Elsevier

Global Food Security

Volume 17, June 2018, Pages 30-37
Global Food Security

Commercial farming within the urban built environment – Taking stock of an evolving field in northern countries

https://doi.org/10.1016/j.gfs.2018.03.005Get rights and content

Highlights

  • Scoping study on sustainability assessment of commercial urban farms in northern cities.

  • Very few studies have quantitatively assessed impacts of commercial urban farms.

  • These large facilities can have difficulties finding a place in the urban space.

  • Holistic decision support tools can help integrating them in the cities of tomorrow.

Abstract

Urban horticulture has historically contributed to the supply of fresh produce to urban dwellers and has been gaining popularity over the last years in the Global North, with growing awareness of environmental and health concerns. Over the past few years, commercial farms have been emerging in major northern cities, promoting a trend of environmentally friendly food, grown in highly efficient installations on top of or in buildings. This paper presents a scoping study, including: (i) a review of the scientific literature addressing environmental, economic and social aspects of commercial farming in urban contexts; and (ii) a consultation exercise to inform and validate findings from the review, consisting of semi-structured interviews with a few practitioners in the Netherlands. The main findings are: (1) while the recent proliferation of commercial farms in major cities shows that these new modes of urban agricultural production are gaining momentum, establishing their viability as compared to conventional agricultural practices is a challenge when it comes to scalability, resource efficiency, and cost-effectiveness; (2) as it is still a relatively new field, very few studies have been conducted to quantitatively assess the impacts of commercial farming in urban areas; (3) given the complex environmental, economic and social dimensions of urban agriculture, holistic decision support tools could help integrating them in urban areas.

Introduction

Global population is projected to reach almost 10 billion by 2050, resulting in a higher demand for food by around 50% compared to 2013 – in a scenario of moderate economic growth; at the same time, income growth in low- and middle-income countries is expected to hasten a dietary transition towards higher consumption of meat, fruits and vegetables, requiring changes in agricultural output and intensifying pressure on natural resources (FAO, 2017). However, while an acceleration in productivity growth is needed, it is also hampered by the fast degradation of natural resources caused by agricultural practices, that have already led to massive land use change in order to meet demand for food, which in turn has amplified the environmental effects.

Agriculture and climate change are interconnected: the former not only contributes to the latter, but is also affected by its manifestations. The effects of agriculture on climate change have been largely demonstrated, mainly through GHG emissions, depletion of underground aquifers, and impacts of tillage, fertilizers and pesticides on soil, air and water quality, and on biodiversity (Clark and Tilman, 2017). Furthermore, the use of fossil fuels, jointly with land degradation such as desertification and deforestation, are the major anthropogenic sources of carbon emissions worldwide (IPCC, 2013). At the same time, rising carbon levels and the effects of global warming on temperatures and precipitations are projected to have impacts on crop yields (Zhang and Cai, 2011). In spite of the uncertainty in defining its net impact on the food system, it is likely that climate change will affect the suitable land area for crops, leading to significant socio-economic costs (Stevanovic et al., 2016).

In a context of climate change and increasing urbanization – over two-thirds of global population are projected to be living in cities by 2050 (United Nations, 2014), while some experts are skeptical about the capacity of the biosphere to produce enough food for the entire human population (Gilland, 2006), interest for local production to contribute to sustainable urban food systems has re-emerged among decision-makers (Baker and de Zeeuw, 2015), and the practice of urban agriculture as a food, income and employment generator is likely to expand (Caputo, 2012). Today, urban cultivation has been widely recognized not only to enhance food security by shortening and thus improving the resilience of food supply chains, but also to provide economic development opportunities, enhance urban public health (Brown and Jameton, 2000), and contribute to mitigate environmental impacts of the food system by reducing food losses and wastage and cutting transportation distances (Benis and Ferrao, 2016).

However, in spite of the growing awareness of its significant benefits for the environment and for communities, urban agriculture has been largely absent in urban planning strategies and policies (Pothukuchi and Kaufman, 2000, Steel, 2008) until very recently, and establishing its viability as compared to conventional agricultural practices is a challenge when it comes to land accessibility, scalability, resource efficiency, and cost-effectiveness. Over the past decade, hundreds of cities, both in the Global North and South, have developed policies and programs on urban food security, nutrition, and urban agriculture (Baker and de Zeeuw, 2015). At the same time, there has been large debate about defining sustainable cities and urban forms that alleviate pressure on natural resources. Some planners defend that “rurban” areas like the Oosterworld in the Dutch city of Almere, which combine housing and farming, can provide great sustainability (Jansma et al., 2014). Others advocate the concept of “green urbanism”, which promotes compact resource-efficient urban development with mixed land uses, as a way of preserving agricultural land (Lehmann, 2010).

