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Purpose The methods for assessing the impact of using abiotic resources in life cycle assessment (LCA) have always been heavily debated. One of the main reasons for this is the lack of a common understanding of the problem related to resource use. This article reports the results of an effort to reach such common understanding between different stakeholder groups and the LCA community. For this, a top-down approach was applied. Methods To guide the process, a four-level top-down framework was used to (1) demarcate the problem that needs to be assessed, (2) translate this into a modeling concept, (3) derive mathematical equations and fill these with data necessary to calculate the characterization factors, and (4) align the system boundaries and assumptions that are made in the life cycle impact assessment (LCIA) model and the life cycle inventory (LCI) model. Results We started from the following definition of the problem of using resources: the decrease of accessibility on a global level of primary and/or secondary elements over the very long term or short term due to the net result of compromising actions. The system model distinguishes accessible and inaccessible stocks in both the environment and the technosphere. Human actions can compromise the accessible stock through environmental dissipation, technosphere hibernation, and occupation in use or through exploration. As a basis for impact assessment, we propose two parameters: the global change in accessible stock as a net result of the compromising actions and the global amount of the accessible stock. We propose three impact categories for the use of elements: environmental dissipation, technosphere hibernation, and occupation in use, with associated characterization equations for two different time horizons. Finally, preliminary characterization factors are derived and applied in a simple illustrative case study for environmental dissipation. Conclusions Due to data constraints, at this moment, only characte, Validerad;2020;Nivå 2;2020-11-10 (alebob)

Background:Global food production systems generate impacts such as eutrophication, caused by nutrient run-offfrom agricultural exploitations and exacerbated by climate change. Hydroponic cultivation methods arecommon in Mediterranean areas, although there is a gap in the literature with regard to their study. This studyaims tofill that gap, by assessing nutrientflows in hydroponic crops.Results:The results showed that most of the nutrients were drained with the leachates (51% on average), afigurewhich could be lower, if the nutrient supply were adjusted to the needs of the plants or if (closed hydroponic)nutrient recirculation were implemented, without compromising the nutrient uptake of the plant. Moreover, thestudy revealed that a significant quantity of nutrients was retained in the substrate (perlite) during the crop,reaching average values of 5% of incoming calcium, 6% of nitrogen, and 7% of phosphorus. In the case ofphosphorus and calcium, a regression model is presented for the estimation of their retention in hydroponiccrops.Conclusions:Although further studies will be needed to confirm the above trends, the study makes a significantcontribution to understanding the metabolism of nutrients in hydroponic crops and tofiner adjustments of thenutrient balance., Peer Reviewed, Postprint (published version)

Food waste represents the largest fraction of the municipal solid waste generated in Europe and its management is associated to suboptimal performance in environmental, health, and social dimensions. By processing detailed multi-fold local data as part of a comprehensive and broadly understandable sustainability framework, this study quantifies the environmental and socio-economic impacts of household food waste management in the Amsterdam Metropolitan Area based on priorities set by local stakeholders. Five alternative short-term management options have been assessed against the current system, relying on poor separate collection and incineration. Four options involve separate collection of food waste followed by biological treatments (home/centralised composting and anaerobic digestion) while one involves a mix of separate collection and centralised mechanical-biological treatment followed by anaerobic digestion. Among these, separate collection followed by anaerobic digestion coupled with effective nutrient and energy recovery is, according to our findings, the preferred option to improve the sustainability of the current system in all dimensions considered, except for the economic pillar due to the collection costs. Home and centralised composting as well as mechanical-biological treatment are associated to more adverse impacts based on our findings. The study informs local stakeholders and authorities on the potential consequences of their options, thereby allowing them to make sound choices for a future waste and circular economy strategy., Environmental Technology and Design

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 o, Peer Reviewed, Postprint (author's final draft)

