Sustainable Cities and Society 95 (2023) 104599 Contents lists available at ScienceDirect Sustainable Cities and Society journal homepage: www.elsevier.com/locate/scs The potential of local food, energy, and water production systems on urban rooftops considering consumption patterns and urban morphology Susana Toboso-Chavero a, b, *, Antonio Luis Montealegre c, d, Sergio García-Pérez e, Jorge Sierra-Pérez f, g, Joan Muñoz-Liesa h, Xavier Gabarrell Durany a, b, Gara Villalba a, b, Cristina Madrid-López a a Sostenipra Research Group (2021 SGR 00734), Institute of Environmental Science and Technology (ICTA;«María de Maeztu» Units of Excellence (CEX2019-000940- M)), Z Building, Universitat Autònoma de Barcelona (UAB), Campus UAB, 08193 Bellaterra, Barcelona, Spain b Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona (UAB), Campus UAB, 08193 Bellaterra, Barcelona, Spain c Centro Universitario de la Defensa de Zaragoza, Academia General Militar, Ctra. de Huesca s/n, 50090 Zaragoza, Spain d GEOFOREST-IUCA Research Group, Department of Geography, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain e Department of Architecture, EINA, University of Zaragoza, María de Luna 3, 50018 Zaragoza, Spain f Department of Design and Manufacturing Engineering, EINA, University of Zaragoza, María de Luna 3, 50018 Zaragoza, Spain g Water and Environmental Health-IUCA Research Group, University of Zaragoza, 50018 Zaragoza, Spain h Department of Civil and Environmental Engineering (DECA), School of Civil Engineering (Escola de Camins), Universitat Politècnica de Catalunya (UPC), Jordi Girona 1-3, 08034 Barcelona, Spain A R T I C L E I N F O A B S T R A C T Keywords: The external resource dependency of urban areas results in the externalization of environmental and socioeco­ Resource self-sufficiency nomic impacts. Implementing food, energy and water production systems on urban rooftops (roof mosaics) can Urban agriculture potentially help cities become more self-sufficient but depends on the city’s urban morphology. We studied the Roof mosaic supply potential and impacts of four roof mosaic scenarios for different urban forms in Cerdanyola, a 58 Industrial ecology Green cities thousand-inhabitant town in the metropolitan area of Barcelona. We combined spatial analysis of potential Circular economy rooftops, metabolism analysis, and social and environmental impacts. The municipality has an average rooftop/ household potential of 31 m2 on which to implement any of the mosaic scenarios, with the highest potential in the single-family housing typology. The highest level of vegetable self-sufficiency was found in housing estates (32%), and the lowest in originary fabrics (28%). Regarding electricity and water self-sufficiency, the highest self-sufficiency level was found in the single-family housing typology (51% and 14%, respectively) and the lowest in housing estates (26% and 8%, respectively). Regarding impacts, the implementation of the electricity and rainwater harvesting systems depicts the most positive indicators in single-family housing areas. However, for housing estates and originary fabrics typologies, the best performance is shown to be in the implementation of rooftop farming systems. 1. Introduction 96% of urban growth will be centered in the African and East and South Asian regions (UN-Habitat, 2020). In Europe, urban dwellers are Cities are spaces with high population densities that are intrinsically exposed to harmful concentrations of air pollutants that are well above dependent on imported resources to function (Agudelo-Vera, Leduc, the stringent recommendation of the World Health Organization (WHO) Mels, & Rijnaarts, 2012; Bai, 2007). Import dependency results from the (European Environment Agency (EEA), 2020). This is particularly rele­ occupation of spaces for housing and services, increasingly densified for vant in cities of middle- and low-income countries in which the highest a growing urban population that triggers a myriad of environmental, exposure to air pollutants (e.g., PM10, PM2.5, O3, NO2) has been found social and economic issues. Northern America (83%), Latin America and (World Health Organization, 2018). the Caribbean (81%) and Europe (75%) already have a high rate of Unequal and sometimes difficult access to resources (particularly urbanization, with most people living in urban centers. In the future, energy, water and food) is also an issue that springs from urbanization * Corresponding author. E-mail address: susana.toboso@uab.cat (S. Toboso-Chavero). https://doi.org/10.1016/j.scs.2023.104599 Received 15 January 2022; Received in revised form 18 April 2023; Accepted 18 April 2023 Available online 26 April 2023 2210-6707/© 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by- nc-nd/4.0/). S. Toboso-Chavero et al. Sustainable Cities and Society 95 (2023) 104599 (UN-Habitat, 2020). In Europe, urban households use the most energy Montero, & Rieradevall, 2015; Zambrano-Prado et al., 2021), Quito (27%, only 17.9% for heating/cooling and other activities in house­ (Ecuador) (Nadal et al., 2019), Bologna (Italy) (Francesco Orsini et al., holds), and energy production (for all types of activities, not only 2014) or Lisbon (Portugal) (Benis, Turan, Reinhart, & Ferrão, 2018) household activities) is the second highest consumer of energy (19.8%); among others. The production of energy has also been widely explored therefore, both activities account for almost 46.8% of Europe’s total at the country scale (Ramirez Camargo, Nitsch, Gruber, & Dorner, energy consumption (Eurostat, 2020). Agriculture is still the largest 2018), city scale (Barragán-Escandón, Zalamea-León, Terrados-Cepeda, consumer of water in European cities (40%), especially in southern & Vanegas-Peralta, 2020; Bazán, Rieradevall, Gabarrell, & countries, followed by energy production, mining and manufacturing, Vázquez-Rowe, 2018; Chung, 2018; Jurasz, Dąbek, & Campana, 2020; and household use (12% - 144 l/person/day) (EEA, 2018). Food provi­ Villa-Arrieta & Sumper, 2019; Zhu et al., 2022) community scale (Awad sion is a challenge in urban areas, particularly as European kcal intake & Gül, 2018; Mehta & Tiefenbeck, 2022) or building scale (Fardi has increased, especially the intake of meat, sugars, salt and fats (Willett Asrami, Sohani, Saedpanah, & Sayyaadi, 2021; Luthander, Nilsson, et al., 2019), reaching 13% of the total annual household expenditure Widén, & Åberg, 2019; Menoufi, Chemisana, & Rosell, 2013), using and representing the second highest expense after housing, water, different methodologies and approaches. In a similar vein, the use of electricity and gas (23.5%) (Eurostat, 2019). rainwater has been analyzed in different ways and with different pur­ In this context, Europe’s organization of urban spaces allows for a poses in cities (de Sá Silva, Bimbato, Balestieri, & Vilanova, 2022), such more efficient means of taking action to tackle climate change. Histor­ as agriculture (Hume, Summers, & Cavagnaro, 2022), domestic appli­ ically, European cities have been traditionally compact, dense and cations (Angrill et al., 2016; Ortiz, de Barros Barreto, & Castier, 2022; walkable, mostly with well-organized public transportation systems Vargas-Parra, Rovira, Gabarrell, & Villalba, 2014) or a mix of them (Ali (Timothy Beatley, 2000). However, strategies that aim to increase the & Sang, 2023; Farreny, Gabarrell, & Rieradevall, 2011). availability of resources from local sources find the variety of building Some studies have assessed the three resources (FEW) from different typologies and urban forms that can be found in European cities to be a perspectives, such as from a technical point of view (Zambrano-Prado challenge. Indeed, features such as size, shape, distribution of open et al., 2021), using system dynamics modeling analysis (Valencia, Hos­ spaces and type of rooftops can considerably affect the success of climate sain, & Chang, 