to the sustainability professionals in April 2021. The response rate was 57% which is high considering that this study already stretched over two years. Overall, the survey largely confirmed the competency set and its elements so that only very few adjustments had to be made. At this point we were confident that no significant learning could be yielded from another action-reflection iteration, which marks the end of the ‘self-reflective spiral’ in action research [54].

4. Results

This section lays out the empirical findings of key competencies by senior-level sustainability professionals within the public domain of Belgium Flanders. The empirical evidence points to the existence of two complementary competency clusters, namely sustainability research competencies and sustainability intervention competencies, which are visualized in Figure 1. Together they enable the profound analysis and understanding of sustainability issues and ensure the development of solutions together with stakeholders and help to foster self-sustaining transitions towards sustainability.

4.1. Sustainability Intervention Competencies

First and foremost, we found overwhelming evidence for the existence of sustainability intervention competencies. They account for 271 out of 356 open codes (76%) in the analysis of the workshop data and were consistently confirmed through all interviews and by the online survey.

Table 2. Sustainability intervention competencies of senior-level sustainability professionals from Belgian Flanders–final coding scheme and raw data examples.

Selective Coding (Competency Cluster)	Axial Coding (Key Competency)		Raw Data Examples (Translated from Original Dutch Data)
Sustainability Intervention Competencies	Interpersonal Collaboration Competency	>Boundary spanning	Resolve conflicts; Identify and resolve conflicts of interests; Compromise; Identify and meet needs of others; Have empathy; Take time and listen; Interact one on one; Mediate; Look for common ground; Create win-win.
		>Stakeholder Engagement	Integration of external stakeholders is crucial; Be locally embedded; Know your stakeholders; Integrate in social networks; Build social capital; Bring stakeholders together; Begin locally and work bottom-up.
		>Co-Creation	Co-creation is very important; Co-creation creates shared responsibility; Teamwork & Co-creation; It is important to work in teams; Produce practical outcomes; Co-creation is crucial; Not getting everyone on board leads to failure of the project.
		>Communication	Communicate with all stakeholders; Broad communication necessary; Clear communication; Translate complex issues; Take notes and write reports; Use the power of press and social media; Use symbols; Advertise.
		>Building Mutual Trust	Plan intervention by someone they trust and who dares to tell the truth; Be trustable and don’t push choices; Be a trustable person when you ask for change; You need trustable scientific knowledge; You cannot work without trust in both directions.
	Capacity Building Competency		Advise stakeholders and build up their knowledge base, Share scientific knowledge with stakeholders; Motivate others; Building intrinsic motivation is important; Be a role model; Takes responsibility and be an example; Make others enthusiast; Stimulate ownership; Strive for shared responsibility; Let others take over; Build a group that feels ownership and shares responsibility; Inspire others.
	Intrapreneurial Competency		Identify needs and be entrepreneurial; Feel ownership; Be personally involved; Be owner of the project; Take the initiative; Be passionate about nature and spread the word; Go for quick-wins; Look for opportunities; Achieve results; Break it down into small achievable goals; Take small actions so that you quickly achieve results; Work locally and look for feasible actions; Feasibility and straightforwardness.
	Strategic Competency		Set objectives, Set priorities; Objectives need to be clear; Take decisions; Stimulate the group to take decisions; Delegate; Dare to think big; Let go of what costs too much energy; Change your strategy where necessary; Act strategic; Think strategic; Timing must be right; It must happen at the right time and in the right place; Be persistent: You rarely achieve goals directly. Sometimes it take 10 to 20 years.
	Political Competency		Politics are influenced by powerful corporations (lobby); Anticipate lobbying by corporations; Never underestimate the industry lobby; Take political agendas into account; Power is necessary; Be aware that politicians want to get votes and be re-elected; Consider which interests might prevail; Be political neutral; Don’t have a hidden agenda; Be open for discussion and debate; Political-thinking is important.
	Implementation Competency		Thinking and acting has to go together; Take action; Push through; Follow up; Implement; Gain support in your organization; Gain support by the general public; Support of stakeholders is crucial; Look for like-minded people to get it done; Look for sponsors with self-interest; Manage the project and the process; Establish continuity and follow-ups; Self-directed succession is important.

summarizes these findings and presents the final coding scheme including raw data examples for sustainability intervention competencies. The professionals elaborated deeply on intervention competencies and stressed the importance for their daily practice. Sustainability intervention competencies enable the development of solutions to sustainability challenges together with stakeholders and to help to foster self-sustaining transitions towards sustainability. Sustainability intervention competencies include six interrelated competencies, namely interpersonal collaboration competency, capacity building competency, intrapreneurial competency, strategic competency, political competency, and implementation competency.

