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Recent studies concerning the integration of agricultural practices in cities demonstrated that Urban Agriculture (UA) can boost new sustainable urban developments. New technologies allow to integrate soil-less cultivation in- and on- mixed-use buildings, creating new synergies between the built environment and the urban food system. Accordingly, resource flows from buildings are an untapped opportunity for the creation of circular urban metabolisms that rely on recycling waste as input for food production systems. On this trail, this research work focuses on evaluating the feasibility of using urine and greywater streams as nutrient solution in a theoretical model of Building-Integrated Agriculture (BIA) located in Amsterdam. Results showed that it is feasible to use urine and greywater as nutrient solutions (NS). However, treated urine showed higher concentration of macronutrients compared to fertilizer recipes found in literature, and therefore needed to be diluted with increasing amount of greywater to match either N or P concentration. Accordingly, P deficiencies in the plants or excessive N concentration were found in the final wastewater-based NS. Future research is highly recommended to assess the quality of plants grown in BIA systems as well as the possible content of harmful viruses and bacteria in the harvested produce.

In response to the growth of urban population and the reduction of resources availability (e.g., arable land, water, and nutrients), new forms of agriculture that can be developed also in urban environment are gaining increasing popularity. Urban agriculture constitutes a viable opportunity for improving the city food security, also fostering local and circular economies, social inclusion, and environmental sustainability. In the different world regions, a diversity of urban farming systems is encountered, with technological levels varying in response to the local socio-economic context, infrastructural networks, and environmental conditions. In developing economies from the South of the world, most interesting innovations include simplified hydroponics, organoponics, and microgarden technologies; whereas, in the global north, innovative solutions for plant cultivation also include rooftop greenhouses and indoor vertical farms with artificial lighting where vegetable crops, mushrooms, and algae may be grown. Beside plant growing solutions, innovation may also stand in the system integration and mutual relationship with the urban fabric (e.g., in terms of resource use or ecosystem service provisioning), or in the business model adopted. The present review paper will describe a number of innovative solutions for plant cultivation in the urban environment, with a special consideration of the economic, environmental, and social sustainability.

In a building-integrated agriculture (BIA) space, peak loads must be estimated to size HVAC equipment in order to maintain indoor air conditions that enhance crop growth. However, the estimation of...

A major concern for sustainable development is urban systems energy consumption. A possible way to gain additional whole system energy efficiencies is to integrate rooftop greenhouses (iRTG) on unoccupied roofs. This work presents actual environmental data (2015–2018) and calibrated energy modelling results to analyze the energy symbiosis between an iRTG and the host building. Simulation results illustrate that annually 98 kWh/m2 of heating energy is passively recovered (84% during night time) from the building by the iRTG. Conversely the iRTG insulating capacity resulted in annual energy saving of 35 kWh/m2 for the host building (equal to 4% of the building’s annual energy needs). When combined an overall 128 kWh/m2 of net energy savings and 45.6 kg CO2 eq/m2 of savings are realised via iRTG. On average, iRTG daytime temperatures can be 5.1 °C warmer (summer) and -4.3 °C cooler (winter) than the building. This presents major potentials for recovery and exchange of heating and cooling energy flows through integrating heating and ventilation air conditioning systems of the building and iRTG. Hence, iRTGs can provide a source of renewable energy as well as a sink for building exhaust air to improve energy efficiencies of urban built environment and urban agriculture. The authors are grateful to the Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya for the award of a research scholarship (FI-DGR 2018) to Joan Muñoz-Liesa; to the Universitat Autònoma de Barcelona for the award of a research scholarship (PIF-2017) to Martí Rufí-Salís; to the Spanish Ministry of Economy and Competitiveness (MINECO) for the financial support to the research project Fertilectiy II “Integrated rooftop greenhouses: energy, waste and CO2 symbiosis with the building. Towards foods security in a circular economy” (CTM2016-75772-C3-1-R; CTM2016-75772-C3-2-R). Authors also acknowledge financial support from the Spanish Ministry of Science, Innovation and Universities, through the “María de Maeztu” program for Units of Excellence (MDM-2015-0552). This work was additionally enabled by the Càtedra JG Ingenieros – Universitat Politècnica de Catalunya and the UK Engineering and Physical Sciences Research Council grand EP/P001173/1. Authors also thank Oriol Baeza, Prof. Xavier Gabarrell, Prof. Joan Rieradevall and the ICTA-UAB staff for their very valuable supporting advise and help.

