1 Introduction

The integration of users in the value creation process is omnipresent. Whoever builds a shelf on their own, uses one's own to-go-cup, designs a kitchen with the help of a digital configurator, whoever re-sells something on eBay, participates in a user-community, repairs their own bike or uses car-sharing is participating in the value creation process.

This phenomenon was called "prosuming" for the first time by Alvin Toffler in the 1980s [1]. But even then, the participation of consumers in the value creation process was not a new occurrence, as people long ago started to repair their own devices, took goods from shelves in the supermarket or handled the petrol pumps themselves [1]. Nevertheless, digitalisation created new opportunities for prosuming, as can be seen in digital configurators or online second-hand trade [2].

As Toffler did not deliver a distinct definition of prosuming [3], the term is used very broadly today. Thus, very different phenomena are associated with prosuming, which, moreover, are labelled very inconsistently using different terminologies. What they all have in common, however, is the integration of the user in the value creation process. Due to this variety, there are a lot of hopes and expectations associated with prosuming.

The discourse in the 2010s was characterised by the opportunities that digitalisation offered for user involvement, e.g. via user communities, crowdworking, etc. [2, 3]. While the economists labelled this integration of the users mainly as a competitive advantage, [4,5,6], sociologists criticised the missing compensation for the work the users invested into the products and services. What Toffler in the 1980s called independence from the market became an expression of neoliberal economic activity in the 2010s [7].

In recent years, the meaning of prosuming has changed again. Today the term is often used to describe individuals who produce electricity for themselves by using their own photovoltaic system and therefore become independent from the electricity market [8,9,10]. In this context, prosuming is strongly connected to sustainability.

2 Research question

The different forms of prosuming are often associated with sustainability. E.g. Lan et al. claim that the cooperation between different prosumers increases the potential for social transformation and therefore improves a sustainable lifestyle. [11] („In addition, prosumers’ value co-creation is proving essential for sharing businesses to realise their social transformation potential in providing better quality of life, such as more convenient, efficient and green daily transport for urban dwellers.”). At the same time, they do not explain how exactly such a cooperation causes an impact on sustainability. The following quote also demonstrates how prosuming is sometimes understood as a cure-all: „The co-creation of urban landscapes for food production is a major step towards more sustainable, liveable, and healthier cities.” [12].

Likewise, the integration of users in product development is seen as a tool for sustainable innovation. Kruger et al. explain this effect with an innovative, transparent, adaptive, and participative setting (ein “innovatives transparentes, adaptives und partizipatives Umfeld.“) [13]. But this neither explains what a sustainable innovation or setting is nor does it explain how exactly this works.

Besides, it is often mentioned that the interaction that is part of most of the prosuming forms increases social cohesion [14]. But how exactly this is realised (i.e. by which means) remains vague.

While the effects of prosuming that affect the companies are well-examined (i.e. [6]), those that affect the users and the environment remain shapeless and obscure.

Usually, impacts are solely discussed for single forms or certain cases of prosuming (i.e. [15,16,17]). But what is missing is an overview illustrating the different effects of prosuming including the differences between the respective forms of prosuming.

This article is intended to deepen the understanding of the effects of prosuming. Therefore, it provides an overview of which effects for users and the environment are associated with prosuming, meaning: What should prosuming contribute to?

At the same time, the overview will differentiate between different forms of prosuming in order to explain which hopes and expectations are associated with which of the forms.

Afterwards, it will be discussed how the effects found are related to sustainability.

Those results can then be used to examine the actual effects of prosuming: What does Prosuming contribute in regard to sustainability?

Knowing the difference between what prosuming should contribute and what prosuming is contributing can be used to formulate (more) realistic expectations and concepts for prosuming.

This article focuses on the hopes associated with prosuming, meaning the positive promises for society and the environment. This does not mean that there are not also negative effects (like the missing compensation or rebound effects). However, those effects exceed the scope of this paper and are thus not discussed further.

