In this section, key literature on circular strategies, relevant circular business models, and related user circular behaviors is critically reviewed. The first subsection discusses circular behaviors related to R frameworks, particularly the renowned 9R framework (around which the writing of this subsection is organized). In the second subsection, two essential user circular behaviors beyond the 9R framework are discussed.
2.1. Behaviors Related to the R Frameworks
The main strategies in a circular economy have been depicted by several R frameworks, which are viewed by many authors as practical guides for a Circular Economy and have been used in academia as well as the industry. Among those, the most prominent framework is the 3R framework, which illustrates Circular Economy as a combination of reduce, reuse, and recycle. Another framework is the 4R framework, which encompasses the previous 3Rs in addition to ‘recover’. A more comprehensive framework, however, is the well-known and frequently cited 9R framework [3
]. It first appeared in an article that aimed to discuss the challenges of transitioning to a circular economy in the Netherlands. The author outlined what she called the nine levels of circularity, descending from high to low levels of priority. These were namely: refuse, reduce, reuse, repair, refurbish, remanufacture, repurpose, recycle, and recover [16
]. The framework was then adapted by Potting et al. [17
], who added ‘rethink’ to the strategies outlined by Cramer. Thus, in total, the framework encompasses 10 strategies; but, the first strategy, ‘refuse’, is coded as R0, whereas the last strategy, ‘recover’, is coded as R9.
In the 9R framework (Figure 2
), the last two strategies (recover and recycle) are about finding useful applications for the product materials. They are the last resorts in the waste hierarchy and the lowest levels of circularity [3
]. Recycling involves converting products into raw materials and then chemically reprocessing them [18
]. This requires the implementation of legislative stipulations and the employment of a waste management system at the country level to ensure the collection of the right volumes and types of recyclable materials from municipal waste and their transport to an industrial facility [19
]. In this regard, users’ participation is essential for the success of the strategy as it increases the efficiency of the collection of end-of-life products [6
]. Moreover, users are sometimes required to separate waste at home and then travel to specific recycling collection points to drop it off. On the other hand, recovery is basically the incineration of waste materials that cannot be recycled [18
]. For that reason, it is regarded as a complementary strategy to recycling [22
The first three strategies in the 9R framework (reduce, rethink, and refuse) are about product design, manufacturing, and use decisions aiming to reduce the consumption of natural resources or to find smarter uses for the products [3
]. ‘Refuse’ is to reject the product itself and offer its function through a completely different product (for instance, a nonmaterial one: a digital product). Morseletto [22
] stated that this strategy could also be about refusing certain materials or specific production processes. ‘Reduce’ is concerned with narrowing resource loops and using less energy and raw materials [22
]. Morseletto [22
] highlighted that this strategy is a less extreme form of ‘refuse’, and that it could be extended to limiting the production rates of new products (such as cars) to encourage ‘reuse’. However, unlike the previous two strategies, ‘rethink’ pertains to product use. Kirchherr et al. [3
], Morseletto [22
], and Kumar Mangla et al. [18
] defined ‘rethink’ as intensifying product use through sharing it among many users. But Morseletto [22
] elaborated that ‘rethink’ has a wider connotation, one that includes reconceptualizing concepts, processes, uses, and the subsequent post-uses of products.
Based on the definitions and the discussion in the previous paragraph, it could be correctly inferred that there are user circular behaviors related to the ‘rethink’ strategy. Kumar Mangla et al. [18
] outlined leasing, renting, and sharing as the main approaches to rethinking product use. These are subcategories within the use-oriented business model. In this model, the company owns the product and gains profit by making it available to users through leasing, renting, sharing, or pooling (i.e., users can simultaneously use the product) [15
]. In terms of economics, Tukker [15
] argued that rented, shared, and pooled products probably have a significantly lower market value than competing products because of the tangible and intangible sacrifices the user has to make when sharing the product with others. However, from an environmental point of view, Tukker [15
] suggested that, in principle, renting, sharing, and pooling could yield high environmental gains, whereas leasing can lead to undesirable user behaviors and increase the environmental burdens.
The use-oriented business model is one of three main new business models called product-service systems (PSS) business models. They are advocated for by many authors as a promising means to encourage sustainability and enhance circularity—according to Michelini et al. [24
] and Tukker [15
]. The other two main types of PSSs are product-oriented and result-oriented business models [15
]. After reviewing the literature on PSSs and conducting a bibliometric analysis, Michelini et al. [24
] concluded that authors consider result-oriented PSS as the only business model of real contributions to circularity. This was attributed to the fact that the user will only pay for a desired result while the product ownership remains with the company (or the firm), and after delivering the service to the user, the company can utilize the product or its modules for a different service, thus increasing circularity. However, Tukker [15
] regarded function-oriented PSS (which is a subtype of the result-oriented PSS model) specifically as the most environmentally promising PSS type.
In general, regarding PSSs in which the ownership of the product is retained by the provider, there are many behaviors expected of users, and other behaviors that are undesired (during use and at the end of the product lifetime). Wastling et al. [7
] identified and classified user behaviors in relation to products owned by the provider:
During product use, users are expected to take care of the product by themselves or through engagement with the company’s after-sales services (such as life extension services). In addition, users are expected to provide the company with information about the state of the product at the start of its use (to confirm that the previous user left the product in a good condition) and during its use (to make the provider aware of any damage or need for maintenance). Wastling et al. [7
] also identified two behaviors to be avoided: using the product for tasks other than the ones it was designed for (misuse), and any behavior that could destroy the product (damaging).