4.1.1. Interpersonal Collaboration Competency

Interpersonal collaboration competency encompasses the sustainability professional’s ability to collaborate in multi-stakeholder settings productively. This competency is by far the most complex one and lies at the heart of the intervention competencies. It includes five elements, namely co-creation, communication, building mutual trust, stakeholder engagement, and boundary spanning (see also Figure 2). First, there is strong agreement amongst the professionals that solutions to sustainability issues and successful transformation can only come from co-creation efforts in multi-stakeholder settings. It is not just bundling resources to develop solutions, but co-creation also fosters a sense of shared responsibility and ownership. Participants made it clear that co-creation is about the process of co-creation as much as it is about results. They stress that co-creation should always aim for feasible outcomes which can be implemented. Second, the professional practitioners outline the role of proper communication with stakeholders which needs to be open as well as motivating and convincing. Professionals describe their ability to translate complex issues into simple messages and underline the usefulness of symbols to transport meaning. One interviewee put it this way: “You can try to gain attention for a river ecosystem with science and numbers, but a playful campaign with an artistic drawing of a fish or a kingfisher may prompt people to action more quickly.” Third, fruitful collaboration requires to build mutual trust amongst stakeholders. Since objectives and agendas can be very heterogeneous, trust is not necessarily present and professionals need the ability to build and nurture trustful relationships. The following quote from the online survey underscores the role of trust in collaboration: “You cannot work without trust in both directions. That is why I am against manipulating stakeholders and force them into the direction you want. That will always express itself in a feeling of ‘being tricked’. Honesty lasts the longest and will build trust.” Fourth, practitioners point out the relevance of stakeholder engagement which is the capacity to identify and thoughtfully interact with relevant stakeholders. It is vital to recognize and understand stakeholder needs which often requires working locally and bottom-up. Integration into local networks helps to build social capital and facilitate collaboration. With deeper stakeholder engagement the complexity of social exchange patterns between actors will rise and simultaneously increase the need for mutual trust as a governance instrument [66]. Sustainability professionals will consequently need the ability to bridge differences and span boundaries. Fifth, we found overwhelming evidence for a boundary spanning capacity in the analysis of the workshop data. 54 out of 111 open codes in the interpersonal collaboration competency cluster concerned boundary spanning. Collaboration can be full of conflict, since heterogeneous stakeholders do not necessarily have similar goals or shared norms and values. Our findings underline the need for conflict resolution, mediation, and the willingness to compromise. Sustainability professionals need to overcome differences and bridge sectoral, organizational, and interpersonal boundaries. Boundary spanning requires time, good listening skills, empathy, and the will to create mutually beneficial situations (win-win). These findings underline the importance of value pluralism and the application of value inclusive tools in sustainability related collaboration [67]. Overall, the interpersonal collaboration competency and its 5 elements account for 111 out of 356 open codes (31%) in the analysis of the workshop data. The sustainability professionals put strong emphasis on its importance during all following action-reflection cycles. Figure 2 illustrates the essential elements of the interpersonal collaboration competency.

4.1.2. Capacity Building Competency

Capacity building competency can best be described as the ability to develop and strengthen resources and capabilities of stakeholders so that they are able to contribute to sustainable development. For this purpose, professionals share resources, topical knowledge, and heavily draw on their lived experience to spread best practices. Clearly, capacity building is about knowledge diffusion and learning, but sustainability professionals are not lecturing stakeholders. Repeatedly, they point out that they try to nurture the stakeholder’s own curiosity and emphasize their efforts to motivate and inspire them. The professionals outline the need to be credible role models in order to be a source of inspiration. These findings point to social learning processes [68] in capacity building. Next to learning aspects, capacity building is also about stimulating a sense of responsibility and ownership. Feeling and gaining ownership have important implications, since they ensure that sustainability projects can become self-sustaining and continue in absence of the sustainability professional. Sustainability professionals frequently invest in the capacity of stakeholders to take ownership and control. To achieve this, they behave altruistic and are willing to sacrifice their own accomplishments as the following quotes from the workshop underline: “Action without ego–let others take the fame”; “Share your victory”; “Stimulate stakeholders to take ownership of your project…as long as there is someone who makes it happen, it is fine.” If sustainability professionals try stimulate ownership by being credible role models, they consequently need a strong sense of ownership themselves.

