Shaping SME purchasing for sustainability: a case study of supplier-buyer relationships and extended product lifetimes

The significance of sustainable purchasing has intensified amid global disruptions such as climate change and the COVID-19 pandemic. By promoting sustainability and improving purchasing models, companies can mitigate supply chain vulnerabilities (Di Mauro et al., 2024), reduce environmental impacts and enhance performance (Amorim et al., 2023). However, the effectiveness of these efforts depends on buyers’ ability to influence suppliers (Eggert and Hartmann, 2021), balance stakeholder (e.g. customers and shareholders) demands and manage internal organisational tensions (Neessen et al., 2021). Since companies are increasingly viewed as “only as sustainable as their suppliers” (Krause et al., 2009), purchasing has become a strategic lever for advancing sustainability outcomes rather than merely an operational activity (Johnsen et al., 2017; Miemczyk et al., 2012).

Within this context, small and medium-sized enterprises (SMEs) emerge as key actors in sustainable development due to their widespread presence and collective economic impact (Denicolai et al., 2021; Klewitz and Hansen, 2014). While individual SMEs often face resource constraints, collectively they hold substantial purchasing power (Ellegaard, 2006), enabling significant influence across supply networks. This duality, i.e. limited firm-level resources but substantial collective influence, renders SME purchasing particularly important for sustainability research. The growing focus on the sustainability of SMEs’ purchasing in research (e.g. Denicolai et al., 2021; Dey et al., 2022; Mura et al., 2020; Prieto‐Sandoval et al., 2019) and policy (European Commission, 2020) underscores this importance. Consequently, improving purchasing and strengthening supplier relationships are increasingly emphasised as pathways through which SMEs can contribute to improved sustainability outcomes (Jia and Chen, 2024).

In this study, “purchasing” is defined broadly as activities related to sourcing, including supplier selection and development, as opposed to logistics or inventory management (Miemczyk et al., 2012). We use the term purchasing models to describe the organising principles that structure these activities, such as the degree of formalisation, centralisation, role distribution and coordination with suppliers (McGowan, 2018; Pressey et al., 2009). These organising principles are especially consequential for SMEs, which, unlike large organisations with formalised purchasing models, typically rely on informal purchasing practices embedded in everyday managerial routines. Their purchasing activities are typically handled by owners or managers, instead of specialised purchasing departments, and thus vary across companies (Dollinger and Kolchin, 1985; Gadde and Håkansson, 2001; McGowan, 2018; Morrissey and Pittaway, 2004; Pressey et al., 2009).

An increasingly important aspect of purchasing decisions is extending product lifetimes, which is recognised as an effective approach for minimising environmental impacts (Den Hollander et al., 2017) while improving economic efficiency through increased utilisation (Nyström et al., 2021). Extending product lifetimes depend on the alignment of decisions between multiple actors over time, often requiring coordination among manufacturers, distributors and customers on product design, use and maintenance as well as responses to user feedback (Johnstone, 2024; Kumar et al., 2022; Nyström et al., 2021). Given that purchasing is shaped through continuous interaction with suppliers, relational dynamics become central to how sustainability ambitions are translated into feasible sustainable purchasing. Building on this, “sustainable purchasing” refers to practices that intentionally integrate environmental and social considerations into the selection, coordination and development of suppliers to advance sustainability outcomes beyond immediate cost concerns (Johnsen et al., 2017).

For SMEs, such coordination is challenging due to resource constraints (Amorim et al., 2023; Denicolai et al., 2021), insufficient purchasing expertise (García‐Quevedo et al., 2020) and weak bargaining power (Eggert and Hartmann, 2021). As a result, SMEs are frequently constrained by the need to prioritise delivery reliability, product quality and suppliers’ problem-solving capabilities over explicitly articulated sustainability requirements (Ellegaard, 2009; García‐Quevedo et al., 2020; Reuter et al., 2012). While those responsible for purchasing need to develop broader sustainability-oriented competences beyond traditional cost-focused skills – such as strategic sourcing and negotiation (Stek and Schiele, 2021) – competence development alone is often insufficient to influence suppliers and coordinate purchasing to ensure extended product lifetimes. Long-term supplier relationships may help SMEs overcome internal resource constraints (Prieto‐Sandoval et al., 2019) by accessing suppliers’ expertise and capabilities (Adams et al., 2012). This highlights the relational nature of sustainable purchasing and the importance of supplier–buyer interactions in shaping sustainability outcomes (Jia and Chen, 2024).

Although SMEs collectively hold substantial purchasing power (Ellegaard, 2006), their sustainable purchasing practices remain insufficiently understood from a relational perspective. Much existing literature adopts company-centric perspectives, such as the resource-based view, institutional theory or stakeholder theory, which tend to conceptualise purchasing as an internal capability or response to external pressures. While these approaches provide valuable insights, they downplay the importance of relational and interactive dynamics through which purchasing practices and sustainability outcomes are collectively shaped over time (Johnsen et al., 2017). As a result, there is still limited understanding of how sustainable purchasing practices aimed at extending product lifetimes emerge in resource-constrained SMEs through ongoing interactions with suppliers. As Dubois et al. (2021) note, while buyer–supplier relationships remain highly relevant, the nature of purchasing challenges continues to evolve, especially for resource-constrained SMEs.

Therefore, given the heterogeneity of SME purchasing practices and their resource constraints, there is a need to examine how sustainability can be effectively integrated into SME purchasing practices and the role supplier relationships play in supporting these efforts. To address this gap, the industrial network approach (INA) is adopted as a theoretical framework. Developed by the research community referred to as the industrial marketing and purchasing group (Dubois et al., 2023; Ojansivu et al., 2022), INA conceptualises purchasing as an interactive process within long-term supplier–buyer relationships rather than as a discrete organisational function (Håkansson and Snehota, 1995; Johnsen, 2018). From this perspective, purchasing outcomes emerge through interaction, adaptation and the combination of resources across organisational boundaries, allowing actors to exploit resources at the network level (Araujo et al., 1999; Araujo et al., 2016).

