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Building-integrated agriculture: Are we shifting environmental impacts? An environmental assessment and structural improvement of urban greenhouses
Abstract
A R T I C L E I N F O Keywords: Life cycle assessment Material flow analysis Resource use efficiency Structural modeling Urban agriculture Urban metabolism A B S T R A C T 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-2 y-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.
... Compared to a controlled greenhouse [66,70,73,74] and although frequently adjusted to crop requirements, climatic conditions in i-RTGs are much more variable due to the top location, which enhances exchanges with the surroundings. Additionally, according to the building's recirculation system, air coming from the greenhouse floor could be efficiently exploited to warm up the lower space, increasing the living quality of indoor environments, such as offices [12]. Therefore, in this study, in addition to measuring tomato plant emissions, the contribution of CO 2 was also analysed. ...
... The environmental performance of existing buildings can be improved by integrating plants inside and outside of them [10], not necessarily by means of high-cost technologies. Innovative systems, such as integrated rooftop greenhouses (i-RTGs) [11][12][13], have demonstrated the multiple benefits provided in terms of energy use efficiency [12], carbon emissions reduction [14], and energy and food production [15,16]. ...
... The environmental performance of existing buildings can be improved by integrating plants inside and outside of them [10], not necessarily by means of high-cost technologies. Innovative systems, such as integrated rooftop greenhouses (i-RTGs) [11][12][13], have demonstrated the multiple benefits provided in terms of energy use efficiency [12], carbon emissions reduction [14], and energy and food production [15,16]. ...
Urban design is currently promoting the inclusion of plants in buildings. However, plants emit biogenic volatile organic compounds (BVOCs), which alone or in combination with other airborne molecules such as CO2, may result in a general increase in tropospheric pollution. Many studies have documented the effects of biotic and abiotic factors on plant BVOC responses, but few have assessed the contribution of typical CO2 levels found in indoor work and meeting spaces. To answer this question, we monitored CO2 and constitutive (MT-limonene) and induced (LOX-cis-3-hexenal) BVOC emissions of a fully developed tomato crop grown hydroponically inside an integrated rooftop greenhouse (i-RTG) in a Mediterranean climate. Two distinctive CO2 assays were performed at the level of the i-RTG by supplying or not CO2. The impact of CO2 on plant physiological emittance was then assessed, and the resulting BVOC rates were compared with reference to EU-LCI values. MT-limonene was ubiquitous among the assays and the most abundant, while LOX-cis-3-hexenal was detected only under controlled CO2 management. The highest levels detected were below the indicated LCIs and were approximately tenfold lower than the corresponding LCI for MT-limonene (50.88 vs. 5000 μg m⁻³) and eightfold (6.63 μg m⁻³) higher than the constitutive emission level for LOX-cis-3-hexenal. Over extended sampling (10 min) findings revealed a general emission decrease and significantly different CO2 concentration between the assays. Despite similar decreasing rates of predicted net photosynthesis (Pn) and stomatal conductance (gs) their correlation with decreasing CO2 under uncontrolled condition indirectly suggested a negative CO2 impact on plant emission activity. Conversely, increasing CO2 under the controlled assay showed a positive correlation with induced emissions but not with constitutive ones. Because of significantly higher levels of relative humidity registered under the uncontrolled condition, this factor was considered to affect more than CO2 the emission response and even its collection. This hypothesis was supported by literature findings and attributed to a common issue related with the sampling in static enclosure. Hence, we suggested a careful monitoring of the sampling conditions or further improvements to avoid bias and underestimation of actual emissions. Based on the main outcomes, we observed no evidence of a hazardous effect of registered CO2 rates on the BVOC emissions of tomato plant. Furthermore, because of the low BVOC levels measured in the i-RTG, we assumed as safe the recirculation of this air along building’s indoor environments.
... For instance, previous studies on integrated rooftop greenhouses (iRTGs) located at the Institute of Environmental Science and Technology (ICTA-UAB, Barcelona region) showed that between 42 and 63% of global warming impacts of 1 kg of tomato were due to the greenhouse structure (Rufí-Salís et al., 2020a). The covering materials accounted for 43% of the associated impacts (Muñoz-Liesa et al., 2021a). Similarly, fertilizers used in tomato crop cycles showed a relative contribution of more than 20% to many impact categories that were analyzed (Sanjuan-Delmás et al., 2018a). ...
... To make a fair comparison, we keep the majority of iRTG variables constant, to only model the side-effects of improving covering material transmissivities (colored in Fig. 2). This required the integration of successive methods and steps to: (i) make the needed structural adaptations to ensure the assessed covering material was compatible with the current greenhouse structure as evaluated in (Muñoz-Liesa et al., 2021a); (ii) quantify greenhouse solar energy gains according to the material's lifetime performance (based on experimental data) and alternative covering materials through a calibrated energy model previously used in this iRTG (Muñoz-Liesa et al., 2021bNadal et al., 2017); (iii) quantify the photosynthetic active radiation (PAR) needed by crops compared to the PAR reached at plant canopy level, according to experimental data recorded in the iRTG (Zambrano-Prado et al., 2021); (iv) model crop output yields according to the alternative materials here assessed based on several tomato crops grown in ICTA-iRTG from 2016 to 2020 (Parada et al., 2021;Rufí-Salís et al., 2020a;Sanjuan-Delmás et al., 2018a); (v) assess the environmental impacts of the entire iRTG system. Finally, iRTG crops and their environmental performance are also affected by the system's environmental boundary conditions (such as exterior outside temperature or radiation), which are integrated through experimental data inputs. ...
... For this reason, no maintenance was assumed for polycarbonate to remove dust accumulation, while two cleaning sessions in the 25 years of lifespan were considered for glass (i.e., every 7-8 years). Electricity needs for the polycarbonate maintenance process were assumed equal to the construction process that was previously reported (Muñoz-Liesa et al., 2021a). This includes energy-related costs to reach the rooftop greenhouse envelope with articulated boom lifts and scissor platforms. ...
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.
... In addition to these, researchers have investigated how implementing building-integrated agriculture (BIA) [33] can contribute to optimizing their energy and resource consumption through the trade-off between the building and the cultivation system; for example, the latter can enhance building insulation while also using recycled waste produced by the users inside the building for its operation, from the perspective of life cycle assessment (LCA). Just as iRTGs (integrated rooftop greenhouses) can reuse the CO2-dense airflow produced by the users inside the building to help plant growth [33], HGRS can potentially reuse building wastewater. ...
... Hydroponic cultivations have mostly been studied not only because they are a sustainable alternative to traditional agriculture in terms of water and soil consumption [13], but also because these soil-less systems can be implemented in urban areas, providing benefits such as an increase in crop production for the population, a reduction in food transportation and waste and the improvement of food safety [16] thanks to a production policy based on "controlled environment agriculture" [17]. In addition to these, researchers have investigated how implementing building-integrated agriculture (BIA) [33] can contribute to optimizing their energy and resource consumption through the trade-off between the building and the cultivation system; for example, the latter can enhance building insulation while also using recycled waste produced by the users inside the building for its operation, from the perspective of life cycle assessment (LCA). Just as iRTGs (integrated rooftop greenhouses) can reuse the CO 2 -dense airflow produced by the users inside the building to help plant growth [33], HGRS can potentially reuse building wastewater. ...
... In addition to these, researchers have investigated how implementing building-integrated agriculture (BIA) [33] can contribute to optimizing their energy and resource consumption through the trade-off between the building and the cultivation system; for example, the latter can enhance building insulation while also using recycled waste produced by the users inside the building for its operation, from the perspective of life cycle assessment (LCA). Just as iRTGs (integrated rooftop greenhouses) can reuse the CO 2 -dense airflow produced by the users inside the building to help plant growth [33], HGRS can potentially reuse building wastewater. ...
Among the several methods investigated over the past few years for the thermal mitigation of buildings in urban areas, green roof systems seem to be one of the most suitable solutions for several reasons, and researchers encourage the further study and implementation of these roofing techniques because of the potential benefits that they offer. So far, intensive, extensive and semi- intensive green roofs are considered to be a better option in terms of both energy efficiency and green area increase. However, there are some aspects that cause green roofs not to be suitable to every application, preventing their use from spreading, such as high maintenance and costs required by these sophisticated systems. Few studies aimed at overcoming the limits of green roofs have hinted at the possibility of implementing hydroponic cultures in green roof systems. This soil-less technology might overcome some issues, such as identifying the suitable substrate to support the growth of the vegetation. This paper aims to provide a systematic review of hydroponic green roof systems (HGRS), based on the rigorous analysis of the evidence gathered from the thorough evaluation of the available literature on the subject, in order to assess their potential use as an alternative to traditional green roofs. The review was carried out by analyzing studies that have assessed the performance of hydroponic green roofs as well as those of comparable systems, such as pond roofs and green roofs. The results of these studies show that HGRS provide similar performances to the above-mentioned systems in terms of the passive conditioning effect, lowering the cooling/heating load of buildings, with slight changes depending on the climatic conditions. However, they offer other significant properties such as higher efficiency in water runoff management, alongside others discussed in this paper, while also requiring minor maintenance. Significant results have been provided; however, gaps in the knowledge have also emerged, and further studies need to be conducted to provide exhaustive information.
... Various studies and their findings related to the environmental assessment and economic profitability of RTGs in different locations are discussed [12,[49][50][51][52][53][54][55][56][57][58][59][60]. It is noteworthy that while RTGs may have higher initial costs associated with the greenhouse structure, they can offer lower environmental impacts, reduced transportation and distribution losses, increased food security, and potential productivity gains. ...