There is great potential to reduce the environmental impact of the building sector, which is now an area of immense importance, through the optimisation of construction materials and components. This study assesses both the design and the construction of Concrete Deep Foundations (CDFs), which are widely used in construction, from an environmental perspective considering the following variables: (i) grade of prefabrication, i.e., fully cast in situ, partly prefabricated, and fully prefabricated; (ii) compressive strength of cast-in-situ concrete; and (iii) building design codes, i.e., current Spanish codes (EHE-08 and CTE), Eurocode with the Spanish annexes, and Eurocode with the United Kingdom annexes. In addition, the results of Dynamic Load Tests (DLTs) and the economic cost of several CDFs are evaluated. Geotechnical and structural designs of CDFs are carried out along with their life-cycle assessment. Some of the main findings include: (i) partially and fully prefabricated CDFs and conducting DLTs reduced the environmental impact in most categories (by up to 44% for global warming emissions) compared to the fully cast-in-situ CDFs, although they were 12–37% more expensive; (ii) changing the compressive strength of the concrete (in piles and cap) in fully cast-in-situ CDFs from 25 to 35¿MPa reduced the environmental impact by up to 14–17% in all categories and economic costs by up to 12%; and, (iii) CDFs with bored piles resulted in the lowest environmental burden when designed with Eurocode and UK annexes (11–31% less impact), as did CDFs with driven piles designed with current Spanish codes (11–18% less impact). The study variables and sensitivity analysis showed a significant effect on the results and should be considered in future construction, research, and building codes., Peer Reviewed, Postprint (author's final draft)

Urban agriculture has emerged as an alternative to conventional rural agriculture seeking to foster a sustainable circular economy in cities. When considering the feasibility of urban agriculture and planning for the future of food production and energy, it is important to understand the relationships between energy flows throughout the system, identify their strengths and weaknesses, and make suggestions to optimize the system. To address this need, we analyzed the energy flows for growing tomatoes at a rooftop greenhouse (RTG). We used life cycle assessment (LCA) to identify the flows within the supply chain. We further analyzed these flows using ecological network analysis (ENA), which allowed a comparison of the industrial system to natural systems. Going beyond LCA, ENA also allowed us to focus more on the relationships between components. Similar to existing ENA studies on urban metabolism, our results showed that the RTG does not mimic the perfect pyramidal structure found in natural ecosystems due to the system's dependency on fossil fuels throughout the supply chain and each industry's significant impact on wasted energy. However, it was discovered that the RTG has strong foundational relationships in its industries, demonstrating overall positive utility; this foundation can be improved by using more renewable energy and increasing the recycling rates throughout the supply chain, which will in turn improve the hierarchy of energy flows and overall energy consumption performance of the system., Peer Reviewed, Postprint (author's final draft)

Assuming specific behavior models, the variety of design codes currently used for the design of concrete beams inevitably results in different solutions, ensuring service during the expected lifetime with a maximum functional quality and safety. However, from a sustainable design perspective, such differences may have remarkable environmental impacts. This paper analyses if the approach of the newest design code, i.e., the Model Code, leads to a reduction in resource consumption and greenhouse gas emissions (GHG) over the life cycle of concrete beams. To do so, a comparative analysis of the environmental impact of concrete beams was carried out depending on the reference code used for their design (i.e., EHE-08 or Model Code). The results show that reducing the amount of reinforcing steel is essential to minimize the life cycle environmental impacts of concrete beams. Every country may have its own design codes and, thus, the reinforcing steel use can vary for structures subjected to the same loads and with equivalent structural reliability. Hence, regulations play a key role in the sustainability of construction assets. Conclusions depend on the beam’s length (L), height (h) and characteristic compressive strength (fck). For short beams (4 m), the greater the h, the greater the reinforcement difference between the two codes. With regard to beams with L = 8 m, these differences can lead to varying steel and GHG savings, e.g., up to 5.0 % with MC-2010 (h = 0.6 m and fck = 35 MPa), almost 40 % with EHE – 08 (h = 0.6 m and 35 MPa < fck = 50 MPa) and more than 30 % with MC-2010 (h = 1.0 m).. For long beams (L = 12.0 m), steel consumption is 0.3 % to 19 % lower when the beam is designed with EHE-08, and this difference decreases as fck increases., Peer Reviewed, Postprint (author's final draft)