These relational and interactive dynamics emphasise the importance of network interconnectedness (Harrison et al., 2023), supporting the findings of previous INA studies that note that sustainability initiatives often diffuse across relationships rather than remaining isolated (e.g. Brüel Grönberg and Hulthén, 2022; Melander and Arvidsson, 2021; Meqdadi et al., 2017; Öberg et al., 2012; Runfola et al., 2025). Prior studies have emphasised not only how sustainability initiatives emerge through ongoing business relationships and influence network configurations (Dominidiato et al., 2025b), but also how network interaction supports prolonged product use (Andersson Wänström et al., 2025; Melander and Arvidsson, 2021). INA thus offers the relational lens needed for examining how, despite resource constraints, SMEs’ purchasing practices can contribute to sustainability outcomes through relationships with more resourceful partners (Baraldi et al., 2023; Johnsen, 2018). Accordingly, this paper addresses the following research question:

The paper presents a single case study of a workwear manufacturer and its distributor and SME customers. The findings contribute to research on sustainable purchasing by demonstrating how high-involvement supplier relationships enable SMEs to address resource constraints by leveraging both internal and external resources to balance operational efficiency with user safety and satisfaction through decentralised yet structured purchasing models. The remainder of the paper is structured as follows: Section 2 presents the theoretical background, Section 3 describes the methodology, Section 4 reports the empirical findings, Section 5 discusses the findings and Section 6 concludes by outlining the theoretical and managerial implications, limitations and directions for future research.

As described earlier, INA conceptualises business networks as consisting of dynamic, long-term business relationships and complex interaction patterns (Håkansson, 1982). These relationships between suppliers and buyers can be viewed as interfaces, through which suppliers and buyers combine and mobilise their resources (Araujo et al., 1999; Araujo et al., 2016). The characteristics of supplier–buyer interfaces can vary considerably depending on their complexity (i.e. number of actors and resources involved) and interaction frequency, both of which influence the degree of involvement in the relationship (Gadde et al., 2003). The degree of involvement shapes how tasks are defined, divided and carried out and consequently leads to changes in supplier–buyer interfaces (Bastholm and Munksgaard, 2020; Gadde and Wynstra, 2017).

Low-involvement relationships are defined by standardised routines, low dependency and minimal adaptation (Gadde et al., 2003). Operational complexity and management costs are thus reduced, as narrow supplier interfaces entail low managerial involvement (Araujo et al., 1999; Gadde and Wynstra, 2017). While buyers maintain flexibility to switch between suppliers with ease (Dubois et al., 2021), supplier transitions can be resource-intensive due to investments in planning and coordination activities for relationships that may not become established (Dubois and Gadde, 2002). Moreover, low involvement relationships often diminish innovation potential by limiting suppliers’ access to user feedback and contextual insights (Ford et al., 2011).

By contrast, high-involvement relationships are characterised as complex due to their resource intensity (Gadde et al., 2003). Through increased interaction – from information exchange to innovation – interfaces become broader as the number of professionals involved increases (Ford et al., 2011; La Rocca et al., 2016). Resource development in these interfaces leads to mutual adaptations (Anderson et al., 1994; Ferreira and Lind, 2023), relationship-specific competencies and consequently strong interdependencies (Ford and Håkansson, 2006; Freytag et al., 2017). However, mutual adaptations also reinforce trust (Brennan et al., 2003), which, in turn, enhances resource allocation efficiency, for example by reducing interaction frequency in routinised exchanges (Håkansson and Snehota, 1995).

While high-involvement relationships lead to improved coordination and efficiency, they also require considerable relationship-specific investments (Håkansson and Ford, 2002). The resulting interdependencies may cause lock-in effects, reducing flexibility to change partners or pursue alternative solutions, as the adaptations that generate value simultaneously constrain future choices (Gadde et al., 2003). Moreover, power asymmetries can lead to unilateral adaptations, with the weaker partner pressured to adjust its resource base without reciprocal effort from the stronger counterpart. This indicates an imbalance in mutual commitment, ultimately undermining trust in the relationship (Hallen et al., 1991). However, more recent research has demonstrated that even small buying firms can influence more powerful suppliers when acting collectively (Johnsen, 2018; Ulkuniemi et al., 2015).

When it comes to sustainability, Dominidiato et al. (2023) emphasise that strong collaboration with suppliers is a key driver of sustainability outcomes in networks. Building on this, both Meqdadi et al. (2017) and Dominidiato et al. (2025a) show that sustainability considerations can alter power dynamics in networks. In particular, they demonstrate that buyer power and expectations shape suppliers’ sustainability outcomes, with relationships weakening or even being terminated when suppliers fail to meet required sustainability standards (Dominidiato et al., 2025a). At the same time, power asymmetries may lead to tensions when balancing cost and sustainability requirements (Reuter et al., 2012). However, trust between suppliers and buyers can offset some of these pressures by encouraging investments in sustainable purchasing (Meqdadi et al., 2017).

To manage these trade-offs related to the level of involvement and potential power imbalances, the companies need both sufficient interactive capacity (e.g. time and personnel) and interactive capability (e.g. knowledge and experience from past interactions; Håkansson and Ford, 2002). In particular, actively managing their network positions to mitigate dependency and ensure mutual benefits requires crucial skills such as the ability to communicate and mobilise other actors (Guercini et al., 2024; Ritter et al., 2004). Since interdependencies grant access to broader resource constellations beyond direct dyads (Gadde et al., 2003), balancing involvement levels with suppliers is essential to optimise relationship value and responsiveness.

The degree of involvement in supplier–buyer relationships also affect the extent of actor involvement, drawing in different organisational functions. In this study, the role of users is particularly relevant for achieving sustainability outcomes. Rather than the customer company or the purchasing manager, it is the user (i.e. an employee within the same company) whose input is relevant in this regard (Laage-Hellman et al., 2014; Landqvist and Lind, 2019). How users can be involved, however, depends on the company’s purchasing models. The INA distinguishes between centralised and decentralised purchasing models. The centralised model entails a central unit that coordinates sourcing-related activities through the development and coordination of relationships and interfaces across suppliers (Gadde and Wynstra, 2017). Centralised purchasing models enable standardisation and cost savings through higher volumes at lower prices (Håkansson and Snehota, 1995) and more efficient purchasing processes (Karjalainen, 2011). In addition, centralisation supports the organisation of high-involvement relationships, depending on managers’ abilities to coordinate interaction with suppliers and manage interdependencies (Gadde et al., 2003).