... Subsequently, Muñoz-Liesa et al. [58] discovered that through structural improvements, the environmental impact of IRTG systems decreased by 24 %. Furthermore, their findings [59] also demonstrated that an optimized steel structure utilizing tensioned cables offered a potential reduction of up to 36 % of the IRTG steel provision, thereby cutting 16 % of environmental impacts due to GHG emissions. ...
The environmental impacts of food systems will increase in tandem with rapid urban population growth, which calls for alternative solutions, such as urban agriculture, to reach the United Nations Sustainable Development Goals. Among several urban agriculture systems, rooftop farming and its subset, rooftop greenhouses, are promising technologies. They optimize land use, increase profitability for building owners, deliver good yields per unit area, increase water use efficiency, and reduce the energy use of both greenhouse and host buildings while mitigating the urban heat island effect. A systematic literature review of the rooftop greenhouse technology was carried out to examine the benefits and challenges associated with this technology. This review was based on 45 articles, covering themes such as the impact of rooftop greenhouse technology on yields, energy use, water use, environmental impacts, and life-cycle costs; some benefits identified are the symbiotic heat, water, and CO2 exchanges between the rooftop greenhouse and its host building, and the possibility of delivering year-round production. The additional investment, operational costs, limited availability of flat roofs, and various regulations were challenges to overcome. The relevance of symbiosis between rooftop greenhouses and buildings to enhancing sustainability, and meeting the SDGs was explored. This review also outlines that rooftop greenhouses are increasing in scale, system diversity, societal acceptance and popularity among commercial operations in large cities. The future of rooftop farming lies in customizing the right technology for selected building typologies globally, where food production is fully integrated into the urban landscape.
... Numerous systems used experimental production methods, including using biochar and struvite as inputs (Arcas-Pilz et al., 2021;Shen et al., 2020), recirculating nutrients in hydroponics systems (Rufí-Salís et al., 2020b), testing different LED lighting schemes (Pennisi et al., 2019), or using waste such as spent coffee grounds and brewers' grains for substrates (Dorr et al., 2021b;, which led to reduced yields, and may not be representative of how such systems would perform after research leads to improvements. Similarly, the integrated rooftop greenhouse in Barcelona, which was one of the first of its kind and the source of many results in this review, contributed large climate change impacts from its infrastructure, but numerous improvements have been identified that would reduce impacts in future systems (Muñoz-Liesa et al., 2021). It seems that numerous results here do not reflect a snapshot of current UA, but rather show the sub-optimized first iterations of potential production methods for the future. ...
... This may be especially important in this application where methodological choices between papers were rather inconsistent. Similarly, a large number of cases came from the same integrated rooftop greenhouse at the Universitat Autònoma de Barcelona in Spain (11 papers total, 8 papers in the meta-analysis, 44 systems, 17% of the systems evaluated), so the results were largely influenced by the material and operational design of this greenhouse (Arcas-Pilz et al., 2021;Llorach-Massana et al., 2017b;Muñoz-Liesa et al., 2021;Rufí-Salís et al., 2020aSanjuan-Delmás et al., 2018;Sanyé-Mengual et al., 2013Toboso-Chavero et al., 2018). ...
The global food system causes massive environmental impacts, and faces the challenge of feeding an even larger, more urbanized population in the coming decades. Urban agriculture (UA) is a type of alternative agriculture, which may have environmental and social benefits, and comes in a large diversity of forms. These environmental benefits and impacts can be modeled with life cycle assessment (LCA). Application of LCA to UA is relatively recent, and has not undergone the same methodological reflections and adaptations that LCA of other sectors has. In this thesis project, I investigated 1) what LCA tells us about the environmental performance of UA, and 2) how best to apply LCA to UA. I performed a review and meta-analysis of UA LCAs, and reviewed literature on the development of LCA for agriculture in general. I did LCAs of nine urban farms and gardens in Paris, France and the Bay Area, California, USA, and (with the FEW-meter project) analyzed resource use and food production at 72 UA case studies. I summarized and generated knowledge on the environmental performance of UA, and created a methodological framework to improve consistency and completeness in UA LCAs.
... However, despite the potential environmental and economic benefits, production in an urban i-RTG may present some limitations due to the shading of surrounding buildings, as well as the bulky structural items, and the loss of transmissivity of fireproof covering materials (e.g., polycarbonate). In fact, given the integration in a city context, the structure must comply with the municipality's structural and fire safety codes, with consequent constraints affecting the greenhouse light environment [8,9]. ...
... The experiment was performed in the i-RTG at the Institute of Environmental Science and Technology (ICTA-UAB) of the Universitat Autònoma de Barcelona (Catalunya, Spain) (41°49′78′' N, 2°10′89′' E) ( Figure 1a). The i-RTG structure consisted of reinforced steel pillars and polycarbonate cladding to satisfy the Spanish Technical Code of Edification and fire safety laws [9]. Tomato plants (Solanum lycopersicum L. cv. ...
The metabolism of a building can be connected to a rooftop greenhouse, exchanging energy, water and CO2 flows, therefore reducing emissions and recycling cultivation inputs. However, integrating a rooftop greenhouse onto a building requires the application of stringent safety codes (e.g., fire, seismic codes), to strengthen and secure the structure with safety elements such as thick steel pillars or fireproof covering materials. These elements can shade the vegetation or reduce solar radiation entering the rooftop greenhouse. Nevertheless, application of additional LED light can help to overcome this constraint. The present study evaluated supplemental LED light application in an integrated rooftop greenhouse (i-RTG) at the ICTA-UAB research institute, located in Barcelona (Spain), for tomato cultivation (Solanum lycopersicum cv. Siranzo). The experiment explored the effects of three LED lighting treatments and a control cultivated under natural light only (CK). Applied treatments, added to natural sunlight, were: red and blue (RB), red and blue + far-red (FR) for the whole day, and red and blue + far-red at the end-of-day (EOD), each for 16 h d−1 (8 a.m.–12 a.m.) with an intensity of 170 µmol m−2 s−1. The results indicate that LED light increased the overall yield by 17% compared with CK plants. In particular, CK tomatoes were 9.3% lighter and 7.2% fewer as compared with tomatoes grown under LED treatments. Fruit ripening was also affected, with an increase of 35% red proximal fruit in LED-treated plants. In conclusion, LED light seems to positively affect the development and growth of tomatoes in building integrated agriculture in the Mediterranean area.
... City planners were targeted to be able to focus on suitable types of urban agriculture (Goldstein et al., 2016(Goldstein et al., , 2017, to find new ways of working with urban agriculture to regenerate urban areas (Battisti, 2019) or to use the results from the studies as guides or frameworks for implementing urban agriculture in different ways (e.g., Sanyé-Mengual et al., 2015b. A few of the articles specifically aimed to help city planners implement urban agriculture in or on buildings (e.g., Munoz-Liesa et al., 2021). Practitioners, i.e., the actors who do the actual growing and start up different urban agriculture enterprises, were targeted in different ways in the articles. ...
The field of urban agriculture has seen an increase in development and attention in recent years, with a large share of literature addressing whether urban agriculture may pose a solution for food insecurity and combat environmental impacts. However, few studies have examined the many sustainability claims of urban agriculture systems, especially for urban farms intended for larger output and commercial ends. In this study, we analyze sustainability assessments of urban agriculture for commercial implementation. We do this by exploring the methods employed for conducting sustainability analyses, outlining the different urban agriculture cultivation systems, analyzing which sustainability aspects are considered, looking into what the sustainability analyses conclude, and studying how authors anticipate the knowledge gained from their sustainability assessments can be used. Environmental aspects of sustainability were more often assessed than other sustainability aspects, and LCA research practice was used for the majority of environmental assessments. Some studies compared the environmental benefits of different types of urban agriculture systems, but this was not conclusive overall as to what systems would be more environmentally beneficial. This suggests that urban agriculture’s sustainability cannot be universally categorized but should be assessed in relation to specific environmental conditions and urban contexts. Future research should aim to develop more nuanced frameworks for evaluating the environmental, social, economic and governance impacts of urban agriculture.
... On the interior and exterior of the greenhouse, a portable meteorological station was used to measure these variables. The productive system relied on short periods (60 to 100 days) for the harvest of vegetables, phytosanitary practices, organic fertilization, and the structuring of a living laboratory that promotes education in security, sovereignty, food safety, and environmental protection environments on a small scale, thereby generating benefits in terms of the food security required in urban areas (Appolloni et al., 2021;Feagan, 2007;Khan et al., 2020;Muñoz-Liesa et al., 2021). ...
The ongoing climate crisis, coupled with contemporary factors, starkly underscores the global vulnerability of
food systems and the pressing need for adaptive approaches. Urban agriculture emerges as a multifaceted remedy
for production, sustainability, and communal well-being. This study probes the role of small-scale organic urban
agriculture in driving sustainable urban development through a focused case study. Essential markers of sustainable
agro-production effectiveness take center stage.
The research scrutinizes yield and productivity within a rooftop agri-food framework spanning eleven months.
A collective of 336 vegetables were reaped, yielding an impressive 82.1% relative yield. Standout performers,
including lettuce, arugula, and mizuna, achieved a relative yield of 4.1 kg/m2, comfortably situated within the
2.1–16 kg/m2 spectrum. This yield potential remains sensitive to intricate agronomic and environmental variables.
The innovative potential extends to conferring food autonomy upon 11,553 families via 432 projects
within Bogota.