4.1.3. Intrapreneurial Competency

Taking the initiative, being passionate about sustainability, daring to take risks, seeking opportunities, and being creative are some of the raw descriptions that emerged during the action research workshop. Professionals describe themselves as independent and entrepreneurial. They are not afraid of breaking with traditions and take personal responsibility as this quote underlines: “Dare to say ‘[inappropriate language]’ to politics, take responsibility, and do it yourself!” Furthermore, the professionals revealed a hands-on approach, an opportunity seeking mindset, and the need to produce feasible results by e.g., stating: “Take small actions so that you quickly achieve results-short term”; “Work locally and look for feasible actions”; “Identify needs and be entrepreneurial.” The opportunity seeking mindset and a strong focus on realizing quick wins came as a surprise to the research team. Sustainability literature often portrays transformation towards sustainability as a rather complex and slow process that requires a long-term perspective [69,70]. However, the participants revealed that this contradiction is only superficial. It is due to the long-term character that the presentation of smaller results and the achievement of milestones gains importance. According to the professionals, starting small and presenting quick wins can make stakeholders and sponsors enthusiast to buy in and stay for the long run. Initially we labeled this ‘entrepreneurial competency’, but this was rejected during the participant reviews, since the sustainability professionals of this study do not see themselves as entrepreneurs for two major reasons. First, all of our participants are employed by an organization in the public domain of Belgium Flanders and have no intention to start a business. Second, participants see the need for financial sustainability of their projects, but reject a profit maximization paradigm which they believe to be inherent to entrepreneurship. The label was changed to ‘intrapreneurial competency’ to consider these concerns. It still carries the attitude, skills and knowledge related to entrepreneurship, but also respects the wish of working in a (non-profit) organization. The online survey underscored the existence and relevance of this competency, and emphasized the need to cope with resource limitations and other restrictions within the organization. This indicates the need for intrapreneurial bricolage when it comes to promote sustainability in organizations [71,72]. Sustainability professionals within existing organizations need a strong will and persistence as this comment outlines: “Usually you are a lonely cowboy within your organization. You cannot do as much as you would like. You have to be very strong, because you don’t get enough appreciation from the organization you work for.” Overall, intrapreneurial competency can be defined as the ability of an employee to behave as an entrepreneur within an existing organization which includes the ability to stand up and assume ownership, to creatively and pragmatically cope with resource constrains (bricolage), to have an entrepreneurial mindset, and a strong sense for opportunity seeking. However, handling short term opportunity seeking and long-term transformation requires a fair amount of strategic thinking and acting.

4.1.4. Strategic Competency

Strategic competency is about the ability to excogitate, formulate, and execute a strategy including the deduction of objectives, priorities, and milestones. Sustainability professionals not only need to think strategically, but also have to act strategically. It requires decisive decision-making skills, the ability to make choices on the spot, and the flexibility to adapt without losing sight of the bigger picture. During the workshop professionals highlighted their strategic approach: “Dare to think big”; “Don’t get stuck in details or disagreements”; “Focus on a bigger goal, let go of what is too small and requires too much energy”; “Change your strategy where necessary.” Our data shows that timing and momentum play important roles in strategic thinking and acting: “You need momentum”; “Timing must be right”; “It must happen at the right time and in the right place”; “Be persistent: You rarely achieve goals directly–sometimes it takes 10 to 20 years!” Another important aspect is goal setting. According to the participants objectives need to be clear, transparent, and well communicated. However, we additionally found that professionals constantly juggle diverging stakeholder needs, objectives, and conflicting agendas. The ability to play politics is closely related to the strategic competency.

4.1.5. Political Competency

Political competency is the ability to engage in political thinking and acting. On the one hand, participants emphasize the need to be politically neutral, to be open to different opinions, and their willingness to debate. Additionally, they underscore the significance of transparent objectives, the need for open communication, and building trust. On the other hand, they are very cautious about hidden agendas, aggressive lobbying, and power issues as the following quotes highlight: “Never underestimate the industry lobby”; “Take political agendas into account”; “Be aware that politicians want to get votes and be re-elected”; “[name organization] is like the mafia”; “Power is necessary.” The interactive workshop exposed the somehow contradictory elements of being open and honest towards stakeholders in combination with a strong awareness of diverging interest and the necessity for political thinking. Even the use of power is not out of the question. The preliminary findings from the data analysis left some participants surprised and puzzled about this matter. Their self-perception was that of being neutral, honest, and certainly not playing political games. However, through the following action-reflection cycles it became clear that the reality of their daily practices and interaction with powerful stakeholders requires political thinking and acting. Some professionals even concluded that they have to become better at it.