The skills required by purchasing managers may vary according to the specific objectives (i.e. cost reduction, innovation and sustainability) and their preferred decision-making styles. Rational decision-making – characterised by systematically gathering and analysing information about suppliers – plays a key role in defining clear criteria for supplier selection (Håkansson and Snehota, 1995; Kaufmann et al., 2017). In contrast, intuitive decision-making, drawing on experience and emotions, enables quicker judgements but may also lead to bias and misinterpretation. When intuition complements rather than replaces rational analysis, purchasing performance improves compared with relying on either approach alone (Kaufmann et al., 2017). In turn, these combined decision-making logics underscore the need for purchasing managers to possess not only core skills such as strategic sourcing and negotiation but also emergent competencies including creativity and the ability to manage interdependent network relationships to effectively navigate sustainability-driven purchasing contexts (Bals et al., 2019; Stek and Schiele, 2021).

In contrast, decentralised purchasing models distribute interaction with suppliers across local units or functions. While such arrangements may lead to internal competition when different units purchase from the same supplier (Håkansson and Snehota, 1995), they facilitate strong user involvement, especially for high-cost, complex or user-specific products (La Rocca and Snehota, 2014; Pedeliento et al., 2019). Although purchasing managers remain relevant in decentralised purchasing, it is often user experience that is crucial for optimising product use (De los Rios and Charnley, 2017; La Rocca and Snehota, 2014). Managers in charge of purchasing must therefore consider user input, especially in the case of purchases that have direct implications for daily operations (Pedeliento et al., 2019).

While decentralised purchasing models help ensure that sourcing remains closely aligned with and responsive to user requirements, users may prioritise subjective attributes, such as aesthetics, over cost or function (Pedeliento et al., 2019). Such choices can increase costs and challenge sustainability outcomes, therefore involving users with specialised knowledge or a critical role in product use becomes essential, since they are more likely to draw on their expertise or align their preferences with organisational priorities (Pedeliento et al., 2019). Additional positive outcomes of involving users in purchasing activities include enhanced usability and job satisfaction and extended product lifetimes (De los Rios and Charnley, 2017).

While Klewitz and Hansen (2014) highlight the potential for engaging employees in sustainability activities at the organisational level, studies on industrial networks have largely overlooked employees’ involvement as users (Harrison et al., 2023). Instead, previous research has focused on users as contributors to innovation, development and production. For example, Landqvist and Lind (2019) and Aspara et al. (2021) emphasise the growing significance of user input in product development, as supported by Vellesalu et al. (2025) who demonstrate the central role of user preferences for extending product lifetimes during development and production. Similarly, Keränen et al. (2021) and Runfola and Monteverde (2023) highlight how user demand supports sustainable innovations. Finally, Monteverde and Runfola (2024) illustrate the various roles users can assume within company activities – such as co-designer or tester – thereby underscoring their importance within business networks.

In SMEs, purchasing is a fundamental yet often informal activity, typically managed by owners or managers (Dollinger and Kolchin, 1985; Gadde and Håkansson, 2001; Pressey et al., 2009). SMEs thus rely on experiential intuition and ad hoc decisions (Ellegaard, 2009; Paik, 2021). While this can result in poor planning and reliance on limited purchasing expertise (Bos-Brouwers, 2010), a lack of formalised structures allows SMEs to be more responsive to changing circumstances (Bos-Brouwers, 2010), particularly with regard to drivers of global uncertainty such as environmental change (Di Mauro et al., 2024). Thus, while a reactive approach may impede long-term planning and lead to higher costs, it can also support flexibility in negotiations and overall agility (McGowan, 2018; McGowan, 2021).

However, this potential for agility and flexibility is limited for SMEs in particular, which often struggle with sustainable purchasing due to resource constraints (Amorim et al., 2023; Denicolai et al., 2021). These include financial restraints, knowledge deficits (García‐Quevedo et al., 2020) and power imbalances with suppliers (Eggert and Hartmann, 2021), which often hinder systematic integration of environmental considerations into purchasing practices (Amorim et al., 2023; Bos-Brouwers, 2010). As a result, SME purchasing often involves trade-offs between cost efficiency, operational reliability and sustainability ambitions, rather than formalised sustainability criteria (Ellegaard, 2009; García‐Quevedo et al., 2020; Reuter et al., 2012).

Although their relative size can result in resource-related challenges, the close involvement of owners in SMEs’ daily operations often strengthen their commitment to sustainability. Their decisions are shaped largely by personal values and beliefs, rather than external pressures or economic considerations, and therefore owners may prioritise sustainability more consistently (Williams and Schaefer, 2013). Close owner involvement also means prioritising shared values, local proximity and trust in supplier relationships (Ellegaard, 2006; Ellegaard, 2009; McGowan, 2018), which supports long-term supplier relationships (Bos-Brouwers, 2010; Kavak et al., 2015).

Prior research on SMEs suggests that close long-term supplier relationships may help small companies overcome internal resource limitations, as suppliers can contribute relationship-specific advantages such as product expertise and training (Adams et al., 2012; Prieto‐Sandoval et al., 2019). Furthermore, suppliers that cultivate personal relationships and close collaboration can help SMEs mitigate potential power imbalances (Ellegaard, 2006; Tong et al., 2022). Therefore, given the centrality of supplier–buyer relationships for SMEs’ sustainable purchasing, applying the INA enables a better understanding of how sustainability outcomes can be achieved beyond immediate cost concerns (Johnsen et al., 2017) by highlighting how companies rely on network interconnectedness to mobilise supplier resources (Araujo et al., 1999; Araujo et al., 2016).

The paper adopts a single-case study design to explore how SME purchasing can be shaped through supplier relationships to extend product lifetimes. The case in focus is a set of supplier–buyer relationships in the Swedish workwear industry, involving six companies within a business network. The six companies include a manufacturer, a service provider (i.e. distributor) and four SME customers. These actors represent different roles within the business network, providing diverse supplier and customer perspectives on the development of supplier–buyer relationships and SME purchasing models. A single-case study is particularly suitable for studying interaction in business networks as it captures the complexity of phenomena within their real-life context (Andersen et al., 2018; Dubois and Gadde, 2002).