Whereas livestock, cereals and oilseeds require large areas of land, horticultural crops offer high yields in small areas and can thus be easily grown in urban gardens, backyards, vacant lots, rooftops or even indoors. Worldwide, a study has shown that urban agriculture would require around one third of the total global urban area to meet the global vegetable consumption of urban dwellers (Martellozzo et al., 2014). Other researchers have measured the potential of large North American and European cities for self-reliance in food if they were to use only their currently vacant urban space, estimating that 77–100% of urban vegetable demand can be met, depending on available areas and farming methods to be implemented, which would lead to different yields (Grewal and Grewal, 2012, Haberman et al., 2014, Orsini et al., 2014, Saha and Eckelman, 2017). Such proposals include large-scale implementation of high-yield urban horticultural production within the built environment. One of the commonly used concepts in the literature of such practices, Building-Integrated Agriculture (BIA), was coined in 2007 (Caplow and Nelkin, 2007) and consists of adapting soilless cultivation techniques such as hydroponics or aquaponics, for use on top of or in buildings in a way that exploits synergies between the buildings and the agricultural activities. On-site production through urban BIA cuts transportation distances and avoids land use change while creating urban jobs. Furthermore, when involving Controlled-Environment Agriculture (CEA), advantages of BIA include year-round production, higher yields, enhanced water use efficiency (Gould and Caplow, 2012) and improved building energy efficiency through the creation of symbiotic relations between the farm and its host building (Nadal et al., 2017). BIA systems can be applied: (i) on the building envelope, i.e., on the rooftop or facades, to take advantage of the availability of natural light; or (ii) indoors, in a fully controlled environment. In the literature, the term Zero-acreage Farming (ZFarming) can also be found, describing all types of urban agriculture characterized by the non-use of farmland or open spaces, and rather using otherwise unused spaces in the urban built environment (Specht et al., 2014). In this category, authors usually also include low-tech alternatives such as rooftop open-air on-soil farming.

Fig. 1 shows examples of different forms of farming systems that are currently sprouting within the built environment of major cities worldwide.

Among existing forms of envelope-integrated systems, rooftop farming is the most popular since rooftops represent large unutilized solar exposed urban areas. Rooftop farming is either practiced on intensive green roofs, or in Rooftop Greenhouses (RG) equipped with hydroponic equipment. In the latter, state-of-the-art installations generally include recirculating water systems, waste heat captured from the building's HVAC system, local renewable energy production such as solar PV, rainwater harvesting systems and evaporative cooling (Gould and Caplow, 2012). A few North American and European companies have already proven that significant amounts of local food can be produced year-round for urban dwellers on unutilized rooftops in dense cities where affordable land is rare.

For facades, Vertically-Integrated Greenhouses (VIG) have been developed as a concept and patented (Adams and Caplow, 2012). VIG systems consist of double skin building facades combined with hydroponic systems. However, to the best of our knowledge, there is currently no existing significant example.

Vertical Farming (VF) is another form of high-yield urban food production that consists of raising crops in controlled environments and using soilless cultivation methods, in multistory buildings within the urban context. Some scientists defend the legitimacy of VF for environmental reasons, arguing that plant cultivation inside the buildings involves less embodied energy and releases less pollution than some agricultural practices on natural landscapes, in addition to the fact that periurban lands are often too toxic for agricultural production (Despommier, 2010). These intensive closed growing systems – using skyscrapers to grow food – are also called Skyfarms (Germer et al., 2011), or Plant Factories (PF) (Kozai, 2013).

Another emerging trend in the field of commercial urban farming are modules that can be operated within the built environment, such as outfitted and insulated Shipping Containers (SC). Equipped with state-of-the-art climate control technology and hydroponic growing equipment, SC farms allow for year-round production and can be installed in vacant lots, warehouses, basements or rooftops. Advantages of shipping containers include their compactness and modularity, large availability, low cost, and ease of shipping.

Section snippets

Methods

Today, approaches of farming the urban built environment as a viable solution to feed cities are gaining momentum among some of those who believe that current sustainable farming methods will not be sufficient or the most effective method to meet the demand for food of a growing urban global population. At the same time, although intensive urban farming is a nascent area, numerous research questions are already emerging around it, from uncertainties about its environmental and economic

Food miles vs. resource intensity

Located within the city and therefore closer to the consumer, high-yield urban agriculture has been claimed by several authors to have a lower carbon footprint than its counterpart rural food production, by cutting transportation distances – “food miles” (Cerón-Palma et al., 2012; Specht et al., 2014). However, depending on local climate conditions and farm typologies, crop production in controlled environments can also be highly energy-intensive, which can considerably exacerbate its

A deferred revolution

On the one hand, the technology behind high-yield indoor farming – controlled-environment soilless culture – has been around for almost eighty years. In 1940, William Frederick Gericke, a professor at the University of California Berkeley, coined the term “hydroponics”, a plant cultivation method where, instead of using nutrients to improve soil quality, the researcher wanted farmers to replace their fields with the indoor soilless system that he had developed throughout years of testing