Urban and building systems are awash with materials. The incorporation of green infrastructure such as integrated rooftop greenhouses (iRTGs) has the potential to contribute to buildings’ and cities’ circularity. However, its greater sophistication than conventional agriculture (CA) could lead to a shift in environmental impacts. One of the key elements for greenhouse building-integrated agriculture (BIA) and CA to achieve high levels of environmental performance is their structural design, which largely impacts the economic and environmental life-cycle costs (by up to 63%). In this context, the study assessed iRTGs life-cycle material and energy flows and their environmental burdens at structural level (m-2y-1) within life cycle assessment (LCA), based on a case study in Barcelona. A structural assessment following European standards allowed the identification of key design factors to minimize the environmental impacts of RTGs’ structure within improvement scenarios. The assessment revealed that a steel structure in a business-as-usual (BAU) scenario contributed from 31.5 to 67.3% of the impact categories analyzed, followed by the polycarbonate covering material (from 21.8 to 45.9%). The key design factors responsible for these environmental impacts were ground height, ventilation design, building integration and urban location. The improvement scenarios compensated for additional steel inputs by up to 35.9% and decreased environmental impacts that might occur in the BIA context by 24.1% compared with the BAU scenario. The assessment also revealed that urban environments do not imply shifting environmental impacts per se, as greenhouse BIA structures can benefit from their advantageous characteristics or be compensated by optimized greenhouse structures. The authors are grateful to the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya for the award of a research scholarship (FI-DGR 2018) to Joan Muñoz-Liesa; to the Spanish Ministry of Education, Culture and Sports grant FPU16/03238 to Susana Toboso-Chavero; and to the European Union's Horizon2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 842460 to Angelica Mendoza Beltran. Authors also acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) for the financial support to the research project Fertilectiy II “Integrated rooftop greenhouses: energy, waste and CO2 symbiosis with the building. Towards foods security in a circular economy” (CTM2016–75772-C3–1-R; CTM2016–75772-C3–2-R) and the Spanish Ministry of Science, Innovation and Universities, through the “María de Maeztu” program for Units of Excellence (MDM-2015–0552). Authors would also gratitude Dr. Violeta Vargas, Dr. Xavier Gabarrell, Dr. Joan Rieradevall, Dr. Martí Rufí-Salís, Dr. Gara Villalba and the ICTA-UAB staff for the very valuable support advise and help.

Urban rooftop farming favours local food production. Although rooftop farming is perceived as 33 a sustainable system, there is a lack of quantitative studies on rooftop farming. There we set up 34 experiments in the community rooftop garden of a public housing building in Bologna, Italy, 35 between 2012 and 2014. We grew lettuce, a leafy vegetable, using three techniques: nutrient 36 film, floating hydroponic and soil cultivation. We also grew tomato, chilli pepper, eggplant, 37 melon, watermelon on soils. Data was analysed by life cycle assessment for environmental and 38 economic performance. Results reveal that the best techniques of lettuce cultivation to address 39 global warming were floating in the summer, with 65-85% less environmental impact per kg 40 than nutrient film; and soil production in the winter, with 85-95% less environmental impact. 41 Furthermore, floating production was 25% cheaper in summer and soil was 65% cheaper in 42 winter, compared to the nutrient film technique. For soil production, eggplants and tomatoes 43 showed the best environmental performances of about 74 g CO2 per kg. Eggplant production in 44 soil gave in the cheapest crop of 0.13 € per kg.

Recent findings suggest that rooftop greenhouses could be more efficient when combined with waste streams in buildings, but there is a gap in quantification of the combined performance of building integrated greenhouses. This paper addresses this deficit for school buildings in London, UK, where urban agriculture is of increasing interest. A building energy simulation (BES) of an archetype school building is developed in EnergyPlus and co-simulated with a validated greenhouse energy simulator (GES). The performance of different greenhouse-building coupling configurations is evaluated to estimate the potential for crop growth, heat recovery and reduction in ventilation demand, through a sensitivity analysis and parametric study. Our results show that a 250 m2 greenhouse on the top floor of the school could produce 6t lettuce with half the energy demand of the same standalone greenhouse. Trade-offs across increase in humidity, yields, and energy efficiency indicate the importance of modelling to ensure optimal designs.