Six companies within a business network are used as embedded units of analysis, as per Yin (2014) recommendations for case study research. The analytical focus is thus on the business network, as opposed to isolated companies, which allows for the complexity of network-level interactions in SMEs’ purchasing in line with INA to be captured. The sample size adheres to guidelines established by Eisenhardt (1989), who suggests using four to ten units to balance empirical richness with analytic manageability. The service provider was first approached via email by the primary researcher due to their unique offering in the workwear market in Sweden. In particular, the company offers product–service solutions aimed at extending product lifetimes in collaboration with both its customers and the manufacturer. As a small company with only two employees, both the CEO and software developer are directly involved in both supplier and customer interactions.

The rest of the sample is comprised of the manufacturer – included in the sample due to its essential role in facilitating the service provider’s offerings – which produces workwear for its own brand and provides e-commerce and logistics systems to the service provider, and the four SME customers (A, B, C and D), which represent two sectors (i.e. construction and manufacturing) and were selected together with the service provider to capture variations in company size, industry and operational practices. The service provider facilitated access to the manufacturer and the SMEs, which were initially contacted via email to participate in the study.

The empirical context, SMEs in the Swedish textile and workwear apparel industry, was selected for three reasons. Firstly, the industry faces a variety of challenges regarding product utilisation and lifetimes (ETC/WMGE, 2019); textile products are among the priority categories identified by Swedish and European policymakers because of their significant environmental, economic and social impacts (European Commission, 2022; Swedish Government Offices, 2021).

Secondly, SMEs make up the majority of the EU textile sector (European Commission, 2020) and account for 99.9% of all companies in Sweden. Notably, small enterprises (0–49 employees) account for 40% of total revenue, while medium-sized enterprises (50–249 employees) account for 20% (The Swedish Agency for Economic and Regional Growth, 2022). This focus aligns with Ellegaard (2009), who recognises SMEs as critical contributors to Western economies. SMEs in the textile and apparel industry face financial and operational constraints in particular, including limited infrastructure and insufficient staff training to enhance sustainability performance (Jia et al., 2020). Therefore, the chosen sample represents a unique case, in line with Flyvbjerg (2006), since the purchasing practices of a significant customer group are addressed in an industry criticised for its negative sustainability impacts.

Thirdly, unlike fashion, workwear – a category of textile products used as personal protective equipment (PPE) in industries like construction, manufacturing and automotive – has received limited scholarly attention (Kambanou et al., 2024), despite its potential to promote extended product lifetimes and reuse through services such as product rental and industrial laundry. For example, collaboration between companies can enable the optimisation of product flows and lifetimes (Kumar et al., 2022), while individual awareness is an important driver for sustainability (Engzell and Kambanou, 2024). However, a lack of user involvement (Vellesalu et al., 2023) and infrequent reuse due to company logos and lower demand for used workwear (Engzell and Kambanou, 2024) are critical barriers.

Data collection was conducted between August 2023 and October 2024 and included interviews, informal conversations and secondary data. A total of 28 interviews were carried out, comprising 12 semi-structured interviews with managers and 16 unstructured interviews with workwear users. The interviews were conducted in English and Swedish depending on the interviewee, and interview transcripts in Swedish were translated into English prior to data analysis. Further details on the interviews are provided in Table 1 below.

The semi-structured interviews investigated how the service provider’s product–service offerings influence SMEs’ purchasing practices and the development of buyer–supplier relationships. The interview guides were developed iteratively, informed by previous interviews and data analysis via systematic combining. The interviews provided insights into the perspectives of both suppliers and buyers, consistent with Eisenhardt and Graebner (2007). Overall, the interview protocols focused on:

1. previous supplier relationships;

2. the initiation and development of relationships between the manufacturer, the service provider and the SMEs;

3. SMEs’ experiences with the products and services, and their quality; and

4. pricing and sustainability outcomes.

The unstructured interviews were conducted during two study visits to Customer D and focused on users’ experiences with workwear purchasing. These interviews explored:

• previous purchasing models;

• expectations regarding the fitting experience; and

• expectations for purchasing workwear via the service provider.

The interview guide was developed based on the interviews with the service provider, during which the fittings with users were described. These interviews were carried out with individual users or as group discussions as they were waiting for fittings with the service provider. Only users from Customer D were interviewed due to access constraints during fitting sessions with the service provider. While the purchasing models differed between the SMEs, the findings of these interviews are seen as generalisable, as they were validated during interviews with the service provider. Moreover, for this study, the user interviews are supplementary to the interviews conducted with managers, since the focus is on understanding the role of supplier relationships.

Informal conversations, an accepted data source in case study research (Ellegaard, 2009), were also conducted with the CEO and software developer of the service provider, as well as the sales representative from the manufacturer, during the study visits. These conversations supplemented the interviews by providing contextual insights into customer collaboration and product usage. All interviews (except for the informal conversations) were recorded and transcribed, resulting in 219 pages of data. The transcripts were shared with the participants for validation, which did not result in any modifications. This process enhanced interpretive accuracy and researcher engagement.

Secondary data included company websites, sustainability reports and records from the online database allabolag.se. Using diverse empirical materials contributed to the breath, depth and richness of the case (Denzin and Lincoln, 2003), thereby supporting an in-depth understanding of (1) how supplier–buyer relationships enable SMEs to overcome resource constraints, (2) how structured decentralised purchasing models can be externally coordinated and (3) how user involvement in SME purchasing contributes to extended product lifetimes.

The analysis followed the logic of systematic combining (Dubois and Gadde, 2002; Dubois and Gadde, 2014), allowing iterative alignment between data collection and theoretical development (see Figure 1). Initial interviews with the service provider highlighted the centrality of supplier–buyer relationships, informing the subsequent focus on INA to structure and interpret the data (Harrison and Easton, 2004). Analysing interviews with customer companies revealed challenges specific to SMEs’ purchasing models in relation to sustainability. These insights, in turn, guided follow-up interviews with the service provider and the manufacturer. These and study visits to user fittings highlighted the importance of employee involvement as users. Thus, data collection was adapted iteratively as new dimensions of the research problem emerged (Miles and Huberman, 1994).