4.1.6. Implementation Competency

Implementation competency is the final element of the sustainability intervention competencies. It can be defined as the ability and motivation to initiate, facilitate, and accomplish transformation towards sustainability including the ability to gain support and dissolve resistance by stakeholders. There was widely shared agreement that one has to have a strong intention to act. Co-creation of solutions to sustainability issues is simply not enough. Acting and implementing is key to foster change towards sustainability. “Thinking and acting has to go together”; “Take action”; “Push through”; “Follow up”; “Implement!” are some quotes from the workshop. Furthermore, the implementation of solutions require proper process management and facilitation. The professionals in this study strongly underscore the importance of gaining support and dealing with resistance throughout the implementation process. They put a lot of effort in gaining support within their organization, external stakeholders, and the general public. Ultimately professionals strive for self-sustaining transformation as these quotes outline: “Self-directed succession is very important”; “Train them so that it builds up its own dynamic”; “Ensure that the project becomes self-supporting and self-steering.” One can see the link to their efforts in capacity building and the willingness to sacrifice personal fame. For the sustainability professionals in this research the achievement of self-sustaining change towards sustainability is the ultimate objective even if that means that they are not needed anymore. Figure 1 displays the corroborated competency set with two complimentary competency clusters, namely sustainability research and sustainability intervention competencies.

4.2. Sustainability Research Competencies

Wiek et al., (2011) [18] made a convincing argument to add an overarching ‘sustainability research and problem solving’ competency to curricula in higher education under which key competencies reside. Our results show that sustainability professionals indeed need the ability to analyze and understand complex sustainability issues. Sustainability research competencies entail basic academic competencies, future-thinking, systems-thinking, and values-thinking competencies which are well-established in higher education literature [24]. However, it is remarkable that these well-established sustainability competencies were not central during the workshop discussions and only surfaced after our comprehensive data analyses. All competencies of this cluster together only accounted for 5% of the workshop data (18 out of 356 open codes). Nevertheless, the following participant reviews, interviews, and the online survey underscore their significance, which we will describe briefly.

Table 3. Sustainability research competencies of senior-level sustainability professionals from Belgian Flanders–final coding scheme and raw data examples.

Selective Coding (Competency Cluster)	Axial Coding (Key Competency)		Raw Data Examples (Translated from Original Dutch Data)
Sustainability Research Competencies	Basic academic competencies	>Critical-thinking	Dare to take a look as an outsider to reveal absurdities; Have a broad perspective and be critical.
		>Analytical- thinking	Think analytically and systematically; Analyze the situation.
		>Research & Data Management	Apply analytical techniques; Measure and analyze the ecosystem.
	Future-thinking competency		Anticipation is important; Dare to think long term; See through things and anticipate; You need an understanding of possible consequences; The value of biodiversity then, now, and where do we want to go?
	System-thinking competency		Reduce complexity to something recognizable; Use system-thinking; You have to map ecology and the social aspects.
	Value-thinking competency		Collaboration has to be based on equality; Search for people with ideals and not the ideal people; Take decisions in balance with your conscience and values; Take responsibility and choose freedom above obedience.

summarizes the results and presents the final coding scheme including raw data examples for the sustainability research competencies.

4.2.1. Basic Academic Competencies

Basic academic competencies such as critical-thinking, analytical-thinking, and research and data management were mentioned by the participants of this research. The professionals indicate that their daily work requires a fair amount of analytical and critical thinking. It is important in the field of sustainability to be able to take a step back and question the status quo. Practitioners apply analytical methods to assess complex systems. Consequently, the capability to collect and analyze data plays an important role. Practitioners mention the need to present findings and (scientific) data to stakeholders on a regular base. Furthermore, they emphasize the relevance of systematic monitoring and impact assessment of their sustainability projects which require critical and analytical-thinking as well as a good comprehension of research and data management. Furthermore, it became clear that basic academic competencies are strongly linked to the topical knowledge base of the professionals.

4.2.2. Systems-Thinking

Systems-thinking is crucial in gaining a sound understanding of sustainability challenges. Participants outline the need to analyze and understand systemic relationships as well as the necessity to cope with the inherent complexity of social, political, and ecological systems. “Use systems-thinking”; “Reduce complexity to something recognizable”; “You have to map ecology and the social aspects” are quotes from our raw data. However, the discussion on systems-thinking did not gain much depth during the workshop as if the systems-thinking competence would be self-evident. Further review revealed that for some, the foundation of systems-thinking had been laid out decades ago through formal education when they became ecologists or biologists for example. For others, it was learning on the job while spearheading sustainability initiatives. Sustainability professionals emphasize the need to analyze and understand social, ecological, and economical interrelationships in complex systems not only to gain insight about the status quo but also to evaluate implications of possible interventions. Quite naturally, this competency is closely tied to futures-thinking.

4.2.3. Futures-Thinking

Futures-thinking can be seen as the ability to imagine and anticipate future developments including a capacity to comprehend their possibility, probability, and desirability. The value to think in future scenarios and anticipate possible consequences of action-reaction in complex systems can be seen in quotes such as: “Anticipation is important”; “Dare to think long term”; “You need an understanding of possible consequences”; “See through things and anticipate!” Without futures-thinking it would be hard to imagine a practitioner to be successful in the field of sustainability. Many times, our participants emphasized the need to have a long-term perspective, to anticipate future developments and to work towards desired future outcomes. Due to the seniority of the professionals, they could heavily draw on their lived experience to devise and evaluate future scenarios. However, judgement on the desirability of future scenarios is often value-laden as our data indicates.

