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Sustainability assessment of urban
rooftop farming using an
interdisciplinary approach
by
Esther Sanyé Mengual
A thesis submitted in fulfilment of the requirements for the
PhD degree in Environmental Sciences and Technology
June 2015
The present doctoral thesis has been developed thanks to a pre-doctoral fellowships awarded
by Esther Sanyé Mengual from the Spanish Ministerio de Ciencia e Innovación.
“The universe does not behave
according to our pre-conceived ideas.
It continues to surprise us.”
Stephen Hawking
The present thesis entitled Sustainability assessment of urban rooftop farming using an
interdisciplinary approach by Esther Sanyé Mengual has been carried out at the Institute of
Environmental Science and Technology (ICTA) at Universitat Autònoma de Barcelona (UAB)
Esther Sanyé Mengual
under the supervision of Dr. Joan Rieradevall, from the ICTA and the Department of Chemical
Engineering at the UAB, Dr. Juan Ignacio Montero, from the Environmental Horticulture Unit at
the Institute of Agriculture and Food Research and Technology (IRTA), and Dr. Jordi Oliver,
from Sostenipra research group (UAB) and Inèdit Innovació
Joan Rieradevall
Juan Ignacio Montero
Jordi Oliver
Bellaterra (Cerdanyola del Vallès), June 2015
Contents
List of tables
I
List of figures
III
Abbreviations
VI
Acknowledgments from a life cycle perspective
IX
Summary
XI
Resumen
XIV
Resum
XVII
Preface
XXI
Structure of the dissertation
XXV
PART I: Introduction and methodology
Chapter 1. Introduction and objectives
5
1.1. The food and the city: increased demand, increased awareness
5
1.2. Urban agriculture: a matter of food security, environmentalism and social needs
7
1.2.1. Concepts and nomenclature of urban agriculture (UA)
7
1.2.2. The multifunctional urban agriculture
12
1.3. Urban rooftop farming: making buildings fertile
14
1.3.1. Concepts and definitions of urban rooftop farming (URF)
15
1.3.2. Urban rooftop farming typologies
16
1.3.3. Current practices
17
1.3.4. Specific opportunities and challenges
21
1.4. Motivations of this dissertation
23
1.5. Objectives of this dissertation
24
Chapter 2. Methodological framework
27
2.1. Methods
27
2.1.1. Social science tools
29
2.1.2. Geographic tools
30
2.1.3. Environmental tools
30
2.1.4. Economic tools
40
2.2. Case studies
43
2.2.1. Rooftop greenhouse: the RTG-Lab
44
2.2.2. Community rooftop garden: Via Gandusio
46
2.2.3. Private open-air rooftop garden: Gran Via
47
PART II: Assessment of urban rooftop farming implementation
Chapter 3. Resolving differing stakeholder perceptions of urban rooftop farming in
Mediterranean cities: promoting food production as a driver for innovative forms
of urban agriculture
53
Abstract
53
3.1. Introduction
54
3.1.1. Urban Rooftop Farming (URF)
55
3.1.2. Research on Urban Rooftop Farming
56
3.1.3. Research objectives
57
3.2. Research design
57
3.2.1. Case study selection
57
3.2.2. UA stakeholders in Barcelona
58
3.2.3. Data and definitions
60
3.3. Data analysis: the potentials, opportunities, and constraints of expanding urban
agriculture in Barcelona
62
3.3.1. Differing perceptions and definitions of urban agriculture in contrast to
experiences on the ground
62
3.3.2. The difficulty of making URF as a municipal priority
64
3.3.3. Current barriers to and opportunities for URF: coupling sustainable local
production with technological complexity
67
3.4. Discussion
72
3.4.1. Contrasts in the definition and values attributed to UA in Barcelona
73
3.4.2. Environmental, social, and economic barriers and opportunities for URF
74
3.5. Conclusions and future actions
75
Chapter 4. Integrating horticulture into cities: A guide for assessing the
implementation potential of Rooftop Greenhouses (RTGs) in industrial and
logistics parks
79
Abstract
79
4.1. Introduction
80
4.1.1. Urban agriculture on buildings: Rooftop greenhouses
81
4.1.2. Goal and scope
82
4.2. Methods: A guide for assessing RTG implementation
83
4.2.1. Guide overview and scope
83
4.3. Methods: Application to a case study
91
4.3.1. The Zona Franca park (Barcelona)
91
4.3.2. Local data
92
4.4. Results of the case study
92
4.4.1. Step 1: Criteria definition in Zona Franca
92
4.4.2. Step 2: Rooftop potential for implementing RTGs in Zona Franca
93
4.4.3. Step 3: Production, self-sufficiency and environmental indicators
96
4.5. Discussion
96
4.5.1. Guide design and application outcomes
96
4.5.2. Future criteria and indicators
97
4.6. Conclusions
100
Chapter 5. Urban horticulture in retail parks: environmental assessment of the
potential implementation of Rooftop Greenhouses (RTGs) in European and South
American cities
103
Abstract
103
5.1. Introduction
104
5.1.1. An industrial ecology approach: integrated Rooftop Greenhouses (i-RTGs)
104
5.1.2. Retail parks as potential location for RTGs
105
5.1.3. Objectives
106
5.2. Methods
107
5.2.1. Study areas
107
5.2.2. Assessing the potential for implementing RTGs in the selected retail parks
111
5.3. Results and discussion
114
5.3.1. Results of implementing of RTGs on retail parks
114
5.3.2. Geographic variability and RTG implementation
118
5.3.3. Influential parameters on potential RTG implementation and benefits
119
5.4. Conclusions
120
PART III: Assessment of rooftop greenhouses
Chapter 6. An environmental and economic life cycle assessment of rooftop
greenhouse (RTG) implementation in Barcelona, Spain
127
Abstract
127
6.1. Introduction
128
6.1.1. RTG benefits
129
6.1.2. Objectives
130
6.2. The ICTA-ICP building rooftop greenhouse
131
6.3. Life Cycle Assessment (LCA and LCC)
132
6.3.1. Goal and scope
132
6.3.2 Life cycle inventory
133
6.3.3 Sensitivity analysis
136
6.3.4 Environmental impact and economic assessment
137
6.4. Results and discussion
138
6.4.1. Greenhouse structure assessment
138
6.4.2. Assessment at the production point: cradle-to-farm gate perspective
140
6.4.3. Assessment at the consumption point: a cradle-to-consumer perspective
141
6.4.4. Sensitivity analysis: crop yield variability
143
6.4.5. Sensitivity analysis: crop yield and distance to conventional production site
145
6.5. Conclusions
146
6.5.1. RTGs contribution to urban agriculture and sustainability: economic and
social aspects
147
6.5.2. Limitations of the study and further research
148
Chapter 7. Environmental analysis of the logistics of agricultural products from
rooftop greenhouses in Mediterranean urban areas
151
Abstract
151
7.1. Introduction
152
7.1.1. Environmental studies in agri-food distribution systems
152
7.1.2. Green and farming systems integrated in buildings of the cities
153
7.1.3. Goal and objectives
155
7.2. Materials and methods
155
7.2.1. Environmental tools: Life Cycle Assessment (LCA)
155
7.2.2. Life Cycle Inventory (LCI)
156
7.3. Results and discussion
160
7.3.1. Environmental impact assessment
160
7.3.2. Cumulative Energy Demand (CED)
161
7.3.3. Scenarios comparison
162
7.3.4. Reusable packaging option for Scenario CLS
163
7.3.5. Short-term implementation analysis: Urban scale impact
163
7.3.6. Economical, business models and building type approaches
164
7.4. Conclusions
164
PART IV: Assessment of community and private open-air rooftop farming
Chapter 8. Environmental and economic assessment of multiple cultivation
techniques and crops in open-air community rooftop farming in Bologna (Italy)
171
Abstract
171
8.1. Introduction
172
8.2. Material and methods
173
8.2.1. Experimental crops
173
8.2.2. Life Cycle Assessment
174
8.3. Results and discussion
178
8.3.1. Comparing cultivation techniques for leafy vegetables
179
8.3.2. Soil production of fruit vegetables
183
8.3.3. Cultivation systems design: sensitivity assessment of availability of re-used
materials and use intensity of the garden
183
8.4. Conclusions
184
Chapter 9. Revisiting the environmental assessment of local food: Relevance of
market data and seasonality. A case study on rooftop home-grown food in
Barcelona (Spain).
189
Abstract
189
9.1. Introduction
190
9.2. Methods
191
9.2.1. Experimental crops
191
9.2.2. Life Cycle Assessment
191
9.3. Results and discussion
193
9.3.1. Environmental burdens of rooftop home-grown food
193
9.3.2. Home-grown food from a local production perspective
198
9.4. Conclusions
201
PART V: General conclusions and further research
Chapter 10. Conclusions and contributions
207
10.1. Answering the research questions
207
10.2. Contributions of this dissertation
215
Chapter 11. Future research and strategies
219
11.1. Assessing the perceptions around urban rooftop farming
219
11.2. Quantifying the potential of urban rooftop farming
220
11.3. Sustainability assessment of urban rooftop farming
332
References
223
Appendixes
241
Appendix 1. Supporting information for chapter 5
243
Appendix 2. Supporting information for chapter 6
262
Appendix 3. Supporting information for chapter 9
279
I
List of tables
Table 1.1. Common and recent definitions of urban agriculture
9
Table 1.2. Specifications of common urban agriculture definitions
10
Table 2.1. LCI data sources used in this dissertation
35
Table 2.2. LCIA methods and indicators used in this dissertation
36
Table 2.3. LCIA indicators of the CML-IA 2001 method
36
Table 2.4. LCIA indicators of the ReCiPe method
38
Table 2.5. LCIA indicator of Cumulative Energy Demand
40
Table 2.6. Economic indicators used in this dissertation
42
Table 3.1. Interview participants: stakeholders’ group, stakeholders, number of
respondents and main relation to urban rooftop farming
61
Table 3.2. Barriers and opportunities around Rooftop Farming (RF) and Rooftop
Greenhouses (RTG), and comparison with previous studies on URF
69
Table 4.1. Description of the panel of experts: Expert, area of expertise, relation to RTG
and involvement in criteria definition [criteria areas: planning (P), agriculture (A),
economic (E), legal (L) and technical (T)]
84
Table 4.2. Definition of technical feasibility scenarios, according to the type of roof and
its material
86
Table 4.3. Variables of the rooftop database, sources, specific indications and relation to
the criteria
87
Table 4.4. Identification of technical and economic feasibility in the GIS process,
according to combination of variables
88
Table 4.5. Potential implementation area, tomato production, GHG emissions and
energy savings (compared to conventional agricultural products) and self-sufficiency
potential (times the yearly average tomato intake is satisfied), by feasibility scenario
(short-, mid- and long-term)
96
Table 5.1. Climatic and socio-demographic conditions, by study area (country and
municipality level)
108
Table 5.2. Characteristics of the selected retail parks and land use distribution, per case
study
109
Table 5.3. Characteristics of the flow exchange and crop outputs, by scenario
112
Table 5.4. Input data to calculate production and self-supply indicators, by case study
and country
113
Table 5.5. Environmental impact factors for indicators calculation (Step 3), by case
study and country
115
Table 5.6. RTG potential, results for Scenario A (isolated RTG), by case study and
country (Indicators were not assessed for Colombia due to the low short-term RTG
potential obtained)
117
Table 5.7. Results for Scenario B (integrated RTG), considering a 100% efficiency, by
case study and country
117
Table 5.8. Results for Rainwater Harvesting (RWH) improvement, by case study and
country
118
II
Table 5.9. Most preferable geographic selection for RTG implementation according to
different criteria, results for Scenario A (isolated RTGs) and Scenario B (i-RTG), by
country
119
Table 6.1. Characteristics of current RTG experiences and projects
129
Table 6.2. Main potential environmental (E), economic (Ec) and social (S) benefits of
Rooftop Greenhouses (RTGs), by scale (global, local, building-greenhouse system and
product). Benefits are divided into two categories: general benefits of local food
production (●) and specific benefits of RTGs (•)
130
Table 6.3. Environmental impact assessment and economic cost of the RTG structure, by
life cycle stage, and comparison with the multi-tunnel structure, for a functional unit of 1
m2 of a greenhouse structure for a timeframe of 1 year
139
Table 6.4. Environmental and economic indicators of the tomato production and
comparison with the production in a multi-tunnel system, for a functional unit of 1 kg of
tomato at the farm gate, by life cycle stage
141
Table 6.5. Environmental and economic indicators of the tomato supply chain and
comparison with the conventional supply-chain (multi-tunnel), for a functional unit of 1
kg of tomato at the consumer, by life cycle stage
142
Table 7.1. Specific global data sources used in the LCIA
156
Table 7.2. Life Cycle Inventory data for Scenario CLS and Scenario RTG, by stages,
elements and flows. All units refer to the functional unit (1kg of tomato delivered to
customer)
160
Table 7.3. Life Cycle Assessment (LCA) of Scenario CLS and Scenario RTG, RTG/CLS
Ratio, savings per functional unit and per ha, by impact factor category and life cycle
stage
161
Table 8.1. LCI data for modified NFT, floating and soil, for 1 m2 and a lifespan of 1
year. Crop inputs are defined per year, crop or day, depending on cultivation systems.