In conclusion, this research highlights the importance of small-scale organic urban agriculture as a viable
approach to sustainable development in urban areas. The results contribute to the existing knowledge on yield
and productivity indicators in sustainable agro-production systems, providing valuable insights for policymakers,
urban planners, and public and private organizations.
... On the interior and exterior of the greenhouse, a portable meteorological station was used to measure these variables. The productive system relied on short periods (60 to 100 days) for the harvest of vegetables, phytosanitary practices, organic fertilization, and the structuring of a living laboratory that promotes education in security, sovereignty, food safety, and environmental protection environments on a small scale, thereby generating benefits in terms of the food security required in urban areas (Appolloni et al., 2021;Feagan, 2007;Khan et al., 2020;Muñoz-Liesa et al., 2021). ...
The ongoing climate crisis, coupled with contemporary factors, starkly underscores the global vulnerability of food systems and the pressing need for adaptive approaches. Urban agriculture emerges as a multifaceted remedy for production, sustainability, and communal well-being. This study probes the role of small-scale organic urban agriculture in driving sustainable urban development through a focused case study. Essential markers of sustainable agro-production effectiveness take center stage.
The research scrutinizes yield and productivity within a rooftop agri-food framework spanning eleven months. A collective of 336 vegetables were reaped, yielding an impressive 82.1% relative yield. Standout performers, including lettuce, arugula, and mizuna, achieved a relative yield of 4.1 kg/m2, comfortably situated within the 2.1–16 kg/m2 spectrum. This yield potential remains sensitive to intricate agronomic and environmental variables. The innovative potential extends to conferring food autonomy upon 11,553 families via 432 projects within Bogota.
In conclusion, this research highlights the importance of small-scale organic urban agriculture as a viable approach to sustainable development in urban areas. The results contribute to the existing knowledge on yield and productivity indicators in sustainable agro-production systems, providing valuable insights for policymakers, urban planners, and public and private organizations.
... Clean energy sources such as solar energy technologies serve to generate electricity for greenhouse heating systems (Gorjian et al., 2021;Yano & Cossu, 2019). In addition, the integration of greenhouses with their associated buildings can significantly contribute to temperature and [CO 2 ] regulation, while reducing domestic [CO 2 ] emissions to the environment (Sanjuan-Delmás et al., 2018;Muñoz-Liesa et al., 2021). Elevated [CO 2 ] levels ranging from 1000 to 5000 ppm stimulate the growth response of radish (Muthusamy et al., 2019;McKeehen et al., 1996). ...
Tea is a globally popular beverage, leading to a significant accumulation of municipal waste. This study investigated the effects of tea waste compost on the growth traits of Raphanus sativus L. or radish while exploring the contribution of clean source carbon dioxide to sustainable production. The research team gathered the tea waste from urban households and allowed it to decompose for four months. Certain volumes of the tea waste compost ranging from 0% to 75% were mixed with locally available loamy textured garden soil (v/v). To simulate the impact of carbon dioxide waste from urban households on plant growth, the first greenhouse was enriched with carbon dioxide to reach elevated concentrations of 1500 ± 100 ppm, while the second greenhouse was maintained at the ambient level of 500 ± 20 ppm. The optimal growth temperature of both greenhouses was supplied with electricity. Using a split plot design, the effects of normal and elevated carbon dioxide levels, different volumes of tea waste compost, and the combined effect of tea waste compost and carbon dioxide levels on growth traits were investigated. The results showed that the elevated carbon dioxide level negatively influences the radish yield, biomass accumulation, and vegetative growth parameters. However, the tea waste compost improves growth traits with increasing volumes in garden soil from 0% to 75% (v/v). In the media containing 75% of tea waste compost, the elevated carbon dioxide level has the same effect as the normal level on growth traits, however, positive effects on total fresh weight but negative effects on measures of total dry weight, leaf dry weight, and total leaf area. These results show that the highest volume of tea waste compost ideally supports the growth of radish, which is mainly related to its high nitrogen content. The high and normal carbon dioxide levels in this volume are unable to dominate each other in terms of growth promotion. However, to reduce the amount of carbon dioxide emitted from houses and to produce fresh products, the waste carbon dioxide of urban houses should be transferred to the greenhouse to provide radishes with higher carbon dioxide levels during photosynthesis. Renewable energy sources such as solar or wind-generated electricity can be used to increase the temperature to the optimal level. This production method should be evaluated in future studies for other horticultural crops that prefer high carbon dioxide levels.
... Food systems that can enhance plant production through regulated nutrient delivery, reduction in pesticides, better water preservation, and reduced waste offer prospects of achieving the goal of sustaining the growing population [87]. Muñoz-Liesa et al. [96] advocate that urban sustainable development can be uniquely supported by using circular-resource systems. Food security may be achieved through smart design and using advanced materials for optimizing specific crop growth while focusing on reducing material costs and waste in urbanized farm systems [87]. ...
... Urban agriculture using optimized greenhouses to reconcile increased food needs and urbanization has been proposed and implemented, for instance, in Montreal with the world's largest urban rooftop greenhouse (https://montreal.lufa.com/, accessed on 20 September 2022) [115][116][117][118]. Innovative indoor systems such as vertical farming with multiple horizontal or vertical growing surfaces could provide a high production yield and close proximity of food supply to consumers while decreasing environmental consequences [119,120]. ...
One of the most important challenges facing current and future generations is how climate change and continuous population growth adversely affect food security. To address this, the food system needs a complete transformation where more is produced in non-optimal and space-limited areas while reducing negative environmental impacts. Fruits and vegetables, essential for human health, are high-value-added crops, which are grown in both greenhouses and open field environments. Here, we review potential practices to reduce the impact of climate variation and ecosystem damages on fruit and vegetable crop yield, as well as highlight current bottlenecks for indoor and outdoor agrosystems. To obtain sustainability, high-tech greenhouses are increasingly important and biotechnological means are becoming instrumental in designing the crops of tomorrow. We discuss key traits that need to be studied to improve agrosystem sustainability and fruit yield.
... Hydroponic cultivations have mostly been studied as a more sustainable alternative to traditional agriculture in terms of water and soil consumption [7] and for their easy implementation in urban areas, determining an increase in crop production for the population, a reduction in food transportation and waste and the improvement of food safety [8] thanks to a production policy based on "controlled environment agriculture" [9]. Only few authors have focused on the thermal benefits [3][4][5][6] of hydroponic systems as green roofs technologies however, studies on buildingintegrated agriculture (BIA) [10] have investigated how these systems can contribute to optimizing their energy and resource consumption through the trade-off between the building and the cultivation system [11]. If studies report comparable thermal and energy performances to traditional green roofs, hydroponic systems can likely become their viable competitors due to their added potential in terms of reduced resource consumption and subsequent lower environmental impact. ...
One of the main goals of building design is indoor comfort, regardless of its use (residential, educational, institutional, etc…). However, to achieve indoor comfort, buildings require a significant amount of energy. In the last decades, designers and researchers have been studying new strategies to improve buildings' energy efficiency, with the purpose of mitigating the negative environmental impact caused by heavy energy consumption. Green roofs have been one of the most investigated solutions because of the many thermal benefits they can offer, and amongst these, hydroponic green roofs gained momentum. This study aims to analyse the rooftop temperature reduction provided during the hot months by a hydroponic green roof, compared to a traditional roof slab and an extensive green roof, in order to assess the different performances of these systems. In situ experiments were conducted to collect surface temperature of the roof slab during summer, with and without the hydroponic system, in order to assess the potential temperature reduction, which subsequently affects the heat flow through the roof and therefore the indoor air temperature. The results show a significant decrease in the external surface temperature of the roof compared to the bare roof, but also slightly better performance compared to the extensive green roof. Despite first promising results, the knowledge on hydroponic green roofs performance remains limited and some drawbacks need to be assessed. For these reasons, further in situ testing should be carried out, under different climatic conditions and experimental setups.
... In this respect, the code ISO 14040 (ISO, 2006a) will be followed to define a methodology to carry out the LCA of ventilated facades. The LCA has been applied to different structures as bridges Penadés-Plà et al., 2020) , walls (Pons et al., 2018, andbuildings Cabeza et al. 2014;Muãoz-Liesa et al. 2021;Sánchez-Garrido et al., 2021). ...
The construction sector represents more than 40% of energy consumption in the European Union, as well as one of the biggest causes of environmental impact. Therefore, this sector needs a great deal of intervention through policies that promote the energetic efficiency of the buildings. One of the most important structural components to reach this energetic efficiency is the facades. In this work, the facade ventilated is chosen due to its better thermal insulation behaviour. The environmental impact of the facade ventilated depends on the thermal insulation material. The goal of this paper is to evaluate the environmental impact of different ventilated facades according to their thermal insulation behavior. For this purpose, the life-cycle assessment is applied in ventilated facades with different materials in different locations. The materials studied are the rock wool, the natural cork and the recycled cork, and the locations considered are the different climatic areas of Spain. To reach a complete environmental assessment all the ventilated facades life-cycle is considered, from cradle to grave. To do this we use the Open LCA software with the Ecoinvent database with the ReCiPe method. The results show that the recycled cork is the thermal insulation with the lowest environmental impact regardless the location.
... LCA quantifies and evaluates the material and energy flows of a system [22]. According to the EC and the literature [23], it is the best method for assessing the environmental impact of any activity. The International Organization for Standardization (ISO) states that, in order to have a global summary of the environmental impact of the product, LCA must be carried out in four phases: (I) definition of the purpose and scope of the assessment (functional unit, quality criteria, system limitations, etc.), (II) life cycle inventory, (III) life cycle assessment, and (IV) interpretation [19]. ...