4.2.4. Values-Thinking

Values-thinking can be defined as the ability to perceive, analyze, reconcile, and negotiate values, norms, principles, and objectives. The professionals discussed issues such as equality, freedom, and taking decision in balance with one’s conscience and values. Furthermore, they outline the importance of self-awareness to analyze and understand values and norms of others. Only with self-awareness it is possible engage in fruitful, honest and respectful discussion with people holding different values. The following quotes from the interviews outline the need for self-awareness and the ability to discuss and negotiate values and norms in interaction with others: “Get insight in your own values, and what is important to you”; “Let them think critically about their values, provoke arguments and question evidence–turn their arguments over and tease–so they are going to question themselves and ground their values on insight.” The values-thinking competency presented itself closely tied to futures-thinking, systems-thinking, and critical thinking. Participants outline its crucial role in analyzing and understanding stakeholders. Therefore, is was attributed to sustainability research competencies, but it clearly has strong ties to interpersonal collaboration. When evaluations of systems, future scenarios, and stakeholders are significantly influenced by values-thinking, the lack of sufficient self-awareness might quickly become a source of conflict in collaboration.

4.3. Knowledge and Learning

4.3.1. Lived Experience

Lived experience is knowledge that evolves over time through everyday practice, engagement with others, experience and responses to events influenced by contextual factors [73]. Lived experience complements scientific knowledge with practicable insights about ‘what works in real life situations’ [74]. The concept is of particular importance for sustainability especially when it comes to demonstrate legitimacy and gain public acceptance of interventions [8,28,74]. We found strong support for the significance of lived experience in daily practice of the practitioners. The sustainability professionals make use of best practice examples to advice and inspire others. Furthermore, sharing lived experience plays an important role in capacity building efforts and in interpersonal collaboration. By demonstrating what has already being carried out, they jump-start co-creation as these quotes underscore: “What are the best practices from the past?”; “Find out what went well in previous projects and what works elsewhere. What should we keep? What can we improve?”; “How do they do it elsewhere: What works? What not?” Participants of this study could draw on vast amount of lived experience due to their seniority. Comments such as: “Don’t try to re-invent the wheel”; “Be aware that this is not the first hype–we had this in the 70ies and 90ies as well!” show that lived experience can nurture critical-thinking and helps to put things in perspective. The practitioners outline that drawing on lived experience can reduce the risk of wasting resources, help understanding values, and facilitates efforts to win stakeholders over. Collaboration with stakeholders regularly provides learning opportunities and fosters the development of practical knowledge. Interestingly, this study has been seen as an opportunity to share lessens-learned with fellow professionals during the workshop. Practitioners felt that participation gave them the chance to fulfil their stewardship for their profession and develop their topical knowledge base.

4.3.2. Topical Knowledge

Topical knowledge in the context of sustainability can be defined as knowledge specifically related to a certain sustainability topic [24]. Topical knowledge is usually developed through formal education and vocational training, but can be self-taught as well. In the field of sustainability, it is often at the core of the practitioners work or as a survey participant put it: “It is the base to do your job right”. We want to emphasize that topical knowledge is not a competency, but we follow Brundiers et al., (2021) [24] argumentation that it should to be integrated into competency frameworks. The professionals of this study outline their topical knowledge about e.g., ecology, nature conservation, and impact measurement. Furthermore, they elaborate on the link between topical knowledge and sustainability competencies. For example, professionals indicate the interaction between topical knowledge and capacity building, as the following quotes from the workshop underline: “Share scientific knowledge with stakeholders”; “Advise stakeholders and build up their knowledge base”. Overall, the sustainability professionals in this research show great confidence in their topical knowledge: “We know a lot about ecology, the environment, sustainability, and the ultimate goal of saving biodiversity”; “You need a sound understanding of ecological and social aspects”; “Get into the matter!”; “Get facts and scientific studies”, but also emphasize the need for continuous learning (see also

Table 4. Integrated learning competency of senior-level sustainability professionals from Belgian Flanders–final coding scheme and raw data examples.

Selective Coding (Competency Cluster)	Axial Coding (Knowledge Category)	Raw Data Examples (Translated from Original Dutch Data)
Integrated Learning Competency	Topical knowledge	You need a sound understanding of ecological and social aspects; Get into the matter; Get facts/scientific studies; Know the structures; We know a lot about ecology, the environment, sustainability, and the ultimate goal of saving biodiversity; Know and apply impact measurement; Measure the impact of your campaign.
	Lived experience	Don’t try to re-invent the wheel; Know best practices; Importance of getting insights from the past; What are the best practices from the past?; What has already happened?; Find out what went well in previous projects and what works elsewhere. What should we keep? What can we improve?; How do they do it elsewhere; hat works? What not?; Be aware that this is not the first hype-we had this in the 70’s and 90’s as well; Be open to external expertise; We have to expand our competences and immerse into other topics.