Purpose: rooftop greenhouses (RTGs) are increasing as a new form of urban agriculture. Several environmental, economic, and social benefits have been attributed to the implementation of RTGs. However, the environmental burdens and economic costs of adapting greenhouse structures to the current building legislation were pointed out as a limitation of these systems in the literature. In this sense, this paper aims to analyse the environmental and economic performance of RTGs in Barcelona. - Methods: a real RTG project is here analysed and compared to an industrial greenhouse system (i.e. multi-tunnel), from a life cycle perspective. Life cycle assessment (LCA) and life cycle costing (LCC) methods are followed in the assessment. The analysis is divided into three parts that progressively expand the system boundaries: greenhouse structure (cradle-to-grave), at the production point (cradle-to-farm gate), and at the consumption point (cradle-to-consumer). The applied LCIA methods are the ReCiPe (hierarchical, midpoint) and the cumulative energy demand. A cost-benefit analysis (CBA) approach is considered in the LCC. For the horticultural activity, a crop yield of 25 kg · m−2 is assumed for the RTG reference scenario. However, sensitivity analyses regarding the crop yield are performed during the whole assessment. - Results and discussion: the greenhouse structure of an RTG has an environmental impact between 17 and 75 % higher and an economic cost 2.8 times higher than a multi-tunnel greenhouse. For the reference scenario (yield 25 kg · m¯²), 1 kg of tomato produced in an RTG at the production point has a lower environmental impact (10-19 %) but a higher economic cost (24 %) than in a multi-tunnel system. At the consumption point, environmental savings are up to 42 % for local RTGs tomatoes, which are also 21 % cheaper than conventional tomatoes from multi-tunnel greenhouses in Almeria. However, the sensitivity assessment shows that the crop efficiency is determinant. Low yields can produce impacting and expensive vegetables, although integrated RTGs, which can take advantage from the residual energy from the building, can lead to low impacting and cheap local food products. -Conclusions: RTGs face law limitations that make the greenhouse structure less environmentally friendly and less economically competitive than current industrial greenhouses. However, as horticultural systems and local production systems, RTGs can become an environmentally friendly option to further develop urban agriculture. Besides, attention is paid to the crop yield and, thus, further developments on integrated RTGs and their potential increase in crop yields (i.e. exchange of heat and CO2 with the building) are of great interest.

The popularity of urban agriculture and green roofs is increasing in cities around the world that recognize the multifaceted benefits to the local community. Rooftop plant production (RPP) systems can be used to grow ornamental plants or food crops using raised beds, row farming, or hydroponic greenhouse. RPP systems maximize the cultivation area of the plant factory with artificial lighting (PFAL). RPP can be used to grow crops that require higher light intensities and greater heights than those plants traditionally grown in PFAL. Further, seedlings started in a PFAL can be transferred to the roof and cultivated with RPP. The environmental benefits of RPP can be a great asset to the sustainability and resource use efficiency (RUE) of the PFAL, while also providing net-positive enhancements to the local community and urban landscape by increasing agricultural awareness, boosting the local economy, mitigating stormwater, and reducing the heat island effect.

The rapid urbanization creates an increased demand for food supply and security in urban system. The imminent risks stemmed from climate change appeal for a greater effort in an overhaul of the customary practices in the planning and management of the urban systems. Urban centers should accommodate the growing need for green infrastructure and edible landscape; options such as farming alternative has gained interest as a possible solution to the urban-scape and the food production stability for the urban inhabitants. This article presents the systemic approach to building integrated agriculture unit prototype's design thinking and proposed a prototype model allowing the locality and place to be incorporated into the design framework. The research concludes that: (1) in line with human-nature connection and raising its priority level within both design research and design practice should consider the environmental, social, economic and spatial criteria for the design thinking exploration; (2) the design results in a flexible system model of the micro building integrated agriculture unit, allowing the units to fit either indoor or outdoor, as a probable solution suited for the locality and the increasing demand for edible greens; (3) indoor units need further study in integration with the indoor climate control and automation as well as added indoor air purification and sensor functions. (4) Prototype units should be capable of providing locally available edible production and social well-being for the urban system.