2022), addressing only urban metabolism in urban change mitigation measures in urban areas (Jenks & Colin A, 2010; growth models (Chang, Hossain, Valencia, Qiu, & Kapucu, 2020), and Oliveira, 2016). Consequently, urban morphology, i.e., the discipline of from a circular city perspective, concluding that a circular city is plau­ urban planning that studies the physical dimension of the built envi­ sible but needs a multidisciplinary analysis (Valencia et al., 2022). ronment (Oliveira, 2016), can play a role in the improvement of the Studies strongly advocate considering environmental, social, economic, coordination and deployment of sustainable urban initiatives (Fang, spatial and cultural dimensions based on participatory process and Wang, & Li, 2015). In a morphology study, cities are split into smaller appropriate methodologies to progress in sustainable and inclusive subsystems based on urban forms, fabrics or tissues to find similar so­ development (Garcia & You, 2016; Kundu, Sietchiping, & Kinyanjui, lutions to their environmental and social performance. Due to the 2020). Therefore, in our study we intend to cover all these aspects. The complexity and heterogeneity of metropolises, smaller sections such as FEW implementation literature in cities has a significant gap in most urban fabrics, which are a physical expression reflecting specific fea­ studies which is the scant consideration given to the multifaceted nature tures, can help to characterize the type of residents that live in these of resource production in cities. Often, studies only focus on a single cities, finding common environmental and social issues in sites with vector (energy or food production, or rainwater harvesting), dis­ similar structural conditions (Braulio-Gonzalo, Ruá, & Bovea, 2020). regarding the three pillars of sustainability - environmental, economic, The urban morphology discipline therefore offers an integrated view and social - and failing to take a systemic and multidisciplinary approach of the analysis and implementation of climate change solutions (Lamb, that accounts for pattern consumption (using local and specific data), Creutzig, Callaghan, & Minx, 2019). Several studies have proposed urban form, and rooftop resident preferences. To the best of our urban morphology as a key factor to assessing different sustainable knowledge, no studies have comprehensively evaluated the urban urban strategies when developing geospatial models. Braulio-Gonzalo strategy for sustainable local production of food, energy and water and Colleagues (2020) developed a methodology for breaking cities which incorporate the physical, socio-economic, and resident preference down into small pieces in order to deploy urban initiatives. Jabareen components on a city scale. Three crucial factors are necessary for the (2006) analyzed the best urban forms for sustainability, and Oliver-Solà successful implementation of any urban strategy, and they are relevant et al. (2011) proposed a method that combines different urban mor­ to city councils, urban planners, and organizations alike. In this paper, phologies with environmental data to aid urban planners in making we assess the implementation of a sustainable urban strategy in a decisions based on environmental criteria. Energy aspects and urban mid-sized city with different urban forms by quantifying the potential morphology have been widely studied for various purposes, namely, to production of food, energy and rainwater harvesting (FEW) on urban link energy systems more efficiently for renewable energy and urban rooftops (termed the roof mosaic by authors (Toboso-Chavero et al., archetypes (Perera, Coccolo, & Scartezzini, 2019) or to understand the 2019)). energy demand and promote energy renovation scenarios (Middel, Häb, This implementation of a sustainable urban strategy will reduce the Brazel, Martin, & Guhathakurta, 2014; Rode, Keim, Robazza, Viejo, & consumption and exploitation of external resources and increase the Schofield, 2014). Furthermore, in the design of sustainable transport, self-sufficiency of the city. To do so, we geospatially assess the potential urban forms play a vital role (Babalik-Sutcliffe, 2013; Feng, Fujiwara, & rooftops of the municipality and characterize their urban forms to Zhang, 2008). implement the production of food, energy and water (FEW) and Local resource production as single systems on rooftops has been compare them to current consumption. Finally, we assess the feasibility addressed in many different studies but without considering together the and desirability of future roof mosaic scenarios. three main consumed resources in cities (food, energy, and water), or The present paper is structured into four major sections, beginning presenting an integrated approach. Rooftop food production has been with the introduction and objectives, after Section 2 on methods, Sec­ extensively studied worldwide (Appolloni et al., 2021; F. Orsini, tion 3 (results and discussion) provides five different sub-sections. Dubbeling, De Zeeuw, & Gianquinto, 2017). There are many studies Firstly, the resource rooftop supply potential by urban form, secondly devoted to food self-sufficiency in cities in different urban spaces and and thirdly, the consumption and production characterization of the different types of cultivation (open-air farming or/and rooftop green­ municipality and urban forms, fourthly the resource potential supply vs houses), such as Berlin (Germany) (De Simone, Pradhan, Kropp, & consumption considering urban morphology; and fifthly, the sustain­ Rybski, 2023), Boston (United States of America) (Saha & Eckelman, ability performance per scenario. We also added some concluding re­ 2017), Barcelona (Spain) (Sanyé-Mengual, Cerón-Palma, Oliver-Solà, marks and further research in Section 4. 2 S. Toboso-Chavero et al. Sustainable Cities and Society 95 (2023) 104599 2. Materials and methods remote sensing data were captured by the National Plan of Aerial Orthophotography (PNOA ©Instituto Geográfico de España – Institut The methodology is organized into three steps (Fig. 1). First, a geo­ Cartogràfic de Catalunya) in September 2016 using a Leica ALS50 spatial model was developed to characterize rooftops and urban forms, i. discrete return sensor with an average density of 0.5 points/m2. The e., the morphological characterization (Section 2.2). The study area DSM was essential to deriving the rooftop slope, azimuth, shading and covers 31 km2, holding 3,583 buildings and 23,726 households. Second, solar radiation, which were later used to select suitable rooftops for we characterized the households of the municipality according to their agriculture and photovoltaic (PV) panels via a multicriteria decision consumption patterns and rooftop use preferences (Sections 2.3 and analysis in a geographic information system (GIS). See supplementary 2.4). A comparison between the potential resource supply and the data 1 for details. consumption patterns helped us define viable scenarios of rooftop uses (Section 2.5). 