The research process is inherently interpretive and shaped by the researchers’ prior knowledge (Easton, 2010). Reflexivity was maintained throughout the study through awareness of how the researchers’ perspectives, experiences and assumptions influence what is studied and how findings are interpreted (Goundar, 2025). For example, because the researchers approached the case through a sustainability lens, there was a risk of overemphasising positive sustainability outcomes while downplaying operational tensions or user resistance. This was mitigated through continuous dialogue among the authors. Emerging interpretations were questioned, compared against interview data from different actors, and revised when alternative explanations were more strongly supported. In addition, triangulation during data analysis enhanced analytic depth and conceptual robustness (Lincoln and Guba, 1985). Specifically, data triangulation entailed the use of multiple methods, enabling a nuanced understanding of supplier–buyer relationships and user involvement. In addition, researcher triangulation supported the selection of relevant theoretical constructs through collective agreement (Denzin, 1989), and ensured a consistent interpretation of the empirical material (Tracy, 2010).

The findings consist of two sections. The first describes the four SMEs and their purchasing practices before engaging in the service provider, as well as summarising challenges. Section 2 describes the service provider’s offering and how the customers’ purchasing models have developed since developing business relationships with the service provider.

The four SMEs exhibited a variety of purchasing practices and different levels of involvement in their supplier relationships before engaging with the service provider (see Table 2 for a summary). Both Customer A (26 employees; small enterprise) and Customer D (85 employees; medium-sized enterprise) relied on decentralised purchasing to acquire workwear. As providers of construction services for residential and commercial projects, both require PPE to comply with relevant safety regulations. Customer A described its purchase as ad hoc, with no predefined annual budget. Workwear was sourced directly by users from local construction stores, often alongside other job-related materials. Company logos were printed at the point of purchase, and invoices were sent directly. In contrast, Customer D had an established contract with a specific construction store, enabling users to try on garments and shoes, place orders online within predefined annual budgets and collect them later. Bulk orders were typically delivered to construction sites. Despite these differences, both companies noted that users favoured decentralised purchasing as it allowed them to physically inspect the PPE and select familiar brands and styles.

Customer B (35 employees; small enterprise) provides specialised services in painting, tiling and other finishing work, using a hybrid approach to purchasing. Centralised annual purchasing was applied for standard garments (e.g. T-shirts, trousers and jackets), which were stored centrally and accessed by users as needed. In contrast, shoes were purchased individually by users through a decentralised approach with a separate supplier. This distinction was justified by the fact that shoes are subject to individual preferences and fit, do not require company logos and are not subject by safety regulations due to the nature of the tasks performed. While the company experienced several issues (outlined in Section 4.2), a hybrid approach to purchasing practices was adopted as it was perceived to enhance operational efficiency and reduce costs.

Customer C (44 employees; small enterprise) manufactures and sells safety products made of plastic and metal; it is required to ensure that all PPE complies with safety regulations. Initially, the company adopted a decentralised approach to their purchasing practices due to its small workforce. PPE purchasing was ad hoc, with employees purchasing workwear and receiving reimbursements. As the company grew, it transitioned to centralised purchasing practices, entering into a rental and industrial laundry agreement with a large service provider that provided access to a fixed number of garments annually. However, shoe purchasing remained decentralised, based on individual preference and fit, similar to the approach used by Customer B, though not due to regulatory exemptions.

While the SMEs noted certain benefits of purchasing practices characterised by low-involvement relationships, they also reported substantial challenges, particularly around cost management, operational efficiency, user satisfaction and safety and garment maintenance. Interviews with both suppliers and customers revealed that these challenges are attributed to a lack of structured purchasing models, insufficient sustainability knowledge and time and financial restrictions. These challenges are further described below and summarised in  Appendix.

Customer A experienced poor cost management due to purchases made at short notice, which led to overconsumption and shortened product lifetimes. The environmental implications of this excess were acknowledged by the CEO of the construction company: “[…] before, quite a lot of clothes got lost and they forgot them everywhere”. Customer D’s users noted that annual budgets constrained purchases of costlier items such as winter equipment.

Customer B faced high inventory holding costs from overstock due to inaccurate forecasting of size and style requirements. The costs were further increased due to the suboptimal quality and thus shorter lifetimes of purchased PPE. Customer C’s costs were driven by contractual rigidity. For example, time-based rental agreements led to sank costs when employee turnover resulted in unused PPE. Worn or aesthetically deteriorated garments remained in circulation, with associated costs for access and laundering still being incurred.

Both Customers A and D described concerns related to allocating working hours for store visits. While this allowed users to physically inspect garments, a preference noted across all four SMEs, this autonomy was costly and time consuming. Further inefficiencies arose from users purchasing incorrect sizes and/or styles and delayed orders.

Customer B described facing operational inefficiencies stemming from a lack of structured routines, which made purchasing time intensive. Fluctuating user needs in terms of sizing complicated planning accuracy, as described by the CEO of the construction company: “The big problem was that, as I said, we are 35 painters. That’s 35 different opinions in terms of shopping for work clothes”. Moreover, it led to increased complexities in terms of coordination, as the surplus stock was donated to prevent resource waste. The company noted the tension between its sustainability orientation and the inefficiencies of its hybrid approach.

Customer C purchased repair services alongside laundry services, which was seen as positive from an environmental perspective. However, it was also described as time consuming, since repairs had to be manually flagged by users. The previously described contractual rigidity limited the supplier to adapt to the changing requirements in terms of styles and materials required for the growing workforce. The frustration with long lead times was described by the senior chief strategy officer (CSO) of the manufacturing company: “It was difficult to get new clothes. They wanted to test and see that they would hold up after x number of washes”. Moreover, the increasing scale of the supplier’s operations led to increasing dissatisfaction with Customer C due to the increasingly impersonal relationship.

The decentralised purchasing practices of Customers A and D allowed users to choose their preferred styles, materials and colours. The importance of physical store visits for SMEs was also emphasised by the manufacturer’s sustainability manager: “It’s a customer group […] where it’s perhaps more important how it feels or how it looks. You choose for yourself”. However, purchasing inappropriate sizes or styles resulted in safety concerns, since workwear needs to match specific job functions. For example, precise alignment of knee pads is important for ergonomic safety. Moreover, users’ purchasing styles that clashed with company branding increased costs due to the need for replacements.

A limited product assortment led to dissatisfaction across all SMEs. Users valued familiar product features (e.g. pocket placement and hammer loops) and thus resisted purchasing from unfamiliar brands. This is exemplified by Customer D’s users: “[…] you are used to everything sitting in a particular way”; “The pocket is from the top and not from the side”. For Customers A and D, local stores mitigated some of these issues by offering a variety of brands. Customer D’s users also described sometimes having difficulties with online purchases, which was confirmed to be an issue common to other customers by the service provider.