Water and electricity consumption for irrigation is shown per day since crop cycles are
different and water demand depends on crop
175
Table 8.2. Environmental and economic indicators for modified NFT, floating and soil
production. Results correspond to the functional unit of 1 kg of product per crop period.
Indicators are Global Warming (GW, kg CO2 eq), Water depletion (WD, m3),
Cumulative Energy Demand (CED, MJ), Human Toxicity (HT, kg 1,4-DB eq.) and
Total cost (TC, €)
179
Table 9.1. Crop yields and irrigation requirements in the experimental trials
191
III
List of figures
Figure 1.1. Evolution and prevision of the percentage of urban population (%) in the
world and main regions (1950-2050)
5
Figure 1.2. Food implications of urban expansion
6
Figure 1.3. Revitalization of local production
7
Figure 1.4. Concepts use in the definitions and nomenclature of urban agriculture
12
Figure 1.5. UA functions along UA development
13
Figure 1.6. Role of urban rooftop farming within urban agriculture and local food
systems
15
Figure 1.7. Typologies and nomenclatures for urban agriculture on buildings and rooftop
farming
16
Figure 1.8. Urban rooftop farming typologies
17
Figure 1.9. Rooftop garden of Cloud 9 (Philadelphia, USA)
19
Figure 1.10. Demonstrative pilots of Urban Farmers and ECF Farmsystems
21
Figure 2.1. Overview of the interdisciplinary methodological framework of this
dissertation
27
Figure 2.2. Overview of the methods used in each chapter of this dissertation
28
Figure 2.3. Qualitative research process through semi-structured interviews
29
Figure 2.4. Geographic information systems (GIS) processes for generating the rooftop
database to compile data of urban planning pieces (e.g., retail parks)
30
Figure 2.5. Phases of the life cycle assessment method
31
Figure 2.6. Phases of the life cycle costing method
40
Figure 2.7. Location of the case studies under assessment
43
Figure 2.8. Characteristics and specifications of the three case studies
44
Figure 2.9. The RTG-Lab: (a) the ICTA-ICP building in the UAB campus, (b) the
greenhouse structure of the RTG-Lab, (c) Lettuce crop in December 2014, and (d) view
of the RTG-Lab from the interior atrium of the rooftop
45
Figure 2.10. The i-RTG concept behind the RTG-Lab: the greenhouse uses residual
flows (energy, gas) from the building and endogenous resources collected in the roof of
the building (rainwater)
46
Figure 2.11. The community rooftop garden of Via Gandusio combines crops with
recreational spaces (a), uses different cultivation techniques such as floating hydroponics
(b) and is a Do-It-Yourself (DIY) garden (c)
47
Figure 2.12. The private open-air rooftop garden of Gran Via is placed in Eixample (a);
a wooden structure (b) delimits the soil-less production area for multiple crops (c),
which uses fertirrigation (d)
48
Figure 3.1. Forms of periurban (situated in the urban fringe) and urban farming (placed
in the city). Urban Rooftop Farming can take form of Rooftop Farming (left) or Rooftop
Greenhouse (right) (own elaboration)
56
Figure 3.2. Map of stakeholders involved in the different stages of the potential
implementation of Urban Rooftop Farming (own elaboration)
60
Figure 3.3. Stakeholders’ position on conceptualizing UA
63
Figure 4.1. Guide diagram: steps and tools followed during the study
83
Figure 4.2. Guide specifications, step by step (Criteria can be Quantitative (QT) or
Qualitative (QL), regarding the type of data needed for validation; and External (E) or
90
IV
Internal (I), if the criteria depend on external conditions (e.g., law, third parts) or can be
decided internally (e.g., economic outputs and RTG dimension))
Figure 4.3. Case study: The Zona Franca park is located in the south of Barcelona
(Catalonia, Spain), a former deltaic zone between the port, the airport and the
Agricultural Park of Baix Llobregat
91
Figure 4.4. Criteria definition for the case study – Rooftop requirements for
implementing RTGs in Zona Franca Park (Barcelona, Spain)
93
Figure 4.5. Potential implementation areas for RTGs in Zona Franca park, and
characterization of short-term implementation buildings, by building use and year of
construction
94
Figure 4.6. Short-, mid- and long-term implementation of RTGs in the Zona Franca
park, according to the established criteria (Scale 1:20.000)
95
Figure 5.1. Integrated Rooftop Greenhouses (i-RTGs) concept: energy [E], water [W]
and gases [G] exchange to optimize both the function of the building (building use) and
the greenhouse (local food production [F]). Based on Cerón-Palma et al. (2012)
105
Figure 5.2. Cultivation parameters for scenario B, CO2 savings and energy savings per
kg of tomato, by case study and heat energy efficiency (%)
116
Figure 6.1. Layout of the RTG-Lab, situation in the ICTA-ICP building, and rooftop
greenhouse dimensions (The RTG elements are detailed in Appendix 2.1)
131
Figure 6.2. System boundaries and life cycle stages of the three assessments: greenhouse
structure (cradle-to-grave), production point (cradle-to- farm gate), and consumption
point (cradle-to-consumer)
132
Figure 6.3. Sensitivity analysis of the environmental indicators related to the crop yield
variability. Solid line indicates the indicator value, and the dotted line indicates the
indicator value for the reference system: tomato produced in a multi-tunnel greenhouse
(constant crop yield of 16.5 kg·m-2)
144
Figure 6.4. Sensitivity analysis of the minimum tomato price to cover RTG production
costs and comparison to current tomato prices in the market, by crop yield
145
Figure 6.5. Environmental and economic indicators for 1 kg tomato from a conventional
supply-chain at the consumption point by transported distance, and comparison with the
value of 1 kg of tomato from local RTGs with a low yield (10 kg·m-2), reference yield
(25 kg·m-2), and high yield (55 kg·m-2)
146
Figure 7.1. Rooftop Greenhouse systems, as a closed cycle for production and
consumption of agricultural products in the cities
154
Figure 7.2. System description and boundaries for Scenario CLS (Current Linear
System) of the logistics of tomato: from Almeria (production site) to Barcelona
(consumption site) through a distribution centre
157
Figure 7.3. System description and boundaries for Scenario RTG (Rooftop Greenhouse)
in Barcelona, as production and consumption site
159
Figure 7.4. Scenarios comparison: Current Linear System (CLS), Current Linear System
with a reusable packaging option (CLS-R) and Rooftop Greenhouse system (RTG)
163
Figure 8.1. The experiment considered three different cultivation types for leafy
vegetables: floating in wooden containers (1a), modified NFT in PVC pipes (1b) and
soil in wooden containers (1c). Experiments were performed between 2012 and 2014
(2). The six crops followed different cycles: spring-summer, summer, autumn or
autumn-winter (2)
176
Figure 8.2. Environmental and economic burdens of soil, NFT and floating production
for leafy vegetables: lettuce. The indicators used are Global Warming (GW, kg CO2 eq),
Water depletion (WD, m3), Cumulative Energy Demand (CED, MJ), Human Toxicity
(HT, kg 1,4-DB eq.) and Total cost (TC, €)
181
V
Figure 8.3. Environmental and economic burdens of soil production for leafy and fruit
vegetables. The indicators used are Global Warming (GW, kg CO2 eq), Water depletion
(WD, m3), Cumulative Energy Demand (CED, MJ), Human Toxicity (HT, kg 1,4-DB
eq.) and Total cost (TC, €)
182
Figure 9.1. System boundaries of the home-grown production system
192
Figure 9.2. Global warming, water depletion and Recipe-norm value of the home-grown
crops for a functional unit of 1 kg and a 1 kcal
194
Figure 9.3. Distribution of the environmental burdens of home-grown crops among life
cycle stages
195
Figure 9.4.Comparison of the global warming impact 1 kg of tomato and lettuce from
private rooftop farming (PRF) with community rooftop farming (CRF), rooftop
greenhouses (RTG) and conventional production (minimum and maximum)
196
Figure 9.5.Sensitivity assessment to the percentage of non-commercial crop yield.
Comparison of the global warming impact 1 kg of tomato and lettuce from private
rooftop farming (PRF) with community rooftop farming (CRF), rooftop greenhouses
(RTG) and conventional production (minimum and maximum)
197
Figure 9.6. Sensitivity assessment of plant density for leafy and root vegetables for
global warming impact (Lettuce 3 and cabbage were excluded for a better representation
of results)
198
Figure 9.7. Avoided global warming impact due to avoided food-miles for a single case
study, annual average and monthly average. The harvesting period is highlighted
199
Figure 10.1. Stakeholders’ position on conceptualizing UA and supporting URF in
Barcelona, and expected trends through demonstration and dissemination activities
208
Figure 10.2. Identification of suitable areas for implementing rooftop greenhouses
209
Figure 10.3. Comparison of the global warming impact of lettuce (a) and tomato (b) in
rooftop greenhouses (RTG), community rooftop farming (CRF), private rooftop farming
(PRF) and conventional production, and potential trends
212
Figure 10.4. (a) Eco-efficiency of crop production in rooftop greenhouses and
community rooftop farming and (b) Comparison of the global warming impact of crop
production in rooftop greenhouses (RTG), community rooftop farming (CRF) and
private rooftop farming (PRF)
213
VI
Abbreviations
1.4 DB eq. 1.4 dichlorobenzene equivalent emissions
ADP Abiotic depletion potential
ALO Agricultural land occupation
AP Acidification potential
CED Cumulative energy demand
CLS Current Linear System
C2H4 eq. Ethylene equivalent emissions
CFC-11 eq. Trichlorofluoromethane equivalent emissions
CML Institute of Environmental Sciences (Leiden)
CO2 Carbon dioxide
CO2 eq. Carbon dioxide equivalent emissions
CSA Community-supported agriculture
CTE Spanish technical code of edification
DIY Do-it-yourself
EEA European Environment Agency
ELCD European Reference Life Cycle Database
EP Eutrophication potential
FAO Food and agriculture organization of the United Nations
FD Fossil depletion
FE Freshwater eutrophication
FET Freshwater ecotoxicity
FU Functional unit
GHG Greenhouse gas emissions
GIS Geographic Information System
GR Green roof
GWP Global warming potential
HDPE High density polyethylene
HTP Human toxicity potential
ICTA Institute of Environmental Science and Technology (UAB)
ILCD International Reference Life Cycle Data System
IPCC Intergovernmental Panel on Climate Change
IR Ionising radiation
IRTA Institute of Agriculture and Food Research and Technology
i-RTG Integrated rooftop greenhouse
ISO International Organization for Standardization
VII
LCA Life cycle assessment
LCC Life cycle costing
LCI Life Cycle Inventory
LCIA Life Cycle Impact Assessment
LDPE Light density polyethylene
ME Marine eutrophication
MET Marine ecotoxicity
MJ eq. Mega joules equivalent
MRD Mineral resources depletion
NFT Nutrient film technique
NLT Natural land transformation
ODP Ozone layer depletion potential
PMF Particular matter formation
POF Photochemical oxidant formation
PO4-3 eq. Phosphate equivalent emissions
PP Polypropylene
PVC Polyvinyl chloride
RF Rooftop farming
RTG Rooftop greenhouse
Sb eq. Antimony equivalent emissions
SETAC Society of Environmental Toxicology and Chemistry
SO2 eq. Sulphur dioxide equivalent emissions
Sostenipra Sustainability and Environmental Prevention research group
TA Terrestrial acidification
TC Total cost
TET Terrestrial ecotoxicity
TP Total profit
UA Urban agriculture
UAB Universitat Autònoma de Barcelona
ULO Urban land occupation
UNEP United Nations Environmental Program
URF Urban rooftop farming
VF Vertical farming
WD Water depletion
IX
Acknowledgments from a life cycle
perspective
To my production stage.
