**Abstract**

As cities densify, areas available for agriculture within the city become increasingly small and infeasible for mass production. In parallel, many cities have seen a rapid rise in establishing community-based micro-farming, operating within marginal spaces of uncertain ownership or regulations. Prominently in Hong Kong, more than 60 urban rooftop farms have spontaneously appeared in the last 10 years on buildings. High application rates for renting plots in these informal farms suggest a strong demand in the population. Motivations cited by participants of rooftop farms are typically social, although social values have yet to be specifically defined or objectively measured. Hong Kong Special Administrative Region Government's new agricultural policy conceives urban agriculture as a commercially productive practice. In consequence, urban rooftop farming lies awkwardly between formal city planning and informal community practices. A study of five rooftop farms in Hong Kong found, through participant opinion surveys and cost-benefit analysis, that the social benefits to participants were multifaceted with a preference on personal socialization and that they were willing to pay for the experience. The results suggest that if the products of rooftop farming could be conceived as being social, rather than food production, individual motivations and state interests could be aligned and the available roof space activated to achieve a more sustainable city.

**Keywords:** urban agriculture, rooftop farming, social benefits, sustainability, cost-benefit analysis

## **1. Introduction**

With the intense contest for ground-level space within high-density urban districts, urban agriculture has taken on multiple forms and occurs in different locations, such as peri-urban farming, urban soil-based farming, indoor farming and rooftop farming [1]. Urban agriculture was initially conceptualized as a response to increasing concerns for food security within the city, with the focus on the potential for mass production within a localized food system that includes production, processing, distribution, consumption and recycling [2]. More than 30% of the food requirements of the City of Oakland are planned to be provided from within the physical limits of the city through city council's sustainable food system [3]. However, within the complex morphology of high-density cities, the contest for space and strict land use and building controls, the large-scale contiguous spaces required for economic mass agricultural production are seldom available. Many micro-farming enterprises, however, have emerged in cities around the world as community gardens and allotment gardens [4]. Occupying small-scale,

marginalized and fragmented "leftover" spaces, these occur on sites of uncertain ownership and ambiguous regulatory control.

A clear expression of this phenomenon is the spontaneous appearance in the last decade of more than 60 rooftop farms on underutilized flat roof spaces across the dense urban districts of Hong Kong [5]. These urban rooftop farms are composed of numerous lightweight surficial planter boxes (as opposed to the built-in planting constructions typical of green roofs) which are individually rented to the general public through community enterprise organizations or provided to relevant groups by corporate or institutional owners. Proximity to the people's living and working spaces have made urban rooftop farms popular, with all farms reporting that they are constantly heavily oversubscribed. Farm owners have suggested that the strong demand for participation is motivated by the opportunities it provides for social interaction, passive recreation, health, education and self-achievement. This contrasts with the HKSAR Government's recent policy initiatives for urban agriculture which are focused on economic and productive values [6]. In consequence, urban rooftop farms in Hong Kong are in an ambiguous situation between formal centralized city planning and informal community enterprise action. To understand the social benefits of rooftop farming within an urban context of contested space and extreme land value, this study looked to monetize social value through cost-benefit analysis and willingness among participants to pay for extra social benefits derived from the practice.

#### **1.1 Social value of urban rooftop farming**

Social value has long been a consideration within environmental justice discourses; however there has been relatively little research on the social values of urban agriculture and almost none on urban rooftop farming [7]. As with urban agriculture, the few policy debates that have occurred on urban rooftop farming have focused on the potential economic value—the monetary profits that might be generated by selling food produced within the city and generalized concerns for global food security. Around the world, however, very few large-scale commercial urban rooftop farms have been successfully established, and these have only been achieved by retrofitting rooftops with large-scale greenhouses, e.g., AeroFarms in the USA [8] and urban farmers in the Netherlands [9]. The large majority of urban rooftop farms have been small-scale social and community enterprises. In recent years, discussion about the practice has migrated onto to potential contribution to urban environment and greening [1, 10–13]. Urban rooftop farms have been suggested as possible patches that might visually and ecologically link existing green spaces and corridors within an integrated green infrastructure system and help mitigate urban heat island effects [14]. It has been shown that urban rooftop farms support far higher biodiversity (some have upwards of 200 plants species) than green roofs [15].

Only recently have discussions of the social values of urban rooftop farming begun to appear in the literature. Although social values are considered an important principle within broader concepts of urban sustainability, their recognition and development are lagging [16]. This is commonly attributed to the fact that social values associated with the external environment, such as green spaces and allotment gardens, are intangible and difficult to measure [17]. Social value is usually assumed to be generated through communal physical activity within a space, for example, social groups collaborating on planting activities [18]. Long return on investment makes social value hard to calculate and difficult to monetarize, metrics that are commonly required for inclusion in policy decision-making [19].