Customers B and C faced user dissatisfaction due to the poor quality and limited variety of their products, as described by the latter’s senior CSO: “We had a lot of people who almost refused to wear our work clothes”. Customer B’s supplier offered only one fabric type and style, which did not satisfy users. Customer C experienced rising user diversity as operations expanded, which drove demand for more inclusive PPE. The supplier’s long testing cycles for new products led to delays and dissatisfaction.

Customers A, B and D described garment maintenance being a low priority among users, who often neglected to maintain garments properly, due to the risk of damaging their personal washing machines and lack of time. Nonetheless, the service provider and manufacturer emphasised that regular laundering was essential to extending product lifetimes. Customer C expressed concerns over the need to manually flag repair and PPE remaining in use due to time-based rental agreements despite being in poor condition. While this helped extend product lifetimes, employees required appropriate and well-maintained workwear to preserve a professional image during public interactions.

Establishing a business relationship with the service provider transformed the SMEs’ purchasing practices. The shift from low- to high-involvement supplier relationships changed their purchasing practices across several critical dimensions, introducing decentralised structured purchasing models to previously ad hoc decision-making; improving cost management; increasing operational efficiency, user satisfaction and safety; and contributing to extended product lifetimes through garment maintenance (summarised in Table 3).

All SMEs implemented predefined annual budgets facilitated by the service provider via the manufacturer’s e-commerce platform. While the platform is typically reserved for large clients with centralised models, the service provider’s close. The platform allows users to access a pre-approved assortment of products, reducing unnecessary purchases and thus facilitating cost management. Furthermore, curated assortments prevent mismatches with company branding. Customer C retained a centralised purchasing model (i.e. a manager makes the purchasing decisions) but opted to purchase PPE outright, avoiding the sunk costs of time-based rental agreements.

Operational inefficiencies were reduced through front-loaded support. The service provider meets users at construction sites early in the business relationship and periodically thereafter. Individual fittings improve sizing accuracy and reduce inefficiencies introduced through user autonomy in style and material decisions. Individual information is input into the e-commerce system by the service provider, which streamlines ordering and delivery. Orders are shipped directly to users’ homes, eliminating work-hour disruptions. Managers benefit from reduced administrative burdens, as the service provider ensures order accuracy and assists with logistics via the manufacturer. This was especially apparent with Company B, as emphasised by the CEO: “I have nothing to do with it anymore […] It’s just something that’s back there and works”.

Customer C now benefits from enhanced coordination without frequent supplier interaction, although the change to a structured purchasing model initially required dedicating significant time and money to pre-approving product assortments, setting individual budgets and conducting individual fittings. However, laundry and garment repairs are now coordinated by the service provider. The benefits of decreased interaction over the low-involvement model used with the previous supplier were highlighted by the quality and environment manager: “It was much more work in the beginning […] the difference is that we are happier with this solution and don’t have to spend as many hours”.

Challenges to user satisfaction and safety were addressed, with most users now managing their own budgets (excluding Customer C). Intuitive and ad hoc purchasing decisions were replaced with planned rational decisions resulting from predefined annual budgets in the e-commerce platform. The structured approach facilitated by the service provider’s high-involvement relationship with the manufacturer promotes better care and discourages overconsumption among users. Moreover, purchasing via the manufacturer’s e-commerce platform enabled a broader choice of products, which was praised by Company A’s CEO: “We have the entire range. In the shop you have a little. But we have the whole factory”.

While all SMEs perceived improved user satisfaction, a learning curve and initial resistance to the e-commerce platform were noted by both the customers and the service provider. The latter’s CEO highlighted this issue: “Ours is a digital service, so it’s dependent on the customers’ digital competence”. This was addressed through increased interaction, initiated by the service provider, to assist users and managers with the e-commerce platform when required. Moreover, the service provider described frequent brand resistance from users, who were accustomed to specific brands and consistent positioning of functional features, such as pockets or tool loops. However, this complaint was mitigated by the superior service and quality of the manufacturer’s products.

Issues with safety risks were overcome through better product matching during individual fittings. For instance, accurate sizing ensures correct placement of safety features such as knee pads, avoids ergonomic issues and contributes to extended product lifetimes. The service provider also prevents material mismatches, such as garments suited for painters being used for concrete work, by guiding users during fittings and educating them on appropriate styles and materials for their specific professions. Again, instances of user resistance, as reported by the service provider, were addressed through sustained interaction and user education throughout the fitting process.

The service provider’s integration of product and service offerings contributes to extended product lifetimes. Fittings ensure appropriate sizing while repair and laundry services (when used) support maintenance. These services are accessible via the e-commerce platform and help to address users’ budget constraints. The resale and redistribution of underused items within or across customer companies further reduce obsolescence and waste. Some user resistance was experienced due to previous purchasing practices involving the continuous replacement of damaged or erroneously ordered products. However, according to the service provider and the SMEs, the personalised, resource-leveraging approach mitigates over-purchasing, enhances user experience and contributes to reduced environmental impact.

This section discusses the findings of our single case study, answering the research question: How do supplier relationships shape SMEs’ purchasing practices with the aim of extending product lifetimes? The discussion is structured into two interrelated areas that address the research question. The first concerns the contribution of high-involvement supplier relationships to improved operational efficiency and sustainability outcomes in SME purchasing through structured and decentralised purchasing models. The second concerns SMEs’ development of high-involvement supplier relationships with an intermediary to mitigate potential challenges of dependency and coordination.

Applying INA offers new insights into how sustainable purchasing can be achieved through high-involvement supplier–buyer relationships leading to novel interaction dynamics (Johnsen, 2018; Johnsen et al., 2017). As SMEs typically lack dedicated purchasing decision makers (Ellegaard, 2009; Paik, 2021), purchasing is commonly carried out by owners or general managers (Dollinger and Kolchin, 1985; Hill, 1972) and thus varies between companies (Morrissey and Pittaway, 2004). This was evident in our case, in which SMEs previously addressed issues reactively – e.g. by increasing budgets in response to overconsumption or resolving delivery problems ad hoc. Users often made spontaneous purchases that resulted in the choice of incorrect sizes or styles, contributing to higher costs and shorter product lifetimes.