First and foremost I would like to thank my supervisors who gave me the opportunity to develop
this thesis. Joan, Juan Ignacio i Jordi, gràcies per la confiança que sempre heu dipositat en mi, la
paciència, els reptes i la vostra dedicació.
I would also like to thank Isabelle Anguelovski, who supervised one of the research studies of
this thesis, for sharing her knowledge and research interests, and for introducing me to the
qualitative research world.
Last but not least I would like to thank Xavier, the chief of the Sostenipra research group, for his
endless support.
To my transport stage.
Giorgio, Francesco, Daniela, Rabab, Giuseppina, Silvia, Ivan and Niccolò thanks a lot for your
support, knowledge exchange and guidance during my research stay in Bologna. Grazie mille per
mostrarmi la vostra agricoltura urbana.
To my use phase.
Thanks to all the colleagues of the research group Sostenipra, who created an inspiring,
comfortable and funny work environment.
Al Pere i el David, que han fet del Z/139 un paradís de la investigació vertical.
A la Júlia, la Katherine, la Sara, na Margot, l’Anna i l’Elena, gràcies pel companyerisme
aromatitzat de cafés, viatges, sopars, esport i amistat.
Als amics del màster, on aquesta tesis va començar: David, Eli, Natalia, Sabo, Violeta i Zora.
Ich möchte auch gern Kathrin bedanken, die nicht nur wissenschaftlich sondern auch persönlich
zu dieser Dissertation beigetragen hat.
To all the colleagues of the Institute of Environmental Science and Technology (ICTA), with
whom I have shared coffees, discussions, seminars, councils and Meet&Eat’s.
To my cradle.
Gràcies, com sempre, Santi, Carme, Xavi i Mònica per exigir-me, recolzar-me i estimar-me
perennement.
A la família i als amics, els de sempre i els nouvinguts, els d’aquí i els d’allà: gràcies, gracias,
thanks, danke, grazie, obrigada.
Als meus runners, per fer-me sentir valenta davant de cada repte.
Al Victor, gràcies pel teu amor i suport infinit.
A vosaltres, Nil i Eric, gràcies per inspirar-me cada dia.
XI
Summary
Urban agriculture (UA) is blooming around cities of the developed world as a response to the
increasing urban population, the growing environmental awareness of the industrial food system
and the need of addressing social gaps. These new local food systems aims to develop sustainable
pathways that re-establish the relations between producers and consumers while boosting local
economies and minimising food-miles. Furthermore, the recent financial crisis and the spread of
vacant lands have revitalised UA projects, not only at the self-managed level (i.e., community,
private) but also at the commercial one. In particular, UA practitioners and farmers have found in
the roofs of the city a vacant space for placing food production leading to the development of
urban rooftop farming (URF). Consequently, rooftop farms, rooftop greenhouses and rooftop
gardens have colonized buildings. Nevertheless, specific assessment of the potential
implementation and the sustainability performance of different URF forms, cultivation
techniques and crops, are necessary.
To address these gaps, this dissertation seeks to answer two main research questions “What is the
potential of urban rooftop farming in qualitative and quantitative terms?” and “What are the
environmental impacts and economic costs of urban rooftop farming systems?”. With this goal, a
methodological framework is proposed and three case studies are analysed, which are pilot
experiences of different forms of urban rooftop farming.
Food production in cities is a complex system that involves several stakeholders, has multiple
scales and affects the three dimensions of sustainability (environment, economy, society). Thus, a
comprehensive assessment might combine different disciplines to approach such topic. This
dissertation follows an interdisciplinary framework that includes (a) qualitative research, to
deepen in the perceptions of the different stakeholders related to UA and URF; (b) geographic
information systems (GIS), to identify and quantify the available and feasible roofs for
implementing rooftop farming; (c) life cycle assessment (LCA), to quantify the environmental
burdens of rooftop farming systems; and (d) life cycle costing (LCC), to quantify the economic
costs of URF. This framework enables to approach URF from the city scale (e.g., planning
perspective) to the system scale (e.g., food products).
A stakeholders’ analysis through qualitative interviews unravelled that the development of
rooftop farming in Barcelona is currently facing some limitations mainly due to a constrained
support from some stakeholders. The main barriers to supporting urban rooftop farming are the
lack of a common definition of urban agriculture, the specific origin of UA in Barcelona and its
urban morphology and the limited social acceptance of some food production techniques.
However, stakeholders valued the sustainability benefits (i.e., environmental, economic and
social) linked to urban rooftop farming, particularly in the context of the development of a local
green economy.
In quantitative terms, urban rooftop farming shows a great potential for increasing the current
local production and reducing the environmental burdens of the city’s “foodprint”. A
multicriteria set is needed to identify the technically and economically feasible roofs for the
implementation of commercial rooftop greenhouses (RTGs) (i.e., availability of space, sunlight,
resistance and slope, and legal and planning requirements). Industrial parks and retail parks are
here analysed and compared. Retail parks show a greater short-term potential (53-98%) than
industrial parks (8%) due to a more resistant architecture, although industrial parks are of great
interest for large-scale URF implementation plans due their extensive area. The potential
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implementation of integrated rooftop greenhouses (i-RTGs) which take advantage from the
residual flows from the building (i.e., residual heat and CO2, rainwater) is an innovative way of
rooftop farming. Benefits of i-RTGs vary in warm regions (e.g., Mediterranean), where unheated
production can be performed, and cold regions (e.g., The Netherlands), where greenhouses
requires heating. The preference between regions for implementing i-RTGs is based, thus, on
whether the goal is increasing food production (i.e., higher crop yields in warm areas) or
reducing environmental burdens (i.e., substitution of energy consumption for heating in cold
areas).
From a life cycle perspective, the rooftop greenhouse lab (RTG-Lab) (Bellaterra, Spain), the
community rooftop garden in Via Gandusio (Bologna, Italy) and a private rooftop garden in the
city centre of Barcelona (Spain) are analysed. URF can become an environmentally-friendly
option for further develop urban agriculture and local food systems in cities. However, results
depend on the type of rooftop farming, the crop and the growing system. The pilot projects
assessed in this dissertation unravelled some trends and drawn some recommendations for the
development of rooftop farming.
Regarding food production in rooftop greenhouses, the greenhouse structure plays a major role in
the environmental impacts and the economic costs (41.0-79.5%), as in conventional agriculture.
Although the greenhouse structure of RTGs have greater environmental impacts than multi-
tunnel greenhouses (between 17 and 75 %), tomatoes from an RTG in Barcelona are more
environmentally-friendly not only at the production point (between 9 and 26% lower) but also at
the consumer (between 33 and 42 % lower). Although tomato production results in 21% higher
cost than conventional tomatoes, the consideration of the entire supply-chain highlights the
competitiveness of RTGs as local food systems.
Regarding rooftop gardens, crop inputs are the most contributing elements. The community
garden employed re-used elements in their design (e.g., pallets) and irrigation was the most
contributing stage (60-75%). In the private garden, fertirrigation (between 33 and 46%) and the
structure of the garden (between 28 and 35%) (i.e., made of raw wood) were the main
contributors. Rainwater harvesting for supplying the water demand of the crops and the
integration of re-used elements in the cultivation structures might enhance the sustainability of
gardens by decreasing the resources consumption of the system.
The comparison of different growing techniques in the community garden highlighted the higher
eco-efficiency of soil production, when compared to hydroponic techniques (i.e., nutrient film
technique, floating system). The assessment of different crops showed the same pattern in the
community and private rooftop gardens. Fruit vegetables have lower environmental burdens than
leafy vegetables since they yield better. However, these rooftop farming forms perform
polyculture, the design of which is commonly oriented to fruit vegetables, resulting in a low plant
density for leafy vegetables. An improved design, which divides the garden, could then improve
and balance these divergences among crop types.
This dissertation contributes to the comprehension of the development process of competitive
and sustainable urban agriculture and urban rooftop farming in cities of developed countries by
developing methodological aspects and generating new data on the topic. The methods and
results advance in the knowledge and understanding of rooftop farming, urban agriculture and
local food in order to support decision-making processes in the design and development of future
rooftop farming projects. Future research and strategies might focus on assessing the perceptions
of stakeholders in other case studies, while focusing on specific aspects such as social
acceptance; quantifying the potential of rooftop farming in other urban areas and cities; and
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assess more case studies and URF forms from a sustainability perspective, paying particular
attention to the integration of the social aspects.
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Resumen
La agricultura urbana está floreciendo en las ciudades de países desarrollados como respuesta al
aumento de población urbana, la creciente concienciación ambiental sobre el sistema industrial
alimentario i la necesidad de resolver ciertas problemáticas sociales. Estos nuevos sistemas de
producción local de alimentos tienen como objetivo desarrollar modelos sostenibles que
restablezcan las relaciones entre productores y consumidores, a la vez que impulsan las
economías locales y reducen el transporte asociado a los alimentos. Por otro lado, la reciente
crisis económica y la expansión de espacios abandonados en las ciudades ha revitalizado los
proyectos de agricultura urbana, no sólo a nivel de autogestión (comunitario, privado) sino
también a nivel comercial. En particular, los nuevos profesionales y agricultores urbanos han
encontrado en las terrazas y cubiertas de la ciudad un espacio vacío donde situar la producción de
alimentos, dando lugar al desarrollo de la agricultura urbana en cubierta. Consecuentemente,
granjas, invernaderos y jardines han colonizado las cubiertas de los edificios. No obstante, una
evaluación específica de la potencial implementación y el perfil de sostenibilidad de las
diferentes formas de agricultura urbana en cubierta.
En este contexto, la presente tesis trata de responder a dos preguntas de investigación: “¿Cuál es
el potencial de la agricultura urbana en cubierta en términos cualitativos y cuantitativos?” y
“¿Cuáles son los impactos ambientales y los costes económicos de las diferentes formas de
agricultura urbana en cubierta?”. Con este objetivo, se propone un marco metodológico y se
analizan tres casos de estudio que son pruebas piloto de diferentes formas de agricultura urbana
en cubierta.
La producción de alimentos en ciudades es un sistema complejo que implica varios actores
sociales, tiene múltiples escalas y afecta a las tres dimensiones de la sostenibilidad (medio
ambiente, economía y sociedad). Por lo tanto, una evaluación exhaustiva debe combinar varias
disciplinas para abordar estos sistemas. Esta tesis sigue un marco interdisciplinar que incluye (a)
investigación cualitativa, para profundizar en las percepciones de los diferentes actores sociales
relacionados con la agricultura urbana y la agricultura urbana en cubierta; (b) sistemas de
información geográfica (SIG), para identificar y cuantificar las cubiertas disponibles y viables
para la implementación de la agricultura en cubierta; (c) el análisis de ciclo de vida (ACV), para
la cuantificación de los impactos ambientales de los sistemas de agricultura en cubierta; y (d) el
análisis de costes de ciclo de vida (ACCV), para cuantificar los costes económicos de la
agricultura en cubierta. Este marco metodológico permite evaluar la agricultura urbana en
cubierta des de la escala ciudad (por ejemplo, des de la perspectiva de planeamiento) a la escala
sistema (por ejemplo, producto alimentario).
