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• An integrated approach was used to quantify greenhouse covering material trade-offs. • Two types of polycarbonates, horticultural glass and ETFE films were assessed. • Lifetime crop yields increased up to +46.6% compared to a polycarbonate panel. • Environmental impacts per kg of tomato decrease up to 41.7% with an ETFE film. • Environmental results greatly differ according to greenhouse functions and crops. Solar radiation transmissivity in greenhouses is a key property largely determined by covering materials. This study compared tomato crop yields and their environmental performance of a polycarbonate rooftop greenhouse with alternative covering materials displaying higher solar transmissivity and lifetime performance. An integrated approach using experimental data with structural, energy modeling was used to model average lifetime crop productivities. At building functional unit (per m2·year), impacts varied between -29.0% and +24.0% compared to the current polycarbonate. Lifetime transmissivities improved up to 20.5% (4 mm-antireflective glass), leading to +46.6% of tomato yields (19.9 ± 2.2 kg/m2), and up to -33.9% of environmental impacts. Ethylene tetrafluoroethylene 60 μm-film resulted in 19.2 ± 2.3 kg tomatoes/m2 but improved environmental performance up to 41.7%. These results demonstrate the importance of employing integrated and life-cycle approaches to combine multiple trade-offs and dynamics within environmental assessments of greenhouse crops. The results are intended to contribute to improving greenhouse cultivation and sustainability. [Display omitted] [ABSTRACT FROM AUTHOR]

Buildings and greenhouses consume vast amounts of energy and natural resources for heating and ventilation. It is still unclear how the synergetic effect of combining greenhouses and buildings' forced waste airflows could improve both systems' energy efficiency. This study quantified the energy recovery potential of exchanging airflows in a rooftop greenhouse (iRTG) integrated with an office building HVAC system in a Mediterranean climate. Using monitored and calibrated energy model data, the results showed that the iRTG can act as a solar collector and as a sink for a building's low-grade waste heat. The magnitude of harvested thermal energy that could be recirculated into the building by the integrated HVAC system was 205.2 kWh/m2y−1 and was limited by greenhouse low transmissivity (54%). The magnitude of building exhaust air was 198 kWh/m2y−1 at temperatures sufficient to heat and cool the iRTG. Compared to a passive ventilated configuration, the integration of active ventilation strategies doubled the energy benefits. Building ventilation requirements directly determined building and greenhouse waste flows and energy benefits, which increased by 63.1% when air changes per hour moved from 1.59 to 3.16. Overall, this demonstrates that greenhouse and building functionalities could be coupled to contribute to urban circularity and sustainability. [Display omitted] • A greenhouse integrated within the building HVAC system was investigated. • Real and modelling data was combined to quantify energy co-benefits. • The iRTG recycled 143 kWh/m2·y of sensible heat from building waste heat. • The iRTG solar capacity conveyed 205 kWh/m2·y of sensible heat to the building. • Active strategies doubled the energy benefits compared to passive mechanisms. [ABSTRACT FROM AUTHOR]

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. [Display omitted] [ABSTRACT FROM AUTHOR]

• A method to assess the potential use of RTG were adapted to a social neighborhood. • 33% of the neighborhood rooftops had a short-term feasibility to become RTG's. • The study area would supply 4.5% of Quito's total demand of tomato and lettuce. • Developed guidelines that show potential to install RTG in Latin-American cities. • This study support the decision-making process in urban planning at a large scale. Today, food security has a critical place in the government agendas of developing countries. In Latin American case, urban contexts have been subject to radical transformations in the last decades, most apparently through the expansion of social housing, which may limit or condition access to food for the neediest population. Nowadays, in Latin America, there are numerous cases of urban agriculture. Quito (Ecuador) stands out for the development of urban agriculture through the Participatory Urban Agriculture Project - AGRUPAR; initiative that has led to the implementation of orchards with organic production, raising of small animals, food processing and marketing of surpluses for food-nutrition security. Above all, it has transcended its urban and peri-urban intervention to rural areas, favoring the urban-rural connection. Also, worldwide the urban agriculture is developed in different forms, one of which is through crops protected by a greenhouse on the roofs: Rooftop greenhouse (RTG). This form of UA uses specific substrates for hydroponic crops and has modern irrigation systems often combined with rainwater harvesting and provides a unique opportunity to improve urban agriculture in Quito. The purpose of this study is to identify the implementation potential of rooftop greenhouses in social neighborhoods in Quito. Standard methods to assess the potential use of rooftop greenhouses were adapted to a social neighborhood. The guidelines follow three steps: Step 1: Characterization based on criteria; Step 2: Available surface determination and Step 3: Production, self-sufficiency and self-supply. "La Comuna Santa Clara de San Millán" was selected as study area. The results showed that 33.2% (7.70 ha) of the neighborhood rooftops had a short-term feasibility to install rooftop greenhouses, with the potential to produce 1,579,140 and 56,720 kg/year of tomato and lettuce respectively. The research has developed reliable guidelines that prove the feasibility to install rooftop greenhouses in similar large Latin-American cities area. [ABSTRACT FROM AUTHOR]