Current European environmental sustainability standards call for achieving a reduction in energy consumption and CO2 emissions for a horizon set in the year 2050. It has been verified that buildings and cities have a higher incidence in this regard. It is necessary to have tools for initial assessment that can quickly analyse whether the improvement scenarios put forward by different organisations and governments will be able to meet the goals set at European level. Universities are an important factor for the intended change and therefore offer an excellent environment for testing such tools. A case study focusing on a university in northern Spain is presented, through an evaluation tool using 3D models including life-cycle assessment. Different reform scenarios are evaluated for two key years, 2030 and 2050. The novelty lies in considering, not only the impact of the operational phase but also the impact of the different stages of the life cycle and processes, obtaining an impact value closer to reality. The results indicate that, even with major retrofitting and adaptation efforts, the European targets are difficult to achieve by 2050. Moreover, solutions such as biomass help to achieve greenhouse gas reductions but not to improve energy efficiency.
... While other materials with higher transmittance may be employed, it is important to consider lifespan and resistance because that will directly affect the life cycle impacts of the infrastructure (Parajuli et al., 2021). Muñoz-Liesa et al. (2021) suggested that both glass and glass films have a similar transmittance of 90% and are environmentally better than polycarbonate. Glass has a long lifespan (15 years) in contrast to film (3-5 years) (Antón et al., 2012). ...
The rise of population in urban areas makes it ever more important to promote urban agriculture (UA) that is efficient in terms of water and nutrients. How to meet the irrigation demand of UA is of particular concern in urban areas where water sources are often limited. With the aim of determining how to reduce water use for irrigation while maintaining productivity and reducing environmental impacts in UA, this study explores the agronomic performance and environmental life cycle impacts and benefits of three different fertigation management practices used in a rooftop greenhouse for tomato crop in Barcelona: 1) open management (OP); 2) recirculation (RC), in which 30% of the drained, unused water is used to irrigate the crop; and 3) the same recirculated management of RC with a further reduction in fresh water input of 15%(RR). Despite the recirculation and reduction of water and nutrients, all three irrigation management practices resulted in similar yields: 16.2, 17.9, and 16.8·kg·m−2 for OP, RC, and RR, respectively. In terms of water-use efficiency, RR management was the most efficient, requiring 48.7·liters·kg−1 of tomato, followed by RC (52.4·L·kg−1) and OP (75.2·L·kg−1). RR presented an improvement of 7% in water-use efficiency. In terms of environmental performance, RC had the best performance in almost all impact categories during the operational phase, especially in regard to marine and freshwater eutrophication, with 44% and 93% fewer impacts than OP due to the recirculation of nutrients and reduced nutrient loss through leachates. In terms of infrastructure, even though recirculation management requires additional equipment, the materials present better performance in the range from 0.2 to 14% depending on the impact category. This study can support evaluation of agricultural projects in the city, through yields and water consumption presented, incentivizing good practices aligned with the sustainability of UA.
... It is in fact a significant potential contribution to meet climate challenges touching on food, energy, agriculture and rural policies [161,162]. Moreover, it is understood-i.e., by energy developers-as a possible driver for the implementation of large-scale PV installations and buildingintegrated agriculture [163], which without the APV function, would not be successful in the authorization process due to land use concerns. ...
As an answer to the increasing demand for photovoltaics as a key element in the energy transition strategy of many countries—which entails land use issues, as well as concerns regarding landscape transformation, biodiversity, ecosystems and human well-being—new approaches and market segments have emerged that consider integrated perspectives. Among these, agrivoltaics is emerging as very promising for allowing benefits in the food–energy (and water) nexus. Demonstrative projects are developing worldwide, and experience with varied design solutions suitable for the scale up to commercial scale is being gathered based primarily on efficiency considerations; nevertheless, it is unquestionable that with the increase in the size, from the demonstration to the commercial scale, attention has to be paid to ecological impacts associated to specific design choices, and namely to those related to landscape transformation issues. This study reviews and analyzes the technological and spatial design options that have become available to date implementing a rigorous, comprehensive analysis based on the most updated knowledge in the field, and proposes a thorough methodology based on design and performance parameters that enable us to define the main attributes of the system from a trans-disciplinary perspective.
Circularity has emerged as a pivotal concept in the realm of sustainable resource management and business operations. Resource exhaustion and environmental degradation propelled by globalization and the culture of consumerism have intensified the focus on the concept of the circular economy around the world. Nevertheless, the evaluation and quantification of circularity achievements remain uncommon in corporate practices. This article employs a systematic literature review to delve into circularity measurements in the managerial life cycle. Key approaches emerging from the academic literature are examined, including life cycle costing, life cycle assessment, life cycle cost–benefit, life cycle benefit analysis, and life cycle sustainability assessment. The review seeks to offer a comprehensive overview of the methodologies employed to assess circularity in corporate processes, highlighting current challenges and opportunities for effective implementation. We adopt a conceptual model of sustainable and circular life cycle management based on specific performance indicators that allow the environmental, social, and economic impact of processes to be assessed throughout the life cycle of products or services. The implementation of Sustainable and Circular Life Cycle Management from a managerial perspective could support firms to eradicate and quantify waste, preserve the inherent value of products and materials, encourage the adoption of renewable energies, and eliminate harmful chemicals.
Researchers and practitioners use life cycle assessment (LCA) as a powerful tool to thoroughly assess the environmental impact of protected agriculture. However, the literature in this field has shown heterogeneity, which is characterized by inconsistent methodologies and assumptions. Identifying prevailing trends and resolving existing limitations is necessary to generate robust results and guide future work. Here, we conduct a bibliometric and systematic review to explore how LCA applications have addressed protected agriculture. The bibliometric analysis unveils trends in scientific productivity, spanning temporal evolution and geographic distribution, while also identifying prominent research avenues. The systematic review traces the historical trajectory of agricultural LCA and scrutinizes methodological decisions across the standard LCA phases: (i) objective and scope, (ii) life cycle inventory, (iii) impact assessment, and (iv) interpretation. We summarize and discuss the reported environmentally friendly practices and provide a qualitative interpretation of the LCA findings. Moreover, we pinpoint key methodological challenges and propose research horizons. It is crucial to note that the environmental benefits of protected agriculture are context-dependent, with climate change emerging as a critical factor influencing crop yields and the sys-tem's input and output resources. This impact is particularly pronounced in terms of water and energy consumption and carbon emissions. In regions with extreme climates, protected agriculture provides solutions for producers aiming to attain high yields of top-quality crops. The integration of circular bio-economy strategies in this context allows mitigation of the environmental trade-offs identified by LCA.
Urban green installations are extensively promoted to increase sustainable and accessible food production and simultaneously improve the environmental performance and liveability of city buildings. In addition to the multiple benefits of plant retrofitting, these installations may lead to a consistent increase in biogenic volatile organic compounds (BVOCs) in the urban environment, especially indoors. Accordingly, health concerns could limit the implementation of building-integrated agriculture. In a building-integrated rooftop greenhouse (i-RTG), throughout the whole hydroponic cycle, green bean emissions were dynamically collected in a static enclosure. Four representative BVOCs, α-pinene (monoterpene), β-caryophyllene (sesquiterpene), linalool (oxygenated monoterpene) and cis-3-hexenol (LOX derivate), were investigated in the samples collected from two equivalent sections of a static enclosure, one empty and one occupied by the i-RTG plants, to estimate the volatile emission factor (EF). Throughout the season, extremely variable BVOC levels between 0.04 and 5.36 ppb were found with occasional but not significant (P > 0.05) variations between the two sections. The highest emission rates were observed during plant vegetative development, with EFs equivalent to 78.97, 75.85 and 51.34 ng g-1 h-1 for cis-3-hexenol, α-pinene, and linalool, respectively; at plant maturity, all volatiles were either close to the LLOQ (lowest limit of quantitation) or not detected. Consistent with previous studies significant relationships (r ≥ 0.92; P < 0.05) were individuated within volatiles and temperature and relative humidity of the sections. However, correlations were all negative and were mainly attributed to the relevant effect of the enclosure on the final sampling conditions. Overall, levels found were at least 15 folds lower than the given Risk and LCI values of the EU-LCI protocol for indoor environments, suggesting low BVOC exposure in the i-RTG. Statistical outcomes demonstrated the applicability of the static enclosure technique for fast BVOC emissions survey inside green retrofitted spaces. However, providing high sampling performance over entire BVOCs collection is recommended to reduce sampling error and incorrect estimation of the emissions.
The sustainable supplier assessment has emerged as a strategic activity that seeks to green the value chain. Plentiful studies evaluating sustainable suppliers in the agroindustry field have been proposed. These investigations focus on selecting or ranking from the best to the worst performance. However, the sorting approach that would be more adequate when it comes to investigating the performance of partners with a view to making improvements to their systems is generally not considered to solve this problem, being an important gap in the literature. In this scenario, this research provides a food supplier sorting model using Value‐Focused Thinking (VFT) and Flexible and Interactive Tradeoff (FITradeoff) method for sorting problematic to suggest upgrades and advancements in the operation of the suppliers searching for a sustainable development. The suppliers were sorted into predefined categories depending on sustainability level: sustainable suppliers; suppliers in path of development; and non‐green suppliers. The method was applied for evaluating suppliers in a Colombian food industry. Finding shows that the proposed model is useful to categorize suppliers, serving to design particular green programs for each class to improve them, while also suggesting a strategic direction to greener the food supply chain in accordance with the goals of the sustainable development.