Un análisis de las percepciones de los distintos actores sociales a través de entrevistas cualitativas
desveló que el desarrollo de la agricultura urbana en cubierta en Barcelona se enfrenta
actualmente a ciertas limitaciones, principalmente a causa de la falta de apoyo de algunos
actores. Las principales barreras son la falta de una definición común de agricultura urbana, el
origen específico de la agricultura urbana en Barcelona y su morfología urbana, y la limitada
aceptación social de algunas técnicas de cultivo. No obstante, los actores sociales valoran los
beneficios sostenibles (ambientales, económicos y sociales) vinculados a la agricultura urbana en
cubierta, en particular en el contexto del desarrollo de una economía verde local.
En términos cuantitativos, la agricultura urbana en cubierta muestra un gran potencial para
aumentar la actual producción local de alimentos y reducir las cargas ambientales del flujo de
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alimentos de la ciudad. Un conjunto de criterios es necesario para identificar las cubiertas técnica
y económicamente viables para la implementación de invernaderos en cubierta comerciales: la
disponibilidad de espacio, la luz solar, la resistencia y la pendiente, y los requisitos legales y de
planificación. Los parques comerciales muestran un mayor potencial a corto plazo (53 a 98%)
que los parques industriales (8%), debido a una arquitectura más resistente, aunque los parques
industriales son de gran interés para un plan de implementación de agricultura urbana en cubierta
a gran escala debido a su extensa área. La potencial implementación de invernaderos en cubierta
integrados, los cuales aprovechan los flujos residuales del edificio (es decir, el calor y CO2
residuales, agua de lluvia), es una forma innovadora de agricultura en cubierta. Los beneficios de
estos sistemas varían en las regiones cálidas (por ejemplo, el Mediterráneo), donde la producción
pasiva en invernaderos se puede realizar, y las regiones frías (por ejemplo, Países Bajos), donde
los invernaderos requieren calefacción. La preferencia entre las regiones para la implementación
de invernaderos integrados se basa, por tanto, en si el objetivo es aumentar la producción de
alimentos (en zonas cálidas, la productividad puede aumentar) o reducir las cargas ambientales
(es decir, en zonas frías, el consumo de energía para calefacción se puede sustituir).
Desde una perspectiva de ciclo de vida, la tesis analiza el invernadero en cubierta del Rooftop
Greenhouse lab (RTG-Lab) (Bellaterra, España), el jardín comunitario en cubierta de Vía
Gandusio (Bolonia, Italia) y un jardín privado en cubierta en el centro de Barcelona (España). La
agricultura urbana en cubierta puede ser una opción sostenible para desarrollar la agricultura
urbana y los sistemas alimentarios locales en las ciudades. Sin embargo, los resultados dependen
de la forma de agricultura en cubierta, el tipo de cultivo y el sistema de cultivo. Los proyectos
piloto evaluados en esta tesis muestran unas primeras tendencias, que permiten listar
recomendaciones para el desarrollo de la agricultura en cubierta.
En cuanto a la producción de alimentos en invernaderos en cubierta, el propio invernadero es el
principal elemento en los impactos ambientales (41,0-79,5%) y el coste económico (64%), como
en la agricultura convencional. Aunque un invernadero en cubierta tiene mayores impactos
ambientales (entre 17 y 75%) que un invernadero convencional, la producción de tomate en el
RTG-Lab en Barcelona resultó tener menores impactos ambientales que un invernadero
convencional, no sólo en finalizar la producción (entre 9 y 26% menor) sino también cuando
llega al consumidor (entre 33 y 42% menor). En cuanto al coste económico, pese a que la
producción de tomates en cubierta resulta un 21% más cara, cuando se considera toda la cadena
de suministro convencional, se pone de manifiesto la competitividad de los invernaderos en
cubierta como sistemas de producción local.
En cuanto a los jardines en cubierta, los consumos del cultivo (es decir, agua, fertilizantes,
energía) tienen el papel más relevante. El jardín comunitario en cubierta emplea elementos
reutilizados en su diseño (por ejemplo, pallets) y el riego fue la etapa más impactante (60-75%).
En el jardín privado en cubierta, la fertirrigación (entre 33 y 46%) y la estructura del jardín (entre
el 28 y el 35%) fueron los principales contribuyentes al impacto ambiental. La recolección de
agua de lluvia para el suministro de la demanda de agua de los cultivos y la integración de
elementos reutilizados en las estructuras de cultivo podrían aumentar la sostenibilidad de los
jardines al disminuir el consumo de recursos del sistema.
La comparación de las diferentes técnicas de cultivo en el caso de estudio comunitario destacó la
mayor eco-eficiencia de la producción en suelo, en comparación con las técnicas hidropónicas (es
decir, la técnica de película de nutrientes, sistema flotante). La evaluación de los diferentes
cultivos mostró el mismo patrón en los jardines en cubierta comunitario y privado. Los cultivos
con fruto (por ejemplo, el tomate) tienen unos impactos ambientales más bajos que los cultivos
de hoja (por ejemplo, la lechuga), ya que las productividades son más altas. Sin embargo, estas
XVI
formas de agricultura en cubierta realizan policultivo, cuyo diseño está habitualmente orientado a
las hortalizas de fruto dando lugar a una densidad de plantación más baja de la que se puede
realizar para cultivos de hoja. Un diseño mejorado, que divide el jardín según cultivos, podría
mejorar y equilibrar estas divergencias entre los tipos de cultivo.
Esta tesis contribuye a la comprensión del proceso de desarrollo de una agricultura urbana y
agricultura urbana en cubierta competitiva y sostenible en las ciudades de los países desarrollados
mediante el avance en aspectos metodológicos y la generación de nuevos datos sobre el tema.
Los métodos y resultados amplían el conocimiento y la comprensión de la agricultura en cubierta,
la agricultura urbana y la producción local de alimentos para dar apoyo a los procesos de toma de
decisiones en el diseño y desarrollo de futuros proyectos de agricultura en cubierta. Futuras
investigaciones deberían centrarse en la evaluación de las percepciones de los actores sociales en
otras ciudades, focalizando en aspectos específicos como la aceptación social; en cuantificar el
potencial de la agricultura en cubierta de otras áreas urbanas y ciudades; y en evaluar más casos
de estudio y formas de agricultura urbana en cubierta desde una perspectiva de sostenibilidad,
haciendo especial énfasis en la integración de los aspectos sociales.
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Resum
L'agricultura urbana està florint al voltant de les ciutats del món desenvolupat com a resposta a
l’augment de població urbana, la creixent conscienciació ambiental entorn el sistema industrial
d'aliments i la necessitat d'abordar problemàtiques socials. Aquests nous sistemes de producció
local d’aliments tenen com a objectiu desenvolupar models sostenibles que restableixin les
relacions entre productors i consumidors, alhora que impulsen les economies locals i redueixen el
transport associat als aliments. D'altra banda, la recent crisi financera i l'expansió dels espais
abandonats a les ciutats han revitalitzat els projectes d’agricultura urbana, no només a nivell
d'autogestió (és a dir, de forma comunitària o privada), sinó també a nivell comercial. En
particular, els nous professionals i els agricultors urbans han trobat en els terrats de la ciutat un
espai buit on situar la producció d'aliments, donant lloc al desenvolupament de l'agricultura
urbana en coberta. Conseqüentment, granges, hivernacles i jardins han colonitzat les cobertes
dels edificis. No obstant, manca una avaluació específica de la potencial implementació i el perfil
de sostenibilitat de les diferents formes d’agricultura urbana en coberta, tècniques de cultiu i
cultius.
En aquest context, la present tesi tracta de respondre a dues preguntes d'investigació "Quin és el
potencial de l'agricultura urbana en coberta en termes qualitatius i quantitatius?" i "Quins són els
impactes ambientals i els costos econòmics de les diferents formes d’agricultura urbana en
coberta?". Amb aquest objectiu, es proposa un marc metodològic i s'analitzen tres casos d'estudi
que són experiències pilot de diferents formes d'agricultura urbana en coberta.
La producció d'aliments a les ciutats és un sistema complex que implica diversos actors socials,
té múltiples escales i afecta les tres dimensions de la sostenibilitat (medi ambient, economia,
societat). Per tant, una avaluació exhaustiva ha de combinar diferents disciplines per abordar
aquests temes. Aquesta tesi segueix un marc interdisciplinari que inclou (a) investigació
qualitativa, per aprofundir en les percepcions dels diferents actors socials relacionats amb
l’agricultura urbana i l’agricultura en coberta; (b) sistemes d'informació geogràfica (SIG), per
identificar i quantificar les cobertes disponibles i viables per a la implementació de l'agricultura
en coberta; (c) l'anàlisi de cicle de vida (ACV), per quantificar les càrregues ambientals dels
sistemes d’agricultura en coberta; i (d) l'anàlisi de costos de cicle de vida (ACCV), per
quantificar els costos econòmics de l’agricultura en coberta. Aquest marc metodològic permet
avaluar l’agricultura urbana en coberta des de l'escala ciutat (per exemple, perspectiva de
planificació) a l'escala del sistema (per exemple, productes alimentaris).
Una anàlisi de la percepció dels diversos actors socials a través d'entrevistes qualitatives va
desvetllar que el desenvolupament de l'agricultura en coberta a Barcelona s'enfronta actualment a
algunes limitacions, principalment a causa de la manca de suport d’alguns actors. Les principals
barreres per al suport a l'agricultura urbana en coberta són la manca d'una definició comuna de
l'agricultura urbana, l'origen específic de l’agricultura urbana a Barcelona i la seva morfologia
urbana i la limitada acceptació social d'algunes tècniques de producció d'aliments. No obstant
això, els actors socials valoren els beneficis sostenibles (és a dir, ambiental, econòmica i social)
vinculada a l'agricultura urbana en coberta, en particular en el context del desenvolupament d'una
economia verda local.
En termes quantitatius, l'agricultura urbana en coberta mostra un gran potencial per augmentar
l’actual producció local d’aliments i reduir les càrregues ambientals del flux d’aliments de la
ciutat. Un conjunt de criteris múltiples és necessari per identificar els sostres tècnica i
econòmicament viables per a la implementació d'hivernacles en coberta comercials (és a dir, la
XVIII
disponibilitat d'espai, la llum solar, la resistència i la pendent, i els requisits legals i de
planificació). Els parcs comercials mostren un major potencial a curt termini (53-98%) que els
parcs industrials (8%), a causa d'una arquitectura més resistent, encara que els parcs industrials
són de gran interès per a un pla d’implementació d’agricultura urbana en coberta a gran escala a
causa de la seva àrea extensa. La potencial aplicació d’hivernacles en coberta integrats, els quals
aprofiten els fluxos residuals de l'edifici (és a dir, la calor i CO2 residuals, aigua de pluja), és una
forma innovadora d'agricultura en coberta. Els beneficis d’aquests sistemes varien en les regions
càlides (per exemple, el Mediterrani), on la producció passiva en hivernacle es pot realitzar, i les
regions fredes (per exemple, Països Baixos), on els hivernacles requereixen calefacció. La
preferència entre les regions per a l'aplicació d’hivernacles integrats es basa, per tant, en si
l’objectiu és augmentar la producció d'aliments (en zones càlides, la productivitat pot augmentar)
o reduir les càrregues ambientals (és a dir, en zones fredes, el consum d’energia per calefacció es
pot substituir).
Des d'una perspectiva de cicle de vida, l’hivernacle en coberta del rooftop greenhouse lab (RTG-
Lab) (Bellaterra, Espanya), el jardí comunitari en coberta de Via Gandusio (Bolonya, Itàlia) i un
jardí privat en coberta al centre de Barcelona (Espanya) són analitzats. L’agricultura urbana en
coberta pot esdevenir una opció ecològica per desenvolupar l'agricultura urbana i els sistemes
alimentaris locals a les ciutats. No obstant això, els resultats depenen de la forma d’agricultura en
coberta, el tipus de cultiu i el sistema de cultiu. Els projectes pilot avaluats en aquesta tesis
mostren unes primeres tendències, que permeten llistar recomanacions per al desenvolupament
de l'agricultura en coberta.
