This research has been funded under the IN-HABIT (Inclusive Health and Well-being in Small and Medium-sized Cities) project as part of the Horizon 2020 Program (Grant Agreement No. 869227). The contents of this document do not reflect the official opinion of the European Union. The responsibility for the information and opinions expressed herein lies solely with the authors.

Modern urbanisation is characterised by rapid population growth, increasing spatial density, and environmental pressures that pose challenges to social cohesion, public health, and ecological sustainability (Piracha & Chaudhary, 2022; Rathnayke & Amofah, 2023). Nitra, Slovakia’s fifth largest city, reflects urbanisation challenges typical of post-socialist cities, shaped by industrial growth, suburbanisation, and socio-economic change (Eliaš et al., 2021). The legacy of socialist-era planning and recent industrial expansion has contributed to urban sprawl, traffic, and declining green spaces (Hardi et al., 2020). Urbanisation and suburbanisation also had serious social impacts, straining housing, services, and social integration of new urban dwellers (Falťan, 2019). The loss of permeable surfaces and insufficient green infrastructure limits access to recreational and social spaces, further reducing opportunities for integration and community-building, particularly for vulnerable groups (Hardi et al., 2020).

Funded under the Horizon 2020 mechanism, the IN-HABIT project addresses some of these challenges by integrating cultural, digital, natural and social innovations into the co-design, co-development and co-management of urban public spaces. In Nitra, the pilot area encompasses public and semi-public green spaces, including a community garden, KOZA. Established in 2010 as a part of the cultural and community centre Hidepark, the initial intention was to create a space that would counterbalance the challenges the city experiences in relation to the availability and quality of green spaces. IN-HABIT interventions in the community garden were co-designed and co-deployed, primarily involving the Slovak University of Agriculture researchers, Hidepark centre employees and volunteers, CUKETA NGO members and individual gardeners, with other experts and practitioners. Landscaping was conducted, the garden was expanded with new functional and recreational elements, while community events and educational workshops were co-organised.

Implementing these solutions intended to bring various social and environmental benefits, primarily focused on inclusive health and wellbeing, and impact multiple stakeholders. Evaluating these effects is crucial to fully capture the broader societal impact of such urban interventions and can guide the decision-making process on future interventions. However, despite the recognised benefits of urban green spaces, quantifying the social impact remains a methodological challenge. As these impacts do not have a financial character, they require a specific approach for their assessment. Given the co-design, co-development, and co-management dimensions of these solutions, including individual stakeholders in the impact evaluation process and capturing their benefits and costs, is integral. However, developing and applying a comprehensive framework involving stakeholders is challenging (Papastergiou et al., 2023).

This study focuses on assessing the social value generated by the IN-HABIT project’s interventions in a community garden in Nitra, utilising the social return on investment (SROI) framework. The SROI framework captures the broader impacts of interventions by linking inputs to outcomes through a theory of change. Adapted from the traditional return on investment (ROI), SROI quantifies effectiveness through a ratio of monetised social outcomes to investments (Banke-Thomas et al., 2015; Edwards & Lawrence, 2021; Nielsen et al., 2021). The analysis uses two valuation strategies: direct stakeholder valuation and a proxy-based approach. In the first approach, we apply contingent valuation, reflecting a significant branch of urban green spaces valuation methods (Papastergiou et al., 2023). The second approach reflects efforts to standardise and make social value comparable in SROI analyses. Social value databases such as the HACT Social Value Bank or the Australian Social Value Bank provide methodologically consistent social values for a wide range of outcomes and thus enable time and human resources to be saved in estimating social value (Frijters et al., 2024; Papastergiou et al., 2023). As a social value database is not available in the Slovakian context, we use the Danish OSVB (202x) based on the WELLBY indicator (Frijters et al., 2024), representing a spatially close and accessible option.

The article is organized as follows: in the theoretical background we discuss the benefits of community gardens, the use of non-market valuation methods in this context and the social return on investment (SROI) framework, in the methodology section we describe how the SROI framework was applied to estimate the social return on investment of a community garden in Nitra, in the next section the results

Urban green spaces, such as parks and community gardens, are vital to city life and contribute to improved quality of life (Corkery, 2019). They support biodiversity, lower urban temperatures, enhance air quality, and promote well-being. As design influences mental health, planners must consider residents’ socio-psychological needs (Enssle & Kabisch, 2020; Solovey & Kovaleva, 2017). Poor mental health, closely linked to poverty and exclusion, affects individuals, families, and society (Victor & Yang, 2012). Loneliness, a significant public health issue, can worsen mental health outcomes (Meltzer et al., 2013; Victor & Yang, 2012). Community gardens are green spaces with numerous health benefits (Austin, 2014, p. 19). Through shared maintenance, they foster social interaction, a sense of belonging, and civic participation (Austin, 2014, p. 22). Motivations for community gardening include improving neighbourhood aesthetics and safety (Glover, 2003), love of nature, environmental ethics (Irvine et al., 1999), building relationships, and physical activity (Armstrong, 2000). They enhance access to healthy food, promote better eating habits, and help prevent obesity through increased physical activity (Al-Delaimy & Webb, 2017). Interest in community gardens, a form of urban agriculture, is growing (Laycock Pedersen et al., 2023).