The design of building foundations has usually been based on tradition, local practice, experience, and structural design codes. Safety is invariably considered the main factor and environmental criteria (or, in general, sustainability) is seldom given due consideration. However, similar safety indicators can be achieved with different variables and a minimum safety factor must always be ensured. The main objective of this study is, from an environmental perspective, to assess the influence of the construction system (cast-in-situ or precast), foundation type (rigid or flexible), and structural code (EC-2 or EHE-08) in the case of a concrete shallow foundation (CSF), using Life Cycle Assessment (LCA). Applying this methodology, the materials (concrete and steel) yielded the highest impacts in all categories, at around 95% for cast-in-situ CSFs and at around 85% for precast CSFs, both in relation to global warming. Consequently, optimization of the amount of these materials is crucial when considering the particular variables selected in this study. The results showed that cast-in-situ and flexible CSFs at moderately shallow depths (and therefore with less steel reinforcement) and precast CSFs with considerable reductions in concrete volumes (due to sloped shapes) had lower environmental impacts. In addition, cast-in-situ CSFs constructed in accordance with the EHE-08 structural code showed lower impacts, while precast CSFs complying with the EC-2 code were environmentally preferable. However, a specific study might be required for specific factors in each case (loads, soil type, structural settlement, among others). Relevant environmental effects associated with the three variables should therefore be given specific consideration in the development of structural design codes and future constructions., Postprint (author's final draft)

Food security in cities is an increasing concern due to the impact of climate change and the concentration of world population in cities. Urban agriculture (UA) aims at enhancing food production in urban areas, providing potential environmental advantages by reducing food transport, packaging and waste generation. Among UA alternatives, rooftop greenhouses (RTGs) are greenhouses built on top of urban roofs, in which mainly soil-less agriculture systems are used to produce food. When RTGs are integrated into the metabolism of their buildings, they exchange CO2, energy and water to improve their performance. This alternative is called integrated RTG (i-RTG). This chapter analyses the use of i-RTGs to improve buildings and cities’ metabolism and its particular application in the area of Barcelona. This analysis aims to define a new agricultural system from a technological and sustainability approach focusing on Mediterranean cities. Our research is based on the development and results of the Fertilecity project. A particular experimental analysis was conducted at ICTA’s i-RTG lab located near Barcelona. The main factors of interest are architectural and engineering requirements, urban integration, CO2 emissions management, energy consumption, food production, social integration and rainwater harvesting. This analysis has used different methods such as life cycle assessment (LCA), life cycle costing (LCC) and semi-quantitative assessments. Multiple integrated results were obtained both at the building and city scale. For example, we proved that the i-RTG and its flow exchanges with the building could help to save heating energy, waste generation, water consumption and CO2 emissions., Peer Reviewed, Postprint (author's final draft)

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 t, Peer Reviewed, Postprint (author's final draft)

