The circular economy (CE) offers an alternative to the prevalent linear production and consumption model. CE aims to eliminate waste, maximise resource efficiency, minimise environmental impacts, support sustainable development, and foster new business opportunities[1], [2]. Despite its growing popularity, CE has faced criticism from scholars calling for interdisciplinary, critical, and coherent perspectives and a shared understanding of CE[3]. Understanding how CE is conceptualised is crucial to avoid it becoming stagnant or merely a form of “greenwashing” [4], [5].

Many scholars have attempted to define CE [3], and it remains a topic of debate in academia [4], [6]. In this study, CE is understood as a system aimed at maintaining the value of products, components, and materials for as long as possible through strategies such as reuse, repair, and resource efficiency [4].

The construction sector plays a particularly important role in the circular transition. The building sector accounts for around 50% of global raw material use and 36% of final energy consumption [7]. Consequently, transitioning the sector towards circular practices is essential. CE in the building sector typically involves keeping materials, products, and components in use for as long as possible with minimal processing. This approach includes reusing building elements, renovating or retrofitting structures, and designing buildings for adaptability and disassembly [8]. Such inner-loop strategies preserve material value, reduce energy consumption, and minimise waste generation compared to recycling or downcycling [9].

Businesses implementing CE can adopt narrow, slow, close, regenerate and inform strategies to reduce resource use and environmental impacts [10]. Narrowing strategies reduce material consumption by increasing efficiency. Slowing strategies extend product lifespans through durability, repair, and reuse. Closing strategies focus on closing material loops through recycling and remanufacturing. Regenerate strategies aim to restore natural systems by using renewable or biobased resources. Informational strategies, such as documentation and data exchange, support these approaches by improving transparency and enabling collaboration [10]. Table 1 presents these strategies with examples from the construction sector.

Implementing CE in the construction sector requires collaboration across multiple actors. CE initiatives often span organisational boundaries and involve customers, suppliers, policymakers, and other stakeholders [4], [11], [12]. In the construction industry, this collaborative approach is particularly complex because the sector comprises many diverse and interdependent stakeholders. Companies, therefore, shift from focusing primarily on internal operations to inter-organisational collaboration within broader ecosystems, where different actors work together towards shared sustainability goals [13].

In this context, employees and end users play particularly important roles. Employees possess practical knowledge of daily operations and often identify opportunities for improving material handling, reuse, and efficiency. Empowering employees to contribute, experiment, and take initiative can therefore enhance CE outcomes within construction companies [14]. End-users also influence circular practices, for example, through their expectations regarding renovation, reuse, and material choices. Trust between companies, employees, and customers can therefore become an important enabler of circular practices [15].

Hence, when companies move from linear activities towards CE activities, they shift from a focus on their own operations to inter-organisational and systemic collaboration within an ecosystem perspective, where various stakeholders work together towards a common goal [16]. Here, collaboration can be understood as: “a process in which autonomous or semi-autonomous actors interact through formal and informal negotiation, jointly creating rules and structures governing their relationships and ways to act or decide on the issues that brought them together; it is a process involving shared norms and mutually beneficial interactions” [17].

However, implementing CE in the building industry requires a shift from traditional linear models to more circular practices. This transition is facilitated by engaging various stakeholders, including customers and employees. Empowering employees to contribute, experiment, and take initiative can significantly enhance CE outcomes [14]. Therefore, involving employees in decision-making processes and providing them with the necessary skills and knowledge can significantly improve the adoption of CE practices within construction sector companies [18]. However, collaboration across the value chain is also vital for a successful CE implementation. This approach involves inter-organisational and systemic collaboration, where diverse stakeholders work together towards a common goal [16], [18]. Such collaboration ensures that CE initiatives are comprehensive and effective, addressing the complex challenges of sustainability in the construction sector. Another important enabler of the success of such collaborations is the trust between the actors involved [15].

At the same time, the construction sector faces several barriers to implementing CE, including a lack of clear governance strategies, underdeveloped waste management systems, and limited end-user awareness of circular solutions [13]. Homeowners often lack guidance and incentives to demand circular solutions, which reduces pressure on developers and suppliers to adopt CE practices [13]. As a result, there is still a need to understand better how circular practices develop within the construction sector and how different actors become involved in these processes. This article addresses the following research question:

What challenges and enablers do construction SMEs encounter when involving employees and end users in efforts to prolong the lifespans of products, components, and materials, and what triggers the initiation of such engagement processes?

In this study, a distinction is made between triggers and enablers of circular engagement. Triggers refer to specific events or disruptions that initiate changes in practices, such as equipment failures, economic constraints, customer feedback, or participation in pilot initiatives. Enablers, in contrast, refer to organisational, structural, or relational conditions that enable such initiatives to develop and stabilise over time, including employee autonomy, trust-based relationships, and close interaction with end-users. In this way, triggers can be understood as initiating moments that open space for change, while enablers support the development and stabilisation of new circular practices.