Through a review of international case studies, social values of urban rooftop farming were initially investigated from three aspects: social capital theory,

**103**

*Social Value of Urban Rooftop Farming: A Hong Kong Case Study*

satisfaction, achievement and leadership in the society [25, 26].

**1.2 Framework of social benefits of urban rooftop farming**

the greatest amount of activity across all the different social values.

Based on these interdisciplinary research studies, a social value framework for urban rooftop farming was developed, specific to the Hong Kong context (**Table 1**). This allows a spectrum of social benefits of urban rooftop farming to be considered, with respect to the diverse stakeholders' (state and individual) interests. The framework compares the social values generated by urban agriculture, green roof installations and rooftop farms; identified from published research papers; and categorized under six factors: health, education, community recreation, urban improvement, social empowerment and social group integration. Urban rooftop farming generates

landscape projects and urban agriculture practices and with the aim of building a systematic framework of social values for urban rooftop farming. As Dika and Singh [20] noted, the decomposition of a broad concept into factors and indicators can improve understanding and help the policy adaptation in specific

Ideas of social values are based on social capital theory which focuses on balancing different social groups by creating a sense of fairness from collaboration [21]. Social group integration and empowerment are key factors discussed by scholars. Dubos [22] suggests that social capital should be considered in two forms: structural network and cognitive value. Doherty further explains that the structural network in an inclusive society should cross generations and identities and consist of the behaviour-related indices of trust, informal networking, mutual support, reciprocity and solidarity [23, 24]. At the same time, cognitive value is a significant assessment for empowered citizens which is usually obtained from increasing self-

As an emergent landscape typology, performance measures for urban rooftop farming have yet to be developed [27]. Methods of measuring performance of built landscape have tended to assess physical objects and functional efficiency [28, 29]. Of the few approaches that have evaluated changes in social aspects, Landscape Performance Series (LPS) and Case Study Investigation (CSI) contain the most instructive framework, as they categorize recreation, health, education and food production as core social value factors that enhance sustainability in landscape

In the absence of previous research on the specific social values of urban rooftop farms, this research drew upon discussions of social values related to urban agriculture in general. This allowed indicators for an urban rooftop farming social values framework to be identified. The urban agriculture matrices framework developed by Design Trust for Public Space program in New York highlighted the significant benefits through increased physical health and social empowerment from growing vegetables [30]. Specifically, physical, mental and dietary health can be summarized from the research outcome. Social empowerment has been further supported via environmental and food education, leadership and socializing activities which are increasingly important by-products of all forms of urban agriculture. Other researchers have identified unique collective social welfare being generated through urban rooftop farming [7, 31, 32]. Tian and Jim addressed the social value of additional open spaces to the surrounding communities through multifunctional roof spaces, noting that given the limited land in highly dense cities, retrofitting urban farms to rooftops can effectively activate large numbers of vacant spaces within the city for social benefits [32]. Prior research studies have also indicated that dynamic factors are involved in the generation of social values through the

*DOI: http://dx.doi.org/10.5772/intechopen.89279*

contexts.

projects [27].

practice of urban agriculture.

*Agricultural Economics - Current Issues*

ownership and ambiguous regulatory control.

**1.1 Social value of urban rooftop farming**

marginalized and fragmented "leftover" spaces, these occur on sites of uncertain

A clear expression of this phenomenon is the spontaneous appearance in the last decade of more than 60 rooftop farms on underutilized flat roof spaces across the dense urban districts of Hong Kong [5]. These urban rooftop farms are composed of numerous lightweight surficial planter boxes (as opposed to the built-in planting constructions typical of green roofs) which are individually rented to the general public through community enterprise organizations or provided to relevant groups by corporate or institutional owners. Proximity to the people's living and working spaces have made urban rooftop farms popular, with all farms reporting that they are constantly heavily oversubscribed. Farm owners have suggested that the strong demand for participation is motivated by the opportunities it provides for social interaction, passive recreation, health, education and self-achievement. This contrasts with the HKSAR Government's recent policy initiatives for urban agriculture which are focused on economic and productive values [6]. In consequence, urban rooftop farms in Hong Kong are in an ambiguous situation between formal centralized city planning and informal community enterprise action. To understand the social benefits of rooftop farming within an urban context of contested space and extreme land value, this study looked to monetize social value through cost-benefit analysis and willingness among participants to pay for extra social benefits derived from the practice.