Public and environmental goods provided by urban green spaces often lack market prices, yet their impacts must still be assessed in planning and policy evaluations. Over the past decades, various non-market valuation methods have been developed to assess their value. Among these, contingent valuation has emerged as the dominant approach due to its ability to estimate the total economic value, capturing both use and non-use values under hypothetical future scenarios. Its popularity stems from its ease of application, relatively low cost, and flexibility across various types of ecosystems and environmental services (Dinda & Ghosh, 2021; Halkos et al., 2022; Papastergiou et al., 2023). In contrast, the choice experiment method has gained traction in recent years as a more sophisticated stated preference approach by evaluating preferences by enabling respondents to make trade-offs between different features of non-market goods, thus mimicking real-world decision-making (Van Oijstaeijen et al., 2022). Other commonly used methods include the travel cost method, which infers value based on expenditures to access urban green spaces, and benefit transfer, which adapts values from existing studies to new contexts (Papastergiou et al., 2023).

A key challenge in impact assessment is creating a decision-making framework that reflects preferences of the citizens to guide where and how green space development should occur. There is a need to take a societal perspective in the assessment, consider different population subgroups, and use locally relevant data. This can shift the focus to the social return on investment (SROI) framework, utilising a holistic approach (Edwards & Lawrence, 2021). SROI was first developed in 1996 by the Roberts Enterprise Development Fund (Corvo et al., 2022). The goal was to go beyond traditional financial returns and measure the actual impact of interventions on people’s lives. This led to the creation of a framework that measures the social, economic, and environmental impacts of investments, commonly referred to as the triple bottom line (Norman & MacDonald, 2004). At its core, SROI calculates a ratio of benefits to investments, translating non-monetary social outcomes into monetary terms (Corvo et al., 2022). Edwards & Lawrence (2021) recommend using the SROI framework when interventions impact the local environment and specific stakeholder groups. As a bottom-up, locally focused method, SROI emphasises individual participants and defines impacts through direct stakeholder engagement. However, the process is stakeholder-involved rather than stakeholder-led (Banke-Thomas et al., 2015; Edwards & Lawrence, 2021; Kadel et al., 2022).

The SROI framework is guided by eight core principles (Social Value UK, 2024). These include: involving all stakeholders affected by an intervention, considering both intended and unintended outcomes, recognising stakeholder values, focusing on material outcomes, avoiding over-claiming, ensuring transparency, validating outcomes, and applying accurate and timely valuation and reporting. These principles inform the six-step SROI process (Nicholls et al, 2012). Step one identifies the objectives and stakeholders of the intervention. Step two maps the theory of change, outlining inputs, outputs, and outcomes. Step three selects indicators to measure results. Step four assesses socio-economic impacts using valuation methods. Step five monetizes benefits using attribution, deadweight, and drop-off. Step six calculates the SROI ratio, followed by a sensitivity analysis and communication of results to stakeholders.

Although most analyses are not peer-reviewed, the SROI framework has been widely applied in areas such as physical and maternal health, mental health (including arts, nature-based, and horticultural activities), public spaces, community health, cultural activities, digital inclusion, and other community-based initiatives (Alomoto et al., 2024; Banke-Thomas et al., 2015; Hartfiel et al., 2023; Hunter et al., 2022; Kadel et al., 2022; Robinson, 2020; Vasiliu et al., 2024). However, limitations include poor comparability of SROI ratios, limited stakeholder involvement, lack of standardised models, weak impact characterisation, overlooked opportunity costs, and challenges in applying robust valuation methods and counterfactuals like deadweight or attribution (Banke-Thomas et al., 2015; Edwards & Lawrence, 2021; Lettieri et al., 2021, p. 263; Kadel et al., 2022; ).