2.2.2. Estimation of the potential supply 2.1. Study area 2.2.2.1. Food: Urban agriculture. The installation of urban rooftop farming, in general, requires a load capacity of higher than 200 kg/m2 Cerdanyola del Vallès (from now on Cerdanyola) is a medium-sized on a flat roof (surface slope ≤10◦ ) and insolation equal to or higher than city of approximately 58 thousand inhabitants (IDESCAT, 2020) and is 3.61 kWh/m2/day (Nadal et al., 2017). For growing vegetables, a roof located in the metropolitan area of Barcelona (AMB; 36 municipalities surface of at least 13 m2 is needed, which can meet the vegetable con­ and of 5.4 million inhabitants) (Catalonia; Spain). The municipality has sumption requirements for one person using soilless cultivation systems a Mediterranean climate with mild winters and hot summers, a seasonal (Zambrano-Prado et al., 2021). Also, the selected vegetables are proven rain pattern that averages 610 l/m2/year and an average global solar to be grown in this type of climate (Boneta, Rufí-Salís, radiation of 4.56 kWh/m2/day (AEMET, 2006). Cerdanyola also has an Ercilla-Montserrat, Gabarrell, & Rieradevall, 2019). average of 1,478 heating degree days (base temperature 18◦ C) and 384 cooling degree days (base temperature 21◦ C) (based on the 2022 year) 2.2.2.2. Energy: Photovoltaic. We assumed that multicrystalline silicon (Eurostat, 2023). The municipality was chosen because its urban forms (multi-Si) photovoltaic panels were installed and that the annual elec­ are well differentiated and representative of those that can be found in tricity (Ee obtained in kWh/year (y)) produced on each rooftop was other European cities: i) a dense historic center, ii) suburban extension, calculated as: iii) different areas of housing estates, iv) dispersed single-family housing Ee = IG⋅ηPV⋅APV⋅PR (1) areas and v) isolated industrial parks (PDU, 2017). In this study, the historic center and suburban extension were grouped with the originary Where IG is the global annual irradiance in kWh/m2/y, Ƞ PV is the fabrics spatial pattern. A more accurate definition of each of the fabrics PV panel efficiency, APV is the area of the installed PV panels in m2, and can be found in Table 1. PR is the PV system performance ratio. The global irradiance (IG) received for the panels depends on the PV tilt angle. We assume that the panels will be mounted following the 2.2. Estimation of the potential supply rooftop slope if it is ≥38◦ or at the optimal angle for energy production (38◦ ) for lower slopes and will be considered an increasing coefficient of 2.2.1. Identification of suitable rooftops 1.19 for solar irradiance, obtained from the PVGIS interactive tool The identification of suitable rooftops was conducted using different (https://re.jrc.ec.europa.eu/pvg_tools/en/#PVP). The module’s effi­ geoprocessing and spatial analyst tools in QGIS (version 3.22.2) and ciency (Ƞ PV) was 16%, which is a typical value for crystalline silicon ArcMap (10.7.1) software (ESRI Inc.) following the methodology of modules. The system performance ratio (PR) coefficient includes the Montealegre, García-Pérez, Guillén-Lambea, Monzón-Chavarrías, & losses in the system caused by cables, power inverters, dirt, etc. and by Sierra-Pérez (2021). We used airborne laser scanning (ALS) data to build the modules, because they tend to lose power over the lifetime of the a digital surface model (DSM) of the city with a 1-meter cell size. These Fig. 1. Diagram of the main steps of the applied methodology. FEW: food-energy-water; MuSIASEM: Multi-scale Integrated Analysis of Societal and Ecosystem Metabolism. 3 S. Toboso-Chavero et al. Sustainable Cities and Society 95 (2023) 104599 Table 1 weight of the water tank that has to be installed on the rooftop. How­ Urban morphologies of the study area. ever, the water tank’s weight limit can be optimized depending on the Morphology Description Spatial pattern roof and building and can be placed in different places (on the roof, on a lower story or underground) (Toboso-Chavero et al., 2019). Originary These plots have fabrics experienced a strong process of 2.2.3. Aggregation: from building to urban morphologies densification. The building areas (i.e., roofs) were provided from the Spanish Continuing the Cadastre (land registry) in shapefile format as polygon geometries compact city is the suburban extension. (Dirección General del Catastro, 2014). After grouping the building This is a morphology footprints according to cadastral reference and height attributes, a whose planning gives 1-meter inside buffer was applied to the building polygons. rise to an ordered road Rooftops were grouped according to their urban form following the system, and a categorization done by the future Metropolitan Plan (Metropolitan subdivision of plots whose development is Urban Master Plan (PDU, currently under development)) (PDU, 2017). focused on the The morphological categories used in this study are defined based on alignment of the their growth pattern and the evolution of the urban form (see Table 1). street. The result is the dense and compact perimeter block. 2.3. Characterization of food, energy, and water (FEW) consumption Housing estates The sprawl city is based on slab-like Domestic energy and water consumption was supplied by the dis­ developments. Among tribution companies for 2018, 2019 and 2020 (note that the coronavirus the slabs, a first pandemic started on 14 March 2020). An average of these three years distinction is made between those which was used. Data by street and number addresses of buildings with five or form part of unitary more households were aggregated by urban form and municipality. organizations, but Vegetable consumption was surveyed during April of 2021 (more which are not aligned than one year since the start of the coronavirus pandemic) along with with the street the residents’ preferences for the use of their rooftops (Table 2). The network. This category includes the survey used a stratified random sample by urban form typology, i.e., well-known massive housing estates, originary fabrics (including historic centers and sub­ housing estates. urban extensions) and single-family housing areas. The survey was Single-family Single-family housing answered by 1100 residents (raw data in open access: 10.5565/ddd.uab. housing areas areas are represented by unitary cat/267206; see outcomes in supplementary data 2). We validated the organization slabs results with the average values from official statistics. aligned to the street network, such as the 2.4. Checking the viability of scenarios contemporary suburban perimeter blocks. As part of We used the supply and end-use matrices from the multiscale inte­ single-family grated analysis of societal and ecosystem metabolism (MuSIASEM) morphologies, the (Giampietro, Mayumi & Ramos-Martin, 2009) to assess the viability and following are self-sufficiency of each urban morphology as defined by Toboso-Cha­ included: those that generate isolated vero, Villalba, Gabarrell Durany, & Madrid-López, (2021). Flow vari­ buildings on plots or ables are defined as the total end use of each resource per year for each more compact fabrics, urban form and the municipality. The intensive variables were calcu­ such as those lated based on human activity (hours, h) per type of household, deter­ produced by grouped mined by the working status and number of people per household as a terraced houses. Nonresidential Public and private proxy using the official time use survey (Generalitat de Catalunya, uses facilities, industrial 2011). A detailed list of the analytical levels and the variables used is parks or other displayed in Table 3. buildings that do not The FEW consumption was crossed with the potential rooftop pro­ fit the patterns described above have duction at the municipality and urban form levels to obtain resource been considered as self-sufficiency. ’others’. 2.5. Integrated assessment of roof mosaic scenarios To assess the different viable rooftop mosaic scenarios, we analyzed system, depending also on the module working conditions and the them in terms of their sustainability performance, i.e., environmental, temperature. The value obtained from PVGIS for this coefficient is 0.79 social and economic performance. The performance indicators (PIs) for flat and 0.76 for sloped roofs. If the slope value was greater than 38◦ , defined are covered in Table 4 based on previous studies, residents’ the pixel value assigned was 0.76 (sloped roof), if not, 0.79 (flat). concerns – retrieved from the survey- and the most used on this topic Furthermore, the area solar radiation model uses a monthly resolution to (Toboso-Chavero, Madrid-López, Gabarrell, & Villalba, 2021; Tobo­ summarize the annual global radiation. See additional details in sup­ so-Chavero et al., 2019). plementary data 1. 