Pel que fa a la producció d'aliments en hivernacles en coberta, el propi hivernacle és el principal
element en els impactes ambientals (41,0-79,5%) i els cost econòmic (64%), com en l'agricultura
convencional. Tot i que un hivernacle en coberta té una majors impactes ambientals (entre 17 i
75%) que un hivernacle convencional, la producció de tomàquet en el RTG-Lab a Barcelona va
resultar tenir un menor impacte ambientals que un hivernacle convencional, no només en
finalitzar la producció (entre 9 i 26% menor) sinó també quan arriba al consumidor (entre 33 i
42% menor). En quant al cost econòmic, tot i que la producció de tomàquets en coberta resulta un
21% més cara, quan es considera tota la cadena de subministrament convencional, es posa de
manifest la competitivitat dels hivernacles en coberta com a sistemes de producció local.
Pel que fa als jardins en coberta, els consums de recursos del cultiu (és a dir, aigua, fertilitzants,
energia) tenen el paper més rellevant. El jardí comunitari en coberta empra elements reutilitzats
en el seu disseny (per exemple, pallets) i el reg va ser l'etapa més impactant (60-75%). En el jardí
privat en coberta, la fertirrigació (entre 33 i 46%) i l'estructura del jardí (entre el 28 i el 35%) van
ser els principals contribuents al impacte ambiental. La recol·lecció d'aigua de pluja per al
subministrament de la demanda d'aigua dels cultius i la integració d'elements reutilitzats en les
estructures de cultiu podria augmentar la sostenibilitat dels jardins en disminuir el consum de
recursos del sistema.
La comparació de les diferents tècniques de cultiu en el cas d’estudi comunitari va destacar la
major eco-eficiència de la producció en sòl, en comparació amb les tècniques hidropòniques (és a
dir, la tècnica de pel·lícula de nutrients, sistema flotant). L'avaluació dels diferents cultius va
mostrar el mateix patró en els jardins en coberta comunitari i privat. Els cultius amb fruit (per
exemple, el tomàquet) tenen uns impactes ambientals més baixos que els cultius de fulla (per
exemple, el enciam), ja que les productivitats són més altes. No obstant això, aquestes formes
d'agricultura en coberta realitzen policultiu, el disseny del qual està habitualment orientat a les
hortalisses de fruit, donant lloc a una densitat de plantació més baixa de la que es pot realitzar per
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cultius de fulla. Un disseny millorat, que dividís el jardí segons cultiu, podria millorar i equilibrar
aquestes divergències entre els tipus de cultiu.
Aquesta tesi contribueix a la comprensió del procés de desenvolupament d’una agricultura
urbana i agricultura urbana en coberta competitiva i sostenible a les ciutats dels països
desenvolupats mitjançant l’avenç d'aspectes metodològics i la generació de noves dades sobre el
tema. Els mètodes i resultats amplien el coneixement i la comprensió de l'agricultura en coberta,
l'agricultura urbana i la producció local d'aliments per tal de donar suport als processos de presa
de decisions en el disseny i desenvolupament de futurs projectes d'agricultura en coberta. Futures
investigacions haurien de centrar-se en l'avaluació de les percepcions dels actors socials a altres
ciutats, focalitzant en aspectes específics com l'acceptació social; en quantificar el potencial de
l'agricultura en coberta d’altres àrees urbanes i ciutats; i en avaluar més casos d’estudi i formes
d’agricultura urbana en coberta des d'una perspectiva de sostenibilitat, fent especial èmfasi en la
integració dels aspectes socials.
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Preface
The present doctoral thesis was developed within the research group on Sustainability and
Environmental Prevention (Sostenipra) at the Institute of Environmental Science and Technology
(ICTA) of the Universitat Autònoma de Barcelona (UAB) from October 2011 to June 2015; as
well as, during the three-month research stay (September – December 2014) at the Department of
Agricultural Science (DIPSA) of the Alma Mater Studorium Università di Bologna (UniBo), in
Bologna, Italy.
This dissertation analyses the municipal compost application and production in the
Mediterranean region from a sustainable perspective. This dissertation is the result of a
multidisciplinary approach that aims to evaluate the implementation of urban rooftop farming
systems in cities. The novelty of the dissertation relies not only on the topic but also on the
integration of qualitative and quantitative tools in order to assess the social, economic and
environmental aspects from a multi-actor perspective. The dissertation provides further
knowledge on urban rooftop farming to support decision-making processes. Methodological
proposals and specific tools are also presented.
The dissertation is mainly based on the following papers and chapters either published or under
review in peer-reviewed indexed journals:
• Sanyé-Mengual E, Cerón-Palma I, Oliver-Solà J, Montero JI, Rieradevall J (2013)
Environmental analysis of the logistics of agricultural products from Roof Top Greenhouse
(RTG) in Mediterranean urban areas. Journal of the Science of Food and Agriculture 93(1):
100–109. (DOI: 10.1002/jsfa.5736)
• Sanyé-Mengual E, Oliver-Solà J, Montero JI, Rieradevall J (2015) An environmental and
economic life cycle assessment of Rooftop Greenhouse (RTG) implementation in Barcelona,
Spain. Assessing new forms of urban agriculture from the greenhouse structure to the final
product level. International Journal of Life Cycle Assessment (DOI: 10.1007/s11367-014-
0836-9)
• Sanyé-Mengual E, Cerón-Palma I, Oliver-Solà J, Montero JI, Rieradevall J (2015) Integrating
horticulture into cities: A guide for assessing the implementation potential of Rooftop
Greenhouses (RTGs) in industrial and logistics parks. Journal of Urban Technology 22(1):87-
111 (DOI:10.1080/10630732.2014.942095)
• Sanyé-Mengual E, Anguelovski I, Oliver-Solà J, Montero JI, Rieradevall J (2015) Resolving
differing stakeholder perceptions of urban rooftop farming in Mediterranean cities :
promoting food production as a driver for innovative forms of urban agriculture. Agriculture
and Human values (online) (DOI: 10.1007/s10460-015-9594-y)
• Sanyé-Mengual E, Martínez-Blanco J, Finkbeiner M, Cerdà M, Camargo A, Ometto AR,
Velásquez LS, Villada G, Niza S, Pina A, Ferreira G, Oliver-Solà J, Montero JI, Rieradevall
J. Urban horticulture in retail parks: environmental assessment of the potential
implementation of Rooftop Greenhouses (RTGs) in European and South American cities.
Journal of Cleaner Production (under review)
• Sanyé-Mengual E, Orsini F, Oliver-Solà J, Rieradevall J, Montero JI, Gianquinto G (2015)
Environmental and economic assessment of multiple cultivation techniques and crops in
open-air community rooftop farming in Bologna (Italy). Agronomy for Sustainable
Development (under review)
• Sanyé-Mengual E, Oliver-Solà J, Montero JI, Rieradevall J (2015) Revisiting the
environmental assessment of local food: Relevance of market data and seasonality. A case
study on rooftop home-grown food in Barcelona (Spain). International Journal of Life Cycle
Assessment (submitted)
• Sanyé-Mengual E, Oliver-Solà J, Anton A, Montero JI, Rieradevall J (2014) Environmental
assessment of urban horticulture structures: Implementing Rooftop Greenhouses in
XXII
Mediterranean cities. In Schenk R, Huizenga D (eds.) Proceedings of the 9th International
Conference on Life Cycle Assessment in the Agri-Food Sector, San Francisco (United States)
(ISBN: 978-0-9882145-7-6).
• Sanyé-Mengual E, Anguelovski I, Oliver-Solà J, Montero JI, Rieradevall J (2014) When the
perception and development of Urban Rooftop Farming depend on how Urban Agriculture is
defined: Examining diverging stakeholders’ experiences and views in Barcelona, Spain, in
Roggema R and Keeffe G (eds.) Finding spaces for productive cities. Proceedings of the 6th
AESOP Sustainable Food Planning conference. (VHL University of Applied Sciences:
Leeuwarden), pp.490-503 (ISBN 978-90-822451-2-7)
• Sanyé-Mengual E, Llorach-Masana P, Sanjuan-Delmás D, Oliver-Solà J, Josa A, Montero J,
Rieradevall J (2014) The ICTA-ICP Rooftop Greenhouse Lab (RTG-Lab): closing metabolic
flows (energy, water, CO2) through integrated Rooftop Greenhouses. in Roggema R and
Keeffe G (eds.) Finding spaces for productive cities. Proceedings of the 6th AESOP
Sustainable Food Planning conference. (VHL University of Applied Sciences: Leeuwarden),
pp.692-701 (ISBN 978-90-822451-2-7)
The following oral communications and posters presented to congresses and conferences also
form part of this doctoral thesis:
• Sanyé E, Cerón I, Oliver-Solà J, Montero JI, Rieradevall J (2011) LCM of green food
production in Mediterranean cities: environmental benefits associated to the distribution stage
of Roof Top Greenhouse (RTG) systems. A case study of Barcelona (Spain). Poster.
LCM2011. Life Cycle Management 2011: Towards Life Cycle Sustainability Management,
August 2011, Berlin (Alemania).
• Sanyé-Mengual E, Cerón-Palma I, Oliver-Solà J, Montero JI, Rieradevall J (2012) Periurban
and innovative agrourban production areas for food self-sufficiency in the Metropolitan Area
of Barcelona. Oral presentation. Agriculture in an urbanizing society, International
Conference on Multifunctional Agriculture and Urban-Rural Relations, April 2012,
Wageningen (The Netherlands).
• Sanyé-Mengual E, Cerón-Palma I, Oliver-Solà J, Montero JI, Rieradevall J (2012) Potential
and benefits of Rooftop Greenhouse (RTG) systems for agriculture production implemented
in polygons of future Smart cities: a case study in Zona Franca (Barcelona). Oral presentation.
Smart Cities World Congress, November 2012, Barcelona (Spain)
• Sanyé-Mengual E, Cerón-Palma I, Oliver-Solà J, Montero JI, Rieradevall J (2012) Potential
benefits of agrourban production systems as a sustainable strategy for food self-sufficiency in
urban areas. Poster. Urban sustainability and resilience (USAR2012). 1st International
Conference for Urban Sustainability and Resilience, 5-6 November 2012, London (United
Kingdom).
• Sanyé-Mengual E, Cerón-Palma I, Oliver-Solà J, Montero JI, Gabarrell X, Rieradevall J
(2013) Ecoinnovation of Rooftop Greenhouses (RTGs) as agrourban symbiotic systems for
urban areas. Poster. 7th International Conference of the International Society for Industrial
Ecology (ISIE2013), 25 – 28 June 2013, Ulsan (Korea).
• Sanyé-Mengual E, Oliver-Solà J, Antón A, Montero JI, Rieradevall J (2014) Environmental
assessment of urban horticulture infrastructures: Implementing Rooftop Greenhouses (RTGs)
in Mediterranean cities. Oral presentation. IX International Conference on Life Cycle
Assessment in the agri-food sector (LCAFOOD2014), 10-12 October 2014, San Francisco
(United States).
• Sanyé-Mengual E, Oliver-Solà J, Montero JI, Gabarrell X, Rieradevall J (2014) Production
and consumption comparison of conventional and local horticulture: cradle-to-farm gate and
cradle-to-consumer analysis of tomato production in Almeria and Barcelona (Spain). Oral
presentation. 11th ISIE Socio-Economic Metabolism section conference, 17-19 November
2014, Melbourne (Australia).
XXIII
• Sanyé-Mengual E, Anguelovski I, Oliver-Solà J, Montero JI, Rieradevall J (2014) When the
perception and development of Urban Rooftop Farming depend on how Urban Agriculture is
defined: Examining diverging stakeholders’ experiences and views in Barcelona, Spain. Oral
presentation. 6th AESOP Sustainable Food Planning Conference, 5-7 November 2014,
Arnhem (The Netherlands).
• Sanyé-Mengual E, Oliver-Solà J, Montero JI, Rieradevall J (2014) The ICTA-ICP rooftop
greenhouse lab (RTG-Lab): closing metabolic flows through Rooftop Greenhouses in
Barcelona, Spain. Oral presentation. 6th AESOP Sustainable Food Planning Conference, 5-7
November 2014, Arnhem (The Netherlands).