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 CO 2 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. Image 1 • Integrated greenhouses are a bioclimatic strategy to improve urban metabolism. • EnergyPlus proves bidirectional energy benefits for buildings and greenhouses. • IRTG recycle notable amounts of low-grade waste heat from buildings. • IRTGs acts as a solar collector and insulation cavity to reduce building energy. • Greenhouses can be integrated into building HVAC for improved efficiencies. [ABSTRACT FROM AUTHOR]

Today, urban agriculture is one of the most widely used sustainability strategies to improve the metabolism of a city. Schools can play an important role in the implementation of sustainability master plans, due their socio-educational activities and their cohesive links with families; all key elements in the development of urban agriculture. Thus, the main objective of this research is to develop a procedure, in compact cities, to assess the potential installation of rooftop greenhouses (RTGs) in schools. The generation of a dynamic assessment tool capable of identifying and prioritizing schools with a high potential for RTGs and their eventual implementation would also represent a significant factor in the environmental, social, and nutritional education of younger generations. The methodology has four-stages (Pre-selection criteria; Selection of necessities; Sustainability analysis; and Sensitivity analysis and selection of the best alternative) in which economic, environmental, social and governance aspects all are considered. It makes use of Multi-Attribute Utility Theory and Multi-Criteria Decision Making, through the Integrated Value Model for Sustainability Assessments and the participation of two panels of multidisciplinary specialists, for the preparation of a unified sustainability index that guarantees the objectivity of the selection process. This methodology has been applied and validated in a case study of 11 schools in Barcelona (Spain). The social perspective of the proposed methodology favored the school in the case-study with the most staff and the largest parent-teacher association (social and governance indicators) that obtained the highest sustainability index (S11); at a considerable distance (45%) from the worst case (S3) with fewer school staff and parental support. Finally, objective decisions may be taken with the assistance of this appropriate, adaptable, and reliable Multi-Criteria Decision-Making tool on the vertical integration and implementation of urban agriculture in schools, in support of the goals of sustainable development and the circular economy. [ABSTRACT FROM AUTHOR]

The integration of rooftop greenhouses (RTGs) in urban buildings is a practice that is becoming increasingly important in the world for their contribution to food security and sustainable development. However, the supply of tools and procedures to facilitate their implementation at the city scale is limited and laborious. This work aims to develop a specific and automated methodology for identifying the feasibility of implementation of rooftop greenhouses in non-residential urban areas, using airborne sensors. The use of Light Detection and Ranging (LIDAR) and Long Wave Infrared (LWIR) data and the Leica ALS50-II and TASI-600 sensors allow for the identification of some building roof parameters (area, slope, materials, and solar radiation) to determine the potential for constructing a RTG. This development represents an improvement in time and accuracy with respect to previous methodology, where all the relevant information must be acquired manually. The methodology has been applied and validated in a case study corresponding to a non-residential urban area in the industrial municipality of Rubí, Barcelona (Spain). Based on this practical application, an area of 36,312 m 2 out of a total area of 1,243,540 m 2 of roofs with ideal characteristics for the construction of RTGs was identified. This area can produce approximately 600 tons of tomatoes per year, which represents the average yearly consumption for about 50% of Rubí total population. The use of this methodology also facilitates the decision making process in urban agriculture, allowing a quick identification of optimal surfaces for the future implementation of urban agriculture in housing. It also opens new avenues for the use of airborne technology in environmental topics in cities. [ABSTRACT FROM AUTHOR]