3 The variety of prosuming

As mentioned before, Toffler did not provide a distinct definition of prosuming but only described what he meant by it using different examples. These included Do-it-Yourself-activities as well as self-services [1]. This broad understanding of prosuming led to the fact that the term prosuming is now used for a lot of different phenomena [18, 19]. It also had the effect that prosuming is interpreted and conceptualised in many different ways [19, 20].

Hellman’s definition of prosuming, which is more concrete than Toffler’s, will therefore be used to define a basic understanding of prosuming. According to Hellman prosuming occurs „if a contribution is made to the production of a good or service that is primarily intended for personal use and from which it derives its utility value, without which the production process remains incomplete, regardless of whether or not payment is required for this service.“ („wenn zur Herstellung einer Sach- oder Dienstleistung, die vor allem für die Eigenverwendung gedacht ist und von daher ihren Gebrauchswert bezieht, ein Beitrag geleistet wird, ohne den der Herstellungsprozess unabgeschlossen bleibt, unabhängig davon, ob für diese Leistung bezahlt werden muss oder nicht.“ [18]).

For Hellmann merely participating in certain parts of the production process is understood as prosuming as well as making a product completely on your own. Thereby the integration of the user may occur in different parts of the value creation process: During product development and production, but also in distribution or marketing [18].

According to the various possibilities for users to participate in the value creation process, different forms of prosuming emerge. Therefore, those are not always labelled consistently. This analysis tries to consider as many of them as possible to cover the phenomenon in its broadness.

Co-Creation: This means to create value together [21] whereby users can be included in the process as well as companies or other stakeholders [5, 21]. As the term is used for different forms of collaboration, it therefore remains rather unspecific, especially regarding the kind of participants included in the process [22].

Mass Customization: The term is mainly characterised by Reichwald/Piller and describes the process of personalising products that are produced at mass-production prices [6]—Enabled by modularised and mostly prefabricated components from which customers can choose and compose according to their specific preferences [6].

User Innovation: This goes back to Henry Chesbrough, who recommends companies should be more open to integrating users into their activities, especially product development processes [4]. According to von Hippel, it is rather important to rely on so-called Lead Users, as they can predict the users’ needs and work on a solution simultaneously [23]. User Innovation can therefore be understood as a company-driven as well as a user-driven process, in which users join independently from companies [24]. In this article, user innovation is understood in the case of the former, as the second understanding is too similar to peer production.

Peer Production (often as Commons-based Peer Production): This describes the voluntary cooperation between different individuals in non-market-driven projects. Peer Production only takes place between users/citizens with no participation of any company. Those users work independently, organise themselves and determine in what way, how much and when they participate on their own. Usually, the goods produced by peer production are intended as common property [25].

Self-provider (energy production): These days prosuming is often used to describe individuals who produce their own energy while using photovoltaic systems [26,27,28]. The owners of the photovoltaic systems are producers and users of the electricity at the same time, which is an understanding that is very close to what Toffler understood as prosuming. In order to create a linguistic demarcation, this form of prosuming will be called self-providing in the remaining paper.

Sharing: This term relates to the „Sharing Economy “, which describes a culture in which fewer individuals are actually owners of products but instead, they are sharing the ownership with others. Sharing includes the forwarding of products as well as the common ownership of a good, and renting a product owned by others [29]. In the case of sharing, companies (B2C) or individuals (C2C) can hold ownership of a product [30].

Do-it-yourself: DIY means that someone is making a product on their own [31]. Therefore, a product must be made individually without the involvement of a company. In recent years, the terms Making or Maker Movement gained some importance. A clear distinction from DIY does not exist. However, the maker movement more often emphasises a sense of community, although the single tasks and projects are often done individually. The maker movement aims to enable individuals to make as much as possible on their own.

Makerspaces, FabLabs, repair cafés etc. are often used to describe the same phenomenon [32]. This is not so much a concept but rather a place, at which different actors can meet to create their products. In these places devices and tools are available to the individuals as well as other personsthat provide their support (https://www.offene-werkstaetten.org/de/seite/offene-werkstaetten). Those facilities aim to enable individuals to produce what they need on their own [31].