• Sanyé-Mengual E, Oliver-Solà J, Montero JI, Rieradevall J (2014) The ICTA-ICP rooftop
greenhouse lab (RTG-Lab): closing metabolic flows through Rooftop Greenhouses in
Barcelona, Spain. Poster. 6th AESOP Sustainable Food Planning Conference, 5-7 November
2014, Arnhem (The Netherlands).
• Sanyé-Mengual E, Oliver-Solà J, Montero JI, Rieradevall J (2015) How to communicate
environmental impacts? Approaching LCA results to consumers for urban food products.
Poster. SETAC Europe 25th Annual Meeting, 3-7 May 2015, Barcelona (Spain)
• Sanyé-Mengual E, Orsini F, Gianquinto G, Oliver-Solà J, Montero JI, Rieradevall J (2015)
Integrating food production in cities for reducing the carbon footprint: accounting the
environmental burdens of rooftop farming systems in Mediterranean cities. Poster. ISIE
Conference 2015 - Taking Stock of Industrial Ecology, 7-10 July 2015, Surrey (United
Kingdom)
• Sanyé-Mengual E, Llorach-Masana P, Sanjuan-Delmas D, Oliver-Solà J, Josa A, Montero JI,
Gabarrell X, Rieradevall J (2015) The ICTA-ICP Rooftop Greenhouse Lab: coupling
industrial ecology and life cycle thinking to assess innovative urban agriculture. Poster. VI
International Conference on Life Cycle Assessment (CILCA 2015), 13-16 July 2015, Lima
(Peru).
• Sanyé-Mengual E, Orsini F, Oliver-Solà J, Muñoz P, Gianquinto G, Rieradevall J, Montero JI
(2015) Environmental performance of rooftop farming as urban food systems: outputs from
case studies in the Mediterranean area. Poster. 7th International Conference on Life Cycle
Management. 30August – 2 September 2015, Bordeaux (France).
Part of this doctoral thesis was developed in the framework of the FERTILECITY project
“Agrourban sustainability through rooftop greenhouses. Ecoinnovation on residual flows of
energy, water and CO2 for food production” funded by the Spanish Ministerio de Economía y
Competitividad (MINECO) (CTM2013-47067-C2-1-R). The project is coordinated by the
Institute of Environmental Science and Technology (ICTA), with the participation of the
Universitat Politècnica de Catalunya (UPC) and the Institute of Agriculture and Food Research
and Technology (IRTA).
In addition, during the dissertation period the opportunity has been given to work in other papers,
which were published in peer-reviewed journals and are also related with the goals of the
dissertation:
• Cerón-Palma I, Oliver-Solà J, Sanyé-Mengual E, Montero JI & Rieradevall J (2012) Barriers
and opportunities regarding the implementation of Rooftop Greenhouses (RTEG) in
Mediterranean cities of Europe. Journal of Urban Technology 19 (4): 87-103.
• Cerón-Palma I, Sanyé-Mengual E, Oliver-Solà J, Montero JI & Rieradevall J (2013) Towards
a green sustainable strategy for social neighbourhoods in Latin America: Case from social
housing in Merida, Yucatan, Mexico. Habitat International 38: 47-56.
Furthermore, the participation in other projects and publications of the Sostenipra research group
provided further knowledge on the application of industrial ecology and sustainability assessment
tools.
XXIV
Projects:
• SMART PARKS: Ecoinnovation in Smart Parks - Analysis of methods and sustainable
strategies to promote symbioses between industrial, urban and agrarian systems in Brazil and
Spain (HBP-2012-0216). Funded by MECD – Spanish Ministry of Education, Culture and
Sports.
• Proyecto piloto sobre ecodiseño (2ª fase) para el desarrollo de 3 ecoproductos en otras tantas
empresas españolas innovadoras. Funded by ENISA – National company for innovation.
• Proyecto M-ECO, Investigación para la mejora de la sostenibilidad del sector de la madera y
mueble en Andalucía a través de la Eco-innovación. Funded by Junta de Andalucía.
Publications:
• Sanyé-Mengual E, Pérez-López P, González-García S, Garcia Lozano R, Feijoo G, Moreira
MT, Gabarrell X, Rieradevall J (2014) Eco-Designing the Use Phase of Products in
Sustainable Manufacturing. The Importance of Maintenance and Communication-to-User
Strategies. Journal of industrial ecology 18(4):545-557
• Sanyé-Mengual E, Romanos H, Molina C, Oliver MA, Ruiz N, Pérez M, Carreras D, Boada
M, Garcia-Orellana J, Duch J, Rieradevall J (2014) Environmental and self-sufficiency
assessment of the energy metabolism of tourist hubs on Mediterranean islands: the case of
Menorca (Spain). Energy Policy 65: 377–387.
• Sanyé E, Oliver-Solà J, Gasol CM, Farreny R, Gabarrell X, Rieradevall J (2012). Life Cycle
Assessment of energy flow and packaging use in food purchasing. Journal of Cleaner
Production, 25: 51 -59.
• Mendoza JM, Sanyé-Mengual E, Angrill A, García-Lozano R, Feijoo G, Josa A, Gabarrell X,
and Rieradevall J (2015) Development of urban solar infrastructure to support low-carbon
mobility. Energy policy (Accepted, May 2015)
• Gasol CM, Sanyé E, Sevigné E, Martínez J, Font X, Artola A, Sánchez A, Anton A, Muñoz P,
Montero JI, Rieradevall J & Gabarrell X (2012). Database Availability. Life Cycle Assessment
Database of the Sudoe Area, in: Joaquim Comas & Sadurní Morera (eds.) Life Cycle
Assessment and Water Management – related issues (ISBN 978-84-9984-163-2)
• Sanyé-Mengual E, Garcia Lozano R, Farreny R, Oliver-Solà J, Gasol CM & Rieradevall J
(2014) Introduction to the Eco-Design Methodology and the Role of Product Carbon
Footprint. In: Muthu, S.S. (ed) Assessment of Carbon Footprint in Different Industrial
Sectors. Vol. 1. Singapore: Springer Singapore.
• Sanyé-Mengual E, Garcia Lozano R, Oliver-Solà J, Gasol CM & Rieradevall J (2014) Eco-
design and product carbon footprint use in the packaging sector. In: Muthu, S.S. (ed)
Assessment of Carbon Footprint in Different Industrial Sectors. Vol. 1. Singapore: Springer
Singapore.
XXV
Structure of the dissertation
This thesis is organised into five main parts and eleven chapters, as follows:
Part I. Introduction, objectives and methodology
Part I is composed of two chapters. Chapter 1 [Background and objectives] introduces the
background of urban rooftop farming, focusing on: the global and urban food issues that have led
to the development of a local food sector; the concepts, types, functions and development of
urban agriculture; the definition of the concepts and types, current projects and practices, and the
specific opportunities and challenges of urban rooftop farming; and the motivations and
objectives of this dissertation. Chapter 2 [Methodological framework] details the
methodological framework of this dissertation by defining the methods and tools employed and
describing the main characteristics of the case studies.
XXVI
Part II. Assessment of urban rooftop farming implementation
Part II is composed of three chapters. Chapter 3 [Resolving differing stakeholder perceptions of
urban rooftop farming in Mediterranean cities: Promoting food production as a driver for
innovative forms of urban agriculture] deepens in the perceptions of stakeholders related to urban
agriculture and rooftop farming in the city of Barcelona by performing qualitative interviews.
The study unravels the challenges, barriers and benefits of the potential implementation of urban
rooftop farming. Chapter 4 [Integrating Horticulture into Cities: A guide for assessing the
implementation potential of Rooftop Greenhouses (RTGs) in industrial and logistics parks]
develops a tool that combines geographic information systems (GIS) and life cycle assessment
(LCA) to quantify and evaluate the implementation of commercial rooftop greenhouses (RTGs)
in industrial and logistics parks. The tool is applied to the case study of Zona Franca in Barcelona
(Spain). Chapter 5 [Urban horticulture in retail parks: environmental assessment of the
potential implementation of Rooftop Greenhouses (RTGs) in European and South American
cities] uses the GIS-LCA tool to anlyse the potential implementation of RTGs in retail parks in
different world regions. The assessment focuses on the potential benefits of integrated RTGs (i-
RTGs) in the different climatic areas and the identification of the constraints and challenges of
such systems.
Part III. Assessment of rooftop greenhouses
Part III includes two chapters on rooftop greenhouses. Chapter 6 [An environmental and
economic life cycle assessment of rooftop greenhouse (RTG) implementation in Barcelona,
Spain.] accounts for the environmental impacts and economic cost of a pilot experience: the
rooftop greenhouse Lab (RTG-Lab) in Bellaterra (Spain). The assessment is performed at three
levels: greenhouse structure, cradle-to-farm gate, and cradle-to-consumer. The local system is
compared with the conventional production in multitunnel greenhouses in Almeria. Chapter 7
[Environmental analysis of the logistics of agricultural products from rooftop greenhouses in
Mediterranean urban areas] focuses on the supply-chain of conventional and local food
products. The assessment details the supply-chain of tomatoes from Almeria to Barcelona and the
potential local supply-chain of tomatoes from RTGs in Barcelona.
Part IV. Assessment of community and private open-air rooftop farming
Part IV assesses open-air forms of rooftop farming. Chapter 8 [Environmental and economic
assessment of multiple cultivation techniques and crops in open-air community rooftop farming
in Bologna (Italy)] quantifies the environmental burdens and the economic costs of fruit and
vegetables crops in a community rooftop garden in Bologna (Italy). Particular attention is paid to
the analysis of different cultivation techniques and crops in order to provide recommendations for
the design of future rooftop gardens. Chapter 9 [Revisiting the environmental assessment of
local food systems: Relevance of seasonality and market data in a case study of rooftop home-
grown vegetables in Barcelona (Spain)] analyses the environmental impacts of a private rooftop
garden in the city of Barcelona. This chapter focuses on the development of the life cycle
methodology for assessing urban food systems from a local production perspective by integrating
market data and seasonality in the analysis.
XXVII
Part V. General conclusions and future research
Part V includes Chapter 11 [Conclusions and contributions] and Chapter 12 [Future research
and strategies] and provides the general conclusions of the dissertation and proposes future fields
of research associated with urban rooftop farming, urban agriculture and local food systems.
[Note: Each chapter from 3 to 9 presents an article–either published or under review. For this
reason, an abstract and a list of keywords are presented at the beginning of the chapter, followed
by the main body of the article].
XXIX
Part I
Introduction, objectives
and methodology
Chapter 1
Introduction and objectives
Picture: Emplacement of a future rooftop greenhouse (Paris, France)
(©Esther Sanyé-Mengual)
5
Chapter 1
This chapter introduces the background of urban rooftop farming. First, the global and urban
food issues that have led to the development of a local food sector are described. Second, an
introduction to urban agriculture is performed by dealing with the concepts, types, functions and
development. Third, the core of this dissertation, urban rooftop farming, is presented by defining
the concepts and types, showing current projects and practices and identifying the specific
opportunities and challenges of these systems. Finally, the last sections outline the motivations
and objectives of this dissertation.
1.1. The food and the city: increased demand, increased awareness
World population is expected to surpass the value of 9.500 million of inhabitants by 2050
(United Nations 2012). Particular attention is paid to urban areas, where population is getting
concentrated. Since 2007, urban areas represent more than half of the population and this trend is
forecasted to grow up to almost 70% by 2050 (United Nations 2014). Urban population is
particularly important in developed countries, where it represents around 80% of the population,
and in emerging areas, where megacities are expanding (e.g., Asia) (United Nations 2014) (see
Figure 1.1).
Figure 1.1. Evolution and prevision of the percentage of urban population (%) in the world and
main regions (1950-2050).
Source: Own elaboration from United Nations (2014).
This fact puts more pressure on the global food security issue, since a growing population results
in an increasing food demand. The United Nations Food and Agriculture Organisation (FAO)
coined the term “food security” in 1945 as ‘a situation that exists when all people, at all times
have physical, social and economic access to sufficient, safe and nutritious food that meets
their dietary needs and food preferences for an active and healthy life’ with the aim of
highlighting the disparities of food access between world regions (Burton et al. 2013).