).

4.3.3. Integrated Learning Competency

Lived experience and topical knowledge are complementary to one another. Both have a strong link with competencies for sustainable development. We included topical knowledge and lived experience in the final competency set, and depicted them as ellipses since they do not constitute competencies (see Figure 1). During the workshop discussions and the following action-reflection cycles the professionals indicated the need for continuous learning: “Be open to external expertise”; “We have to expand our competences and immerse in other topics”; “We need to learn more about social sciences”. Participants explain that their theoretical and practical knowledge evolves through action in the field as well as keeping up with the latest literature. Scientific facts and field experiences are constantly matched and evaluated in an integrated learning process. It is quite remarkable that even with 24 years of work experience on average and a proven track record in spearheading successful sustainability projects throughout their long careers these professionals still emphasize their need for continuous learning. Based on multiple moments of participant review and extensive triangulation we suggest that topical knowledge and lived experience are bound together by an integrated learning competency. Table 4 summarizes the results and presents the final coding scheme including raw data examples for integrated learning competency.

5. Discussion of Findings

This study collected and analyzed qualitative data on senior sustainability professionals who operate in the specific context of the public sector in Belgium Flanders. Since sustainability professionals in Belgium are not affiliated to one single category in formal job classification systems, we applied fixed selection criteria for their identification. However, future research and official statistics (e.g., censuses, labor force surveys) would greatly benefit from a new category or an official overview of jobs linked to sustainability. This would help comparing findings beyond the scope of a single study.

Our findings contain dynamic aspects due to the evolutionary character of the action research methodology. Findings are embedded in the specific context of the participants. Consequently, one needs to address the potential of and limitations for the generalizability by comparing findings with outcomes of other empirical research to outline and discuss similarities and differences, which we will do in this section. Throughout the entire action research process the professionals strongly emphasized the need for competencies to devise and implement solutions together with stakeholders in a collaborative process in order to achieve self-sustaining transformation towards sustainability. Thereby, this study delivers empirical evidence for the existence and importance of sustainability intervention competencies which is in line with other recent literature [8,11,32].

Interpersonal collaboration lies at the heart of the intervention competencies. The ability to collaborate with stakeholders has been seen as a key competency by educational experts [15,24,37], alumni of sustainability programs [9,10,33], and professional practitioners [4,8,11,32]. Our findings strongly support these earlier notions and present a more fine-grained picture. Through rigorous data analyses, extensive triangulation, and multiple participant reviews we identified five elements of interpersonal collaboration competency, namely co-creation, communication, building mutual trust, stakeholder engagement, and boundary spanning. Higher education literature consistently refers to communication, teamwork, and stakeholder engagement as part of an interpersonal competency [18,24,75]. Salovaara ad Soini (2021) emphasize that “interpersonal competence was most often mentioned with emphasis on collaboration” by sustainability professionals [9] (p. 79). Based on our findings we propose to specify interpersonal competency to interpersonal collaboration competency. Furthermore, the senior sustainability professionals that participated in this study elaborated extensively on boundary-spanning aspects of collaboration. This is in line with calls in higher education literature to integrate a transboundary competence into sustainability related study programs [36,76,77]. Furthermore, our findings underscore that the ability to build mutual trust is of essence in interpersonal collaboration. Perez Salgado et al., (2018) mention trust as an influential factor for successful collaboration and co-creation by sustainability professionals in the Netherlands. Our empirical findings suggest that the ability to build mutual trust is vital since it is interwoven with all other elements of interpersonal collaboration. Our findings are in line with research on cross-sector partnerships which presented quantitative evidence of trust being an important governance mechanism and acting as a gatekeeper of knowledge exchange in multi-stakeholder collaboration [66,78].