Urbanisation is transforming human societies in many ways. Besides bringing benefits to people in cities, it also has negative impacts such as food security. One way to meet the challenge is urban agriculture; however, traditional agricultural practices are not suitable within urban areas due to limited availability of land. Therefore, the alternative option is to grow crops inside or on top of buildings, e.g. building integrated agriculture (BIA). But, there is limited research and information available for designers and planners to design such buildings. The presented research project bridges the gap between agriculture and architecture by proposing a building integrated agriculture information modelling tool in integration with Building information modelling. The plugin tool has data on plants’ requirements and automatic response to environmental factors. Environmental factors include temperature, light, water, nutrients, air, humidity, spacing and support. In this paper, seasonal tomato is selected as a reference crop, and the impact of environment (temperature, light, water, nutrients and spacing) on its health is discussed and simulated for germination stage. The undertaken project contributes to the concept of BIA and BIM maturity level, which would help to design an optimum environment building for plants.

Current urban food systems are categorized as unsustainable, for the well-being of urban consumers and the environment. Furthermore, health risks are higher in urban areas compared to rural areas. This is caused by soaring prices and difficulty of accessing nutritious food. Most of the raw produce sold in markets, lost half of their nutrients due to logistics from out of town, which results in high carbon footprint. On the other hand, the COVID-19 pandemic has created a shift within consumer behaviour that impacts health and waste. This phenomenon encouraged the authors to analyze effective food systems, in the design of building-integrated agriculture. The overall study questions criteria for sustainable processing, agriculture design strategies, and implementation of agriculture systems in urban space design. Research methods used are theoretical reviews, precedent study of Sunqiao Urban Agriculture District located in Shanghai, China and survey analysis conducted through online questionnaire. The results cover a set of conceptual strategies which include site design, mass compositions, spatial programming, lighting and ventilation, spatial forms, façade, and energy patterns which are then applied to create a building-integrated agriculture that plays a role in pandemic mitigation, community resilience, and promotes sustainable development within the food sector.

In response to the burgeoning building integrated agriculture (BIA) discourse and industry, and assumptions of this land use form as a climate change adaptation strategy, this study considers the impact of rooftop greenhouses (RTGs) on the thermal performance of the built environment in current and future climate conditions. Based on empirical evidence, the study simulates the thermal impact of completely retrofitting an existing building in a Southern African urban context with passively controlled, non-integrated RTGs under current and future climate change affected climatic conditions. The study concludes that the current greenhouse technologies used in South African rooftop farms provide limited thermal modulation capacity for farmers, as well as generally negatively affecting the thermal performance of the associated buildings. Simulating both highly and poorly insulated buildings reveal contrasting impacts on the indoor thermal environment, with a 0.73 °C decrease and 0.55 °C increase in mean temperatures, respectively. Conversely, the highly insulated simulation reveals an annual energy consumption increase of 3.5%, which progressively worsens under higher climate change induced temperatures. These findings, based on current practices in the BIA industry, hope to inform both the choice of technology, as well as the development of appropriate greenhouse technologies to maximise their performance and enable co-benefits as often assumed in the industry.