All of these different concepts are understood as different forms of prosuming, because in all of them, users play an active role in producing goods and services, as per the definition by Hellmann. In the literature, other terms can also be allocated to one of the mentioned concepts. For example, Hanekop/Wittke mention the term „collaborative production “, which can be understood either as common-based peer production or user innovation, depending on the exact case [3].

4 Approach: semi-systematic literature review

A semi-systematic literature review was carried out to obtain an overview of the possible effects of the various forms of prosuming on individuals and the environment.

Semi-systematic literature reviews enable gaining an overview of a certain topic, especially if it is discussed using different terminology by different authors [33]. Rather than analysing all of the existing articles on one topic, a semi-systematic literature review tries to capture a certain topic in its broadness by the evaluation of selected articles [33]. In this way, a specific state of research can be determined, even on a very broad and complex topic [34].

This article aims to provide an overview of the possible sustainability effects of prosuming. Prosuming, as mentioned before, includes various types and manifestations, so a semi-systematic literature review appears to be a suitable method to explore it.

The initial literature for the review was found using the literature database Web of Science. The search was limited to the last ten years. To include as many forms of prosuming as possible, the following search string was used:

Prosuming OR Mass Customization OR Peer Production OR Co-Creation OR Sharing OR Makerspace OR “Maker Space” OR Lead User OR User Innovation OR Open Innovation OR DIY

These forms of prosuming were combined with „AND „Sustainab* “ OR „Social Sustainab*” “to receive articles related to sustainability. The term “making” was excluded from the search as it has too many meanings and is used quite often in the English language.

After an initial screening of the results, it was decided to also exclude the following words: Corporate Social Responsibility/CSR, CHINA, Social Media, Public, and Tourism, as the texts that included those words often described or analysed business models and therefore did not focus on the perspective of the prosumers.

In the end, these filters and restrictions led to 11,772 results.

A semi-structured literature review does not define the number of texts to be considered for selection or analysis. For this reason, the concept of theoretical saturation was applied [35]. First, an unspecific number of cases is analysed. If it then becomes apparent during the research process that the data is not sufficient to answer the research question, new cases are added. This procedure is repeated until the inclusion of new material no longer provides any new insights, at which point theoretical saturation is reached.

For this review, the first 1000 texts were considered with the option of adding more of the 11,772 texts in case the first selection would not be sufficient to achieve theoretical saturation. Those 1000 texts were sorted by relevance as defined in the Web of Science database [35].

From the first 1000 results, those texts were excluded that evidently did not include a connection to the effects of the prosuming forms on humans or the environment. For example, texts were excluded that dealt with the barriers or drivers to the use of prosuming, but not with its effects. To do so, the titles and abstracts were scanned. Finally, there were 263 articles left.

Afterwards, the abstracts of the remaining 263 articles were read and evaluated to identify whether they were suitable for the elaboration of potential sustainability effects. Special attention was paid to ensuring that the texts did not primarily describe the effects for the companies or dealt solely with the implementation of user integration or the barriers for prosuming.

After this second round of sorting, 108 texts were left, 18 of which were not available. Consequently, the analysis started with 90 articles. The analysis was guided by Grounded Theory, a method for developing new concepts from data [35].

Therefore, the texts were initially analysed to identify passages in which the effects of prosuming were discussed. Those passages were then read thoroughly (effectswere often found in the introduction or the conclusion). The effects of prosuming were recorded in the form of codes. Coding is a process used in qualitative empirical social research to develop concepts in conjunction with the material [35, 36]. Concepts are created by abstracting, comparing and summarising text modules. In this case, the concepts revealed the sustainability effects of prosuming.

During the elaboration process, the prosuming form of sharing quickly became saturated and when the results of the coding process started repeating themselves, no further texts on this topic were included. In contrast to this, there were only a few useful texts found regarding peer production and especially Mass Customization.