The valuation of social benefits in SROI case studies often relies on financial proxies derived from secondary sources, including social value banks such as the Open Social Value Bank, UK Social Value Bank, Australian Social Value Bank, and Simetrica-Jacobs Social Value Bank. However, access to these databases is often paid, and their values are context-dependent, which may limit their applicability to specific stakeholder groups. Another common approach is the use of the contingent valuation method, which assesses willingness to pay for social or environmental goods (Boardman et al., 2018, p. 433; Ferreira & Marques, 2015; Szott & Motamed, 2023, p. 17). In addition, Scholten’s Value Game is often used as an interactive, low-cost method to estimate the monetary value of social benefits based on stakeholder perceptions. Through focus groups or interviews, participants identify key benefits, compare them to market goods, and rank them on a reference scale, enhancing understanding of stakeholder values and supporting intervention design (Scholten, 2019, p. 6).

The aim of the paper is to estimate the social value of the community garden in Nitra and the solutions deployed under the IN-HABIT project to promote several dimensions of health and well-being. The applied approach represents the testing of a replicable social return on investment framework. The SROI framework is extended by estimating benefits for the diverse actors involved in the co-creation, co-design, and co-management processes, and considering the opportunity cost of time. By performing two valuation strategies, two distinct approaches to estimating social value are tested and compared.

In this study, we estimate the social value of the community garden and related implemented solutions using the Social Return on Investment (SROI) framework, seeking to answer the following research questions:

What are the key social outcomes the community garden generates, particularly regarding health and well-being?

To estimate the social value, the standardised six-step SROI methodology (Figure 1) was applied: (1) Establishing scope and identifying stakeholders – including gardeners, volunteers, CUKETA NGO, and the project team, covering 2022–2024 (with impacts from 2023); (2) Mapping outcomes – identifying inputs, outputs, and outcomes using financial data and stakeholder input, and developing a theory of change; (3) Evidencing outcomes and giving them a value – using contingent valuation and Scholten’s Value Game, alongside values from the Danish Open Social Value Bank, weighted by survey data; (4) Establishing impact – adjusting for deadweight, attribution, and drop-off based on interviews, with future value discounted; (5) Calculating the SROI – estimating return per euro invested, including sensitivity analysis with Monte Carlo simulations; and (6) Reporting, using and embedding – presenting results and limitations.

Figure 1. Figure 1. The SROI process and data sources used Source: Own elaboration.

The case study area is in Nitra, Slovakia, on the outskirts of the city’s urban neighbourhoods. Since the beginning of the IN-HABIT project, the implementers have regularly met with gardeners and volunteers to plan the redevelopment and expansion of the garden. Hard (physical interventions) and soft (activities and events) were co-designed during 2 workshops with community members, with the involvement of experts in design, landscape architecture, dendrology and permaculture. 2 additional practical co-design workshops were organised with 3 women experts from Slovak School of Permaculture to co-validate the solutions. These were followed by 18 additional workshops, with educational elements and physical implementation of the proposed solutions. A gate to the garden was constructed, a chicken sanctuary was built, garden plots were demarcated, edible, honey-bearing and medicinal herbs were planted along the walkways, and a shelf for surplus sharing was built. A new garden workshop was installed, and an old garden pergola for hosting community events and lectures was rebuilt. 3 new garden sections were created, one for gardening, one for education and one for relaxation purposes. A new water feature was introduced – a pond built showcasing various aquatic plants and water garden ecosystems. The community garden expanded from the original 411m² by a total of 575m². In the co-deployment of these solutions, waste materials were mostly used. The inclusion of demonstration plots and an educational and recreational area aimed to showcase sustainable gardening practices, provide hands-on learning opportunities, and foster community engagement in urban agriculture.

Multiple secondary and primary data sources were input into the analysis. The use of each primary and secondary source at each stage of the analysis is shown in figure 1. Data on financial inputs, implemented activities and outputs were obtained from the records of the IN-HABIT project team and CUKETA NGO (a civic association co-managing the garden with several other groups). Within the financial inputs, all inputs of the IN-HABIT project were included, and other inputs spent by identified stakeholders. In addition to financial inputs, we also accounted for the opportunity cost of time. By convention, the opportunity cost of beneficiaries’ time was not considered (Nicholls et al, 2012, p. 32).