2.2.2.3. Water: rainwater harvesting. The only condition for water har­ vesting is the load capacity of the roof, which must be able to hold the 4 S. Toboso-Chavero et al. Sustainable Cities and Society 95 (2023) 104599 Table 2 Datasets and sources for the current study of the socioeconomic profile of residents. DATASETS Consumption of Consumption of energy Consumption of water Work status Household Human activity Preferences for the vegetables occupation rooftop’s systems SOURCES Survey (open Distribution company Distribution company Survey (open Survey (open Official statistics ( Survey (open access access data) (confidential data) (confidential data) access data) access data) Generalitat de data) Catalunya, 2011) Table 3 Definition of end-use and supply matrices and variables. Resources: vegetables (kilogram, kg); gram, g), electricity (kWh; MJ), and water (cubic meter, m3; liter, l). Levels (scales) Fund elements Variables end-use municipality (n) human activity (HA)/year of household activities extensive variables matrix n-1 resource total consumption (kg; kWh; m3)/year [housing estates intensive variables originary fabrics resource metabolic rate (resource consumption (g; MJ; l)/hour of household activities) single-family housing] supply matrix municipality (n) human activity (HA)/year of rooftop uses resource losses (kg; kWh; m3)/year (maintenance) n-1 resource total requirement (kg; kWh; m3)/year [housing estates originary fabrics resource savings (kg; kWh; m3)/year single-family housing] (Angrill et al., 2016). In terms of urban forms, single-family housing Table 4 areas have a great potential due to the area of the rooftops (13,6 ha; Performance indicators (PIs) applied in the case study and the type, source or 19%); however, out of these three urban forms, the “others” category method proposed of these indicators. (nonresidential uses) has the highest potential, with an area of 31.2 ha, Type of Performance indicators Method/source which is 43% of the total potential roof area in the municipality. The indicator rooftops of the municipality represent an average of 18.4% of the total Sustainability % Resource self-sufficiency MuSIASEM land area. Comparing the percentage of rooftop surface to land occupied Increase of green spaces (m2) Taylor et al., 2011; Van Herzele by urban form, the originary fabrics have the highest ratio (19.5%), & Wiedemann, 2003 Environmental kg CO2 savings/year LCA- Recipe method (H), while the lowest ratio is for single-family housing areas (7.5%). There­ Goedkoop et al 2013 fore, more land area is needed in single-family housing areas, and in Global Warming (kg CO2 eq) LCA- Recipe method (H), contrast, there are fewer open spaces (i.e., space between buildings) in Goedkoop et al 2013 the originary fabrics. Housing estates (12.3%) are in between these two Social Energy poverty coverage The Green/EFA group of the (number of households) European Parliament, 2016 urban forms. Water poverty coverage Lawrence, Meigh, & Sullivan, We observed that only 46% of the total rooftop area of the munici­ (number of households) 2002 pality has potential for the implementation of PV panels, since the rest of Maintenance investment MuSIASEM// Project data & the rooftops are not suitable due to either their slope or orientation. In (hour/household/year) Distribution companies this respect, originary fabrics and single-family housing areas reduce Economic Investment (€/household) Distribution companies Monetary savings Public prices rooftop potentiality for PV panels to 45 and 46%, respectively, whereas (€/household/year) housing estates leave a slightly less room for PV panels, reducing their potentiality of use to 42%. Potential rooftop areas for growing vegeta­ bles were reduced to 8% in the municipality. Regarding urban forms, the 3. Results and discussion reduction was insignificant for housing estates (-4%), but there was a very relevant decrease in roof surface area for originary fabrics (-49%) 3.1. Rooftop supply potential by urban form and single-family housing (-57%); this means that level, well-oriented roofs are more common in housing estates than in the originary fab­ The municipality depicts, as Fig. 2 illustrates, a historic center sur­ rics and single-family housing areas. rounded by suburban extension districts and housing estates and also The comparison of supply and consumption reflects differences some isolated housing estates mixed with wide extensions of single- among urban forms (Fig. 2). Concerning vegetables, the situation of family housing areas. The historic center and suburban extension dis­ maximum production and minimum consumption is mainly identified in tricts, i.e., originary fabrics, occupy almost the same amount of land as housing estates and some areas of the originary fabrics. On the other the housing estates - approximately 70 hectares (ha) - and have a similar hand, single-family housing areas are characterized by medium to high number of households, 7,619 and 7,637, respectively. In contrast, the production but also by high consumption. In relation to energy and single-family housing areas occupy almost four times more land (253 water resources, the behavior is slightly different, as housing estates ha) than the other two urban forms and have only 11% more house­ depict the highest production and the lowest consumption, while single- holds. This greater occupation of land means that approximately 45% of family housing and originary fabrics display high production but also the gross floor area of the municipality is colonized by single-family high consumption of both energy and water. The category “others” ex­ housing areas. hibits the optimal case of minimum consumption and maximum pro­ The municipality has a total of 72.7 ha of rooftops (Table 5) to be duction, but this is a consequence of accounting only for household exploited for different purposes. All of them can be used for rainwater consumption without including the nonresidential uses. Specific details harvesting, as it is feasible to collect rainwater on any typology of roofs 5 S. Toboso-Chavero et al. 6 Sustainable Cities and Society 95 (2023) 104599 Fig. 2. Food, energy, and water consumption vs. production on rooftops. The first map identifies the three urban forms, e.g., housing estates, originary fabrics and single-family housing areas, as well as the others category. The rest of the maps represents the consumption vs. production of food, energy and water. The bar charts show the resource self-sufficiency by urban form and the total of the municipality. HE: housing estates; OF: originary fabrics; SF: single-family housing areas; others: public and private facilities and industrial parks; mun: municipality. S. Toboso-Chavero et al. Sustainable Cities and Society 95 (2023) 104599 Table 5 Characterization of the rooftops at the municipality and urban form scales. Note the category others refers to public and private facilities and industrial parks. URBAN FORMS Municipality (total) housing estates originary fabrics single-family housing others m2 rooftop vegetables 274,707 35,251 31,885 37,752 165,185 m2 rooftop electricity 334,245 36,907 63,095 88,506 145,738 m2 rooftop water 727,254 87,664 136,118 191,054 312,418 m2 land 5,650,695 714,910 696,334 2,532,754 1,706,697 number of households 23,726 7,619 7,637 8,470 0 m2 rooftop/m2 land (vegetables) 0.049 0.049 0.046 0.015 0.097 m2 rooftop/m2 land (electricity) 0.059 0.052 0.091 0.035 0.085 m2 rooftop/m2 land (water) 0.129 0.123 0.195 0.075 0.183 m2 rooftop/household (vegetables) 11.6 4.6 4.2 4.5 7.0 m2 rooftop/household (electricity) 14.1 4.8 8.3 10.4 6.1 m2 rooftop/household (water) 30.7 11.5 17.8 22.6 13.2 can be found in an open access map https://uab.maps.arcgis.com/apps/ respectively, suggesting higher consumption of all measured resources. mapviewer/index.html? Examining the metabolic rates