Therefore, a new search in Web of Science was started, in which the terms „sharing “ and „co-creation “ were excluded, but all other filters and words remained the same. This resulted in 20 additional texts that were available for analysis. Since not every text chosen for the review mentioned the effects of prosuming on people and the environment, in the end, these effects were extracted from a total of 57 suitable texts.

5 Results: Many hopes and expectations are associated with prosuming [35].

254 codes were found describing the potential effects on humans and the environment. As this is too detailed to extract impacts, the codes were merged, so that 40 effects of prosuming were identified. These can be seen in Table below.

 

Impacts on humans and the environment

CC

MC

UI

PP

SP

Sh

OW

DIY

Economic

Source of revenue for prosumer

x

    

x

  

Reduction of costs

    

x

x

  

Independence from market

   

x

x

 

x

x

Individual

Freedom

  

x

x

  

x

x

Transparency

    

x

   

Access to knowledge

x

  

x

x

 

x

 

Access to tools/materials

x

  

x

 

x

x

 

Learning new skills

x

   

x

 

x

x

Creativity

      

x

x

Self-efficacy

  

x

   

x

 

Empowerment

x

   

x

x

x

x

Market equality

x

       

Inclusion

x

      

x

Ensuring own needs

x

x

x

     

Social capital

    

x

 

x

 

Collective

Participation

 

x

  

x

  

x

Citizenship/Engagement

x

 

x

   

x

 

Democracy

   

x

    

Solidarity

   

x

 

x

  

Trust

      

x

 

Social cohesion

   

x

x

x

x

x

Equity/Fairness

     

x

  

Social growth

x

 

x

     

Equality

   

x

 

x

x

 

Critical thinking

      

x

 

Ecological

Saving of resources

     

x

x

 

Reduction of overproduction/ overconsumption

 

x

   

x

  

Extension of service life of product

 

x

   

x

  

Extension of life of product

 

x

   

x

x

x

Sustainable innovation

x

 

x

   

x

 

Sense of responsibility

       

x

Sufficiency

       

x

Increase of the share of renewable energy

    

x

   

Local production

    

x

   

CO2-reduction / reduction of emissions

    

x

x

  

Energy saving

    

x

x

x

 

Improvement of air quality

     

x

  

Reduction of waste

     

x

 

x

Strengthening of environmental awareness

       

x

Eco-friendly production (e.g. 3D-printing)

      

x

 

Based on the analysed texts there was no impact of prosuming to be found which was associated with all forms of prosuming. It rather occurred that every form of prosuming had its own focus. This focus resulted in four different dimensions into which the prosuming forms could be categorised: economic (blue), individual (yellow), collective (red) and ecological (green).

The economic dimension in the case of prosuming relates to the economic situation of the prosumers and includes financial sources for revenue or discharge.

The individual dimension refers to the free development of the individual. It includes impacts that help the individual to develop themselves, to make their own decisions, and to act according to their own wishes and needs.

The collective dimension includes effects that strengthen society and societal (Table) cohesion. Thus, pertains to how prosumers could be integrated into common activities and how society could become more equal and fair. Table below shows which prosuming form is affected by which of the mentioned dimensions.

 

Co-Creation

Mass Customization

User Innovation

Peer Production

Self-provider (energy production)

Sharing

DIY

/Making

Maker-spaces

/FabLabs

Economic

x

   

x

x

  

Individual

xx

(x)

x

x

x

(x)

xx

x

Collective

x

 

x

xx

x

x

xx

(x)

Ecological

(x)

x

(x)

(x)

x

xx

xx

x

  1. The number of “x”s symbolises how much a dimension affects a certain form of prosumin

The ecological dimension includes effects that should reduce negative impacts on the environment.

The rating was based on the total number of codes within a dimension put in relation to the amount of codes assigned to other forms of prosuming. It is important to mention that this rating should not be taken as a quantification since this is a qualitative approach.