High-involvement relationships supported more frequent interaction in the early stages, with managers and the service provider jointly defining assortments, budgets and user requirements. The close involvement of the manufacturer, typically inaccessible to SMEs, further streamlined the purchasing process with managers and users having access to the former’s e-commerce platform. The involvement of the service provider made purchasing more structured and decentralised with the involvement of different actors, with the support of the service provider to facilitate the process and resolve issues. In particular, five supplier-led mechanisms facilitated both operational improvements and sustainability outcomes (see Table 4). Together, these mechanisms expanded the supplier–customer interface (Bastholm and Munksgaard, 2020; Gadde et al., 2003; La Rocca and Snehota, 2014), supporting a product–service configuration in which all involved actors had relevant roles in supporting extended product lifetimes.

These novel interaction dynamics involving users supported more sustainable purchasing, improving both job satisfaction and product lifetimes (De los Rios and Charnley, 2017) while also generating operational efficiencies typically associated with centralised purchasing (Håkansson and Snehota, 1995). Consequently, the SMEs are able to integrate environmental and social considerations in their purchasing to achieve sustainability outcomes beyond immediate cost concerns (Johnsen et al., 2017). The findings thus align with Denicolai et al. (2021), who argue that SMEs embedded within knowledge-intensive and resource-diverse networks are better positioned to manage innovation and sustainability transitions.

This study thus demonstrates that SMEs do not require internal formalisation or centralisation to implement structured purchasing models. While prior research describes SME purchasing as informal, reactive and largely unstructured (Ellegaard, 2009; Gadde and Håkansson, 2001; Paik, 2021), our findings indicate that high-involvement supplier relationships can enable structured purchasing models. In this study, these relationships organise purchasing activities by embedding them in interactional and service-based configurations. This suggests that effective purchasing may rely less on internal systems than previously assumed (Håkansson and Snehota, 1995; Pressey et al., 2009) and that operational and sustainability goals are instead achieved with the support of suppliers.

Finally, this study highlights the underexplored role of users as embedded contributors to sustainability outcomes (Harrison et al., 2023). Although recent research has begun to recognise consumer communities as actors within business networks (Monteverde and Runfola, 2024) and explore their role in supporting sustainability in innovation and production (Keränen et al., 2021; Runfola and Monteverde, 2023; Vellesalu et al., 2025), far less attention has been given to users as individuals, particularly employees using products in their daily tasks.

Our findings underscore the significance of employees as product users in operational settings such as workwear purchasing. User input regarding product fit, familiarity and functional requirements is shown to be effectively captured and channeled through high-involvement supplier relationships facilitated by intermediaries such as a service provider. This coordination supports both cost-efficiency and extended product lifetimes. This not only highlights users as important contributors to sustainability (Monteverde and Runfola, 2024) but also introduces a user-centric lens to purchasing research, which has traditionally focused on managerial actors.

Although prior research suggests that decentralised purchasing and multi-actor involvement may increase interaction costs (Gadde and Snehota, 2019; Håkansson and Snehota, 1995), most SMEs in this study largely reported reduced administrative and operational costs. For Customers A, B and D, a manager was no longer required to handle purchasing decisions directly, and users spent less time purchasing due to on-site fittings. Repetitive purchases were streamlined through the manufacturer’s e-commerce platform, resulting in reduced reliance on information exchange (Hill, 1972), and thus also reduced interaction costs. These findings suggest that high-involvement relationships with an intermediary can mitigate the transaction costs typically associated with decentralised purchasing.

Previous research presents two contrasting views on SMEs’ ability to develop high-involvement supplier relationships. Some studies highlight difficulties in relation to power imbalances and the costs of managing such relationships (Eggert and Hartmann, 2021), whereas others argue that engaging with external actors can enhance SMEs’ capacity to address sustainability challenges in novel ways (Klewitz and Hansen, 2014). Our findings align with the latter perspective. The intermediary bridged the relationships between the SMEs and the large manufacturer, strengthening the SMEs’ capacity to implement sustainable purchasing models. Prior research suggests that such intermediaries can lower transaction costs, mitigate power asymmetries and facilitate access to broader networks (Adobor and McMullen, 2014; La Rocca and Snehota, 2014). In our case, this support helped SMEs navigate the typical trade-offs between sustainability and cost-efficiency, which are often difficult to manage under resource constraints (Reuter et al., 2012).

Building on previous research, which highlights that small buying firms can increase their power by acting collectively (Johnsen, 2018; Ulkuniemi et al., 2015), the findings of this study likewise demonstrate that SMEs are not constrained by their size. While high-involvement relationships can introduce dependency risks, particularly under conditions of power asymmetry (Hallen et al., 1991), this study found no evidence of diminished bargaining power. On the contrary, despite their small purchase volumes and decentralised purchasing models, the SMEs were not marginalised by the manufacturer. Instead, the service provider acted as a relational intermediary, enabling SMEs to access supplier resources otherwise unavailable to them. This intermediation not only counterbalanced potential power asymmetries but also supported the development of SMEs’ purchasing practices towards more sustainable, cost-effective and user-responsive models. This finding aligns with Tong et al. (2022), who show that networked collaboration and platform-based coordination can strengthen SME bargaining power even in asymmetric supplier networks.

Finally, previous research has generally portrayed user involvement in organisational sustainability initiatives positively (cf. Klewitz and Hansen, 2014). For example, consumers can contribute to a company’s sustainability performance (Monteverde and Runfola, 2024) by providing input during product development and innovation (e.g. Landqvist and Lind, 2019; Runfola and Monteverde, 2023; Vellesalu et al., 2025). This dynamic was also evident in our study, in which the manufacturer benefitted from the service provider’s role in mediating user feedback in terms of product development. However, the findings also reveal notable challenges for the SMEs and the intermediary. As noted in previous research, decentralised purchasing can lead users to prioritise aesthetics over functionality and cost (Pedeliento et al., 2019). Our findings build on this liability of user involvement by illustrating additional issues, including user resistance to new brands and styles and the learning curve associated with adopting a new e-commerce platform.