Unidad de excelencia María de Maeztu MdM-2015-0552 Building-integrated rooftop greenhouse (i-RTG) agriculture has intensified in recent years, due to the growing interest in the development of new agricultural spaces and in the promotion of food self-sufficiency in urban areas. This paper provides a first assessment of the indoor dynamics of bioaerosols in an i-RTG, with the aim of evaluating biological air quality in a tomato greenhouse near Barcelona. It evaluates the greenhouse workers' exposure to airborne pollen and fungal spores in order to prevent allergy problems associated with occupational tasks. Moreover, it evaluates whether the quality of the hot air accumulated in the i-RTG is adequate for recirculation to heat the building. Daily airborne pollen and fungal spore concentrations were measured simultaneously in the indoor and outdoor environments during the warm season. A total of 4,924 pollen grains/m3 were observed in the i-RTG, with a peak of 334 pollen grains/m3day, and a total of 295,038 fungal spores were observed, reaching a maximum concentration of 26,185 spores/m3day. In general, the results showed that the most important source of pollen grains and fungal spores observed indoors was the outdoor environment. However, Solanaceae pollen and several fungal spore taxa, such as the allergenic Aspergillus/Penicillium, largely originated inside the greenhouses or were able to colonize the indoor environment under favourable growing conditions. Specific meteorological conditions and agricultural management tasks are related to the highest observed indoor concentrations of pollen grains and fungal spores. Therefore, preventive measures have been suggested in order to reduce or control the levels of bioaerosols indoors (to install a system to interrupt the recirculation of air to the building during critical periods or to implement appropriate air filters in ventilation air ducts). This first evaluation could help in making decisions to prevent the development of fungal diseases, specifically those due to Oidium and Torula.

Recently, the application of Vertical Farming into cities has increased. Vertical farming is a cultivating vegetable vertically by new agricultural methods, which combines the design of building and farms all together in a high-rise building inside the cities. This technology needs to be manifest both in the agricultural technique and architectural technology together, however, little has been published on the technology of Vertical Farming. In this study, technology as one of the important factor of Vertical farming is discussed and reviewed by qualitative approach. In the first, identifying existing and future VF projects in Europe, Asia, and America from 2009 to 2016. Then a comprehensive literature reviewed on technologies and techniques that are used in VF projects. The study resources were formed from 62 different source from 2007 to 2016. The technologies offered can be a guide for implementation development and planning for innovative and farming industries of Vertical Farming in cities. In fact, it can act as a basis for evaluating prospective agriculture and architecture together. The integration of food production into the urban areas have been seen as a connection to the city and its residents. It simultaneously helps to reduce poverty, adds to food safety, and increases contextual sustainability and human well-being.

Providing healthy food for the world’s growing urban population is a recognized global challenge and it is likely that current modes of conventional, large-scale farming will over time be increasingly complemented by local, urban farming practices. Apart from its acknowledged social benefits, urban farming is also widely viewed as a more resource-efficient alternative to conventional remote farming. Especially indoor, soilless cultivation in urban areas is being portrayed as a particularly sustainable solution. However, as this technique relies on controlled environments, its ongoing operation can be quite energy-intensive and related carbon emissions should be carefully weighed against reduced emissions, such as those from transportation. To further this goal, this article presents a simulation-based environmental analysis workflow for Building-Integrated Agriculture (BIA) in urban contexts, that includes detailed solar radiation, water and energy specific models. The aim of the workflow is to guide the user through decision-making on the potentialities of implementing BIA in a given neighborhood while maximizing crop yields and minimizing water and energy consumption. The workflow was applied to three hi-tech urban farming scenarios in Lisbon, Portugal: a polycarbonate Rooftop Greenhouse (RG), a Vertical Farm (VF) with windows and skylights on the top floor of a reinforced-concrete building as well as a completely opaque VF with no penetration of natural light on the ground floor of a reinforced-concrete building. Global Warming Potential (GWP) related to water, transportation and operational energy of these three case studies were compared to GWP of (i) the currently existing supply chain for tomato, and (ii) a hypothetical low-tech unconditioned rooftop urban farm. Results show that the RG and the top floor VF had the best overall environmental performance, respectively cutting greenhouse gas emissions in half and in three in comparison with the existing supply chain for tomato. By allowing this preliminary assessment of alternative farm locations and properties, the workflow provides the user with actionable information for early-stage holistic assessment of BIA projects.