In summary, it can be said, that co-creation is especially associated with the effects of the individual dimension. Co-creation offers the possibility to gain knowledge and therefore to obtain new competencies [11, 16]. According to this, prosuming is attributed to an inclusive effect. Due to participation in the value creation process, individual needs can be met more easily [12]. Also, Co-creation is intended to lead to more sustainable innovations [11, 13, 37].

With mass customisation, neither economic nor collective impacts are associated. Instead, this concept emphasises the opportunity for users to better meet their needs [38, 39] and to extend the service life of the products by personalising them. Also, the reduction of overproduction is mentioned a few times [39], because mass customisation is often based on on-demand production. Besides, modularisation as a central feature of MC is often associated with expanding the life of the components of the products, as they can be removed and reused [40]. However, it should be noted that the ecological effects of Mass Customization are also often challenged [39, 41][40].

User Innovation shows no connection to economic effects (at least not for the users). This is not surprising as this form of prosuming is not characterised by intrinsic motivation [42]. Instead, it is characterised by the opportunity for users to express themselves and to experience self-efficacy [43]. What is particularly valuable about user innovation is that users have the opportunity to recognise problems with products or niches in the market themselves and try to resolve them independently [44]. This is why user innovation is expected to generate a better fulfilment of needs. Also, it is expected that lead users participate in user innovation projects to create value for others and not primarily for themselves as they are intrinsically motivated [42]. Furthermore, this intrinsic motivation offers the potential for developing sustainable innovation, as the users are not above all interested in economic value [42, 44, 45].

Peer production is also not considered to have any economic effects for prosumers or any ecological effects. Instead, the focus is on the participatory effect, which is the result of the basic idea behind peer production (independence from the market and co-creation of several actors) [46, 47]. This in turn could support democratic processes or solidarity [47] and therefore strengthen social cohesion. Another characteristic of peer production is the equality of participants [46].

Self-supply in the energy sector is associated with all four dimensions: Generating one’s own electricity strengthens the user’s independence from electricity providers [8, 48] and reduces costs [27, 48]. This independence also leads to empowerment [9, 49]. Due to self-sufficiency, the users are also promised transparency which is not offered to them in the electricity market [48]. This fosters equity [9]. Through networking with other self-producers of electricity, connections to others can be established [48]. For example, users can establish local energy communities which strengthens the community. This also strengthens social cohesion [9]. Moreover, prosuming in the energy sector minimises the impact on the environment: Decentral photovoltaic systems increase the proportion of renewable energy, which can reduce CO2 emissions [8, 9, 26]. In addition, prosumers often adapt their consumption of electricity to the amount of electricity that is available at a certain moment, which reduces their overall electricity consumption [9, 26].

Sharing is seen as a form of prosumption that offers a lot of ecological advantages. Through the sharing of products, infrastructure and resources overconsumption is reduced and resources are saved [14, 50, 51]. If several individuals or households share a product, less of it has to be produced. Handing down or giving away a product, which is also a part of sharing, increases the service life of a product [14]. This in turn also means that less has to be produced [52, 53], which then saves resources as well as energy and reduces waste [30, 54, 55]. It also allows users easier access to products and promotes social cohesion [50, 53].

Similar to Mass Customization, the impacts of DIY/Making relate primarily to the individual factors, as in most cases it includes activities that are performed independently of others. To produce goods on one's own, prosumers can improve their skills and also gain new knowledge [32, 56]. Thereby they become independent and free and can be creative [17, 56]. Also, the prosumers can produce exactly the goods they need if they make them themselves. Making your own products thus leads to empowerment [17, 31]. Prosumers therefore become independent from the market [56]. Doing it yourself and Making is also associated with a higher sense of responsibility towards the products [17, 57]: Individuals who make things themselves value the products and resources more strongly. Apart from that, DIY/Making is often associated with recycling. The ability to produce something on your own promotes the ability to reuse and remanufacture things, which reduces waste and strengthens environmental awareness [32, 56].