To answer this question, the study draws on qualitative case studies of eight Danish small and medium-sized enterprises (SMEs). The empirical material consists primarily of semi-structured interviews with company representatives, supplemented by follow-up conversations and observations conducted between January 2023 and June 2024.

Denmark provides a relevant setting for this investigation due to its long-standing focus on sustainability and supportive policy environment for CE adoption. The construction sector is dominated by SMEs, which often operate within trust-based networks. These relationships among companies, employees, and end users create favourable conditions for collaboration, knowledge sharing, and the development of circular practices. By examining Danish cases, this study explores how trust and everyday interactions influence efforts to prolong product and material lifespans.

The analysis is grounded in practice theory and learning theory, with a focus on how circular practices unfold in real-life settings within the construction sector. Practice theory helps illuminate how decisions are made on construction projects, often shaped by on-site demands and contextual situations [19], where numerous stakeholders influence the actual practices [20].

When companies attempt to implement circular practices, they often start by modifying formal elements, such as procedures, or developing circular policies [21]. However, these top-down changes are often not enough. Successful implementation requires integrating with, or transforming existing practices on the ground. In the construction sector, this means aligning new requirements with the everyday routines of the building professionals.

The empirical material presented in the following section is based on case studies including eight companies working in the construction sector. The analysis addresses practices within individual companies as well as the learning that occurs in collaborations between a company and the involved actors.

In the analysis, circular practices are examined as evolving practices shaped by interactions between actors, material arrangements, and situated problem-solving within everyday work contexts. An overview of the construction SMEs is provided in Table 2.

Each of the 8 selected cases is introduced in the following with a focus on the circular strategies they are working with, and the initiatives selected for the following analysis are highlighted as practices. They are chosen based on the following parameters: 1) They should involve end users and/or employees. 2) The company has identified them as central for their daily practices. 3) They have been implemented for long enough for the companies to have gained experience with their positive and negative consequences.

The cases analysed in this study are all SMEs. Larger construction companies were also screened during the selection process, but no relevant cases were identified for inclusion in the analysis.

During the case analysis, four different perspectives on circular practices were identified. Each of these is analysed below, focusing on the actual practice, the situations, the learning processes that led to these practices and the role of end users and/or employees in implementing them. In the following, the cases are analysed with regard to their CE practices and learning that have followed the initiatives.

The analysis of eight Danish construction sector SMEs reveals that CE practices often emerge from bottom-up disruptions in which frontline employees and end users play a central role in initiating and shaping new ways of working. This finding adds an important nuance to the existing CE literature, as the cases show that the initiation of circular practices rarely stems from formal strategy, policy expectations, or dedicated CE planning, but instead grows out of concrete operational frictions such as economic pressures, equipment failures, project complexity, customer dissatisfaction, or engagement in external pilot programmes. These disruptions created opportunities in which existing routines became untenable, opening space for employees and users to propose and try out alternatives. This insight highlights the importance of understanding CE transitions as situations of practice-based learning rather than as outcomes of strategic intent.

Taken together, the findings suggest that circular economy initiatives in SMEs can be understood as practice-based processes in which operational disruptions trigger experimentation, while organisational and relational conditions enable the gradual stabilisation of emerging circular practices.

This finding contributes to the circular economy literature by highlighting how circular practices may emerge through bottom-up disruptions and situated learning processes rather than through formal strategic initiatives. While previous studies often emphasise policy drivers, business models, or technological innovation, the present study shows how everyday operational frictions can create opportunities for employees and end-users to initiate and shape circular practices.

Across the cases, trust emerges as a key enabler of the circular practices developed. Internally, trust between managers and employees enabled staff to propose unconventional solutions, experiment, and negotiate new routines. This observation resonates with the literature on learning in organisations [26]. Bottom-up CE initiatives depend on relations, as employees will only share tacit operational knowledge and take responsibility for new practices when they trust that management supports adaptive problem-solving. Externally, trust between companies and their customers shaped the feasibility of offering reused materials and refurbished components, echoing studies that identify trust as a prerequisite for collaborative CE models and reverse value chains [33]. In the construction sector, where material reuse challenges established norms of “newness,” trust becomes essential for building acceptance of alternative solutions. Thus, trust facilitated the disruptions and learning processes observed in the SMEs.

CE was not introduced through abstract policy directives or top-down strategic innovation, as often identified as drivers in the literature [21], but rather through situated learning and problem-solving at the operational level. Employees developed new routines around equipment use, not through formal CE training, but through practical challenges related to cost, availability, and durability. These examples reinforce the importance of practice-based learning, where knowledge is co-created through experimentation and everyday work. It reflects the “slow” and “narrow” strategies discussed by Konietzko et al. [9], in which CE is achieved by prolonging resource lifespans and using them more efficiently. Importantly, this learning often occurred in response to disruptions such as economic constraints, equipment degradation, or customer complaints, which created space for change.