Intrapreneurial competency is a novel aspect of intervention competencies. Salovaara and Soini (2021) very briefly mention that graduates of a sustainability master program are “maintaining an entrepreneurial approach to their profession” despite being part of an organization [9] (p. 80). Our findings strongly suggest that the intrapreneurial competency is a vital factor in the careers of the Belgian sustainability professionals. Due to their vast experience and seniority, our research participants were able to reflect on failure in their work and unsuccessful projects. They identified slow decision-making processes, inflexible structural aspects (e.g., laws and regulations), and resource restrictions as major obstacles to achieve transitions towards sustainability. It seems plausible that the intrapreneurial competency is a direct response to these limitations for at least two reasons. First, we find many indications of intrapreneurial bricolage in our data. Intrapreneurial bricolage can be described as creatively working with resources at hand; which is in essence a strategy to cope with resource limitations in an organization. Clearly, our findings are limited to Belgian sustainability professionals in the public domain, but case study research on multinational corporations such as ABB, Nokia, and Philips has shown that sustainability managers in commercial settings respond to resource constrains in a very similar way (2012) [71,72]. For example, Venn and Berg (2013) outline that sustainability managers involved in poverty alleviation “creatively cope with resource constraints and tensions arising from traditional financial metrics… [and] do not hesitate to invest private resources… [because] they believe in their contribution to sustainable development and the corporate mission…” [72] (p. 119). Second, our findings show that sustainability professionals have a strong focus on opportunity seeking, feasibility, fast action, and quick-wins. These are aspects of proactiveness and opportunity recognition which in turn are important indicators of intrapreneurial behavior according to management literature [79]. It is our strong believe that it would be fruitful to do more research on the intrapreneurial competency of sustainability professionals in the future.

Political and strategic competencies are closely linked to one another. The ability of political thinking has been mentioned in literature before [18,80], but still lacks a solid empirical underpinning. Our findings offer a first glimpse at an easily overlooked aspect of the work of sustainability professionals, namely dealing with powerful actors whose agendas can be very different. We acknowledge that the participants of this study work in the public domain and therefore might be more sensitive to politics and power-play. However, management research on multi-stakeholder collaboration in cross-sector partnerships has also shown the potential for conflict and power issues due to asymmetric resource positions of stakeholders [66,81,82]. Venn and Berg (2014) [66] indicate that stakeholders might try to counterbalance power positions which can make cross-sector collaboration a lengthy and difficult process. This is in line with earlier findings from Perez Salgado et al., (2018) stating that “no stakeholder has absolute power to dictate proceedings and that significant time is needed to negotiate the power relations which are at play between stakeholders” [8] (p. 173). They argue that the ability of political-strategic thinking, deliberations, and actions should be a crucial aspect of intervention competencies. Strategic-thinking is frequently mentioned in HE literature as an important component of sustainability related competency sets [18,24,41]. However, definitions and interpretations of the term ‘strategic’ vary in higher education literature to a great deal which can cause serious misunderstandings. Furthermore, the combination of political and strategic aspects is far from ideal. Therefore, we propose to split strategic-political-thinking into two different (but closely related) competencies and enrich their definitions by considering also strategic-action and political-action as integral elements. Clearly, this only provides a starting point and requires future research to investigate both competencies in more depth.

Implementation competency has proven to be a key competency for the sustainability professionals in this study. The ability to initiate and facilitate a process of transformation towards sustainability requires the motivation to act, conflict resolution, gaining support inside and outside the organization, and coping with resistance. This evidence is in line with Willard et al., (2010) [4] findings that sustainability professionals need to have change management skills as well as more recent research that outlines the ability of ‘getting things done’ [8,11,32]. Lately, implementation competency gets recognized as a crucial part of competencies for sustainable development by educational experts [24]. Our study outlines implementation as a vital part of sustainability intervention competencies. Additionally, we show that sustainability professionals strive for self-sustaining change. They build up capacity of stakeholders, put a lot of effort in inspiring others, and stimulate ownership. They are even willing to sacrifice personal fame if that helps to achieve transformation towards sustainability. This altruistic approach might inspire future research to look at personality related factors more closely.

This study presents insights into an integrated learning competency and its interrelatedness with topical knowledge and lived experience. The strong emphasis on continuous learning comes to a surprise, since the majority of participants of this study are in the middle and ending stages of their careers. Nevertheless, their emphasis on learning makes sense, since sustainability issues are highly complex and often pose ‘wicked’ problems [83]. Devising solutions regularly spans far beyond the capacity of any single person, organization, or sector [3]. Consequently, professionals engage in multi-stakeholder collaboration to solve sustainability issues together. On the one hand, the constant exposure to new insights and new knowledge provides relentless learning opportunities for sustainability professionals. On the other hand, learning and understanding can be very challenging due to large ‘cognitive distance’ between collaborating stakeholders [84,85]. Reducing cognitive distance, simply to understand stakeholders, would therefore translate into a continuous demand for learning. Additionally, the field of sustainability science evolves constantly and the professionals made it clear that they have to keep up with (scientific) literature. Maybe it is a combination of learning opportunity and learning necessity that explains the need for learning even for very experienced sustainability professionals. That practitioners constantly improve their topical knowledge and lived experience has been documented by Perez Salgado et al., (2018) [8] and Willard et al., (2010) [4] as well. Furthermore, integrated learning is linked to other competencies. We believe that situated knowledge [6] and situated learning [5] in communities of practice [7] play an important role in the acquisition and evolution of sustainability related competencies [17,34]. Our findings also suggest that social learning processes [68] play a key role in capacity building. The professionals emphasized the importance of being a role model to inspire and motivate others to learn, take responsibility, and feel ownership. This is in line with Holtz et al., (2018) [86] study on local collaboration to support low-carbon transitions. They outline that social learning fosters the development of a joint vision, shared expectations, and help to align stakeholders with diverging interests. Overall, we have shown the importance of integrated learning and call for more research on topical knowledge, lived experience, and social learning processes.