Makerspaces offer particularly high hopes. This is probably due to the mixture of independent action and the connection to other "makers", as this would enable them to learn new skills and acquire new knowledge [57]. Makerspaces also allow prosumers access to certain resources [56], which supports feelings of freedom, self-efficacy and empowerment [31, 32]. Being connected to others also promotes social capital, social cohesion as well as social growth [57, 58]. Critical thinking is furthermore expected from the collaboration of various energetic prosumers [32]. But there are not only individual and collective effects expected from Makerspaces. They are also claimed to have a positive impact on the environment. Repair cafes and FabLabs encourage the reuse of products and the sharing of resources so that the lives of the products are extended [31, 56]. Especially FabLabs offer production structures and processes that are environmentally friendly [59].

In conclusion, prosuming is associated with different hopes and expectations that differ according to the specific forms of prosuming. In this respect, prosuming seems to be particularly related to individual and collective expectations.

6 Prosuming effects go beyond the usual sustainability goals

As the literature review showed, prosuming is associated with several different hopes and expectations. To what extent those can be seen as effects for sustainability is discussed in the following.

This first requires the definition of a suitable concept of sustainability.

Usually, sustainability or sustainable development is defined with reference to the Brundlandt report, in which sustainable development was mentioned institutionally for the first time and understood as a “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” [60].

Sustainability therefore primarily refers to people's needs and the means to be able to satisfy them in the present and in the future. In this sense, the current fulfilment of needs must always happen considering its effects on the future [61].

An effect of prosuming can therefore be understood as an impact on sustainability if, by the integration of users in the process of value creation, a present need is fulfilled without limiting the possibility of realising a future need. As the Brundtland Report does not specify what these needs are, this definition could include almost all of the potential effects that were identified.

Furthermore, sustainability is often considered using the three-pillar model. This divides sustainability into three different domains: ecological, economic, and social sustainability. Although the dimensions found in the analysis seem to resemble those of the three-pillar model, they should not be understood as equal. Unlike the three-pillar model, which is not based on any methodological survey [62], the dimensions found emerged from the data. The dimensions found therefore also differ in terms of content from the three sustainability pillars. In contrast to the three-pillar model, the economic dimension described above focuses on the economic situation of individuals. In descriptions of the three-pillar model, on the other hand, economic sustainability is rather viewed as a global task, which also includes saving resources (which is part of the ecological dimension in my analysis) [63, 64]. This difference can be explained by the focus of this article, which is on the effects on the individual and the environment. Furthermore, saving resources and energy is often associated with ecological contexts in the texts, so they cannot be related to the economic effects on sustainability. For example, Lange 2017 mentions: „The ecological benefit of this type of product is obvious and lies in the extension of the service life of consumer goods and the associated saving of resources." („Der ökologische Nutzen dieses Typs ist eindeutig und liegt in der Verlängerung der Nutzungsdauer von Gebrauchsgütern und der damit verbundenen Ressourceneinsparung.“) [31].

The four dimensions identified should be used to clarify the different priorities of the prosuming forms and not to define sustainability using different pillars, as this approach has some weaknesses. For example, the three-pillar model cannot differentiate between the dimensions, as there is no common definition of the different pillars [65].

It would also be conceivable to define the needs mentioned in the Brundtland report in concrete terms based on the UN's Sustain Development Goals. In both political and scientific discourse, these often serve as an orientation for advancing sustain development.

As the table below shows, most of the potential prosumption effects found can be assigned to the 17 SDGs.Footnote 1 Assignment here means that the possible prosumption effects are based on the sub-goals of the individual SDGs or correspond to the indicators that the UN identifies for each SDG.