among people living in these urban webmap=7e72e430e1204418b3ceb6257d27e4ae forms, the highest rates of vegetable and electricity consumption Assessing the availability of rooftops per household (Table 5), the correspond to the single-family housing areas (11.4 g/hour (h) and 0.85 municipality has an average of 31 m2 rooftop/household (hh), including MJ/hour, respectively) and the lowest to the housing estates (10.5 g/h the “others” category that contributes to 13.2 m2/hh for the entire and 0.75 MJ/h, respectively). Single-family housing areas consume municipality, approximately 42% of the total. By urban form, single- approximately 8.6% more vegetables, 13% more electricity and 20% family housing obtained the highest value (22.6 m2/hh), and the more water than housing estates do, which serves as a relevant reference lowest was for housing estates (11.5 m2/hh), caused by a higher density for resource consumption in these single-family housing areas. The of households in housing estates and, therefore, less availability of roofs. originary fabrics exhibit a more heterogeneous behavior. Inhabitants of For PV implementation (municipality:14.6 m2/hh), the tendency was these areas consume less vegetables and electricity than inhabitants of the same, but this availability was reduced by more than half, which single-family dwellings but consume almost the same amount of water. means only 4.8 m2 for housing estates, 8.3 m2 for originary fabrics and The originary fabrics are usually an amalgam of different types of 10.4 m2 for single-family housing areas. As for the amount of space buildings, from low-rise apartment blocks to single-family housing; thus, available for growing vegetables, the trend changes and housing estates consumption tends to be more variable compared to that of housing have the highest ratio with 4.6 m2/hh and the lowest is for the originary estates and single-family housing areas, which are more homogeneous fabrics (4.2 m2/hh). urban forms. When these outcomes are compared with those of other studies, some differences can be highlighted. The vegetable metabolic rate within this 3.2. Consumption characterization of the municipality and urban forms municipality is higher than that of Catalunya and lower than that of a nearby municipality (Badia del Vallès) composed only of housing es­ The total consumption of residents in the different urban forms re­ tates, 9.9 g/h versus 13.1 g/h (Toboso-Chavero et al., 2021).The elec­ veals remarkable differences in the extensive indicators (Fig. 3). Single- tricity metabolic rate, the results (municipality: 0.81 MJ/h) are similar family housing areas account for 11% more dwellings than the originary to those of Barcelona (0.72 MJ/h), Europe (0.74 MJ/h) and the afore­ fabrics and housing estates; however, vegetable consumption is 16% and mentioned municipality (0.82 MJ/h) (Pérez-Sánchez, Giampietro, 21% higher than in the originary fabrics and housing estates, respec­ Velasco-Fernández, & Ripa, 2019; Toboso-Chavero et al., 2021; Velas­ tively. The same is true for electricity consumption, where consumption co-Fernández, 2017). In this case, the municipality has a lower water is also 14% and 26% higher, respectively. Concerning water consump­ metabolic rate than Catalunya and Badia del Vallès (Madrid & Cabello, tion, single-family housing areas consume a quarter more than housing 2011; Toboso-Chavero et al., 2021). estates, but no more than the originary fabrics, which is only 8% lower when there are 11% fewer households. Comparing housing estates and originary fabrics, which have a 3.3. Production characterization of the municipality and urban forms similar number of households, the vegetable, electricity, and water consumptions are higher in the originary fabrics by 4%, 10% and 20%, Three possible resources (vegetables, electricity and water) for Fig. 3. Resource consumption (lines; extensive variable) and resource metabolic rate (bars; intensive variable) of the municipality and the different urban forms derived from the end-use matrix (see supplementary data 1). HE: housing estates; OF: originary fabrics; SF: single-family housing areas; MUN: municipality; h: hour; y: year; M: million. 7 S. Toboso-Chavero et al. Sustainable Cities and Society 95 (2023) 104599 potential rooftop production were assessed (Table 6). The combination point of view, flat roofs have more potential for implementing any type of energy or vegetable production with rainwater harvesting is possible of FEW resource, so the promotion of flat roofs in new constructions because no additional space is needed, and only a water tank is required, could lead to more suitable exploitation of these spaces; evidently, other which can be placed on the roof, in other parts of the building or un­ technical, social and economic criteria should also be considered. derground (Angrill et al., 2012). Housing estates have the lowest ratio of m2 of rooftops per household The viability assessment returns, depending on the type of urban (11.5 m2/household (hh)) and have the smallest apartments, averaging rooftop farming, between 78% (open-air farming, OAF) and 104% 86 m2. Hence, there is an actual need to provide additional common (rooftop greenhouses, RTG) of consumption supplied by rooftop pro­ spaces for these families. On the other hand, originary fabrics have more duction for the main vegetables consumed in Cerdanyola: tomatoes, heterogeneous buildings, rooftops and consumption patterns than lettuces, peppers, and green beans (59 kg/person/year). However, when housing estates because of the combination of different constructions, each urban form is assessed on its own, these percentages decrease mixing the old and new constructions of blocks and houses, and type of considerably because most available areas appear to be in the “others” household. This urban form shows the lowest ratio of rooftops and open category. The FEW consumption of the “others” category is not included, space, meaning that it is the most compact area, with few intermediate and only household consumption is included. The highest self- spaces between buildings and no possibility for further construction. The sufficiency is detected in housing estates, both in OAF (32% of self- average rooftops are 127 m2; therefore, some will be too small to sufficiency) and RTG (43% of self-sufficiency), due to their lower implement rooftop farming. However, the best solution would be to use vegetable consumption; the highest vegetable total production is iden­ these rooftops for green infrastructures to grant these areas more green tified in single-family housing areas (535 tons), due to their having a spaces. Regarding single-family housing areas, rooftops are the most greater surface area of rooftops. limited, averaging 104 m2, but they have the highest open spaces be­ The municipality has the potential to supply 36-71% of the total tween buildings and are the largest households (102 m2) with the electricity. However, the largest potential is again in “others”, at almost highest FEW consumption. It would be more viable to implement PV half (16-32%) of the potential production of electricity in the munici­ panels in single-family housing areas due to the open space they have to pality. Comparing by urban form, the self-sufficiency of this resource in use for soil-based agriculture and their characteristic small and sloping single-family housing doubles (25-51%) that in housing estates (13- roofs. Therefore, urban forms are the key to implementing the most 26%), while the originary fabrics are somewhere in between (19-39%). suitable systems on roofs as climate change adaptation strategies. The municipality has the potential to collect approximately 377,699 Considering the physical characteristics of these urban forms would m3/year of rainwater. For potential rainwater harvesting, combining it make it easier to promote a strategy for self-sufficiency in