Places for People, Places for Plants:
Evolving Thoughts on Continuous Productive Urban Landscape
A. Viljoen1, K. Bohn2, M. Tomkins1, and G. Denny3.
1
University of Brighton, Mithras House, School of Architecture and Design, Faculty of
Arts and Architecture, Lewes Road, Brighton BN2 4AT, UK.
2
Bohn & Viljoen Architects, 18 Copleston Road, London SE15 4AD.
3
University of Cambridge, Department of Architecture, Faculty of Architecture and
History of Art, 1-5 Scroope Terrace, Cambridge CB2 1PX
Keywords: CPUL, urban agriculture, architecture, sustainable urban design, food
miles, greenhouse gas emissions, allotments, behaviour change, embodied desire,
desire-in- use
Abstract
This paper reviews the role of urban agriculture within the context of the
Continuous Productive Urban Landscape (CPUL) design concept. CPUL proposes a
coherent strategy for the introduction of interlinked productive landscapes into
cities thereby creating a new sustainable urban infrastructure. The paper focuses on
urban agriculture as one of the major components of CPUL. Making reference to
recent high-profile international exhibitions and publications, the paper traces
urban agriculture’s remarkable shift from a fringe interest to one at the centre of
contemporary urban/architectural discourse. The paper discusses examples of
recent and emerging research with respect to greenhouse gas emissions, behaviour
change and urban design, to further inform our understanding of the potential
impact of CPUL and urban agriculture on the city. The paper concludes that, while
urban agriculture is receiving a great deal of attention, the theory underpinning its
design and the rationale for developing policy to support its practice will require
sophisticated cross-disciplinary research to articulate the concept's full potential as
an element of essential infrastructure within future sustainable cities. The case for
CPUL has to be made by taking into consideration multi-faceted and crossdisciplinary arguments, which collectively provide strong evidence in support of
CPUL and urban agriculture.
INTRODUCTION - A CPUL OVERVIEW
Continuous Productive Urban Landscape (CPUL) is a design concept advocating the
coherent introduction of interlinked productive landscapes into cities as an essential
element of sustainable urban infrastructure. Central to the CPUL concept is the creation
of multi-functional open urban space networks that complement and support the built
environment (Fig.1). The concept grew out of design research exploring the role of urban
agriculture within urban design (Viljoen and Tardiveau, 1998), and was first designed for
and then defined by Bohn and Viljoen Architects respectively in 1998 and in 2005
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(Viljoen A. 2005).
Key features of CPUL space include urban agriculture, outdoor spaces for people,
natural habitats, wildlife and circulation networks for public and non-vehicular traffic
(Fig.2). The CPUL network connects existing open urban spaces, maintaining and in
some cases modifying their current use and forming ecological corridors. CPUL impacts
on the city qualitatively with respect to citizens' experience and quantifiably with respect
to reduced negative environmental impact (Viljoen A. 2005).The concept recognises that
each site and city will present a unique set of conditions and competing pressures
informing the final shape and extent of the CPUL (Fig. 3).
Within the CPUL concept, urban agriculture refers in the main to fruit and
vegetable production. Typical urban agriculture practice ranges from small scale “food
gardening” to high yield, space-efficient urban market gardening. Urban agriculture is
inherently suitable for inclusion in localized zero-waste systems, whereby composting can
be used to reduce waste (Drechsel and Kunze 2002).
The CPUL design concept is underpinned by a number of robust and interrelated
social, environmental and economic arguments for what would amount to a radical
change in the configuration and programming of open urban space within an overarching
desire to find more self-sustaining ways of living. Greenhouse gas emission reduction,
peak oil data, and increasing urbanisation all contribute to and challenge the concept.
For urban agriculture, a solid body of literature exists describing its social impact
with respect to food security, to development policy and the positive social impact of
urban agriculture in places with high indices of social deprivation (Egziabher et al. 1994;
Koc et al. 1999; Caridad Cruz and Sánchez Medina 2003; Mougeot 2005; van
Veenhuizen 2006).