This paper contributes to research on sustainable purchasing by demonstrating how high-involvement supplier relationships enable structured decentralised purchasing models that support extended product lifetimes without compromising operational efficiency, even providing advantages in terms of cost. The findings advance our understanding of how buyers can respond to evolving purchasing challenges (Dubois et al., 2021), particularly in the context of sustainability (Di Mauro et al., 2024). By integrating insights from INA, SME purchasing and sustainability literature, the study shows how SMEs can leverage external and internal resources, relational coordination and user involvement to address purchasing-related sustainability challenges. In doing so, the paper reconceptualises decentralised purchasing models – not as a liability but as a latent organisational strength – capable of generating strategic benefits. These insights advance contemporary purchasing literature by shedding light on SME purchasing in relation to sustainability – an area that remains unexplored despite the recognised importance of SMEs (Denicolai et al., 2021; Ellegaard, 2006; Klewitz and Hansen, 2014).

The paper makes three theoretical contributions to literature on sustainable purchasing, particularly in the context of SME purchasing. Firstly, it highlights the interactive dynamics that shape sustainable purchasing models. In particular, developing high-involvement supplier relationships enables SMEs to overcome internal resource constraints by partnering with more resourceful firms (Baraldi et al., 2023; Dubois et al., 2021), leveraging supplier expertise (Ellegaard, 2009) and applying joint learning (Denicolai et al., 2021). Contrary to dominant assumptions that associate decentralisation with inefficiency and high costs (Håkansson and Snehota, 1995; Karjalainen, 2011), our findings show that decentralised purchasing models can enable both operational efficiency and sustainability outcomes when embedded in appropriate relational and infrastructural arrangements. This reframing opens a new line of inquiry into how purchasing models can be strategically designed and orchestrated rather than merely evaluated in binary efficiency terms.

Secondly, it identifies certain mechanisms – individual fittings, user budget constraints and resale and redistribution practices – that broaden the supplier interface (La Rocca and Snehota, 2014), enabling product-service configurations in which all actors take on distinct roles in extending product lifetimes. Beyond complementing prior work linking inter-organisational relationships to improved sustainability outcomes (Denicolai et al., 2021; Meqdadi et al., 2017; Meqdadi et al., 2020; Monteverde and Runfola, 2024; Öberg et al., 2012; Runfola and Monteverde, 2023; Runfola et al., 2025), this micro-level perspective on the supplier–buyer interface opens up new theoretical avenues with regard to how sustainable purchasing models can be deliberately designed and orchestrated to leverage distributed resources (e.g. knowledge) for competitive advantage.

Thirdly, our study shows how externally structured and decentralised purchasing models can better align sustainability outcomes with SMEs’ resources, such as users. This finding challenges assumptions regarding purchasing formality (McGowan, 2018; Pressey et al., 2009) and the exclusion of end users from decision-making (Pedeliento et al., 2019). By introducing a more user-centric lens to sustainable purchasing practices, the study shows how buyers that involve users through leveraging internal and supplier resources can advance sustainability outcomes in downstream networks to extend product lifetimes. This is a departure from previous research that has largely focused on sustainability in upstream supplier networks (e.g. Brüel Grönberg and Hulthén, 2022; Dominidiato et al., 2025a; Meqdadi et al., 2020) and managerial purchasing (e.g. Bos-Brouwers, 2010; Kaufmann et al., 2017; Stek and Schiele, 2021).

The findings offer actionable insights for SMEs, intermediaries, manufacturers and policymakers for enabling sustainable purchasing through high-involvement relationships.

For SMEs, partnering with more resourceful suppliers can enable a shift from ad hoc purchasing practices to be structured decentralised purchasing models. Rather than developing managerial capabilities or organisational routines internally, SMEs can leverage users and supplier resources to support sustainable purchasing. Instead of requiring internal reorganisation, supplier-led mechanisms can instead facilitate engaging employees as users in purchasing, particularly for products suited to individual needs. While such purchasing models result in benefits such as reduced costs and waste, and improved user satisfaction and safety, SMEs must consider the risks of potential lock-in and limited bargaining power when there is a lack of alternative solutions.

Service providers as intermediaries play a pivotal role by structuring purchasing models around SME needs and user input. They help mitigate power asymmetries with large manufacturers to provide access to resources normally not available to SMEs, while providing value-added services like fittings, maintenance and redistribution. However, intermediaries must also manage dependencies to avoid passive lock-in. Their ability to coordinate users and manufacturers is central to sustaining adaptive yet purchasing models.

For manufacturers, partnering with intermediaries offers market access and first-hand user insights. This can enable tailored offerings, support sustainable strategies and enhance design responsiveness. Integrating user feedback into product development can improve sustainability outcomes and regulatory alignment.

Finally, policymakers can support these dynamics by promoting SME networks and incentivising user-centric purchasing models. Funding, infrastructure and best-practice sharing can help unlock SMEs’ underused potential in driving sustainable procurement and extended product lifetimes.

In sum, sustainable SME purchasing does not depend on internal centralisation but can be achieved through relational coordination and structured supplier engagement. This provides a practical roadmap for advancing both operational efficiency and sustainability in networked settings.

This study reflects a single case study based on semi-structured interviews with managers and unstructured interviews with users. Future research would benefit from additional data sources, such as managerial diaries, which, when combined with interviews, serve as observational data (Zimmerman and Wieder, 1977, cf. Wulff, 2019). Diaries allow researchers to “be present in multiple places simultaneously” by offering real-time insights and supporting interview preparation (Wulff, 2019). Moreover, semi-structured interviews with users could further illuminate their experiences being involved in structured purchasing.

The applicability of the study is significant within the Swedish context, where sustainability is a central concern for both industry and policymakers. This contextual specificity should be considered when assessing the transferability of the findings to other settings. Comparative studies between similar SMEs in different contexts as well as longitudinal data collection from various actors would provide a deeper understanding of how supplier–buyer relationships evolve and influence sustainability outcomes through structured, decentralised purchasing models.

Importantly, the products studied here, i.e. workwear, are not components for end-consumer products or services but rather tools to enable service delivery and production. Future studies should examine how changes in purchasing models and relational development influence company performance in indirect purchasing contexts. In addition, the inclusion of other companies in the business network (e.g. laundry, repair or logistics providers) could help reveal network-level effects of supplier–buyer relationships that shape SMEs’ sustainable purchasing practices.