Social value has long been a consideration within environmental justice discourses; however there has been relatively little research on the social values of urban agriculture and almost none on urban rooftop farming [7]. As with urban agriculture, the few policy debates that have occurred on urban rooftop farming have focused on the potential economic value—the monetary profits that might be generated by selling food produced within the city and generalized concerns for global food security. Around the world, however, very few large-scale commercial urban rooftop farms have been successfully established, and these have only been achieved by retrofitting rooftops with large-scale greenhouses, e.g., AeroFarms in the USA [8] and urban farmers in the Netherlands [9]. The large majority of urban rooftop farms have been small-scale social and community enterprises. In recent years, discussion about the practice has migrated onto to potential contribution to urban environment and greening [1, 10–13]. Urban rooftop farms have been suggested as possible patches that might visually and ecologically link existing green spaces and corridors within an integrated green infrastructure system and help mitigate urban heat island effects [14]. It has been shown that urban rooftop farms support far higher biodiversity (some have upwards of 200 plants species) than

Only recently have discussions of the social values of urban rooftop farming begun to appear in the literature. Although social values are considered an important principle within broader concepts of urban sustainability, their recognition and development are lagging [16]. This is commonly attributed to the fact that social values associated with the external environment, such as green spaces and allotment gardens, are intangible and difficult to measure [17]. Social value is usually assumed to be generated through communal physical activity within a space, for example, social groups collaborating on planting activities [18]. Long return on investment makes social value hard to calculate and difficult to monetarize, metrics

Through a review of international case studies, social values of urban rooftop

that are commonly required for inclusion in policy decision-making [19].

farming were initially investigated from three aspects: social capital theory,

**102**

green roofs [15].

landscape projects and urban agriculture practices and with the aim of building a systematic framework of social values for urban rooftop farming. As Dika and Singh [20] noted, the decomposition of a broad concept into factors and indicators can improve understanding and help the policy adaptation in specific contexts.

Ideas of social values are based on social capital theory which focuses on balancing different social groups by creating a sense of fairness from collaboration [21]. Social group integration and empowerment are key factors discussed by scholars. Dubos [22] suggests that social capital should be considered in two forms: structural network and cognitive value. Doherty further explains that the structural network in an inclusive society should cross generations and identities and consist of the behaviour-related indices of trust, informal networking, mutual support, reciprocity and solidarity [23, 24]. At the same time, cognitive value is a significant assessment for empowered citizens which is usually obtained from increasing selfsatisfaction, achievement and leadership in the society [25, 26].

As an emergent landscape typology, performance measures for urban rooftop farming have yet to be developed [27]. Methods of measuring performance of built landscape have tended to assess physical objects and functional efficiency [28, 29]. Of the few approaches that have evaluated changes in social aspects, Landscape Performance Series (LPS) and Case Study Investigation (CSI) contain the most instructive framework, as they categorize recreation, health, education and food production as core social value factors that enhance sustainability in landscape projects [27].

In the absence of previous research on the specific social values of urban rooftop farms, this research drew upon discussions of social values related to urban agriculture in general. This allowed indicators for an urban rooftop farming social values framework to be identified. The urban agriculture matrices framework developed by Design Trust for Public Space program in New York highlighted the significant benefits through increased physical health and social empowerment from growing vegetables [30]. Specifically, physical, mental and dietary health can be summarized from the research outcome. Social empowerment has been further supported via environmental and food education, leadership and socializing activities which are increasingly important by-products of all forms of urban agriculture. Other researchers have identified unique collective social welfare being generated through urban rooftop farming [7, 31, 32]. Tian and Jim addressed the social value of additional open spaces to the surrounding communities through multifunctional roof spaces, noting that given the limited land in highly dense cities, retrofitting urban farms to rooftops can effectively activate large numbers of vacant spaces within the city for social benefits [32]. Prior research studies have also indicated that dynamic factors are involved in the generation of social values through the practice of urban agriculture.

#### **1.2 Framework of social benefits of urban rooftop farming**

Based on these interdisciplinary research studies, a social value framework for urban rooftop farming was developed, specific to the Hong Kong context (**Table 1**). This allows a spectrum of social benefits of urban rooftop farming to be considered, with respect to the diverse stakeholders' (state and individual) interests. The framework compares the social values generated by urban agriculture, green roof installations and rooftop farms; identified from published research papers; and categorized under six factors: health, education, community recreation, urban improvement, social empowerment and social group integration. Urban rooftop farming generates the greatest amount of activity across all the different social values.


**Table 1.** *Social value framework for urban rooftop farming.*