Other areas of research relevant to CPUL are just starting to appear: Academic
research assessing the impact of green space in the urban environment with respect to
human well-being is beginning to be disseminated, as evidenced by presentations at the
2nd International Conference on Urban Landscape and Horticulture 2009. In Great Britain,
with the exception of work on localization undertaken by the New Economics
Foundation, research relevant to the economic viability of urban agriculture remains rare;
this is a subject area where new research is essential. During the late 1990ies, it was
similarly difficult within Great Britain to access detailed contemporary studies into the
embodied energy and associated greenhouse gas emissions of foodstuffs. In recent years,
a number of studies have helped address all these concern, and will be discussed below.
Within design disciplines, the dissemination of new ideas takes place as much
through the medium of exhibitions as through the publication of academic papers. In
these disciplines, a rapid increase in interest, exploration and dissemination of ideas about
designing urban space for urban agriculture is evident. Figure 4 records, from the
perspective of the CPUL concept, the relationship between a number of organisations,
researchers and key publication advocating, testing and developing urban agriculture.
Two organisations with a strong web presence, City Farmer (www.cityfarmer.org) and
RUAF (www.ruaf.org) have provided a long-standing resource for activists and
researchers, each broadly addressing a different constituency with City Farmer providing
community/activist support and RUAF addressing issues related to urban poverty and
development. The publication in 1996 of the book “Urban Agriculture: Food, Jobs and
Security” (Smit J. 1996) was a landmark in defining an international role for urban
agriculture and may be considered seminal to a sequence of publications, academic and
popular. While planning for urban agriculture has already been on the agenda, the
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publication in 2005 of “CPULs” (Viljoen A. 2005) was the first time a book was devoted
to presenting a design strategy for the coherent integration of urban agriculture into cities.
A further milestone in the exploration of design consequences and possibilities
arising from urban agriculture was reached in 2007, when the Netherlands Architecture
Institute (NAi) Maastricht curated an exhibition titled “Die Eedbare Stad / The Edible
City". This brought together an international group of leading architects and artists all, at
that time, exploring urban agriculture within their work. Since then, the number of similar
exhibitions and “public works” hosted by leading international design institutions has
continued to increase and includes the UK Design Council led "DOTT 07 Urban Farming
Project" in Middlesbrough (2006/07), The Canadian Centre for Architecture’s exhibition
"Actions: What you can do with the city" (2008), the "Vertical Farming" exhibition at
Exit Art, New York (2009) and the Dutch art organisation STROOM’s "Foodprint"
programme commencing in June 2009 in the city of Den Haag.
These activities are likely responsible for urban agriculture and CPUL beginning
to be integrated into planning policy within the UK. Evidence for this can be found in the
Greater London Authority's / Design for London’s proposals for the “Green Grid”, a
network of open spaces within the city including provision for productive landscapes
(bldgblog, 2009). Concurrently, the Greater London Authority's Planning and Housing
Committee is undertaking an investigation into the planning system’s role in supporting
and encouraging commercial food growing in London (Jones J., pers. commun. 2009).
Notwithstanding these developments, the publication, “Agriculture in Urban
Planning” (Redwood 2009) concludes that architects and planners require further
“awareness of and sensitivity to including “green” and agricultural features into the
design process”.
DISCUSSION: NEW AND EMERGING RESEARCH
GHG emissions and urban agriculture
Urban agriculture has the unique potential to reduce GHG emissions by reducing
the energy use required to transport food from source to consumer. For practitioners in the
fields of urban and landscape design, accessing and contextualizing this impact is not
always straightforward.