Rooftop agriculture (RA) is a building-based form of urban agriculture that includes both protected and nonprotected farming practices, such as rooftop greenhouses as well as open-air rooftop gardens and farms. The use of underexploited urban spaces on buildings for farming purposes is considered a useful strategy for targeting global concerns (e.g., the limitations in food security and land access, impacts of climate change or social exclusion). While previous studies have addressed selected RA cases and the general worldwide dissemination of RA, a systematic evaluation integrating the constantly evolving sector and its diversity (both commercial and noncommercial) is currently lacking. Here, we provide an overview of the current status of RA based on a metadata analysis of 185 publicly accessible cases. This paper summarizes the global trends and spatial distribution of RA cases and presents their main features. The results present the global distribution of different RA types over time, their diverging farming purposes and further characteristics (such as farm sizes, building typologies, growing systems, products and reported yields, activities, implementation of resource-efficient practices, or economic and social activities). The results indicate an emphasis on RA cases in North America (44% of the analyzed cases) and show that RA practices are mainly represented by open-air farms and gardens (84%), as the growing sector of rooftop greenhouses is still relatively small. Similarly, commercial cases are scarce, with the majority of RA cases targeting social-educational goals or the improvement of urban living quality. This tendency suggests a range of currently untapped business opportunities that, if developed, may contribute to the evolution of more sustainable and resilient city food systems providing fresh crops from the inner urban fabric. In conclusion, the research showed a rising global interest in RA, although stronger policy intervention is crucial to upscale RA practices to reach decisive environmental, economic and social benefits at the city level.

International audience; Rooftop gardens are a promising way to supplement the growing demand for local food production, and are especially relevant in large cities with acute space constraints. However, they face the challenge of achieving viable food productivity while minimizing their impacts on the environment, two priorities that often oppose one another. Also, the actual impacts of management practices, which are deemed environmentally friendly in principle, are rarely quantified. Therefore, evaluations that encompass all components of urban gardens and a comprehensive range of environmental issues are necessary to reveal potential trade-offs and provide guidance in the design of these systems. In this study, we evaluated the environmental and economic impacts of rooftop gardening practices, focusing on crop and substrate selection, which are key parameters in system design but whose consequences have seldom been evaluated so far. Life cycle assessment (LCA) and life cycle costing (LCC) were used to analyze a case study in the center of Paris (France). The production systems considered involved crop rotations of tomato and lettuce each grown in three different substrate types: compost and wood chips; compost, wood chips, and earthworms; and conventional potting soil. Despite the large environmental burdens of compost production, systems with compost performed better environmentally and economically than the system involving potting soil, specifically having 17-47% less greenhouse gas emissions per kg of product. Across systems, length of cultivation and yield appeared to be the most influential determinants of the environmental impacts. Within the compost systems, the most impactful component was the material used for garden infrastructure, and substrate production for the potting soil systems. This is the first study that considers compost as a substrate, weighs its benefits and impacts, incorporates it into a complete garden, and compares it to potting soil. Our results demonstrate that careful system design could significantly abate environmental impacts. They provide critically needed information to people implementing urban rooftop agriculture and considering the trade-offs involved in each decision.; Rooftop garden

Innovative forms of green urban architecture aim to combine food, production, and design to produce food on a larger scale in and on buildings in urban areas. It includes rooftop gardens, rooftop greenhouses, indoor farms, and other building-related forms (defined as “ZFarming”). This study uses the framework of sustainability to understand the role of ZFarming in future urban food production and to review the major benefits and limitations. The results are based on an analysis of 96 documents published in accessible international resources. The analysis shows that ZFarming has multiple functions and produces a range of non-food and non-market goods that may have positive impacts on the urban setting. It promises environmental benefits resulting from the saving and recycling of resources and reduced food miles. Social advantages include improving community food security, the provision of educational facilities, linking consumers to food production, and serving as a design inspiration. In economic terms it provides potential public benefits and commodity outputs. However, managing ZFarming faces several challenges. For some applications, the required technologies are known but have not been used or combined in that way before; others will need entirely new materials or cultivation techniques. Further critical aspects are the problem of high investment costs, exclusionary effects, and a lack of acceptance. In conclusion, ZFarming is seen as an outside-the-box solution which has some potential in generating win–win scenarios in cities. Nevertheless, ZFarming practices are not in and of themselves sustainable and need to be managed properly.