It is widely accepted that urban agriculture provides multiple benefits to society. Rooftop greenhouses are a form of urban agriculture that takes advantage of urban resources (urban land, sunlight spaces) and waste flows (energy, nutrients) to provide food and other ecosystem services to cities. However, the integration of urban greenhouses within buildings is a complex issue that must be addressed in-depth. Compared to the well-known conventional greenhouses, the urban environment requires an assessment to later optimize greenhouse structures and covering materials. The aim of our study was to environmentally assess rooftop greenhouses and propose improving scenarios. Life cycle assessment was used to detect environmental hotspots and to evaluate different impact categories of an iRTG case study in the Barcelona area. Results showed that the greenhouse environment and ventilation design directly determine greenhouse structures and environmental impacts. Optimized strategies showed a potential reduction of up to 35% of the amount of structural steel used, while less improvement potential existed for covering materials (5%). Compared to conventional greenhouses, 1.6 times more steel and up to 8 times more energy were required to build the urban greenhouse in this study. The assessment revealed that these differences can be reduced by optimizing greenhouse structures to avoid a shift of material flows and environmental impacts from building urban greenhouses compared to conventional greenhouses. In turn, the assessment presented here provides guidelines on how to design and plan urban greenhouse constructions in future assessments. That will facilitate the incorporation of urban agriculture in cities based on consistent environmental assessments, ultimately contributing to the low-carbon future development of cities.
Improvements to the world’s food supply chain are needed to ensure sufficient food is
produced to meet increasing population demands. Growing food in soilless hydroponic systems
constitutes a promising strategy, as this method utilizes significantly less water than conventional
agriculture, can be situated in urban areas, and can be stacked vertically to increase yields per acre.
However, further research is needed to optimize crop yields in these systems. One method to increase
hydroponic plant yields involves adding plant growth-promoting bacteria (PGPB) into these systems.
PGPB are organisms that can significantly increase crop yields via a wide range of mechanisms,
including stress reduction, increases in nutrient uptake, plant hormone modulation, and biocontrol.
The aim of this review is to provide critical information for researchers on the current state of the
use of PGPB in hydroponics so that meaningful advances can be made. An overview of the history
and types of hydroponic systems is provided, followed by an overview of known PGPB mechanisms.
Finally, examples of PGPB research that has been conducted in hydroponic systems are described.
Amalgamating the current state of knowledge should ensure that future experiments can be designed
to effectively transition results from the lab to the farm/producer, and the consumer.
Despite considerable interest in urban and peri-urban agriculture (UPA) in recent decades, its contributions to urban sustainability and human wellbeing remain contested. This systematic literature review examines the geographical landscape of the peer-reviewed literature on UPA and assesses its reported outcomes on sustainability and wellbeing. Following systematic review protocols, we undertook a two-step literature screening and quality assessment process. From a total of 4,029 articles, based inclusion-exclusion criteria, we filtered 320 articles for quantitative and 86 for qualitative assessment. Quantitative analysis confirmed an exponential increase in literature on UPA since 2015 and a regional bias towards the Global North. The qualitative analysis identified six thematic outcomes of UPA under three sustainability pillars - environmental sustainability; material well-being; labour and livelihoods; land tenure and urban planning; and food and nutritional security as part of economic sustainability; and subjective and relational wellbeing as well as gender and social differentiation as elements of social sustainability. Environmental sustainability was most discussed, followed by subjective wellbeing and food and nutritional security. Gender and social differentiation issues were least represented in the papers. There remain knowledge gaps around how urban policy and planning can recognise, leverage, and scale up the sustainability and wellbeing co-benefits of UPA.
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, 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.
Environmental merits are a common motivation for many urban agriculture (UA) projects. One powerful way of quantifying environmental impacts is with life cycle assessment (LCA): a method that estimates the environmental impacts of producing, using, and disposing of a good. LCAs of UA have proliferated in recent years, evaluating a diverse range of UA systems and generating mixed conclusions about their environmental performance. To clarify the varied literature, we performed a systematic review of LCAs of UA to answer the following questions: What is the scope of available LCAs of UA (geographic, crop choice, system type)? What is the environmental performance and resource intensity of diverse forms of UA? How have these LCAs been done, and does the quality and consistency allow the evidence to support decision making? We searched for original, peer-reviewed LCAs of agricultural production at UA systems, and selected and evaluated 47 papers fitting our analysis criteria, covering 88 different farms and 259 production systems. Focusing on yield, water consumption, greenhouse gas emissions, and cumulative energy demand, using functional units based on mass of crops grown and land occupied, we found a wide range of results. We summarized baseline ranges, identified trends across UA profiles, and highlighted the most impactful parts of different systems. There were examples of all types of systems—across physical set up, crop type, and socio-economic orientation—achieving low and high impacts and yields, and performing better or worse than conventional agriculture. However, issues with the quality and consistency of the LCAs, the use of conventional agriculture data in UA settings, and the high variability in their results prevented us from drawing definitive conclusions about the environmental impacts and resource use of UA. We provided guidelines for improving LCAs of UA, and make a strong case that more research on this topic is necessary to improve our understanding of the environmental impacts and benefits of UA.
Purpose
Rooftop greenhouses (RTGs) are agricultural systems that can improve the food supply chain by producing vegetables in unused urban spaces. However, to date, environmental assessments of RTGs have only focused on specific crops, without considering the impacts resulting from seasonality, combinations of crops and nonoperational time. We analyze vegetable production in an RTG over 4 years to determine the crop combinations that minimize yearly environmental impacts while diversifying food supply.
Methods
The system under study consists of an integrated RTG (i-RTG) with a hydroponic system in Barcelona, in the Mediterranean region. By using life cycle assessment (LCA), we evaluate the environmental performance of 25 different crop cycles and 7 species cultivated during the period 2015–2018. Three functional units are used: 1 kg of edible fresh production, 1 unit of economic value (€) in the wholesale market and 1 kcal of nutritional value. The system boundaries consider two subsystems: infrastructure (greenhouse structure, rainwater harvesting system and auxiliary equipment) and operation (fertilizers and their emissions into water and substrate). In addition, we perform an eco-efficiency analysis, considering the carbon footprint of the crop cycles and their value at the wholesale market during their harvesting periods.
Results and discussion
Spring tomato cycles exert the lowest impacts in all categories, considering all three functional units, due to the high yields obtained. In contrast, spinach and arugula have the highest impacts. Regarding relative impact, the greenhouse structure presented a large impact, while fertilizer production had notable relative contributions in tomato cycles. Moreover, nitrogen and phosphorus emissions from fertigation are the main causes of freshwater and marine eutrophication. By combining the most eco-efficient cycles, we can see that growing two consecutive tomato cycles is the best alternative with the functional unit of yield (0.49 kg CO2 eq./kg), whereas a long spring tomato cycle combined with bean and lettuce cycles in the autumn/winter is the best scenario when using market (0.70 kg CO2 eq./€) and nutritional value (3.18·10−3 kg CO2/ kcal).
Conclusions
This study shows that increasing the diversity of the system leads to better environmental performance of greenhouse urban agriculture if suitable crops are selected for the autumn/winter season. The functional unit involving the economic value and the eco-efficiency analysis are useful to demonstrate the capability of the growing system to produce added-value vegetables under harsher conditions while categorizing and classifying the crops to select the most suitable combinations based on economic and environmental parameters.
Cities are rapidly growing and need to look for ways to optimize resource consumption. Metropolises are especially vulnerable in three main systems, often referred to as the FEW (i.e., food, energy, and water) nexus. In this context, urban rooftops are underutilized areas that might be used for the production of these resources.
We developed the Roof Mosaic approach, which combines life cycle assessment with two rooftop guidelines, to analyze the technical feasibility and environmental implications of producing food and energy, and harvesting rainwater on rooftops through different combinations at different scales. To illustrate, we apply the Roof Mosaic approach to a densely populated neighborhood in a Mediterranean city. The building‐scale results show that integrating rainwater harvesting and food production would avoid relatively insignificant emissions (13.9–18.6 kg CO2 eq/inhabitant/year) in the use stage, but their construction would have low environmental impacts. In contrast, the application of energy systems (photovoltaic or solar thermal systems) combined with rainwater harvesting could potentially avoid higher CO2 eq emissions (177–196 kg CO2 eq/inhabitant/year) but generate higher environmental burdens in the construction phase.
When applied at the neighborhood scale, the approach can be optimized to meet between 7% and 50% of FEW demands and avoid up to 157 tons CO2 eq/year. This approach is a useful guide to optimize the FEW nexus providing a range of options for the exploitation of rooftops at the local scale, which can aid cities in becoming self‐sufficient, optimizing resources, and reducing CO2 eq emissions.
Rooftop agriculture (RA) is an innovative form of urban agriculture that takes advantage of unused urban spaces while promoting local food production. However, the implementation of RA projects is limited due to stakeholders’ perceived risks. Such risks should be addressed and minimized in policymaking processes to ensure the sustainable deployment of RA initiatives. This paper evaluates the risks that stakeholders perceive in RA and compares these perceptions with the currently available knowledge, including scientific literature, practices and market trends. Qualitative interviews with 56 stakeholders from Berlin and Barcelona were analyzed for this purpose. The results show that perceived risks can be grouped into five main categories: i) risks associated with urban integration (e.g., conflicts with images of “agriculture”), ii) risks associated with the production system (e.g., gentrification potential), iii) risks associated with food products (e.g., soil-less growing techniques are “unnatural”), iv) environmental risks (e.g., limited organic certification) and v) economic risks (e.g., competition with other rooftop uses). These risks are primarily related to a lack of (scientific) knowledge, insufficient communication and non-integrative policymaking. We offer recommendations for efficient project design and policymaking processes. In particular, demonstration and dissemination activities as well as participatory policymaking can narrow the communication gap between RA developers and citizens.