Within the United Kingdom, a detailed study of food miles was published in 2005
(DEFRA 2005). This report noted that, in total, food transport in the UK produced 19mt
of carbon dioxide in 2002 of which 10mt were emitted in the UK, and that the food chain
was responsible for 17% of UK greenhouse gas emissions. In 2008, a report
commissioned by the Greater London Authority assessed the greenhouse gas emissions
associated with London’s food sector and concluded that transport, storage and
distribution accounted for 19% (3.6 Mt CO2 e/yr) of London’s food related GHG
emissions, while primary production and manufacture of food accounted for 59% (11 Mt
CO2 e/yr) (Brook Lyndhurst 2008). The report also noted that the European Commission
estimated that 31% of European Union consumption emissions are food related (European
Commission 2006).
A recent study from the USA (Weber et al. 2008) contextualises the relative
impacts of a localized food supply system with respect to food type and degree of
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processing and manufacture. Weber et al. used input/output life cycle analysis to assess
the GHG emissions associated with food production and supply chains for the USA which
is, like in many industrialised countries, dominated by remote industrialized production
methods. Weber et al.'s study categorised GHG emissions by food type and production
stage and concluded that, on average, transportation represented 11% and the production
phase 83% of life-cycle GHG emissions. The study shows that a majority of food's
climate impact is due to non-carbon-dioxide emissions, mainly due to nitrogen fertilizer
application, other soil management techniques and manure management. While these
non-carbon-dioxide impacts are found in all food sources, they are especially
concentrated in meat and dairy production.
Weber et al. conclude that “a dietary shift can be a more effective means of lowering an
average household’s food-related climate footprint than “buying local.” Shifting less than
one-day-per-week’s worth of calories from red meat and dairy products to chicken, fish,
eggs, or a vegetable-based diet achieves more GHG reduction than buying all locally
sourced food” (Weber et al. 2008, pp3508). This conclusion makes it clear that urban
agriculture cannot be viewed or assessed in isolation, and only makes sense from a GHG
emissions standpoint if it is seen as part of a general behaviour shift that includes a
reduction in the consumption of meat and dairy products. If it is accepted that meat and
dairy product consumption should be reduced, then disregarding their impact, Weber et
al.’s paper shows that fruit and vegetables have the second highest GHG emissions
impact per household, and furthermore they have the highest GHG transport impact.
(Weber et al., 2008 Fig 1 pp 3510).
In a “low carbon” economy and one that attempts to reduce energy consumption, a
valid case can be made for urban agriculture, in particular when it integrates waste
minimization techniques, such as composting, or the minimising of heating/refrigeration
during the growing or storage process. This requires the careful selection of production
and processing systems and their integration into the urban infrastructure and food supply
systems, if savings due to reduced transport are not to be eliminated by energy use
elsewhere.
Such a conclusion does not come as a great surprise, as, after all, historic
arguments made prior to the petro-chemical era provide evidence for the advantages of
locating fruit and vegetable production adjacent to urban areas. The writings of Johann
von Thünen (Chisholm 1972), in particular, deserve revaluation.
Behaviour change potential of urban agriculture
At another scale, that of the individual non commercial grower, evidence is emerging
for behaviour change potential related to food growing. In the UK, the allotment has
shown itself to be a catalyst for changes related to diet and health. Surveys undertaken by
one of the authors, Denny, within Cambridge and Middlesbrough, reveal the allotment’s
continuing influence across all socio-economic ranges. Most notable are a substantial
increase in the quality and quantity of food being consumed by allotment gardeners
during the growing-season, and decreased dependency on grocery stores as a source for
fresh produce: 70% in growing-seasons and 24% during the off-season. Changes in ‘foodmiles’ reduced personal carbon emissions by an average of 950 kg CO2/year, even while
still predominantly utilizing grocery stores during off-season months and maintaining an
overall dependence on fossil fuelled transport year round. Allotment tenants also surpass
the recommended 30 minutes/day of daily activity, through time spent within the
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allotment itself and through active-commuting related to food procurement. Furthermore
allotment holders who ate less than the recommended daily intake of fruit and vegetables
before they had an allotment, increased their fruit and vegetable intake once they started
growing food, and this increase was reflected in an increased proportion of fruit and
vegetables purchased thought the year. If this trend is validated in further research, it will
indicate the significant behaviour change impact that may be attributed to even relatively
modest urban agriculture interventions.