SDG

Effects of prosuming

No poverty

Source of revenue for prosumer, reduces costs, independence from market

Zero hunger

 

Good health and well-being

Improvement of air quality

Quality education

Learning new skills, access to knowledge, critical thinking, empowerment

Gender equality

 

Clean water and sanitation

Reduction of emissions

Affordable and clean energy

Increase share of renewable energy, energy saving

Decent work and economic growth

Saving of resources, local production

Industry, innovation, and infrastructure

Sustainable innovation, CO2-reduction, local production, eco-friendly production

Reduced inequalities

Market equality, independence from market, learning of new skills

Sustainable cities and communities

Improvement of air quality, CO2-reduction, eco-friendly production

Responsible consumption and production

Saving of resources, sustainable innovation, local production, strengthening of environmental awareness, reduction of waste, reduction of overproduction/overconsumption, sense of responsibility, sufficiency, extension of service life of products, extension of life or product components, eco-friendly production

Climate action

Reduction of emissions, saving of resources

Life below water

 

Life on land

Eco-friendly production

Peace, justice and strong institutions

Participation, independence from the market, democracy, solidarity, citizenship/engagement, trust, social cohesion

Partnership for the goals

Participation, social cohesion

Concerning this assignment to the SDGs, an effect of prosuming could be considered a sustainability impact if, by involving users, it satisfies a current need or protects a future need that is covered by at least one of the 17 SDGs.

No effects for sustainability therefore would be: Freedom, self-efficacy, creativity, securing one’s own needs, control, and access to resources. It is noteworthy that these possible effects are less related to the collective than to the individual and therefore belong to the ‘individual dimension’.

7 Do we need "individual" sustainability?

This finding therefore raises the question of whether sustainability should also include individual goals such as the free development of one’s personality, self-realisation, etc.

In the SDGs, sustainability is understood as aiming to guarantee proper living conditions for all human beings, rather than fostering the free development of individuals. This is hardly surprising considering that the SDGs were proclaimed as global goals, i.e. goals that affect all people and countries equally. In other words, it initially addresses basic needs that are also intended to create a balance within the world. As long as even the basic needs of people (security, peace, sufficient food, access to drinking water and healthcare) are not guaranteed in some regions of the world, the free development of the individual is unlikely to be given much weight. If sustainability is understood as something that is intended to ensure the fulfilment of basic needs, it would be enough to focus on the previous goals of sustainability.

In addition, including the individual effects of prosuming in the concept of sustainability would stretch it even further and make it therefore even more vague than it already is. This is also what is criticised on multidimensional sustainability concepts. Grundwald/Kopfmüller, for example, argue that instead of blurring the concept of sustainability, one of the dimensions (usually the ecological one) should be prioritised [61, 66].

Such prioritisation is, however, contradicted by the fact that sustainability can only succeed if it is treated holistically [67].

Authors who are in favour of a holistic view of sustainability are already questioning the three-pillar model, as the division into three different domains leads to them being antagonistic to each other [67].

The fact that the three pillars have already been expanded elsewhere also militates against a focused and narrow definition of the concept of sustainability. The UN itself has drawn up indicators to assess sustainability efforts and added an institutional dimension. This also includes access to knowledge and the internet as an indicator of sustainability, as well as science and research [68]. This critique of the three-pillar model indicates that the existing pillars are not sufficient or at least not exhaustive and that a concept for a holistic sustainability strategy may need to be broader than the current one.

But why should individual goals be part of a sustainability concept at all? Individualism, freedom and self-expression are values that are an integral part of the Western world, as they are manifested in the American Declaration of Independence or for example the German constitution (Art. 2) and can also be found in the Universal Declaration of Human Rights. Art 22 and 26 mention the free development of the personality. This indicates that human needs do not consist solely of material provision and security, but also include individual or personal fulfilment. Needs, as has been demonstrated, are the starting point for considering sustainability. Grunwald and Kopfmüller also describe human rights as an "indispensable premise" in the sustainability discourse. In particular, they emphasise the empowering and self-determining nature of human rights [61].