these areas. with electricity production, this rainwater could be utilized for toilet However, consumption is another key parameter to consider when flushing, covering 18% of the municipality’s total requirements. In the proposing a suitable strategy. This study was conducted under corona­ case of crop irrigation in combination with urban rooftop farming (OAF virus pandemic conditions; therefore, time use or resource consumption and RTG), self-sufficiency soars to 101 and 129% in OAF and RTG, could be influenced by these conditions. To account for the electricity respectively. Again, the larger total surface area of rooftops in single- and water consumption patterns, the average of three years, 2018, 2019 family dwellings means that they have the highest potential for har­ and 2020, was used. The difference between electricity consumption in vesting rainwater and also in terms of self-sufficiency. Nevertheless, in 2018 and 2019 entailed an increase in total consumption of 0.77%, and all urban forms, the crops could be irrigated exclusively with rainwater, between 2019 and 2020 there was an increase of 0.79%; energy con­ and there would even be a surplus for other uses. sumption during both periods increased by nearly the same amount, Apart from the potential production of these resources in the mu­ although 2020 was the pandemic year with a lockdown lasting almost nicipality, it is also necessary to account for losses arising from con­ two months. In terms of water consumption, the differences were more ventional and centralized systems (Table 6), i.e., losses from the relevant between years. The difference between 2018 and 2019 entailed transformation and distribution of centralized electricity systems, losses a decrease of 0.9% in water consumption, while the difference between from harvesting, transportation of centralized food and water distribu­ 2019 and 2020 was an increase of 7.8%. Therefore, a considerable rise in tion losses. The highest losses are assigned to conventional electricity water consumption can be detected in the lockdown year (2020). systems by 63% (Domene & García, 2017), followed by vegetable losses Housing estates have an average electricity consumption of 3,000 by 25% related to harvesting and distribution (Caldeira, De Laurentiis, kWh/hh/year, originary fabrics of 3,290 kWh/hh/year and single- Corrado, van Holsteijn, & Sala, 2019) and water centralized systems by family housing areas of 3,394 kWh/hh/year. These consumption 7.4% (retrieved from a water distribution company). Consequently, all levels are similar to the Catalan average (3,400 kWh/hh/year) (Gen­ of these losses from centralized systems could also be reduced by eralitat de Catalunya, 2020a), and below the Spanish average (3,918 applying strategies of local production in municipalities, i.e., the roof kWh/hh/year), and the European average (3,700 kWh/hh/year) mosaic that we propose. (Enerdata, 2020). In the municipality (88 m3/hh/year), the lowest average water consumption is in housing estates (73 m3/hh/year), and 3.4. Food, energy, and water potential supply vs. consumption considering the originary fabrics and single-family housing areas are very similar (87 urban morphology and 85 m3/hh/year, respectively). Compared with the average in Spain (130 m3/hh/year (2017)) or the European average (111 m3/hh/year), The urban forms analyzed in this study are characterized by different there is a significant difference (The European Federation of National features that affect the implementation of the roof mosaic. Housing es­ Associations of Water Services, 2017). The municipality’s vegetable tates areas are distinguished by more extensive and flatter roofs than the consumption (59 kg/person/year) is higher than the Catalan average other urban forms. The effect of this feature was demonstrated by the (32 kg/person/year) (Generalitat de Catalunya, 2020b). Therefore, the small difference between roofs available for energy and those for self-sufficiency of each urban form depends not only on the availability growing vegetables (only flat roofs), reducing their potential by only of rooftops but also on the type of resident. 4%. However, in the other urban forms, the reduction was approxi­ mately 50%. Likewise, the average roof surface in housing estate 3.5. Municipality and urban form performance per scenario buildings is 420 m2, which is almost three times larger than that of the other two urban forms. Housing estate buildings have remarkable po­ According to the survey outcomes, most of the residents (77% total; tential for implementing rooftop farming, although these areas display women: 74.5%, men: 80%) would prefer to implement the production of viable open space between buildings that could also be used for urban electricity on their roofs (see details of the survey in supplementary data farming, i.e., soil-based agriculture. Therefore, from an environmental 2), thus choosing the most conservative and nondisruptive option. 8 S. Toboso-Chavero et al. Table 6 Supply matrix with the different resources (vegetables, electricity, and water at the municipality (MUN) and three urban forms. PV: photovoltaic panels; OAF: open-air farming; RTG: rooftop greenhouses; RWH: rainwater harvesting. NA: not available; SV: same value as each scenario; kh: kilohours; M: million. FLOWS SUPPLY MATRIX VEGETABLES ELECTRICITY WATER End use Human Savings % Self- End use (kWh/ Human Savings % Self- End use Human Savings % Self- (kg/year) activity (kh/ (kg/year) sufficiency year) activity (kh/ (kWh/year) sufficiency (m3/year) activity (kh/ (m3/year) sufficiency year) year) year) Centralized Imported resource 3.742.841 NA 0 0 76.755.686 NA 0 0 2.088.367 NA 0 0 Centralized Exported resource 0,00 NA 0 0 0 NA 0 0 0 NA 0 0 Decentralized PV + RWH 0 0,0093 54.693.528 71% 175 375.699 18% (municipality) housing estates 0,0010 5.911.321 26% 21 45.287 8% originary fabrics 0,0017 9.724.183 39% 33 70.318 11% single-family 0,0025 14.623.427 51% 46 98.698 14% housing others 0,0040 24.434.597 32% 75 161.395 8% Decentralized OAF + RWH 3.173 2.911.894 78% 175 375.699 101% (municipality) housing estates 407 373.661 32% 21 45.287 95% 9 originary fabrics 368 337.981 28% 33 70.318 163% single-family 436 400.171 29% 46 98.698 194% housing others 1.908 1.750.961 47% 75 161.395 44% Decentralized RTG + RWH 1.846 3.889.851 104% 175 375.699 129% (municipality) housing estates 237 499.154 43% 21 45.287 121% originary fabrics 214 451.492 37% 33 70.318 208% single-family 254 534.568 38% 46 98.698 246% housing others 1.110 2.339.020 62% 75 161.395 55% Decentralized ALL SYSTEMS 1.255 1.700.436 45% 0,0046 27.346.764 36% 175 375.699 227% (municipality) housing estates 161 218.204 19% 0,0005 2.955.661 13% 21 45.287 213% originary fabrics 146 197.368 16% 0,0009 4.862.092 19% 33 70.318 366% Sustainable Cities and Society 95 (2023) 104599 single-family 172 233.685 17% 0,0012 7.311.713 25% 46 98.698 433% housing others 754 1.022.495 27% 0,0020 12.217.298 16% 75 161.395 97% Losses 1.105.096 NA 0 0 130.616.756 NA 0 0 168.883 NA 0 0 Total 4.847.936 NA SV SV 207.372.442 NA SV SV 2.257.250 NA SV SV requirement S. Toboso-Chavero et al. Sustainable Cities and Society 95 (2023) 104599 Rainwater harvesting was accepted by 43% of the residents to imple­ The category “others” has the highest number of roof areas; thus, ment on their roofs. The last option was rooftop farming (OAF and RTG), there is a large area to exploit. However, their FEW consumption is not which was only accepted by 20-21% of the residents. They opted for included in this study, only the municipality’s domestic consumption. more manageable and normalized systems on their roofs such as solar Additionally, these private and public facilities and industrial uses tend panels. Residents found more organizational and implementation issues to have roofs with a very low load capacity and are made of metal sheets, with rooftop farming