Bibliografia., S'espera que la sostenibilitat de les xarxes de subministrament d'aigua sigui un tema important en un futur pròxim a causa de la falta d'accés a l'aigua en àrees específiques, al creixement de les ciutats i a la renovació de xarxes velles. En aquest sentit, analitzar a nivell ambiental aquest sistema és clau per planificar futures xarxes, la qual cosa pot prevenir impactes ambientals significatius. A més, l'eficiència en l'ús de l'aigua a les ciutats és una altra qüestió important i cal analitzar els nous usos urbans de l'aigua, com l'agricultura. Aquest és el cas de l'agricultura vertical, que consisteix en la integració de sistemes agrícoles en edificis. Tot i que aquests sistemes de producció d'aliments urbans poden augmentar la demanda d'aigua a les ciutats, representen una oportunitat per reduir el consum i el transport d'aigua relacionats amb l'agricultura a nivell regional. Investigacions prèvies sobre xarxes d'abastament d'aigua es centren en analitzar estudis de casos específics a nivell municipal o regional, mostrant resultats molt diferents. Per tant, es requereix una avaluació integral del sistema des d'una perspectiva general per entendre quins són els factors clau que afecten els impactes ambientals de les xarxes. A escala edifici, la millora de l'eficiència en l'ús de l'aigua pot prevenir impactes ambientals significatius al llarg del cicle urbà de l'aigua, especialment per a nous usos de l'aigua com l'agricultura vertical. En aquest context, estudis anteriors han discutit el potencial d'aquests sistemes o implementat anàlisis basades en dades teòriques. No obstant això, encara falta manca avaluar cultius realitzats en un casos d'estudi reals. Aquesta tesi té com a objectiu aprofundir en aquestes àrees de coneixement analitzant el sistema urbà des de l'escala ciutat a alternatives locals específiques i busca respondre a les següents preguntes: (i)Quins són els principals factors que afecten els impactes ambientals de les xarxes d'abastament d'aigua a, Se espera que la sostenibilidad de las redes de suministro de agua sea un tema importante en un futuro próximo debido a la falta de acceso al agua en áreas específicas, al crecimiento de las ciudades y a la renovación de viejas redes. En este sentido, analizar a nivel ambiental este sistema es clave para planificar futuras redes, lo cual puede prevenir impactos ambientales significativos. Además, la eficiencia en el uso del agua en las ciudades es otra cuestión importante y es necesario analizar los nuevos usos urbanos del agua, como la agricultura. Este es el caso de la agricultura vertical, que consiste en la integración de sistemas agrícolas en edificios. Aunque estos sistemas de producción de alimentos urbanos pueden aumentar la demanda de agua en las ciudades, representan una oportunidad para reducir el consumo y el transporte de agua relacionados con la agricultura a nivel regional. Investigaciones previas sobre redes de abastecimiento de agua se centran en analizar estudios de casos específicos a nivel municipal o regional, mostrando resultados muy diferentes. Por lo tanto, se requiere una evaluación integral del sistema desde una perspectiva general para entender cuáles son los factores clave que afectan a los impactos ambientales de las redes. A escala edificio, la mejora de la eficiencia en el uso del agua puede prevenir impactos ambientales significativos a lo largo del ciclo urbano del agua, especialmente para nuevos usos del agua como la agricultura vertical. En este contexto, estudios anteriores han discutido el potencial de estos sistemas o implementado análisis basados en datos teóricos. Sin embargo, todavía falta una evaluación de cultivos realizados en un caso de estudio real. Esta tesis tiene como objetivo profundizar en estas áreas de conocimiento analizando el sistema urbano desde la escala ciudad a alternativas locales específicas y busca responder a las siguientes preguntas: (i) ¿Cuáles son los principales factores que afectan a los impactos a, The sustainability of water supply networks is expected to be a major issue in the near future due to the lack of access to water in specific areas, the growth of cities and the refurbishment of old networks. In this sense, analysing the environmental performance of this system is key to planning future networks—this can prevent significant environmental impacts. Moreover, water use efficiency in cities is another important issue and new urban uses for water, such as agriculture, need to be analysed. This is the case for vertical farming, which consists of the integration of agricultural systems in buildings. Although these urban food production systems can increase the demand for water in cities, they represent an opportunity to reduce the water consumption and transport related to agriculture at the regional level. Previous research on water supply networks focus on analysing specific case studies at municipal or regional level, showing very different results. Thus, a comprehensive assessment of the system from a general perspective is required to understand which are the key factors affecting its environmental impacts. At the building scale, improving water efficiency can prevent significant environmental impacts along the urban water cycle, especially for new water uses such as vertical farming. In this context, previous studies have discussed the potential of these systems or implemented analysis based on theoretical data. However, the assessment of crops conducted in a real case study is still lacking. This dissertation aims at contributing to understand more deeply these research fields, analysing urban areas from the city level to specific alternatives at the building level, and seeks to answer the following questions: (i) What are the main factors affecting the environmental impacts of water supply networks in cities and which improvements should be implemented? – city scale (ii) How effective are water-saving technologies used at the building level in urba