The Croydon Experiment: ideas for using the city as a laboratory
Croydon is a borough of Greater London covering 88,064 sq km, often
characterised by post war large-scale office blocks, multi-storey car parks and road
developments. The Croydon experiment was set up by Tomkins in 2009 to explore the
relationship between how individuals practice urban agriculture at a small scale and the
design and form of contemporary urban space. The authors were interested in the evident
contradictions between the often opportunistic way people grow food in cities, and the
formal layout of towns and cities.
The research work undertaken in Croydon looks at a 25 ha test site to the west of
its well-established fruit and vegetable market on Surrey Street. Research into Croydon’s
potential to grow food locally suggests that the market’s position within the town centre
could be exploited as part of a network in support of UA. The experiment addressed two
questions, firstly how viable is roof top food growing within an urban environment and
secondly what type of growing (commercial or individual / community based) would be
most appropriate for this location?
Research began with an analysis of the underlying physical urban geography,
where all suitable horizontal food growing areas where mapped for their potential to grow
food. This analysis showed that 7.25 ha of the 25 ha site where suitable for food growing.
Interestingly, the majority of this (4.25ha) is accounted for by roof top space including
two multi storey car-park roofs. Using potential yields of 31 tonnes a hectare, the site is
potential a net exporter of 43.65 tonnes of vegetables for the test site’s 1425 residents.
The activity of food growing within the built environment is often undertaken as a
contradictory activity, not envisioned by the original architects and designers. Residents’
ability to adopt post-occupancy activities of altering or transgressing is clearly evident in
public parks and open space. Here we commonly witness many user defined pathways or
“desire-lines” that criss-cross grassed areas often ignoring the tarmac pathways laid down
by urban and landscape designers. Another way of critically analysing this is to consider
the original design as having embodied-desire (the desire to keep people off grassed areas
literally “embodied” in tarmac) and the user’s desire-lines as evidence of desire-in-use
(the incremental everyday activity of a preferred walking path from A to B).
In 2008, this critical and somewhat philosophical thinking was tested within the
25ha test site in central Croydon. A visualisation tool in the form of a fold-out ”Edible
MAP” indicating potential food growing sites was produced . Also, a temporary food
producing “garden in the sky” was constructed that covered 4 car parking bays on the
often underused roof tire of a 0.24 ha multi-storey car park. (Fig. 5 & Fig. 6).
In design terms, the embodied desire of the “CAR-park” can be characterised as a
stopping point for fossil fuel based transport and shopping. The invertion of this is the
“car-PARK”, whereby a food growing element is installed as an example of desire in-use.
Food growing harvests a renewable energy source (food) from sunlight and would
initially seem to contradict the design intentions of the building. Practically speaking the
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turning of a CAR-park into a car-PARK was achieved with relative ease with reference to
ownership rights, health and safety, structural consideration and the environmental assets
of sunlight and water. The delivery of soil and plants was also straightforward due to the
car parks internal ramps and lifts. The same principle could be applied to the myriad of
small, underutilized spaces that litter the UK city landscape.
The car-PARK installation received considerable coverage in the local press and
attracted a steady stream of visitors, indicating an interest in urban agriculture.
The unique city centre location of the car-PARK, has the potential to integrate
food growing and harvesting with residents current food consuming habits –
predominately shopping. If this model were to be followed, the position of the growing
space in relation to other shopping or daily activities becomes an important consideration.
There are three main ways a space like this could operate on a permanent basis, as a
commercially viable market garden, as an education / recreational facility or as a space
for individual growers - allotments in the sky.
With regard to the concept of continuous productive landscape, it is clear that the
road system forms a “continuous” path from the front of houses to the CAR-park.