systems. Nonetheless, this proportion increases if fiber cement or other nonresistant materials (Nadal et al., 2017). Thus, the proposal is a combination of all of them (27%), i.e., production of this is a limitation to implementing rooftop farming systems. energy and vegetables and rainwater harvesting. The survey conducted Scenario 1 (PV+ RWH) obtained the most positive indicators at the confirmed the challenges associated with implementing open-air municipality level; by urban form, housing estates show better outcomes farming or greenhouse systems on rooftops. While there is a feasible in scenarios 3 and 4, with both dedicated to vegetable rooftop farming. capacity to implement these systems, there are several real-world This urban form has higher self-sufficiency in vegetables and lower challenges that must be addressed. These challenges include lack of monetary investment and environmental impacts. Because these areas agreement among neighboring communities, resistance to change, have mostly flat roofs, they are ideal for implementing OAF or RTGs; economic difficulties, and other issues. It should be noted that this however, these types of production systems were only accepted by 18% survey was conducted one year after the start of the coronavirus of the residents of this urban form. These types of roofs can be found in pandemic and amid the third wave in Catalonia; therefore, some re­ most housing estates. In contrast, these areas tend to have households at sponses could be influenced by these conditions. According to these risk of water and energy poverty (Baldwin Hess, Tammaru, & van Ham, results, four different scenarios were proposed for this municipality: the 2018). They are also distinguished by large open spaces among buildings combination of electricity production and rainwater harvesting (sce­ that could be used for urban farming. Hence, the most viable option nario 1); vegetable production and rainwater harvesting (scenario 2 would be a combination of all the systems to alleviate these needs, i.e., with OAF and scenario 3 with RTGs); and the combination of all of them, the roof mosaic. Single-family housing acquired the most positive in­ where half of the roofs would produce electricity and the other half dicators. In particular, electricity production could support 51% of vegetables with OAF and RTGs and rainwater harvesting on all roofs electricity requirements if PV panels are installed on all their roofs. (scenario 4). These single-family roof areas are usually small and steep; therefore, it is In consonance with the outcomes of the different indicators by sce­ more feasible to implement PV panels than rooftop farming and also nario and urban form (Table 7), the highest values in vegetable self- because these urban forms have large open space of soil to make better sufficiency appear in scenario 3 (RTG + RWH) and in the housing es­ use of it for vegetable farming. Finally, for the originary fabrics, the tates urban form despite the RTG option being less accepted by resi­ indicators depict average values; thus, no clear conclusion can be drawn. dents. Accordingly, the largest area of new green spaces is in scenarios 2 However, with the physical analysis of these areas, it is evident that they and 3 (11.6 m2/hh) for the municipality, and for housing estates (4.6 are the ones with the least open spaces. They are compact, so a greater m2/hh) due to a higher number of flat rooftops than in the other urban area of green space is required. Therefore, most of these roofs could be forms. On the other hand, for energy and water self-sufficiency, the used for urban farming (scenarios 2 and 3), or the largest roofs could be single-family housing areas obtained the highest share because they used for rooftop farming and the smallest roofs could be used for the have more rooftops that are suitable for energy and water production implementation of electricity production systems, according to scenario systems, and there are fewer households in these sites. The originary 4. In this urban form, the acceptance of the type of production system fabrics have more heterogeneous buildings and roofs; therefore, their was uneven, with 87% acceptance for PV panels and only 24% accep­ values are in the middle. tance for rooftop farming systems. Likewise, all the rooftops of these In terms of environmental indicators, the highest CO2 savings urban forms can feasibly harvest rainwater. correspond to scenario 1 (PV + RWH) and the single-family housing At the municipality level, the current local government proposed a areas due to a higher number of rooftop surfaces. In contrast, scenario 1 general action plan for 2020-2023 (Ajuntament de Cerdanyola del has the highest environmental impact in terms of kg CO2 eq due to Vallès, 2019). Among the policies they proposed for the coming years, it building these new facilities, and scenario 2 (OAF +RWH) and housing is their intention to install renewable energy production infrastructure estates represent the lowest environmental impact, which means that in some municipal facilities and to draft a new green infrastructure plan. scenario 2 is the least environmentally impacting system to construct Consequently, with the new data from this study in hand (see open ac­ because fewer materials and energy are required. cess map: https://uab.maps.arcgis.com/apps/mapviewer/index.html? Concerning social indicators, energy poverty obtains the highest webmap=7e72e430e1204418b3ceb6257d27e4ae), both proposals value in scenario 1 and single-family housing areas. This scenario would could include more precise planning. Similarly, at the AMB scale cover 71% of the household energy requirements in the municipality, through the Metropolitan Urban Master Plan (PDU), of which this mu­ and approximately 16,906 households could benefit from these systems. nicipality is part, the future urban territory is defined and structured, Additionally, for water poverty, all scenarios have the same potential, and a connected network of green infrastructures of green avenues, and the highest share is for single-family housing because of a higher streets, connectors, parks and paths is being proposed (AMB, 2020). rooftop surface area. The implementation of water systems on roofs According to the outcomes of this study, these proposed green and would cover the water consumption of approximately 4,268 households, productive spaces on roofs—applying scenarios 2, 3 or 4—would i.e., 18% of the total households. Comparing the maintenance invest­ contribute from 14 to 27 ha to the green network proposed by the AMB. ment of hours for families shows that scenario 1 is the least time- Moreover, following the New Green Deal of the European Union (EU), consuming, while scenarios 2 and 3 are the most demanding due to any of these four scenarios we present are in harmony with the policy the care of the crops in these systems. areas of the EU action plan, which are farm to fork, sustainable agri­ For economic indicators, scenario 3 requires the highest investment culture and clean energy (European Commission, 2019). Thus, this study for the whole municipality; albeit, by urban form, the highest invest­ is an asset for all the proposed policies at the local and supralocal levels ment corresponds to single-family housing areas in scenario 1 due to to enhance the current and future situation of this and other there being more m2 to cover and fewer families to split the cost. municipalities. Conversely, the lowest investment in all scenarios, except for scenario 3, is allocated to housing estates due to a larger number of households to 4. Conclusions share the cost. However, single-family housing areas obtain the highest monetary savings in all scenarios. The highest savings are assigned to This study presents the roof mosaic urban strategy and illustrates the scenario 1, i.e., the combination of PV and RWH. current consumption profiles and resource potential production of urban 10 S. Toboso-Chavero et al. Sustainable Cities and Society 95 (2023) 104599 Table 7 Municipality and urban form performance per scenario proposed; no: number; PV: photovoltaic panels; RWH: rainwater harvesting; OAF: open-air farming; RTG: rooftop greenhouses. 