Previous studies assessing the environmental impacts of drinking water supply networks have considered a bottom-up approach, analysing single case studies. This paper presents a top-down approach for the assessment of the operational phase of a water supply network. A representative sample of 50 cities was statistically analysed to find relations between different variables regarding electricity and water consumption linked with the environmental impacts of the network. The results show that some of the variables are clearly related to the relative energy consumption of the network. Such is the case for population size, where small municipalities have up to 14 times higher relative electricity consumption compared with medium-sized municipalities (1.15E-2 as opposed to 8.3E-4 kWh/m3 registered water km of network) due to case-specific factors such as a strong gradient between a water tank and the consumption point. Similarly, the cases showing low population density exhibit 7 times higher relative electricity consumption because of the longer distances that must be covered and the correlation between population density and size. The values found for greenhouse gas (GHG) emissions derived from the energy consumption are consistent with results from previous studies: on average, 5.53 kg of CO2 eq. emissions/inhabitant·year are released, but the variability is very high, ranging from 0.005 to 67.8 kg of CO2 eq. emissions/inhabitant·year. No clearly significant correlations were found between the relative water demand and variables such as seasonality or income per capita, which might indicate that water consumption depends on individual decisions of the population rather than on the variables assessed. Models for the estimation of water demand, length of network and electricity consumption were defined. However, the modelling of electricity consumption presented more difficulties because of its high variability. A protocol for data collection should be defined and impl, Peer Reviewed, Postprint (author's final draft)

The final publication is available at Springer via http://dx.doi.org/10.1007/s11367-015-0963-y, Purpose: Urban water cycle construction processes are an important element to consider when assessing the sustainability of urban areas. The present study focuses on a structural and environmental analysis of cylindrical water tanks. The goal is to optimise cylindrical water tanks from both an environmental (environmental impacts due of life cycle assessment (LCA)) and a geometric perspective (building material quantities for construction purposes depending on the tank characteristics). Methods: A sample of 147 cases was defined based on different positions (buried, superficial and partially buried), dimensions (combinations of heights and radii) and storage capacities (between 100 and 10,000 m3). A structural analysis was conducted for a defined set of cases to determine the quantities of steel and concrete required for its construction. The environmental impacts of the entire life cycle were assessed through a life cycle assessment (LCA). Additionally, environmental standards (the less impactful option for each dimension assessed: geometry, storage capacity and position) defined in the study were applied to realistic cases to evaluate potential environmental savings. Results and discussion: The LCA shows that materials are the main contributor to environmental impacts (more than transport, installation and end of life cycle stages). For this reason, the results of the structural and environmental assessments coincide. Taller water tanks have shown to be less impactful (60 to 70 % less impact for a 10.000-m3 tank). Regarding the position, superficial water tanks have shown to have between 15 and 35 % less impact than buried ones. The environmentally preferred water storage capacity is between 1000 and 2500 m3, being between 20 and 40 % less impact. For instance, an 8000-m3 tank would emit 1040 t of CO2 eq. Applying the environmental standards 170.5 t of CO2 eq could be saved (16 % of the total amount). Conclusions: The results of this study show that among the case, Peer Reviewed, Postprint (author's final draft)

The final publication is available at Springer via http://dx.doi.org/10.1007/s11269-015-0958-2, The environmental impacts resulting from sewer networks are best analysed from a life-cycle perspective to integrate the energy requirements into the infrastructure design. The energy requirements for pumping wastewater depend on the configuration of the city (e.g., climate, population, length of the sewer, topography, etc.). This study analyses and models the effect of such site-specific features on energy consumption and related effects in a sample of Spanish cities. The results show that the average annual energy used by sewers (6.4 kWh/capita and 0.014 kWh/m3 of water flow) must not be underestimated because they may require up to 50 % of the electricity needs of a typical treatment plant in terms of consumption per capita. In terms of Global Warming Potential, pumping results in an average of 2.3 kg CO2eq./capita. A significant positive relationship was demonstrated between the kWh consumed and the length of the sewer and between other factors such as the population and wastewater production. In addition, Atlantic cities can consume 5 times as much energy as Mediterranean or Subtropical regions. A similar trend was shown in coastal cities. Finally, a simple predictive model of the electricity consumption was presented that considers the analysed parameters., Peer Reviewed, Postprint (author's final draft)

Postprint (published version)