However, the pedestrian and potential food grower has to circumnavigate several
obstacles, including an obsured entrance, in order to make a continuous connection across
the urban landscape to the car-PARK
The building therefore does not form part of a normal pedestrian path from the
residential sites to shopping areas. Any food grower would have to take a considerable
detour to combine food harvesting with shopping. This is not uncommon for existing
allotments, nor would it be an issue for commercial growers using the rooftop for
cultivation. While we can show (as a group of academics and professionals) that the
building structure can be modified, perhaps the greatest obstacle to making this a space
available for everyday use, is not just the lack of physical continuity for pedestrians but
also the lack of continuity within the routines and obligations of everyday life .
If the desire is to encourage residents to grow their own food (desire-in-use),
further research would have to examine residents’ willingness to change, not only their
daily routines and desire-lines but also most likely their diets and shopping habits. There
is still much work to be done to demonstrate residents would adopt this – requiring a
radical change in their subjectivity and social/institutional relations as well as confronting
the wider context of the environment and green house gas emissions.
However, it is possible to demonstrate quantitatively that the 25 ha could be
extremely productive in terms of food, and perhaps it is simply the case that particular
spaces have particular potentials. For the car park roof top appropriate uses are likely to
include commercial growing or education in preference to recreation or allotments.
CONCLUSION
This paper confirms the growing interest in urban agriculture and the CPUL
concept within the fields of architecture and urbanism. To translate this interest into
practice and to support CPUL becoming an essential element of sustainable urban
infrastructure, it will require further cross-disciplinary research. The design, planning,
horticultural and landscape professions will need to relearn old and develop new skills to
support, in particular, the practice of urban agriculture.
Recently published research attempting to quantify the GHG emissions impact of
current food supply systems indicate that the environmental case for urban agriculture
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cannot be made in isolation from a consideration of consumer behaviour and the means of
production, processing and storage of food stuffs.
Preliminary research findings indicate potential for pro environmental and health
behaviour change from modest levels of food growing undertaken by individuals. “The
Croydon Experiment” assesses how available space in the city could be utilized for urban
agriculture and speculates that, for individual non-commercial growers, it will be essential
to integrate time and space for urban growing into the routines and obligations of
everyday life.
The authors contend that the case for CPUL is evolving and that it has to be made
by taking into consideration multi-faceted and cross-disciplinary arguments, which
collectively provide a strong case in support of CPUL and urban agriculture.
Literature Cited
bldgblog. 2009. http://bldgblog.blogspot.com/2009/06/london-yields-harvested.html
(accessed 22nd June 2009)
Brook Lyndhurst. 2008. London’s Food Sector: Greenhouse Gas Emissions.
Greater London Authority.
Caridad Cruz, M. and Sánchez Medina, R. 2003. Agriculture In The City: A Key to
Sustainability in Havana, Cuba. Ian Randle Publishers, Kingston.
Chisholm M. 1972 Chapter 2, Johann Heinrich von Thünen in Rural Settlement and Land
Use. Hutchinson & Co. pp 20-32
DEFRA. 2005. ED 56254, Issue 7, The Validity of Food Miles as an Indicator of
Sustainable Development. Final Report for DEFRA.
https://statistics.defra.gov.uk/esg/reports/foodmiles/final.pdf
Drechsel, P. and Kunze Eds, D. 2002. Waste composting for urban and peri-urban
agriculture: Closing the urban-rural nutrient cycle in sub Saharan Africa. CABI
publishing.
Egziabher, A.G. Lee-Smith, D. Maxwell, D.G. Memon, P.A. Mougeot, L.J.A. and Sawio,
C.J. 1994, Cities Feeding People: An Examination of Urban Agriculture in East Africa
International Development Research Centre, Ottawa.