11 S. Toboso-Chavero et al. Sustainable Cities and Society 95 (2023) 104599 rooftops that allow the design of viable future scenarios for imple­ Table 8 menting food, energy, and water rooftop systems in a medium-sized Summary of the three urban forms in the municipality. Mediterranean city. We used a georeferenced physical and socioeco­ Urban form Rooftops Buildings Open space nomic analysis to gain an integrated perspective of their potential for a housing most of them flat middle and high-rise open space among more self-sufficient and less environmentally impacting urban scenario. estates and large blocks constructions The city studied has three main urban forms: housing estates, orig­ originary heterogeneity of heterogeneity of compact areas, few inary fabrics and single-family housing areas, as well as the “others” fabrics roofs buildings open spaces category, which includes public facilities and industrial and retail parks. single-family small and steep semidetached and those with the housing detached housing most open spaces The morphology related to rooftops, buildings, and open space is sum­ areas marized in Table 8. Every urban form is distinguished by different features that more or less support the implementation of one or another FEW system. By rooftops under study should be carried out, such as type of rooftop characterizing the city by urban forms, the analysis is more specific and material, load capacity or accessibility. Further efforts should be made precise and aids in fostering policies in similar physical areas. This study to find viable urban mitigation and adaptation strategies to climate serves as a reference for other European cities with these urban forms. In change according to urban forms and resident typologies. Catalonia, many cities are composed of these types of morphologies (PDU, 2017). For instance, Barcelona has a historic center, a vast sub­ Declaration of Competing Interest urban extension district, housing estates, and some isolated single-family housing areas. The authors declare that they have no known competing financial When considering the consumption of these urban forms and their interests or personal relationships that could have appeared to influence potential production, we can see that the lowest consumption rates are the work reported in this paper. in housing estates, which consequently demonstrate the highest self- sufficiency in vegetable production (19%-43%). However, electricity Data availability production does not occur due to the large number of households and less space on roofs. Conversely, single-family housing inhabitants were Data are shared with a link in the manuscript and in the supple­ the highest consumers of vegetables, electricity and water (together with mentary data 1 and 2. the originary fabrics), but because the buildings only house one family per dwelling, they have a greater roof surface area and therefore would benefit most from self-sufficiency in electricity (25% and 51%) and Acknowledgements water (14%-443%). However, not in vegetable self-sufficiency because most of them are steep rooftops on which farming systems cannot be The authors would like to thank the SOM ESS Cerdanyola association placed. On the other hand, originary fabrics have average values for and the city council of Cerdanyola del Vallès, and the energy and water both consumption and potential production due to the diversity of their companies for their collaboration, and all the residents of Cerdanyola for buildings, type of families and roofs. their availability in this project. The four scenarios proposed reveal significant shares of self- sufficiency in vegetables (16-104%), electricity (13-71%) and the Funding sources required irrigation water (13-433%) for the municipality and the different urban forms. It is also important to create new green spaces This research has received financial support from Secretaria General between 2.1 and 11.6 m2/hh, with housing estates being the urban form de Recerca i Universitats from the departament of Recerca i Universitats that would benefit the most. In the same way, these scenarios would help (Generalitat de Catalunya), project number: 2020PANDE00021, the to considerably reduce energy and water poverty and their carbon European Research Council (ERC) Consolidator project: Integrated footprints (662-33,323 tonnes CO2 eq/year) by producing their own System Analysis of Urban Vegetation and Agriculture (818002-URBAG), FEW resources on-site. Therefore, these scenarios can facilitate the the Spanish Ministry of Science, Innovation and Universities, through adaptation of municipalities and Catalonia to climate change, where the “Maria de Maeztu” programme for Units of Excellence (CEX2019- predictions are not very optimistic regarding temperature increase and 000940-M), and the funding and recognition awarded to the research lack of precipitation (Altava-Ortiz & Barrera-Escoda, 2020). The use of group Sostenipra (2021 SGR 00734) by the Department of Research and urban forms for assessing consumption patterns could aid us in sug­ Universities of the Generalitat de Catalunya, the Spanish Ministry of gesting more specific urban climate solutions and adapting these areas Education, Culture and Sports (grant FPU16/03238), the Greenhouses to climate change accordingly. to Reduce CO2 on Roofs (GROOF) project (UE. Interreg NWE 474, 2017- Further insights into these urban forms in other small, medium, and 2021), and the Sustainable Energy Transition Laboratory (SENTINEL, large cities using this bottom-up methodology will be useful to evaluate Horizon 2020 GA 837089). The research leading to this publication has if they follow the same pattern. Similar urban climate solutions can be also received funding from the European Union’s Horizon 2020 research implemented, leading to further knowledge on the physical and socio­ and innovation programme under grant agreement No 862663 (FoodE). economic aspects of these urban forms and how to take advantage of The publication reflects the author’s views. The Research Executive their constructions and the type of resident. One of the key challenges is Agency (REA) is not liable for any use that may be made of the infor­ the availability of local data pertaining to consumption patterns, citi­ mation contained therein. zens’ preferences, and cadastre (land registry). Nonetheless, the EU is taking steps to overcome this hurdle through the INSPIRE directive, Supplementary materials which seeks to establish a comprehensive infrastructure for spatial in­ formation in all member states (European Commission, 2023). In addi­ Supplementary material associated with this article can be found, in tion, a close collaboration among stakeholders (public institutions, the online version, at doi:10.1016/j.scs.2023.104599. inhabitants, academia, businesses, etc.) is crucial for successfully implementing these types of urban solutions. Concerning technical is­ References sues related to the implementation of these food-energy-water systems, this methodology serves as a first approach at the neighborhood, com­ AEMET. (2006). Atlas of solar radiation in Spain. Retrieved February 2, 2017, from www munity, or urban form level, however, a more specific study of the .aemet.es/es/serviciosclimaticos/datosclimatologicos/atlas_radiacion_solar. 12 S. Toboso-Chavero et al. Sustainable Cities and Society 95 (2023) 104599 Agudelo-Vera, C. M., Leduc, W. R. W. A., Mels, A. R., & Rijnaarts, H. H. M. (2012). European Commission. (2019). The European Green Deal. European Commission, 53. 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