Sustainability research competencies include competencies such as basic academic competencies, future-thinking, systems-thinking, and values-thinking competencies which are well established in higher education literature. However, this study revealed a rather huge volume difference of data between the two competency clusters. All sustainability research competencies together accounted for only 5% of the workshop data. These well-established competencies were not central during the workshop discussion and only surfaced after a comprehensive data analysis. Naturally one has to be very careful to interpret this difference, due to the qualitative nature of this data. However, it is interesting to note that a similar difference has also surfaced in a study with sustainability professionals in Canada by A.MacDonald et al., (2020) [11]. A possible explanation for this could be that sustainability research competencies did not get mentioned that much during the workshop discussions since they might be self-evident and practitioners focus more on strongly on practical applications. This would be in line with the findings of L.MacDonald and Shriberg (2016) who report that alumni of sustainability leadership programs “have a strong preference for skills with direct translation into the workplace as opposed to more internally focused processes that can be difficult to bring into professional settings directly” [33] (p. 369). We asked the professionals for a critical reflection on the unequal data distribution. Some professionals indicate: “Research competencies are basic and intervention competencies are about performance, doing, and promoting”; “The intervention competencies are more tangible for a professional in the field—they are the tools with which he works on a daily basis.” Clearly, more research is needed to explore this phenomenon in greater depth.

6. Conclusions

This study contributes to the increasing empirical evidence of an overarching sustainability intervention competency of sustainability professionals [4,8,11,32] and provides a fine-grained picture of its six key competencies, namely interpersonal collaboration competency, capacity building, intrapreneurial competency, strategic competency, political competency, and implementation competency.

Awareness of sustainability intervention competencies can assist organizations to develop new recruitment strategies, selection processes, and training programs. It can guide human resource management to re-think and recalibrate their strategies. Furthermore, insights in sustainability intervention competencies can help associations of sustainability professionals to devise training programs, enhance certification systems, and to provide opportunities for competency related exchange between members. The Belgian sustainability professionals expressed their strong demand for on-the-job training and underscore their continuous learning efforts. Some explicitly mention the need to further develop their capacity for political thinking and acting. Furthermore, this study presents novel insights on the importance of an intrapreneurial competency for practitioners in the field of sustainability. Research from management science points out that the demand for this competency is not limited to professionals the public domain, but for mangers in corporations as well [71,72]. Without doubt, organizations could tremendously benefit from employees that have abilities of entrepreneurs, but stick with their organization to advance its mission and foster success. Identification and development of intrapreneurial competencies should therefore be on the agenda of sustainability related human resource management. However, our empirical evidence points out that sustainability professionals apply intrapreneurial bricolage to cope with internal resource constrains. This automatically brings up the question of (lacking) organizational support and should trigger organizations to provide sufficient room for entrepreneurial experimentation and innovation (white-space).

Furthermore, our findings contribute to the knowledge of and debate on key competencies in higher education. We have shown that a closer look at practitioners who successfully operate in the field of sustainability is valuable, since it transcends the perspective of students and educational experts. This can help to mitigate the risk of gaps between what is taught in higher education and what is needed in practice. De Haan (2006, 2010) [17,34] outlined that situated learning can play an important role in the competency development of students in higher education. Formal and informal learning in (simulated) real-world settings can embrace the acquisition of sustainability competencies [37,75,87,88]. Especially the development of sustainability intervention competencies will need these pedagogical setups in order to prepare students for their work as future professionals.

Due to the qualitative nature of the research presented in this study, our findings are limited in terms of generalizability. However, we have shown that this study can offer insights beyond the scope of the participants due to the rigorous selection process of participants and comprehensive pattern matching of outcomes with other empirical research on sustainability professionals [43,89]. Nevertheless, quantitative evaluations of competencies for sustainable development will be beneficial. Furthermore, Mochizuki and Fadeeva (2010) [90] addressed the claim of ‘universality’ of key competencies and showed the local embeddedness of some competences, with references to and examples from several countries, such as Denmark, Germany, Japan, Thailand, and Laos. Hence, we suggest to promote and advance (action) research in other countries of the Global South and North to further explore sustainability competencies of professional practitioners.