At the global scale, satisfying the food demand will face several challenges. First, agricultural
production is required to become more sustainable and more intensive to boost crop yields
without enlarging crop areas. However, multiple factors put against the wall the availability and
functionality of fertile soil. Second, urbanization exerts a direct occupation of fertile areas, which
PART I: Introduction and objectives
6
are usually displaced to less suitable places. Third, past agricultural practices have led to
agronomic constraints, such as a reduction in nutrient availability and environmental risks (e.g.,
chemical contamination). Finally, climate change has made crops more vulnerable by increasing
the recurrence and effects of negative phenomena, such as droughts, and by expanding the areas
affected by desertification and water scarcity (Godfray et al. 2010; Pelletier and Tyedmers 2010;
Foley 2011; FAO 2013a).
At the city scale, the increase of population implies an expansion of the urbanized area, causing
two main issues: the destruction of farmland and the disconnection of consumption and
production areas (Seto et al. 2011; Paül and McKenzie 2013). The urban sprawl not only
occupies and displaces farmland area but also increases the land value, leading to an
abandonment of some farming activities as land speculation becomes more profitable (Robinson
2004). Consequently, the importance of farmland and its potential food supply of periurban areas
are notably reduced (Figure 1.2) (Allen 2003; Zeng et al. 2005; Thapa and Murayama 2008;
Zasada 2011; Paül and McKenzie 2013). However, an increased population demands a larger
amount of food and, thus, the rift between production and consumption areas is enlarged,
enlarging the food miles of products which need to be imported to meet the urban food demand
(Figure 1.2).
Figure 1.2. Food implications of urban expansion.
In this context, the design of sustainable cities is in the global agenda, such as the “Thematic
Strategy on the Urban Environment” proposed by the European Commission (European
Commission 2005). Cities are open systems that rely on external resources, leading to an
important contribution to global environmental impacts (Girardet 2010). Although occupying
only 2% of Earth’s surface, the environmental burdens of urban activity extend beyond city
borders. Notwithstanding that cities generate 75% of the global economic output, they are
responsible for 75% of carbon emissions and consume up to 80% of the global energy and
material supply (UN-Habitat 2011a; UN-Habitat 2011b; UNEP 2013). Regarding food,
sustainable cities may enhance the local production and consumption of food products thereby
reducing the food miles of citizen diets (UNEP 2011a; UNEP 2013; UN-Habitat 2013a).
Particularly in developed countries, beyond policy recommendations to improve urban
sustainability, the environmental awareness of citizens and the development of alternative food
supply-chains have boost a renewed local food sector (Weatherell et al. 2003). The development
of regional and local food systems have approached the relationships between producers and
consumers while shortening the food supply-chains (Hinrichs 2000; Marsden et al. 2000; Steel
2008). Farmers’ markets, community-supported agriculture (CSA) schemes or on-site retailing
have contributed to supply the growing demand of local food products, which are largely
accepted by consumers, who perceived local products as a higher quality, fresher, more nutritive
PART I: Introduction and objectives
7
and more traceable option (Lee 2001; La Trobe 2001; Boyle 2003; Seyfang 2004). Furthermore,
consumers identify local food systems as a sustainable alternative from a socio-economic
perspective since they support the local economies and, thus, the local society (Chambers et al.
2007). However, urban agriculture is expected to address certain needs and supply the demand
for local food while complementing the conventional market of fresh produce, rather than
providing cities with all the fresh produce requirements and substituting the industrial agriculture
market, due to land constraints among others (Badami and Ramankutty 2015).
The expansion of the local food market counteracts the effects of urbanization by two main
processes (Figure 1.3). First, the increased demand of local food revitalizes the farmland close to
cities, where farmers can develop feasible businesses by using short-supply schemes.
Furthermore, customers value the locality of products and accept premium prices for local food
(Feldmann and Hamm 2015), giving higher margins to farmers and making periurban areas
attractive for new businesses. Second, the local food movement encompasses also the boosting of
periurban and urban agricultural (PUA) activities which provide citizens with fresh produce by
occupying empty spaces in urban areas, such as vacant lots or rooftops (Cohen et al. 2012;
Grewal and Grewal 2012).
Figure 1.3. Revitalization of local production.
1.2. Urban agriculture: a matter of food security, environmentalism
and social needs
Within the local food movement, urban agriculture experiences have spread over cities in the last
years with the aim of increasing the urban area devoted to food production thereby contributing
to urban food security and resilience (Mok et al. 2013; Ackerman et al. 2014; Tornaghi 2014;
Orsini et al. 2014; Specht et al. 2015). This section introduces the concepts, nomenclature and
development of urban agriculture, as well as the multifunctionality of such experiences.
1.2.1. Concepts and nomenclature of urban agriculture (UA)
There are multiple definitions of “Urban agriculture” (UA) that have been used in the literature
and in policy-making. Main differences among them are linked to spatial, production, function
and market specifications. Definitions range from generic and global, such as the FAO
conceptualization, to recent and specific, such as in the Five Borough Farm project. Common and
recent definitions of UA are collected in Table 1.1. The specific aspects of the spatial,
production, function and market dimensions of each are shown in Table 1.2.
PART I: Introduction and objectives
8
PART I: Introduction and objectives
9
Table 1.1. Common and recent definitions of urban agriculture.
Source
Definition
FAO
Urban and peri-urban agriculture (UPA) can be defined as the growing of plants and the raising of animals within and around cities
RUAF
foundation
Urban agriculture can be defined shortly as the growing of plants and the raising of animals within and around cities. The most striking feature
of urban agriculture, which distinguishes it from rural agriculture, is that it is integrated into the urban economic and ecological system: urban
agriculture is embedded in -and interacting with- the urban ecosystem. Such linkages include the use of urban residents as labourers, use of typical
urban resources (like organic waste as compost and urban wastewater for irrigation), direct links with urban consumers, direct impacts on urban
ecology (positive and negative), being part of the urban food system, competing for land with other urban functions, being influenced by urban
policies and plans, etc.
US EPA
City and suburban agriculture takes the form of backyard, roof-top and balcony gardening, community gardening in vacant lots and parks,
roadside urban fringe agriculture and livestock grazing in open space. Urban agriculture is an important source of environmental and production
efficiency benefits. The use of best management practices (BMPs) and integrated farming systems protect soil fertility and stability, prevent excessive
runoff, provide habitats for a widened diversity of flora and fauna, reduce the emissions of CO2, increase carbon sequestration, and reduce the incidence
and severity of natural disasters such as floods and landslides
Five Borough
Farm project
Urban agriculture can be defined as growing fruits, herbs, and vegetables and raising animals in cities, a process that is accompanied by many
other complementary activities such as processing and distributing food, collecting and reusing food waste and rainwater, and educating,
organizing, and employing local residents. Urban agriculture is integrated in individual urban communities and neighborhoods, as well as in the
ways that cities function and are managed, including municipal policies, plans, and budgets
Mougeot 2000,
based on Smit et
al. 1996
UA is an industry located within (intraurban) or on the fringe (periurban) of a town, a city or a metropolis, which grows or raises, processes
and distributes a diversity of food and non-food products, (re-)using largely human and material resources, products and services found in and
around that urban area, and in turn supplying human and material resources, products and services largely to that urban area
Mok et al. 2013
Horticultural activities within an urban or peri-urban setting, rather than animal husbandry, aquaculture, or arboriculture, since food plant
cultivation is the dominant form of urban agriculture
PART I: Introduction and objectives
10
Table 1.2. Specifications of common urban agriculture definitions.
Source
Spatial
Production
Function
Market
Within cities
Around cities
Plant growing
Animal
husbandry
Agroforestry
Non-food
products
Multifunctional
Soil
protection
Water
protection
Climate
protection
Resource
efficient
Biodiversity
Social
inclusion
Health
Education
Leisure
Local
oriented
FAO
●
●
●
●
●
●
●
RUAF foundation
●
●
●
●
●
●
●
US EPA
●
●
●
●
●
●
●
●
●
●
●
Five Borough Farm project
●
●
●
●
●
●
●
Mougeot 2000, based on Smit et al. 1996
●
●
●
●
●
●
Mok et al. 2013
●
●
●
PART I: Introduction and objectives
11
The definition of UA depends on the framework were it was conceptualized. There are global
definitions that also encompass UA in developing countries, such as by the inclusion of non-food
products (e.g., fuel). Other definitions were framed in a specific context. The Five Borough Farm
project was developed in the city of New York and the definition only refers to agriculture within
the city, while excluding the periurban areas. Some definitions emphasize the role of urban
agriculture as a local food system, while others pinpoint the multifunctionality of such activities
by identifying further benefits (such as education).
Among this variety and , this dissertation focuses on urban agriculture in developed countries,
which is often referred to as Global North, and uses the following definition, which summarizes
the discussion around UA conceptualizations of the Working group 1 of the COST Action
“Urban Agriculture Europe” (Lohrberg and Timpe 2012) (identified in orange in Figure 1.4):
Definition of urban agriculture used in this dissertation
Urban agriculture are farming operations taking place in and around the city that beyond food
production provides environmental services (soil, water and climate protection; resource
efficiency; biodiversity), social services (social inclusion, education, health, leisure, cultural
heritage) and supports local economies by a significant direct urban market orientation.
Thus, there are some difficulties to reach a global definition of urban agriculture. The lack of a
common definition of UA among stakeholders and organizations becomes a gap that needs to be
covered prior to the development of urban agriculture planning and policy. The variety of
definitions is partly based on the diversified nomenclature of UA. Thus, the multiple natures and
types of UA have led to a proliferation of ways to name these experiences. Figure 1.4 illustrates
the confusing cloud of concepts and specifications when defining and naming urban agriculture,
in terms of type of property, production, management and objective. This issue is core in the
Chapter 3 of this dissertation.
PART I: Introduction and objectives
12
Figure 1.4. Concepts use in the definitions and nomenclature of urban agriculture.
1.2.2. The multifunctional urban agriculture
Urban agriculture is characterized by being multifunctional. Main functions are enhancing food
security, providing environmentally-friendly food, educating and promoting health habits, and
building and empowering communities (e.g., Altieri et al. 1999; Lee 2001; Saldivar-tanaka and
Krasny 2004; Kortright and Wakefield 2010; Bendt et al. 2013; Hu et al. 2013; Orsini et al.
2014). Although projects can focus on a single function, UA activities tend to provide many
secondary ones. For example, a school garden aims to provide education on food and
environment. However, school gardens also improve the health habits of children and source the
school kitchen with local and ecologic food (Morris 2002; Morgan et al. 2010). The different
PART I: Introduction and objectives
13
functions of UA can be explained throughout the development of urban agriculture along the last
century (Figure 1.5).
Figure 1.5. UA functions along UA development.
(a) Food security
During the war periods and Great Depression (’30), urban agriculture was essential for
guaranteeing the food security of the United States and Europe. In this period, the administration
promoted the development of urban gardens in both public and private spaces, where citizens
could cultivate vegetables for feeding the population. They were the War gardens (WWI), Relief
Gardens (Great Depression) and Victory gardens (WWII) (Bassett 1981; McClintock 2010; Mok
et al. 2013). A matter of food security was also the increase of urban agriculture in Cuba to
access fresh food during the collapse of the socialist bloc between 1989 and 1993 (the Special
Period) (Altieri et al. 1999; Cruz and Medina 2003).
Recently, urban agriculture has been partly revitalized due to food security. The financial crisis
of 2008 caused a rapid rise of food and commodity prices, which resulted in a higher number of
citizens that were unemployed, facing financial and food insecurity issues which were improved
by their engagement in UA activities (Carney 2011; Taylor and Taylor Lovell 2012). Beyond the
global economy context, the creation of low-income neighbourhoods in cities has also led to the
origin of “food deserts”: urban areas with a limited access to affordable fresh food, where urban
gardens play a key role in coping community food insecurity (Guy et al. 2004; Wrigley et al.