While many urban authorities in Europe are confronted both with increasing demands by urban dwellers for allotment gardens, vacant urban soil tends to be scarce and/or polluted by past industrial activities. A possible solution for local authorities could therefore be to promote rooftop gardening. Little technical information exists however on certain forms of rooftop urban agriculture, called Z-Farming. In 2012, a pilot experiment was run in Paris (France). Simple and cheap systems of rooftop gardening were tested on a rooftop, using as crop substrates only local urban organic waste so as to contribute to the urban metabolism. Production levels, physical and chemical evolution of substrates and heavy metal contents in cropping substrates and edible vegetables were measured. Available results show (i) high levels of crop production compared to the reduced use of inputs, and (ii) very low levels of heavy metal pollutants in the edible parts of the crops. These encouraging results allow us to consider that rooftop gardening is possible. It will nevertheless be necessary to identify more precisely the types of roof that can be used, and to assess more fully the generic result of the low level of pollution, as well as the global sustainability of these cropping systems.
This paper quantifies environmental impact aspects of the recent pneumatic roofing system made of multi-layer etfe films in a lifetime perspective. A comparison with a similar high transparency system, a glazing system, is needed in order to understand its environmental efficiency. Two existing covering systems (an etfe pneumatic roof and a glazing roof), designed to contain a thermal buffer zone between buildings, have been chosen in order to apply the Life Cycle Assessment methodology: the material and building stage have been considered, giving a further insight to evaluate different design choices and technical solutions. The results about the LCA application in the building field show the advantage of the lightweight structure, reducing the involved material amount and highlight the importance of the light technical solutions assessment both at the material stage (relating to their own specific gravity), both at the roof subsystems stage and even better at a building scale.
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 692
Urban agriculture (UA) is spreading within the Global North, largely for food production, ranging from household individual gardens to community gardens that boost neighborhood regeneration. Additionally, UA is also being integrated into buildings, such as urban rooftop farming (URF). Some URF experiences succeed in North America both as private and community initiatives. To date, little attention has been paid to how stakeholders perceive UA and URF in the Mediterranean or to the role of food production in these initiatives. This study examines the promotion and inclusion of new forms of UA through the practice of URF and contributes to the nascent literature on the stakeholder and public perceptions of UA. It seeks to understand how those perceptions shape the development of new urban agriculture practices and projects. Barcelona (Spain) was used as a Mediterranean case study where UA and URF projects are growing in popularity. Through semi-structured interviews with 25 core stakeholders, we show that UA is largely perceived as a social activity rather than a food production initiative, because the planning of urban gardens in Barcelona was traditionally done to achieve leisure and other social goals. However, several stakeholders highlighted the potential to increase urban fertility through URF by occupying currently unused spaces. As a result, the positive valuation of URF depends on the conceptualization of UA as a social or food production activity. In turn, such conceptualization shapes barriers and opportunities for the development of URF. While most UA-related stakeholders (e.g., food co-ops, NGOs) preferred soil-based UA, newer stakeholders (e.g., architects) highlighted the economic, social and environmental opportunities of local and efficient food production through innovative URF.
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.
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.
Today 50 percent of the world's population lives in cities. This entails an excessive exploitation of natural resources, an increase in pollution, and an increase in the demand for food. One way of reducing the ecological footprint of cities is to introduce agricultural activities to them. In the current food and agriculture model, the fragmentation of the city and the countryside means energy use, CO2 emissions from transport, and large-scale marketing requirements. Rooftop Eco.Greenhouses (RTEG) consist of a greenhouse connected to a building in terms of energy, water, and CO2 flows; it is a new model for a sustainable production, an eco-innovative concept for producing high quality vegetables and improving the sustainability of buildings in cities. The main objective of this study is to examine the barriers and opportunities regarding the implementation of RTEG in Mediterranean cities in Europe. The work method consisted of discussion seminars involving an interdisciplinary group of experts in the area of agronomy, architecture, engineering, environmental sciences, industrial ecology, and other related disciplines. The barriers and opportunities of RTEG take into account social, economic, environmental, and technological aspects and were determined and analyzed according to three scenarios of implementation: residential buildings, educational or cultural buildings, and industrial buildings. We would highlight the interconnection of the building and the greenhouse as an opportunity of RTEG, making use of water, energy, and CO2 flows between both, as well as the decrease in food transportation requirements. The methodology applied to the study was positive due to the interdisciplinary participation of experts which facilitated a global vision of the implementation of the project.
The environmental impact of greenhouse production in France is poorly documented. Environmental benefits versus drawbacks
of greenhouse production are not well known. Assessments that intregrate pesticide toxicology and transfer of mass and energy
are scarce. Here, we compared the main types of tomato production, heated, year-round production in plastic houses or glasshouses,
and seasonal production under polytunnel. Environmental impacts where assessed by life cycle analysis. Analyses were performed
after the construction of a database relating the integrality of matter and energy fluxes, regarding the structure of the
system, the inputs for production, and the waste products. Results show that greenhouse heating had the highest environmental
impacts, including toxicological impact. For instance, the mean environmental impact of heated crops under plastic or in glasshouses
was 4.5 times higher than in tunnels. Furthermore, pesticides in tunnels had a 3- to 6-fold higher impact in terms of terrestrial
or aquatic ecotoxicology or human toxicology. Our results were compared with data from other temperate production regions.
KeywordsGreenhouse tomato production–Environmental impact–Life cycle impact assessment
The circular economy (CE) concept has received increasing attention among different parties on various levels recently. Due to the concern on significant resources consumption in the construction industry without concerning the physical limit resources, a paradigm shift of linear economy to CE model is inevitable for conserving the resources and promoting the efficient use of resources. Adopting CE into the construction industry can promote the successful transition to sustainable construction. Although early stage of development in the construction industry, the scientific contribution of CE agenda in the construction industry is significantly increasing. Therefore, this review aimed to identity the implications, considerations, contributions and challenges of CE in the construction industry by systematically analyzing the recent literature. In addition to existing trends and considerations, this study highlighted the numerous challenges under design, materials selection, supply chain, business model, uncertainty and risk, collaborations among actions, knowledge of understanding, relevant policy, integration of urban metabolism, and methodology for CE evaluation. The study found that CE implementation into the case-specific building with full scale evaluation is yet to be conducted, and a comprehensive CE integration and methodology framework is yet to be developed. A prospective integrated framework for CE adoption and evaluation method is proposed by analyzing the contemporary issues. It is believed that the analyzed critical issues for CE adoption, identified future research direction, and proposed frameworks and methodology should help further development of CE research and contribution to effective implementation of CE into the industry for promoting sustainable construction.
Urban agriculture systems, such as rooftop greenhouses, are attractive alternatives for mitigating the impacts of the extensive food supply chains that currently feed cities. In this study, we study the opportunity that nutrient recirculation offers to improve the environmental performance of agricultural systems. In particular, we analyze the environmental burdens of a hydroponic closed-loop production system that recovers nutrients and reduces water demand by recirculating the irrigation water leaching from the substrate bags along with nutrients that have not been assimilated by the plant. The closed-loop system is compared to a linear system in which there is no nutrient or water recovery. Based on two green bean crop cycles in a Mediterranean rooftop greenhouse, we analyze the yield, climatic variables and water and nutrient balances, and apply life cycle assessment (LCA) to study the environmental impacts.
The results of this study indicate that closed-loop systems save daily 40% of irrigation water and between 35 and 54% of nutrients. Moreover, leachate reuse leads to reduced eutrophication impacts, but it can entail nutrient deficiencies. However, implementing a closed-loop system requires additional infrastructure causing larger impacts than linear systems in terms of global warming and fossil resource scarcity. The results of the LCA were highly sensitive to the yield, the crop production period and the meteorological conditions. Based on these results, we design improved scenarios, providing recommendations for reducing the impacts of closed-loop systems for more sustainable cities.
Improving sustainability of organic tomato value chains requires increase of production and reduction of losses and related environmental burden. This paper presents the study conducted on organic tomato produced and consumed in Sweden. Using life cycle analysis (LCA) method with SimaPro8.2 LCA software, the cumulative energy demand (CED) and global warming potential (GWP100) were investigated within the system boundary of cradle-to-consumer gate. The system was modeled as fresh tomato value chain (FTVC) and dried tomato value chain (DTVC). The functional unit (FU) was 1 ton of fresh product at farm that will be delivered to customer either as fresh or dried tomato. Sensitivity analysis was done considering changes in drying energy consumption. The results indicated that calculated CED values were 44.58 GJ and 49.40 GJ per functional unit for FTVC and DTVC respectively. Similarly, GWP100 values were 547.13 kg CO2 eq and 467.44 kg CO2 eq for FTVC and DTVC respectively. Agricultural production has been identified as hot-spot stage in both FTVC and DTVC cases. Next to agricultural stage, post-harvest and transport stages have been hot-spot stages for energy demand and climate impact respectively. Energy for greenhouse heating and irrigation as well as material for greenhouse construction contributed to the high impact of tomato cultivation stage. Packaging and drying activities at post-harvest stage and fuel consumption at transport stage contributed more to environmental burden. The drying process increased the energy demand while it reduced climate change impact. The drying process also could reduce the product losses and increase the product shelf life. This could improve the sustainability of locally produced organic tomato value chains, especially if integrated with renewable energy sources.