At the end of use: it is desired that users return the product on time and in a satisfactory condition for the next use. Moreover, users’ assistance with reverse logistics might be required. For instance, instead of collecting the product from the user, the company might demand that the user take the product to a post office [7
All the previous behaviors are within the use-oriented or result-oriented PSS business models. However, Tukker [15
] argued that the product-oriented PSS business model is, still, the easiest to introduce and the best to be implemented by companies aiming to achieve incremental environmental gains. Among the different PSS types, product-oriented is the closest to the classic, pure product business model, which is geared toward making revenue from selling more products. However, in the product-oriented PSS business model, the company adds extra services around the product [15
]. This type of PSS is related to the five middle strategies in the 9R framework (concerned with product and component lifetime extension). In the following paragraphs, we will discuss these strategies and the user circular behaviors related to them.
As presented in the 9R framework, the five product life extension strategies are namely: reuse, repair, refurbish, remanufacture, and repurpose. ‘Reuse’ is an essential Circular Economy strategy. It is one of the inner technical loops of the Circular Economy system diagram (famously known as the butterfly diagram) [5
]. The strategy is present in every R framework, including the 3R framework (reduce, reuse, recycle) and its variations, such as (reuse, remanufacture, recycle) [3
]. ‘Reuse’ involves having an old product (which is in a good condition) used by another user to fulfill the same function [3
]. However, Morseletto [22
] distinguished between two types of ‘reuse’: The first type is when the product’s ownership changes from one user to another after the product is gifted, resold, or discarded. The second type of ‘reuse’ is related to products within a PSS business model, where the company contracts the product to different users at different times. The author argued that in the first case, the exhibition of the behavior depends upon the user’s predisposition to use a second-hand product [22
According to Cramer [16
], to refurbish is to “improve the product”. Relatedly, Kirchherr et al. [3
] define ‘refurbish’ as “restore an old product and bring it up to date”. Refurbishing, typically, involves replacing parts of the product, but it rarely involves disassembly [22
]. Remanufacturing, on the other hand, is a process that involves “disassembling, cleaning, inspecting, repairing, replacing, and reassembling the components of a part or a product in order to return it to an ‘as-new’ condition” [27
]. That is why remanufacturing is also called second-life production, whereas refurbishing is called light remanufacture [22
]. In their article, Lüdeke-Freund et al. [28
] described remanufacturing and refurbishing as “more comprehensive overhauls”. Both strategies require companies to incorporate reverse logistics in their business models to collect used products and components, then reprocess them into products of as-new quality, to be sold at lower prices [28
]. Users would have some role to play in such a business model; however, typically, refurbishing and remanufacturing are executed by, respectively, the product seller or manufacturer in their facilities and not by individual users in their places of work or residence [30
Repair strategy includes repair and maintenance conducted to fix the product defects in order to keep using it for its original function [3
]. Here, it is important to mention that Morseletto [22
] correctly noted that “maintenance”—in the definition of repair provided in the 9R framework—does not mean keeping the product sound while it is still functioning. Rather, it is a form of repair, and in some cases, maintenance could include repair in addition to other activities [22
]. Nevertheless, preventive, or predictive, maintenance is surely a user circular behavior (as outlined and discussed by Wastling et al. [7
], Ackermann [31
], Haines-Gadd et al. [32
], and others). It is a user behavior that contributes to extending the product’s life and ultimately slowing resource loops.
Finally, from amongst the 9R strategies, product repurposing stands out as a cost-effective and less process-intensive strategy. It is defined as transforming the product, its components, or materials to serve a new purpose after it has fulfilled its first purpose [33
]. Compared to other strategies, product repurposing requires minimal or no energy to perform, fewer resources, and no transportation to industrial facilities (users can perform repurposing at their places). Consequently, its potential pollution is minimal. In addition to that, it could minimize the need for dedicating large spaces to landfills. Moreover, on the individual user level, it contributes to financial savings [34
]. It is a circular strategy and a circular user behavior. However, despite its economic and environmental benefits, limited research has been conducted on product repurposing. Furthermore, the few studies on product repurposing have focused mainly on non-electrical, non-mechanical products.
Scott and Weaver [35
] took a user perspective approach to investigate repurposing. The authors conducted in-depth interviews with users who practice different types of repurposing. They discovered that what motivates users to repurpose was not an affinity for sustainable consumption, but rather a combination of a desire to express oneself, an anticipated pleasure from the process, emotional attachment to the product, economic drive, social influences, and (to a lesser extent) the user’s environmental consciousness. Other authors explored a special type of repurposing: upcycling. It is characterized by an increase in the value of the product after repurposing [36
]. Bridgens et al. [36
] aimed to understand the contexts, motivations, barriers, and potential benefits of “creative reuse” (i.e., repurposing) and upcycling in affluent Western societies. The most interesting user motivation highlighted by Bridgens et al. was the availability of 3D printing technologies to produce any extra parts needed for the transformation. Equally interesting was the barrier of stigma toward making objects from waste. On the other hand, Sung et al. [37
] focused only on the drivers and the facilitators of upcycling, and through an extensive literature review, the authors identified different personal, social, and situational determinants.
Other studies focused on the product-related factors that facilitate repurposing or encourage users to perform it. Aguirre [33
] followed an ethnographic approach to investigate the practice of repurposing in 3 major cities and 12 communities in Mexico. Lai and Shu [38
] considered do-it-yourselfers as lead users and analyzed 57 do-it-yourself (DIY) projects—shared online—of repurposing IKEA home furniture. The factors identified by these two studies could be summarized as follows: the product is modular and designed for disassembly, the product’s material is durable, the product’s components provide immediate functionality if dismantled, and (because of its geometry or symmetry) the product has an inviting affordance—one that stimulates the user to repurpose. Furthermore, Aguirre [33
] identified the product-related barriers that would discourage people from repurposing, such as having sharp edges or containing hazardous materials.