2004; Smoyer-tomic et al. 2006; Beaulac et al. 2009; Alkon and Agyeman 2011; McClintock
2011; Carney 2011; Block et al. 2011; Tornaghi 2014). Furthermore, urban agriculture also
contributes to the urban food resilience after disasters, such as extreme climatic events which are
progressively becoming more regular.
(b) Low environmental impact food
In 1962 “Silent spring” of Rachel Carson (1962)warned about the environmental risks of the
modern agricultural industry and the use of chemicals, increasing the environmental awareness of
food and agriculture. As a result, citizens initiated backyards and urban gardens which became a
source of chemical-free food that was also an alternative to the conventional food industry
(Bassett 1981; Howe and Wheeler 1999; Mok et al. 2013). During this period, urban farms and
PART I: Introduction and objectives
14
community gardens expand in number (Howe and Wheeler 1999) by offering not only
environmentally-friendly but also healthy products.
Environmental concerns have been since then a motivation to engage in urban agriculture
experiences. Currently, UA is dominated by organic practices that close organic waste flows and
preserves biodiversity (Howe and Wheeler 1999; Kortright and Wakefield 2010; Lin et al. 2015).
Furthermore, the traceability of products is still a motivation behind urban gardens, which aim to
guarantee the consumption of chemical-free food (Kortright and Wakefield 2010; Calvet-Mir et
al. 2012a).
(c) Education and health
The Agenda 21 defined in the United Nations Conference on Environment & Development in
Rio de Janerio (known as Rio 92) included the promotion of environmental education, public
awareness and training. During the implementation process of Agenda 21, gardens have gained
popularity in education entities. School gardens have become a common tool to approach
children to nature, life sciences and health (Bell 2001; Coffey 2001). Furthermore, education
opportunities are an added-value of home gardens (Kortright and Wakefield 2010). Currently,
urban farms and projects offer education programs and training (Cohen et al. 2012).
The participation in UA experiences improves the health of citizens. School gardens can
improves children health by enhancing positive changes in diet habits (Morris 2002; Morgan et
al. 2010). Community gardens play also a key role on health and several studies linked the
participation in community gardens to an improved wellbeing (Wakefield et al. 2007; Alaimo et
al. 2008; D’Abundo and Carden 2008; Kingsley et al. 2009; Wilkins et al. 2015). Furthermore,
healing properties at the individual level have been related to gardens, which can help
participants in the recovering process from traumatic experiences (Marcus and Barnes 1999;
Gerlach-Spriggs et al. 2004).
(d) Community building and empowerment
Urban agriculture has notable effects at the community scale by supporting community building
and empowerment processes. Even more, addressing social issues has been sometimes the main
goal of UA projects. Community-led UA projects become a place of encounter between
neighbours that boost social inclusion, self-organization and cohesion, which commonly lead to a
community empowerment (Howe and Wheeler 1999; Armstrong 2000; Lyson 2004; Lawson
2005; Teig et al. 2009; Carney 2011; Block et al. 2011; Guitart et al. 2012).
Some community UA initiatives have focused towards food sovereignty as a form of
empowerment (Carney 2011; Kirwan and Maye 2012). Via Campesina (2002) defined food
sovereignty as the community’s right to define its own food and agricultural systems. In this
context, UA projects are a way of re-commoning the urban land for food production (Tornaghi
2014), while creating an alternative food supply way to the global industrial food system
(Wekerle 2004; DuPuis et al. 2011; Block et al. 2011).
1.3. Urban rooftop farming: making buildings fertile
Urban rooftop farming (URF) is the focus of this dissertation. URF play a key role as a form of
building-based urban agriculture that is growing in popularity within the local food systems
(Figure 1.6). This section describes the concepts and definitions linked to urban rooftop farming,
the current practices and typologies and main opportunities and challenges of these systems.
PART I: Introduction and objectives
15
Figure 1.6. Role of urban rooftop farming within urban agriculture and local food systems.
1.3.1. Concepts and definitions of urban rooftop farming (URF)
Urban rooftop farming (URF) is part of the building-based urban agriculture that has recently
occupied built infrastructures. Within the literature, building-based UA has been conceptualized
as Vertical farming, Building-Integrated Agriculture (BIA) or Zero-Acreage farming (ZFarming).
Traditionally, building-based UA has been identified with the term Vertical Farming, which was
defined by Dickson Despommier as:
Farming inside tall buildings within the cityscape (Despommier 2008; Despommier 2009;
Despommier 2010; Despommier 2011).
Also, Ted Caplow (Caplow 2009) coined the term Building-Integrated Agriculture (BIA) as:
A new approach to production based on the idea of locating high-performance hydroponic
farming systems on and in buildings that use renewable, local sources of energy and water.
However, both concepts were based on a high-tech perspective of building-based UA and current
building-based practices were excluded from these definitions.
Recently, Specht et al. (2014) introduced the term Zero-acreage farming (ZFarming) which
included:
All types of urban agriculture characterized by the non-use of farmland or open space,
thereby differentiating building-related forms of urban agriculture from those in parks,
gardens, urban wastelands, and so on.
Therefore, this definition encompassed from vertical greenhouses or indoor farms to rooftop
gardens, rooftop greenhouse or edible walls, regardless the type of technology used.
Figure 1.7 displays the different concepts and forms of building-based UA. Zfarming and BIA
would be the more general concepts. Skyfarming (Germer et al. 2011) and Vertical farming refer
exclusively to vertical farms which are commonly new buildings entirely devoted to food
production. Within existing buildings, current practices are edible walls, indoor farming (i.e.,
which usually employs artificial lighting such as LED) and rooftop farming.
PART I: Introduction and objectives
16
Figure 1.7. Typologies and nomenclatures for urban agriculture on buildings and rooftop
farming.
This dissertation focuses on urban rooftop farming (URF), defined as follows:
Definition of urban rooftop farming used in this dissertation
Urban rooftop farming is the development of farming activities on the top of buildings by taking
advantage of the available spaces in roofs or terraces. URF can be developed through open-air
and protected technologies and used for multiple purposes.
1.3.2. Urban rooftop farming typologies
Urban rooftop farming typologies can be defined based on multiple factors, such as urban
agriculture (Figures 1.4 and 1.5). To simplify the understanding of the main typologies of URF,
these were defined based on two main variables: type of farming and objective.
• Type of farming differentiates between protected and open-air practices, rather than detailing
the type of cultivation or technology employed. Thus, URF can be classified in protected
rooftop farming (i.e., rooftop greenhouses) or open-air rooftop farming.
• Objective is also a dichotomy category. URF are globally divided into commercial (i.e., for-
profit) and social activities. Social URF can though range from private rooftop farming in
terraces to rooftop gardens addressing social inclusion in low-income neighbourhoods.
Then, four main URF typologies are established (Figure 1.8):
• Commercial rooftop greenhouses, such as Lufa Farms in Montreal.
• Socially-oriented rooftop greenhouses, such as the educative RTG of the Manhattan school
for children in New York.
• Rooftop farms, such as Brooklyn Grange in New York.
• Socially-oriented rooftop gardens, which encompass from community rooftop gardens in
residential buildings (e.g., Via Gandusio in Bologna) to therapeutic rooftop gardens in
hospitals (e.g., Wiegmann-Klinik in Berlin).
PART I: Introduction and objectives
17
Figure 1.8. Urban rooftop farming typologies.
1.3.3. Current practices
Urban rooftop farming has sprout over cities in developed countries mainly in the form of rooftop
farms and rooftop greenhouses (Thomaier et al. 2015). Dominated by commercial initiatives,
urban rooftop farming provide local food which is mostly environmentally-friendly (e.g.,
chemical-free, organic practices) and devoted to the community (e.g., CSA, local retailers). This
section compiles some examples of rooftop farms and greenhouses.
(i) Cultivation techniques
Different cultivation techniques are used in rooftop farming, which are in this dissertation
classified as follows:
• soil production, refers to the use of soil as growing media for vegetables production.
• soil-less production, refers to the use of alternative substrates to soil as growing media for
vegetables production (e.g., perlite, coconut fiber).
• hydroponic production, refers to the use of water as the growing media for vegetables
production (e.g., Nutrient Film Technique, NFT).
(ii) Open-air rooftop farming
Rooftop farms and gardens are the most common type of URF project (Thomaier et al. 2015).
Numerous rooftop farms have been developed in the recent years, mostly in North America,
where urban agriculture has notably raised. Rooftop farms are commonly experiences that use
soil production and promote organic farming (i.e., compost), as well as sell added-value products
(e.g., marmalade). The projects commonly provide further benefits to the community, such as
offering education programmes. Due to its novelty, some farms also rent their space for the
organization of events (e.g., Brooklyn Grange).
PART I: Introduction and objectives
18
The Brooklyn Grange1 is one of the most known rooftop farms in New York (United States).
Founded in 2010, the company already has two rooftop farms and a bee apiary on multiple
rooftops in New York. Beyond food production, Brooklyn grange participates in youth education
programs through the association City Growers2 as well as has a training program on urban
agriculture and beekeeping.
• Brooklyn Grange
Type
Commercial rooftop
greenhouse
Flagship farm ©Brooklyn Grange
Navy Yard Farm ©Brooklyn Grange
Name
Brooklyn Grange
Location
Long Island and Brooklyn,
NY, United States
Area
4,000 m2 - 6,000 m2
Year
2010 – 2012
Building type
Business building
(Flaghsip)
Navy yard building
Supply-chain
CSA
Retailers
Wholesale
Produce
Vegetables, honey, sauces
Management
Soil production following organic practices
The project Hell’s kitchen farm3 is an urban rooftop farm installed in the Hell’s Kitchen
neighbourhood, known this way due to the scarcity of affordable fresh produce. Managed and run
by volunteers, the farm addresses the nutritional security by providing local and healthy food to
the community through a Community Supported Agriculture (CSA) program.
• Hell’s Kitchen rooftop farm
Type
Rooftop farm
©Hell’s Kitchen
Name
Hell’s Kitchen
Location
New York, United States
Area
380 m2
Year
2010
Building type
Church
Supply-chain
CSA
Produce
Basil, Beans, Blueberries, Cabbage, Collard Greens, Chives, Cucumbers,
Eggplant, Garlic, Kale, Lettuce, Oregano, Peas, Peppers, Potatoes,
Radishes, Rosemary, Scallions, Tomatoes
Management
Soil production in raised beds, use of self-made compost
1 http://brooklyngrangefarm.com/
2 https://citygrowers.org/
3 http://www.hkfp.org/
PART I: Introduction and objectives
19
Other consolidated rooftop farms are the Eagle Street Rooftop farm4 (Brooklyn, New York), the
Higher Ground Farm5 (Boston, New York) and the HK Farm6 (Singapore). There are other
examples of rooftop gardens that are focused on addressing certain social or environmental
issues. Cloud 97 is a non-profit organization that has recently launched a demonstrative rooftop
garden in Philadelphia (New York) to increase the citizens’ awareness of the environmental and
social benefits of rooftop farming. Cloud 9 also provides education and workshops on the topic
(Figure 1.9).
Figure 1.9. Rooftop garden of Cloud 9 (Philadelphia, USA).
Source: ©Cloud 9.
(iii) Rooftop greenhouses
Rooftop greenhouses are mostly commercial projects located in North America. These type of
experiences use high-technology practices, such as hydroponics and controlled-environment, in
order to maximize the crop yield while minimizing the costs and the environmental burdens of
the activity. In Canada, Lufa Farms8 constructed the first commercial-scale rooftop greenhouse in
2010. The pilot greenhouse was the Ahuntsic which combined different cultivation techniques in
a polyculture greenhouse with differentiated thermal areas. In the United States, Gotham Greens9
also runs a rooftop greenhouse built up to a former warehouse in New York. Both companies
have expanded their businesses by constructing new rooftop greenhouses. Also in New York, the
Vinegar Factory10 is a supermarket that has a rooftop greenhouse on the top of the store to
produce some of their vegetables.
4 http://rooftopfarms.org/
5 http://www.highergroundrooftopfarm.com/
6 http://www.hkfarm.org/
7 http://cloud9rooftopfarm.org/