In today's growing cities, where land is an expensive commodity and direct exposure to sunlight is a valuable asset, rooftops constitute vast underexploited areas. Particularly with growing urban environmental concerns, the potential of transforming these areas into productive spaces-either for food cultivation or energy generation-has emerged as a viable option in recent years. Both food production and energy generation have benefits in the urban environment. Rooftop farming is an environmentally and economically sustainable way of exploiting urban rooftops, reducing "food miles" and providing local jobs, while roof-integrated solar photovoltaic (PV) modules provide clean energy, are increasingly cost-effective, and offer job opportunities. In both cases, a rooftop network of production could directly supply a portion of a necessary resource-either food or electricity-to the local community while concurrently reducing the burden on the environment. To provide a basis for comparing the implementation of these productive uses of rooftops in Mediterranean cities, this article applies a Cost-Benefit Analysis (CBA) to a mixed-use neighborhood located in Lisbon to assess the following uses: (1) open-air rooftop farming on intensive green roofs; (2) food production in low-tech unconditioned Rooftop Greenhouse (RG) farms; (3) Controlled-Environment Agriculture (CEA) in high-tech RG farms; and (4) solar PV energy generation. Relative costs, cost-saving benefits and added value of these four alternative productive uses of rooftops were modeled over 50 years and deducted from present value, considering two levels of analysis: (a) effects directly incurred by the operator of the systems; and (b) societal effects on the local community. To the authors' knowledge, this is the first comprehensive comparison of rooftop PV versus rooftop farming technologies. The results have shown food production to be more beneficial than energy generation, for both the owner of the system and the local community, under the modeled conditions and given the selected items of comparison. In particular, the results show that rooftop greenhouse farming can provide significant benefits over rooftop green roof and solar PV systems when assessed from a holistic perspective that accounts for impacts on both the operator and the local community.
Vertical farming is emerging as an effective measure to grow food in buildings and can increase food production in urban areas in a more sustainable manner. This study presents a comprehensive environmental assessment of food production in an integrated rooftop greenhouse (i-RTG) – an innovative vertical farm consisting of a rooftop greenhouse connected to a building – and considers rainwater, residual heat (energy), residual air (CO2) and food from an industrial ecology perspective. This synergistic connection preserves resources and improves conditions in the greenhouse and the building. The goal of the study is to show the feasibility of the system and to calculate the environmental impacts from its whole life cycle, from infrastructure to end of life, by comparing these impacts with those of conventional production. The results show that the system is feasible and produced 30.2 kg/m² of tomato over 15.5 months. The synergy with the building allows the cultivation of winter-fall crops without supplying heating and maintained an average temperature 8 °C higher than that outdoors. Moreover, rainwater was used to irrigate the crops, reducing consumption from the water supply network by 80–90%. The environmental assessment showed that the operation of the i-RTG has more impacts than the infrastructure (structure of the greenhouse, rainwater harvesting system and equipment) due to the use of fertilisers, which account for 25% of the impacts in four of the six impact categories studied. Regarding the infrastructure, the greenhouse structure and rainwater harvesting system of the building have substantial environmental impacts (over 30% in four of the six impact categories). Comparison with a conventional greenhouse demonstrates that the i-RTG has a better environmental performance, showing between 50 and 75% lower impacts in five of the six impact categories (for instance, 0.58 kg of CO2 equivalent per kg of tomato vs. 1.7 kg), mainly due to the reduced packaging and transport requirements. From this study, it was concluded that optimisation of the amount of infrastructure material and management of the operation could lead to even better environmental performance in future i-RTG projects.
Rooftop greenhouses (RTGs) can generate significant advantages provided RTGs and buildings are connected in terms of energy, water and CO2 flows. Beyond the production of high-value crops, environmental benefits such as re-use of waste water, application of residual heat and absorption of carbon dioxide are derived from urban RTGs. Social benefits viz the creation of employment, social cohesion and so on are also important assets of RTGs. This chapter is focussed on RTGs technology. RTG share many common aspects with conventional greenhouses, but at the same time RTGs show attributes that should be discussed separately. Synergies such as using residual heat, rain water for irrigation, CO2 exchange, etc. are part of the common metabolism greenhouse-building. This chapter will concentrate on the available technology from conventional greenhouses which is more suitable for RTGs, particularly concerning greenhouse structure, covering materials, climate control and soilless cultivation systems.
This chapter focuses on the elements that must be considered when designing rooftop gardens and integrating them within buildings. Different types of rooftop gardens and how they can be integrated within existing and new buildings in order to enhance their environmental performance, better connect with their users and contribute to the amelioration of the urban environment are presented together with a description of necessary factors for implementation. These include: techniques and technologies for cultivation (i.e. simple planters, green roofs and hydroponics), necessary structural loadbearing capacity of the host building and protection from wind. The chapter also gives an overview of existing innovative and experimental projects of rooftop gardens, ranging from those that require little to high investment.
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.
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Global food systems are as vital for human survival as they constitute a major threat to the environment, being key drivers of climate change, water use, toxic emissions and habitat change. In a business as usual scenario, these impacts will most likely increase, driven by population and economic growth, which will lead to a higher demand for food, and probably for the most environmentally intensive food categories: meat and dairy products. Existing literature suggests deep paradigmatic changes to address this situation, such as (i) large-scale dietary changes on the consumption side, and (ii) structural changes towards more efficient food supply chains on the production side. As both of these measures are related to urban systems, in terms of food consumption habits and the potential of local production, Urban and Peri-Urban Agriculture (UPA) may assume a relevant role in food systems sustainability. In order to estimate to what extent the implementation of UPA would play a role in mitigating the environmental impacts of urban food systems, this paper uses LCA to estimate their respective mitigation potential. The Global Warming Potential (GWP) and Land use (LU) were assessed for per capita Current Average Consumption (CAC) in Lisbon, and this baseline model was subsequently adapted in order to measure the effects of changes: (i) in the diet, through a comparison with the Recommended Healthy Diet (RHD) model; and (ii) in the food supply chain, by measuring the impacts of eliminating losses and wastage across the food supply chain and shortening transportation distances through local food production. The results show that the highest potential for environmental impacts mitigation is related to dietary changes. However, strategies for enhancing the efficiency of the food supply chain are relevant, as reducing losses and wastage, shortening transportation distances and taking into account technology improvements can further increase the mitigation potential.
Urban agriculture appears to be a means to combat the environmental pressure of increasing urbanization and food demand. However, there is hitherto limited knowledge of the efficiency and scaling up of practices of urban farming. Here, we review the claims on urban agriculture’s comparative performance relative to conventional food production. Our main findings are as follows: (1) benefits, such as reduced embodied greenhouse gases, urban heat island reduction, and storm water mitigation, have strong support in current literature. (2) Other benefits such as food waste minimization and ecological footprint reduction require further exploration. (3) Urban agriculture benefits to both food supply chains and urban ecosystems vary considerably with system type. To facilitate the comparison of urban agriculture systems we propose a classification based on (1) conditioning of the growing space and (2) the level of integration with buildings. Lastly, we compare the predicted environmental performance of the four main types of urban agriculture that arise through the application of the taxonomy. The findings show how taxonomy can aid future research on the intersection of urban food production and the larger material and energy regimes of cities (the “urban metabolism”).
Firstly, this article discusses the greenhouse engineering situation in three geographic areas which are relevant in the field of protected cultivation: Northern Asia, The Netherlands and the Mediterranean. For each area, the prevailing greenhouse type and equipment is briefly described. Secondly, the main technological constraints are pointed out and finally the research directions are discussed. For all areas under consideration, attempts to design more efficient greenhouse systems are under way. In Northern Asia progress is being made towards the optimisation of greenhouses as a solar collector and to the development of new heating strategies. Important subjects addressed in The Netherlands are energy conservation and the replacement or alleviation of human labour by increasing mechanisation. In the Mediterranean there is growing interest in semi-closed greenhouses with CO2 enrichment and control of excessive humidity. All geographic areas share the need of having an optimised climate control based on the crop response to the greenhouse environment. All areas also share the requirement of being respectful to the environment, therefore future greenhouses are expected to use engineering to produce with minimal or zero emissions.
Saving energy in greenhouses is an important issue for growers. Here, we present a method to minimize the total energy that is required to heat and cool a greenhouse. Using this method, the grower can define bounds for temperature, humidity, CO2 concentration, and the maximum amount of CO2 available. Given these settings, optimal control techniques can be used to minimize energy input. To do this, an existing greenhouse climate model for temperature and humidity was expanded to include a CO2 balance. Heating, cooling, the amount of natural ventilation, and the injection of industrial CO2 were used as control variables.
Standard optimization settings were defined in order to compare the grower’s strategy with the optimal solution. This optimization resulted in a theoretical 47% reduction in heating, 15% reduction in cooling, and 10% reduction in CO2 injection for the year 2012. The optimal control does not need to maintain a minimum pipe temperature, in contrast to current practice. When the minimum pipe temperature strategy of the grower was implemented, heating and CO2 were reduced by 28% and 10% respectively.
We also analyzed the effect of different bounds on optimal energy input. We found that as more freedom is given to the climate variables, the higher the potential energy savings. However, in practice the grower is in charge of defining the bounds. Thus, the potential energy savings critically depend on the choice of these bounds. This effect was analyzed by varying the bounds. However, because the effect can be demonstrated to the grower, the outcome has value to the grower with respect to decision making, an option that is not currently available in practice today.