European Commission. 2006. Environmental Impact of Products (EIPRO): Analysis of
the life cycle environmental impacts related to the final consumption of the EU – 25.
http://ec.europa.eu/environment/ipp/pdf/eipro_report.pdf
Koc, M. MacRae, R. Mougeot, L. J. A. and Welsh, J. Eds. 1999. For Hunger-proof Cities
Sustainable Urban Food Systems. International Development Research Centre,
Toronto.
Redwood, M. 2009. Agriculture in Urban Planning: Generating Livelihoods and Food.
Earthscan and the International Development Research Centre (IDRC)
Smit, J. Ratta, A. and Nasr, J. 1996. Urban Agriculture: Food, Jobs and
Sustainable Cities. UNDP, Habitat II Series.
Mougeot, L.J.A. 2005. AGROPOLIS: The Social, Political and Environmental
Dimensions of Urban Agriculture. Earthscan and the International Development
Research Centre (IDRC)
New Economics Foundation. 2001. (7/8/01) NEF survey (online) Available from:
http://www.neweconomics.org/gen/m6_i121_news.aspx (accessed 21/11/07)
van Veenhuizen, R. Ed. 2006. Cities Farming for the Future:
Urban Agriculture for Green and Productive Cities. International Institute of Rural
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Reconstruction and ETC – Urban Agriculture, Philippines.
Viljoen, A. 2005 Continuous Productive Urban Landscapes CPULs: designing urban
agriculture for sustainable cities. Architectural Press.
Viljoen, A. and Tardiveau, A. 1998. Sustainable Cities and Landscape Patterns.
Proceedings PLEA 98 Lisbon. 49-52.
Weber, C.H. and Scott Matthews, H. 2008. Food-Miles and the Relative Climate Impacts
of Food Choices in the United States. Envron. Sci. Technol, 42 (10), 3508-3513.
Figures
Fig.1 The CPUL concept. Green corridors provide a continuous network of productive
open space containing foot paths and cycle ways. Fields for urban agriculture and other
outdoor work and leisure activities are located within the network and serve adjacent
built-up areas. Image: Bohn&Viljoen Architects
Fig.2 Imagine a CPUL as an open urban space where intensive urban agriculture and
convivial outdoor places for residents compliment each other and are designed and built
into a coherent infrastructural landscape. Images: (left) Bohn&Viljoen Architects "Cuba:
Laboratory for urban agriculture" (2002) ,(right) Bohn&Viljoen Architects "The
Continuous Picnic" (2008).
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Fig.3 London LeisurEscape. A CPUL proposal connecting Tate Modern in central
London to East Croydon. The image shows how parts of parks may be given over to
urban agriculture and selected roads be “greened” without compromising other uses.
Image: Bohn&Viljoen Architects
Fig.4 The increasing number of exhibitions about urban agriculture and CPUL hosted by
arts and architecture institutions and galleries indicates how these subjects are entering
the international architectural and urban design discourse. The chart is not exhaustive, but
reflects trends evident to the authors in their practice. Image: Bohn&Viljoen Architects
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Fig. 5. Mikey Tomkins Edible Map for Surrey Street car park and environs in Croydon.
Walking the local neighbourhood with this Edible Map as a guide, the food-flâneur could
start to picture a very different landscape of vegetable plots, orchards or beehives. But the
Edible Map is more than a visualisation tool. It also attempts to investigate examples of
agricultural yields that the immediate area around Surrey Street could produce. This will
allow the itinerant urban resident or visitor to visualise what percentage of their current
vegetable diet could be supported using a locally grown food. Image Mikey Tomkins.
Fig. 6 The temporary conversion of Surrey Street CAR-park into a productive car-PARK.
This installation was created as part of Croydon’s eco-expo during October 2008.
Croydon Council’s Urban Design Team & Environment and Sustainability Team
advertised the event as follows: “Could this be a glimpse of Croydon's future? With fuel
prices soaring and the urgent need to cut food-miles to food-footsteps to halt global
warming, urban agriculture is making more sense each day”. Image Mikey Tomkins.
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