Beyond food production: community building

Social impacts of conventional on-soil urban horticulture on vacant plots or in open-air rooftop gardens have been widely investigated (Proksch, 2011, Eigenbrod and Gruda, 2015), and were shown to include a large set of benefits to local communities. In addition to providing access to fresh and nutritious food, urban horticulture involves volunteer and social works, youth educational programs and job trainings, stimulating the creation of powerful community ties and giving urbanites the chance

Conclusions

Rather than spreading out across hectares of land, the farms of tomorrow might grow food within climate-controlled, artificially-lit urban facilities, using less land, less water, yet producing year-round fresh, colorful and tasty vegetables anywhere in the world. This would allow our growing urban areas to provide food to their residents while mitigating desertification and deforestation, whereas commercial farming industry would offer urban jobs, contributing to offset the unemployment

Acknowledgments

Generous support for this work has been provided by FCT (Portuguese Science and Technology Foundation), under the MIT Portugal Program in Sustainable Energy Systems, through the doctoral degree grant SFRH/BD/52306/2013. Interviews were carried out in the Netherlands during a research visit by the main author at the University of Amsterdam, partially supported by the InnoEnergy Ph.D. School funding for special activities.

References (60)

  • Z. Tong et al.

    A case study of air quality above an urban roof top vegetable farm

    Environ. Pollut.

    (2016)
  • Adams, Z.W., Caplow, T., 2012. Vertically-Integrated Greenhouse. US 8,151,518 B2....
  • H. Arksey et al.

    Scoping studies: towards a methodological framework

    Int. J. Soc. Res. Methodol. Theory Pract.

    (2005)
  • Baker, L., de Zeeuw, H., 2015. Urban food policies and programmes: an overview. In: Cities and Agriculture: Developing...
  • C. Banerjee et al.

    Up, up and away! The economics of vertical farming

    J. Agric. Stud.

    (2014)
  • K. Benis et al.

    Potential mitigation of the environmental impacts of food systems through Urban and Peri-Urban Agriculture (UPA) – a life cycle assessment approach

    J. Clean. Prod.

    (2016)
  • Benis, K., Reinhart, C., Ferrão, P., 2017b. Building-integrated agriculture (BIA) in urban contexts: testing A...
  • F.H. Besthorn

    Vertical farming: social work and sustainable urban agriculture in an age of global food crises

    Aust. Soc. Work

    (2013)
  • K. Bohn et al.

    Second Nature Urban Agriculture: Designing Productive Cities

    (2014)
  • K. Brown et al.

    Public health implications of urban agriculture

    J. Public Health Policy

    (2000)
  • D. Buehler et al.

    Global trends and current status of commercial urban rooftop farming

    Sustainability

    (2016)
  • Caplow, T., Nelkin, J., 2007. Building-integrated greenhouse systems for low energy cooling. In: Proceedings of the 2nd...
  • Caputo, S., 2012. The purpose of urban food production in developed countries. In: Sustainable Food Planning: Evolving...
  • M. Carlini et al.

    Modelling and simulation for energy production parametric dependence in greenhouses

    Math. Probl. Eng.

    (2010)
  • I. Cerón-Palma et al.

    Barriers and opportunities regarding the implementation of Rooftop Eco. Greenhouses (RTEG) in Mediterranean Cities of Europe

    J. Urban Technol.

    (2012)
  • M. Clark et al.

    Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice

    Environ. Res. Lett.

    (2017)
  • D. Despommier

    The Vertical Farm: Feeding the World in the 21st Century

    (2010)
  • C. Eigenbrod et al.

    Urban vegetable for food security in cities. A review

    Agron. Sustain. Dev.

    (2015)
  • European Commission, 2008. Commission Regulation (EC) No...
  • FAO, 2017. The Future of Food and Agriculture - Trends and Challenges....
  • Cited by (60)

    • Policy and regulatory constraints in the biodiesel production and commercialization

      2023, Sustainable Biodiesel: Real-World Designs, Economics, and Applications
    • The embodied carbon emissions of lettuce production in vertical farming, greenhouse horticulture, and open-field farming in the Netherlands

      2022, Journal of Cleaner Production
      Citation Excerpt :

      The carbon footprint studies (Table A.1, #1–3) did not document all data, such as photoperiods and yields, which made it difficult to validate the findings presented or compare them to the other CBVFs in a robust manner. The quantity of energy used (Avetisyan et al., 2013), the source of energy (Delden et al., 2021), the local climate conditions affecting resource use efficiency (Graamans et al., 2018), and local farm typologies (Benis and Ferrão, 2018) make the sustainability of food systems context specific, meaning that the emissions vary per region. To the authors’ knowledge, no quantitative comparison of carbon emissions associated with both the life cycle of the farm and the crop, from cradle to grave, exist for CBVFs relative to open-field farming and both soil-based and hydroponic greenhouse horticulture within the Dutch context.

    View all citing articles on Scopus
    View full text