This review summarizes and organizes the literature on life cycle assessment (LCA), life cycle energy analysis (LCEA) and life cycle cost analysis (LCCA) studies carried out for environmental evaluation of buildings and building related industry and sector (including construction products, construction systems, buildings, and civil engineering constructions). The review shows that most LCA and LCEA are carried out in what is shown as "exemplary buildings", that is, buildings that have been designed and constructed as low energy buildings, but there are very few studies on "traditional buildings", that is, buildings such as those mostly found in our cities. Similarly, most studies are carried out in urban areas, while rural areas are not well represented in the literature. Finally, studies are not equally distributed around the world.
The advice on climate-smart food consumption given by authorities and NGOs includes the recommendation to “eat seasonal foods”. However, no clear definition of seasonality is given in the literature. This study investigated how the carbon footprint of yearly per capita consumption of tomatoes and carrots in Sweden was affected by seasonal consumption according to interpretations of seasonality found in communications from Swedish NGOs and authorities. The results showed that the carbon footprint of carrot and tomato consumption was strongly affected by consuming according to either a strict definition of seasonality, which excluded both production in heated greenhouses and long-distance transport, or a definition which only allowed Swedish produce. The reduction potential was approximately 60%, but the consumption pattern was also highly restrictive, with e.g. tomatoes only being consumed during three months according to the strictest definition. The reduction from eating only Swedish products was not due primarily to characteristics commonly associated with seasonal production (shorter transport or low energy demand in cultivation), but to the use of renewable fuel instead of fossil energy. The methodology chosen in this study resulted in carrots having a more distinct season than tomatoes, since the energy use for heating greenhouses (which are needed all year round in cold climates) was evenly allocated across all tomatoes harvested during one year, while the carbon footprint of carrots was assumed to increase with time due to increased energy demand for storage and storage losses. Hence, modern production techniques challenge the traditional concepts of seasonality. On an absolute scale including the whole food sector, the reduction in greenhouse gas emissions from eating seasonal is limited, as emissions from vegetable production make up a minor proportion of the total emissions from food consumption.
Recently, the application of rooftop greenhouses (RTGs) to integrate agriculture into cities has increased, although the area where they can be potentially implemented has not been quantified yet. Consequently, this paper aims to design a guide to evaluate the potential implementation of RTGs in industrial and logistics parks and to apply the guide to the case study of Zona Franca Park (Barcelona, Spain). Eight percent of the rooftops were identified as feasible for a short-term implementation of RTG, according to the defined technical, economic, legal, and agricultural criteria. Estimations indicated that the annual tomato production in this area could account for almost 2,000 tons, which is equivalent to the yearly tomato demand of 150,000 people. Besides, this production could substitute imported tomatoes, and avoiding their distribution would represent savings of 65.25 t of CO2 eq·m−2.
This paper provides a review on three streams of life cycle studies that have been frequently applied to evaluate the environmental impacts of building construction with a major focus on whether they can be used for decision making. The three streams are Life Cycle Assessment (LCA), Life Cycle Energy Assessment (LCEA) and Life Cycle Carbon Emissions Assessment (LCCO2A). They were compared against their evaluation objectives, methodologies, and findings. Although they share similar objectives in evaluating the environmental impacts over the life cycle of building construction, they show some differences in the major focuses of evaluation and methodologies employed. Generally, it has been revealed that quite consistent results can be derived from the three streams with regard to the relative contribution of different phases of life cycle. However, discrepancies occur among the findings obtained from the three streams when different compositions of fuel mixes are used in power generation, or when the overall impacts are not contributed mostly by greenhouse gases emissions. The use of different functional units in different studies also makes it difficult to compare results with benchmarks or results from previous studies. Besides, there are drawbacks in boundary scoping, methodology framework, data inventory and practices which impair their usefulness as a decision making support tool for sustainable building designs.
The closed greenhouse is an innovative concept in sustainable energy management. In principle, it is designed to maximize the utilization of solar energy through the seasonal storage. In a fully closed greenhouse, there is not any ventilation window. Therefore, the excess sensible and latent heat must be removed, and can be stored using seasonal and/or daily thermal storage technology. This stored excess heat can then be utilized later in order to satisfy the thermal load of the greenhouse. Thermal energy storage (TES) system should be designed based on the heating and cooling load in each specific case. Underground thermal energy storage (UTES) is most commonly chosen as seasonal storage. In addition, a stratified chilled water (SCW) storage or a phase change material (PCM) storage could be utilized as short term storage system in order to cover the daily demands and peak loads. In this paper, a qualitative economical assessment of the concept is presented. Here, a borehole thermal energy storage (BTES) system is considered as the seasonal storage, with a PCM or a SCW daily storage system to manage the peak load. A BTES primarily stores low temperature heat such that a heat pump would be needed to supply the heat at a suitable temperature.A theoretical model has been developed using TRNSYS to carry out the energy analysis. From the economical feasibility assessment, the results show that the concept has the potential of becoming cost effective. The major investment for the closed greenhouse concept could be paid within 7–8 years with the savings in auxiliary fossil fuel considering the seasonal TES systems. However, the payback time may be reduced to 5 years if the base load is chosen as the design load instead of the peak load. In this case, a short-term TES needs to be added in order to cover the hourly peak loads.
In this study we analysed the environmental and economic profile of current agricultural practices for greenhouse crops, in cold and warm climates in Europe, using four scenarios as reference systems: tomato crop in a plastic greenhouse in Spain, and in glasshouses in Hungary and the Netherlands, and rose crop in a glasshouse in the Netherlands. This study is in the context of the EUPHOROS project “Efficient Use of Inputs in Protected Horticulture”. The aim of EUPHOROS project is to improve horticultural production systems in Europe by developing cleaner production alternatives from both an environmental and economic point of view. The methodologies selected for the study were Life Cycle Assessment for the environmental analysis and cost-benefit analysis for the economic assessment. Dutch reference systems used a combined heat and power (CHP) system for the production of thermal energy and electricity. Two approaches were used to study the multifunctionality of CHP: system expansion and energy allocation. The main environmental burdens in the four scenarios were energy consumption, greenhouse structure and fertilizers. Environmental impacts due to energy consumption can be reduced by using co-generation or geothermal water in glasshouses. The structure contribution can be decreased with the improvement of recycled materials and design. Adjustment of fertilizer doses and closed irrigation systems are recommended in Spain and Hungary. The best economic perspectives to reduce inputs are energy savings in glasshouses and reduction of fertilizers in Spain and Hungary. The study shows the importance of including economic and environmental aspects in sustainability studies.
This environmental impact assessment of the current situation of Dutch tomato production in a Venlo greenhouse in a temperate climate was developed as part of the EUPHOROS project. The project aims to develop a more sustainable greenhouse system with a reduction of external inputs yet with high productivity and an efficient use of resources. The environmental impact analysis was based on using the Life Cycle Assessment (LCA) methodology as defined by the ISO 14040. The crop production system was structured in several stages and processes to facilitate the study and interpretation of results. The stages considered were structure, auxiliary equipment, climate control system, fertilizers, pesticides and waste. The main results and issues to be improved are described and presented in this paper. The use of a cogeneration system (CHP) and the consequent production of electricity create a methodological question on how to handle allocation between products. This paper shows two different methods for dealing with co-production: considering electricity as an avoided product and energy allocation at CHP. Depending on the approach considered values can range between 12 to 31 MJ/kg of tomato or 0.78 to 2.0 kg CO2 eq/kg of tomato for instance. Climate control system had a high energy demand with major contributions to all the impact categories (81.1 to 96.1% of the total) and the rockwool substrate accounted for 57.0 to 81.7% of the auxiliary equipment contribution. More effort should be made to recycle rockwool and reduce the high energy demand associated with the expansion of the mineral in the manufacturing processes. The structure was a major burden due to the high amount of steel and glass. Energy environmental impacts could be reduced, because of the avoided electricity production by the power plant, by using a combined heat and power plant to meet greenhouse electricity demands, resulting in a surplus which could be delivered to the public grid. Further research should also be oriented to developing efficient technologies to improve the intensive use of materials and energy.
This paper explores the possibilities for reducing future energy use for eating to a sustainable level. A backcasting approach is used to generate an image of the future where energy use for eating is 60% lower in 2050 than in 2000. The currently known potential to reduce energy use in the food supply system for producing, transporting, storing, cooking and eating food is explored and described in terms of a number of distinct changes that are numbered consecutively and presented in both a quantitative and qualitative way. Sweden is used as the case and all data regarding energy use apply for Swedish conditions. An exercise like this illustrates the possible outcome of taking sustainability seriously. If sustainability is to be achieved, some images of the future are needed so that potential targets can be identified. This paper does not present forecasts, but illustrates the kind of changes needed in order to achieve sustainable energy use in the food system.
Green roofs are a passive cooling technique that stop incoming solar radiation from reaching the building structure below. Many studies have been conducted over the past 10 years to consider the potential building energy benefits of green roofs and shown that they can offer benefits in winter heating reduction as well as summer cooling.This paper reviews the current literature and highlights the situations in which the greatest building energy savings can be made. Older buildings with poor existing insulation are deemed to benefit most from a green roof as current building regulations require such high levels of insulation that green roofs are seen to hardly affect annual building energy consumption.As over half of the existing UK building stock was built before any roof insulation was required, it is older buildings that will benefit most from green roofs. The case for retrofitting existing buildings is therefore reviewed and it is found there is strong potential for green roof retrofit in the UK.
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