The cases show that the SMEs mainly implement narrowing and slowing CE strategies, such as reducing waste, improving equipment utilisation, and extending the lifespan of materials through reuse and renovation. These strategies fit well with existing work routines and can be developed through incremental, practice-based learning. Closing strategies, such as refurbishment and recycling, were used in only a few cases, and regenerative approaches were largely absent, reflecting the greater infrastructural and organisational demands these strategies place on SMEs. Across several cases, informational strategies were present but applied in simple, task-oriented ways, such as apps for surplus materials or equipment tracking. Overall, the strategy pattern indicates that SMEs adopt the CE practices that are easiest to integrate into daily operations. In contrast, more complex circular strategies require support beyond the capacity of individual firms.

In several cases, employee engagement emerges as a central enabler of CE, confirming the literature on the importance of empowering operational staff [18]. Employee autonomy and initiative are crucial in implementing reuse strategies. In several cases, employees did not just execute new procedures; they co-developed them, integrating CE into their own routines and identities.

The end-users played an essential role in triggering and legitimising. Customer preferences, whether for aesthetic continuity, reduced waste, or affordable reuse, challenged companies to reconsider standard procedures. This observation supports claims that demand-side engagement is vital to CE transitions in the construction sector.

However, the data also reveal limits: end-user interest in reused materials was higher in certain segments (e.g., summer cottages, renovation), while new builds often still favoured new products. It highlights the importance of contextual awareness in CE implementation and suggests that consumer education and framing remain necessary.

The companies did not start with fully developed CE practices. Instead, they learned by doing. Practices like reusing solar panels, managing surplus materials, or improving machinery use were developed incrementally, refined through feedback and experience. It highlights the importance of tolerance for trial-and-error and the value of organisational learning over time.

While public procurement and regulation provide important incentives for circular solutions [8], our findings suggest that immediate initiation of CE practices in SMEs often emerges from operational disruptions, employee insights, or customer feedback. In this sense, regulation shapes the broader enabling environment, while concrete problems in daily work act as the practical triggers for change.

These findings also have implications for circular economy policy and organisational practice. Rather than focusing solely on regulatory targets or formal strategies, policies may need to support experimentation and collaboration at the operational level, for example, through pilot programmes, local reuse networks, or initiatives that connect SMEs with circular resource flows.

This study examined how construction SMEs engage employees and end users in efforts to prolong the lifespans of products, components, and materials within a circular economy perspective. Drawing on qualitative case studies of eight Danish companies, the findings show that circular practices can emerge from concrete disruptions in daily work rather than from formal strategic initiatives.

Danish SMEs face challenges when involving employees and end users in efforts to prolong the lifespans of products, components, and materials. These challenges include entrenched work routines, limited time and resources for experimentation, customer expectations tied to “newness,” and the practical complexities of handling reused or surplus materials. At the same time, the cases also reveal powerful enablers that make such involvement possible: high levels of trust, proximity between managers and frontline staff, employee autonomy, and strong relational ties with customers. These organisational and relational features provide the foundation for employees to share tacit knowledge, propose changes, and assume responsibility for new circular practices, while also helping customers accept reused or refurbished solutions.

The analysis further demonstrates that engagement processes are not triggered by circular ambitions alone but by concrete disruptions in daily work. Economic constraints, unexpected equipment failures, customer dissatisfaction, or proactive employees all created moments when existing routines became untenable, opening space for learning. Such disruptions acted as triggers enabling new CE practices to emerge through situated problem-solving. In this sense, the circular transition observed in SMEs is best understood as an incremental and practice-based process, driven by operational frictions rather than strategic planning. This observation underscores that effective CE implementation depends not only on policy incentives but also on organisational cultures, trust-based relations, and learning capacities that allow disruptions to be transformed into opportunities for more circular ways of working.

At the same time, the initiatives identified in this study remain relatively small in scale and highly dependent on committed individuals, relational trust, and favourable circumstances. It underscores that SME-driven CE practices, while valuable learning laboratories, cannot by themselves transform the wider construction sector. Achieving broader circularity will require larger companies to adopt organisational structures that better support employee involvement and customer dialogue, as well as regulatory frameworks and procurement systems that reward experimentation, material reuse, and collaboration across the value chain. Policymakers and managers should therefore focus on creating the conditions that enable practice-based learning, including reducing uncertainties around reused materials, supporting local piloting and experimentation, strengthening collaboration between SMEs and larger actors, and encouraging companies to view operational disruptions not as isolated problems but as opportunities for circular improvement. In this way, practice-based insights from SMEs can inform a more systemic approach to CE transition in the construction sector.

Overall, the study contributes to the circular economy literature by demonstrating how bottom-up learning processes and situated problem-solving can drive circular practices in construction SMEs. The findings show that employees and end-users play a crucial role in identifying opportunities, experimenting with new routines, and legitimising alternative solutions such as reuse and refurbishment. In this way, circular practices often evolve incrementally through everyday work practices rather than through top-down strategic planning.

Future research could explore how similar practice-based learning processes unfold in larger construction firms or in other national contexts with different institutional conditions.