Reflecting the SROI framework’s emphasis on stakeholder engagement in the evaluation process, we performed an in-depth structured interview with a representative of CUKETA NGO, structured interviews with gardeners (n=16, 25.4 % of all gardeners), and a more broadly-based questionnaire survey for users of the IN-HABIT project solutions (n=29). Their function was mainly to identify key outcomes and societal benefits of the community garden, as well as to estimate social value. The interview with the representative of CUKETA NGO was conducted in March 2024 and helped clarify the space’s functioning, define the stakeholders, and identify the benefits from the organization’s perspective. Personal structured interviews with gardeners were conducted between March and April 2024. The interviews focused on identifying and describing the perceived benefits of the community garden and evaluating these benefits. Complementary questions were asked to obtain information to estimate attribution and deadweight in the impact calculation phase, as well as about the characteristics of the interviewees. The responses of the gardeners helped to clarify how the different activities implemented led to the identified results. A more quantitative approach was applied using responses to a questionnaire survey for users of IN-HABIT solutions conducted between May and July 2024. On a scale of 0 to 5, respondents marked the extent to which the activities and workshops contributed to different elements of well-being and life satisfaction, quality of leisure time and healthy lifestyle, and social and spatial well-being. Based on responses from individuals who stated that they had participated in activities in the community garden an average score was created for each element. These sources were combined to clarify social value creation in the context of the implemented activities.

Two valuation strategies were utilised and tested to quantify the social benefits. The first approach used primary stated preference methods in the form of contingent valuation willingness to pay scenario (integrated in gardener interviews) and Scholten’s Value game (Scholten, 2019) in the case of CUKETA NGO and volunteers. The presence of a payment mechanism for community members and the possibility of establishing a hypothetical scenario with a low cognitive burden formed suitable conditions for the use of contingent valuation. During the interview, gardeners were presented with a hypothetical scenario involving hypothetical payment for a field rental at a community garden described to reflect the KOZA community garden and the activities carried out during the 2023 season as closely as possible. The WTP question was formulated as an open-ended question. The interview also included questions specifying the counterfactual (deadweight and attribution). In the case of CUKETA NGO, the value game was realized during the interview. In the case of volunteers, a focus group was carried out with the participation of three individuals. Firstly, the participants had to define a set of market goods to which they attributed value and with which they would like to be endowed. They then had to form a scale out of these goods based on their perceived value, highest to lowest. Then participants were asked to place the annual benefits of the community garden on this scale. Social value was estimated as the mean value of the market goods between which the benefits of the community garden were located on the scale.

To save analytical capacity in the future while leveraging standardised data, social values obtained from a social value bank were tested in the second valuation strategy. The Danish Open Social Value Bank (OSVB) (2023) was selected as the relatively closest since a social bank created for the Slovak or even Central European context is not available. OSVB contains a database of indicators and associated social values. From the indicators contained in the OSVB, the indicator best matching one of the key community garden benefits identified in the ‘theory of change’ framework was selected for each stakeholder. Given that the defined OSVB proxy indicators imply a change in the quality of health and wellbeing, it was necessary to appropriately ‘weigh’ the number of participating gardeners and volunteers to realistically reflect the fact that such a change occurred in only a proportion of them. In the case of gardeners, we used the questionnaire results for users of IN-HABIT solutions. The questionnaire responses allowed us to estimate the number of cases where a community member experienced given outcomes.

This paper assessed the social value of health and well-being interventions implemented through the IN-HABIT project in Nitra’s community garden, using an extended SROI framework. A stakeholder-informed theory of change revealed key outcomes, including enhanced psychological well-being, community cohesion, environmental awareness, and knowledge sharing. Two approaches to estimating the social value of a community garden were compared. Under the first valuation strategy, engaged groups were directly involved in utilising contingent valuation and Scholten’s Value game. Findings indicate that each Euro invested yields 2.15 Euros in social benefits. If only the investments of the IN-HABIT project are accounted for, social benefits increased to 2.42 Euros. The second strategy, based on financial proxies from secondary sources, led to significantly higher estimated values. Under this approach, each Euro invested is projected to yield 4.27 Euros in social benefits, rising to 4.80 Euros when considering only IN-HABIT’s investments.

The analysis was limited by the scope of the periods under study. Some long-term benefits may only become apparent in the later period. Regarding data collection, the number of interviews and respondents may limit the representativeness of the findings, although the study sought broad stakeholder involvement and used many data sources. There are also limitations inherent to SROI framework and the analysis underscores the importance of refining the social value estimation process. Although the stakeholder-informed valuation strategy ensures contextual relevance, it is inherently subjective, and the value could be over- or underestimated. Furthermore, the usage of Social Value Bank data may result in inflation or misrepresentation of value if the proxy used does not fully align with the local context or intensity of the benefit, as shown in the case of the volunteers.

Further research should include the development of a comprehensive framework for assessing the social value of innovative solutions within inclusive and green public spaces in cities, involving a wide range of engaged groups, specific target groups but also project implementers and other actors involved in co-design, co-creation, and co-management given the fuzzy position of those involved. Scholten’s Value Game could be further extended as a tool for estimating social value with low cognitive burden; it could be used to show differences in the perceived value generated by different stakeholders and the uninvolved public, and its ability to withstand biases in different contexts should be tested.