Burgeoning population and rapid urbanisation have contributed to two challenges facing cities today: food security and an increasing carbon footprint due to food imports. This paper examines the viability of rooftop farming in urban centres in Asia. A context-specific exploration—sited in Singapore—looks at the challenges of building integrated agriculture. Findings suggest that Singapore's public housing estates are suitable for rooftop farming. Implemented nationwide, such a scheme could result in a 700% increase in domestic vegetable production, satisfying domestic demand by 35.5%. Reducing food imports would also decrease Singapore's carbon footprint by 9,052 tonnes of emissions annually.

The ICTA-ICP Rooftop Greenhouse Lab (RTG-Lab) is a research-oriented RTG situated in the UAB Campus (Bellaterra, Barcelona). In contrast to current RTGs, the RTG-Lab integrates energy, water and CO2 flows into the building’s metabolism. This integrated RTG (i-RTG) is an eco-innovative concept that will enhance the sustainability of both systems involved while producing high-value crops and maintaining indoor comfort in buildings with lower energy inputs. The RTG-Lab, within the Fertilecity project, aims to demonstrate the feasibility of producing vegetables in i-RTGs in the Mediterranean context and to quantify the environmental and economic performance of the metabolic integration between the greenhouse and the building. To do that, experimental crops (lettuce and tomato) in soil-less culture systems (perlite) will start on Fall 2014. Preliminary data of the metabolic integration is described in this contribution. First, the residual heat from the building will be introduced in the greenhouse to maintain crop temperatures. Moreover, the airflow from the building will help the ventilation of the greenhouse in hot episodes. Second, the rainwater collected in the rooftop of the building will be used for the irrigation of the crop, leading into a 100% water self-sufficient crop. Third, the airflow from the building has a higher CO2 concentration than the greenhouse air. This CO2 will be used by the crop when supplied to the greenhouse, as in current CO2-injection techniques in industrial horticulture.

The aim of this study was to analyze current practices in commercial urban rooftop farming (URF). In recent years, URF has been experiencing increasing popularity. It is a practice that is well-suited to enhancing food security in cities and reducing the environmental impact that results from long transportation distances that are common in conventional agriculture. To date, most URF initiatives have been motivated by social and educational factors rather than the aim of creating large sustainable food production systems in cities. The commercial operation of urban rooftop farms, should they become profitable, is likely to attract notable private investment, allowing a significant level of high quality urban food production to be achieved. There is a reasonable amount of literature available on urban farming that deals with its potential, and its limitations. However, it does not focus on commercial operations. In contrast to other surveys and theoretical papers, this study of URF focuses on large and commercial operations. The analysis showed that commercial URFs can be grouped into two main types: Firstly, hydroponic systems in greenhouses where mostly leafy greens, tomatoes, and herbs are grown; secondly, soil-based open-air farms that grow a large variety of vegetables. Hydroponics is frequently seen as the key technology for commercial urban food production. While the technology is not in and of itself sustainable, hydroponic farms often make an effort to implement environmentally friendly technologies and methods. However, there is still untapped potential to systemically integrate farms into buildings. The findings of this study identified where future research is needed in order to make URF a widespread sustainable solution.

Every person physically consumes products made from biomass. Our lives are thus inextricably tied to the crisis facing global agricultural land and water supply. The design of truly sustainable cities must, therefore, incorporate a more comprehensive assessment of the energy, water and land consumed during food production, processing, storage, preparation, distribution and disposal. One way of doing this is building-integrated agriculture (BIA) – high-performance hydroponic farming systems located on and in buildings, using renewable, local sources of energy and water. Integrating farming into the built environment has the potential to significantly reduce fossil fuel consumption, improve urban ecology, enhance food safety and security, enrich the lives of city dwellers and conserve building energy. This chapter begins by providing an overview of global food system challenges. A detailed analysis of BIA follows, including technical descriptions of BIA systems, environmental performance, economic models, sustainability challenges and future trends.

The relationship between the sun and built form is an essential determinant of the nature of a city. Solar energy affects the design of sustainable cities in a number of ways, from the establishment of urban form to the design of buildings in terms of orientation, glazing and shading devices, and the incorporation of active devices such as photovoltaic and solar thermal panels. Urban solar strategies should vary significantly according to climate and latitude. There is great potential for solar inputs to shape urban form and to supply a significant portion of urban energy use.