The increasing emphasis on measures that combine personal development and sustainability, such as the "Education for Sustainable Development" initiative, also suggests that individual factors should be considered for a holistic approach to sustainability. In this concept of education for sustainable development sustainability is seen as something that can only succeed, if the individuals can reflect on their own actions or values, can work together with others, participate, or be creative. Following the original definition from the Brundtland Report, sustainability is crucial to preserving the world as a place worth living in for future generations. However, shaping the world and adapting it to new circumstances, dangers and situations requires creativity. And is a place worth living in not also a place where individuals can express themselves freely?

In addition to personal freedom and opportunities for personal development, the empowerment of the individual is also a goal that could potentially have meaningful effects on sustainable development. Empowerment is a key objective in the tradition of Toffler [1]. In his view, empowerment could help to free users from market dependency. The de-growth movement also pursues this goal. Such ideas can be found in repair cafés, which engage in the reuse or repair of products and where individuals can produce their own goods [31, 69]. Those movements also challenge the division of labour between consumption and production which is typical of capitalism. Instead of just making decisions, it is important for consumers to learn skills that have been increasingly lost in the course of industrialisation because they have been outsourced to companies due to the increasing degree of specialisation. Consumers are therefore able to be producers at the same time. The maker movement, which has self-imposed the aim of enabling everyone to make what they need themselves and thus of making consumers less dependent on the market, also represents such empowerment [17]. Prosuming can hence potentially not only contribute to a more economical use of resources but also create entirely new forms of consumption and production. Empowering people to create forms of consumption and production that are different from capitalistic ones could also be seen as a meaningful competence to preserve the world as a place worth living in for future generations unless capitalism is seen as an economic model without alternatives for the future world.

8 Limitations

Firstly, the identified potential sustainability effects of prosuming does not claim to be an sxhaustive list, as theoretical saturation cannot guarantiee that no relevant text (possibly in another language) was missed. In addition, due to the restriction of the literature search to the database Web of Science, English-language articles were overrepresented in the analysis. It was also not possible to weigh the sustainability effects, as quantifying the frequency of the promised effects is not in line with the applied qualitative methodology. Furthermore, this overview cannot draw any conclusions about the actual prosuming effects, as only very few of the analysed texts included an actual examination of the effects. Most authors described the effects as expectations for the respective prosuming form.

It would also be useful to investigate the connection between the individual factors as it is conceivable that some of them influence and condition each other.

9 Conclusion

The aim of this article was to identify and systematise the numerous promises associated with prosuming. Through a semi-systematic literature review, it was shown that prosuming is associated with many different potential effects, which can be categorised into four dimensions: economic, individual, collective, and ecological. The different forms of prosuming each have a different focus on these potential effects.

The prosumption effects, identified by the semi-systematic literature review, address various sustainability goals defined by the UN (SDGs). However, some impacts have not yet been included in conventional sustainability models and can mainly be categorised under the individual dimension. This raises the question of whether these individual goals or values should also be part of sustainability concepts, especially if sustainability is understood as a holistic concept. This is supported in particular by the fact that the free development of personality is a human right and that creativity should be seen as a valuable skill in creating the future. The initiative for Education for Sustainable Development also shows that the individual promotion of personality and creativity is particularly important for shaping a sustainable future. In addition, the empowerment of individuals could contribute to the development of new economic models that achieve a fairer distribution of resources than the current capitalist, growth-orientated system. Empowerment in particular can be understood as the decisive effect of prosumption as defined by Toffler.

In the beginning, the question of what prosuming should do was raised. The described results refer to a large number of hopes and expectations for humanity and the environment that are associated with prosuming. Consequently, these hopes indicate that prosuming is seen in many ways as a contribution to greater sustainability. Prosuming is intended both to secure the economic situation of the user and to contribute to the common good as well as to a more careful use of natural resources and the environment.

The results found show that the hopes associated with prosuming go beyond what is generally understood as sustainability. This raises the question of whether current sustainability models are sufficient to ensure holistic sustainable development.

The results presented can be used as a basis for determining the actual effects of prosuming in the future (what can prosuming actually do?). Therefore, it may be necessary to further differentiate which of the effects listed are target effects and which are perhaps rather a means of achieving them.