Combined MFA and LCA approach to evaluate the metabolism of service polygons: A case study on a university campus
Introduction
Material Flow Analysis (MFA) is a tool employed to analyze the metabolism of countries, regions and cities (Brunner and Rechberger, 2004). The Organization for Economic Cooperation and Development (OECD, 2008) recommends the use of MFA to analyze the flows of natural resources and materials into, through and out of a specific system, using the principles of conservation of matter. The results of MFA can be expressed by means of indicators that compare all inputs, stocks and outputs.
Yan et al. (2013) conducted an MFA in China to investigate the country's consumption of zinc and to assess the economics and environmental impacts involved in its use. In Japan, Ohno et al. (2014) used the MFA to quantify unintentional flow of alloying elements in steel during recycling of end-of-life vehicles, and results demonstrated the relevance of quality-based scrap recycling for efficient management of alloying elements. Other studies involving MFA on a global scale have been performed, e.g., for copper in Brazil (Tanimoto et al., 2010) and France (Bonnin et al., 2013), anthropogenic arsenic in Taiwan (Chen et al., 2013), drinking water supply in Italy (Lagioia et al., 2012), and plastic materials in India (Mutha et al., 2006). As for regional studies, MFA has been used to evaluate the metabolism of the region of Catalonia, Spain (Sendra, 2008), to account urban material flows and stocks in the metropolitan area of Lisbon, Portugal (Rosado et al., 2014), and to investigate total goods imports into and exports of out of Brussels, Belgium (Duvigneaud and Denaeyer-DeSmet, 1975), and into and out of Hong Kong (Newcombe et al., 1978). On a local scale, MFA has been applied in the cooked mussel processing industry (Bugallo et al., 2012), to evaluate energy and water flows in museums (Farreny et al., 2012), and to analyze the efficiency and materials ranking of industrial areas (Sendra et al., 2007).
Life Cycle Assessment (LCA), on the other hand, is the main technique used to identify all product and service inputs and outputs (Alting and Legarth, 1995, Guinée et al., 2011), and to quantify all the environmental impacts from a life-cycle perspective (ISO, 2006a, ISO, 2006b). Almeida et al. (2013) stated that LCA is one of the main techniques to identify new initiatives to improve environmental management, audit and monitor companies, and search for assessment methodologies and indicators to underpin decision-making. In recent years, many LCA studies have been published for a wide variety of products (Guinée et al., 2011). Currently, in the industrial sector, LCA is largely applied to biofuels (Luo et al., 2009, García et al., 2011, Ometto et al., 2009), energy (Cherubini and Strømman, 2011, Pérez Gil et al., 2013, Silva et al., 2014a, Singh et al., 2013), products based on renewable materials (González-García et al., 2012, Silva et al., 2013, Silva et al., 2014b), solid waste and water treatment (Fuchs et al., 2011, Galvez-Martos and Schoenberger, 2014, Gentil et al., 2010, Kiatkittipong et al., 2009), and other industries.
The proposal of combining the MFA and LCA techniques is advantageous, particularly in studies of complex systems that comprise numerous products and services, such as countries, cities, regions, economic sectors, and industrial or service polygons (Gabarrell et al., 2014). In such cases, the stand-alone use of MFA allows for a macro-analysis of the metabolism. However, it does not allow for the calculation of environmental impacts or identification of hotspots in as much detail as LCA. Conversely, the stand-alone use of LCA in such systems is unfeasible due to the numerous products and services involved. Thus, combining the MFA and LCA methodologies seems to be the best way to surmount these obstacles. The combined MFA + LCA is a new approach, and to date, few studies on the topic have been published. This approach can provide an in-depth and more synergetic analysis of system metabolism than the individual use of these techniques.
In this regard, some MFA + LCA studies have been conducted in recent years. In an urban infrastructure system, Venkatesh et al. (2009) applied the MFA + LCA approach to analyze the wastewater pipeline network in Oslo, Norway. Their MFA focused on analyzing material flows used in new pipelines, material inputs due to rehabilitation, installation, operation and maintenance phase, and predicting material and energy flows. The overall results of MFA indicators were used in an LCA study to analyze Greenhouse Gas (GHG) emissions. The authors found that GHG emissions occur mostly in the pipeline operation and maintenance phases, mainly due to internal coating of pipes for corrosion resistance, the replacement of smaller parts of a pipeline stretch, the inspection and cleaning, and other activities.
In the construction sector in Spain, Rincón et al. (2013) applied MFA + LCA to evaluate five different facade construction systems. They used MFA to evaluate the total requirements and the ecological rucksack, and LCA to assess environmental impacts. By means of MFA, they identified significant extractions of natural resources for construction activities. As for their LCA results, they reported that the operational phase of construction accounted for 97.00% of total energy consumption.
With regard to waste management, Wäger et al. (2011) used a MFA + LCA approach to study Waste Electrical and Electronic Equipment (WEEE), calculating the impacts of collection, pre-processing and end-processing for Swiss WEEE collection and recovery systems. Their MFA results revealed that 113,000 tons of WEEE were collected in 2009. These authors applied LCA to assess environmental impacts, considering three scenarios: recovery, incineration and landfilling – recovery and landfilling showed lower environmental impacts per ton of WEEE than incineration in the categories of global warming and ozone layer depletion potential.
Kiddee et al. (2013) used MFA + LCA to evaluate toxic substances in WEEE and their potential environmental impacts, as well as several waste management strategies adopted in some countries. Their LCA results indicated the need for greater care in the design of electronic devices to decrease their environmental impacts, mainly for the potential of carcinogens, ozone layer depletion, ecotoxicity, acidification, climate change, eutrophication, and land use.
In Colombia, Rochat et al. (2013) used the combined MFA + LCA approach with multi-attribute utility theory to assess end-of-life scenarios for Polyethylene Terephthalate (PET) materials in the city of Tunja. Their findings indicated that recycling is the most environmentally-friendly alternative to optimize PET waste treatment.
More recently, Sevigné-Itoiz et al. (2014) adopted MFA + LCA to analyze the environmental consequences of recycling scrap aluminum in Spain, with emphasis on GHG impacts. According to their findings, the most likely destination for scrap aluminum not used in Spain in the coming years will be Asia. Moreover, GHG emissions can be avoided by increasing export flows, but scrap exports should be considered as the loss of a key resource for consistent development from a linear toward a circular economy.
As shown above, most MFA + LCA studies still focus on waste management, especially on WEEE. Moreover, to the best of our knowledge, no MFA + LCA study on educational services has been published so far. Educational institutions can be classified as a type of service polygon, and they are among the most longstanding and deeply rooted services in society due to the function they perform. Their common service outflows are knowledge, research and culture. However, the operation of educational institutions requires the consumption of materials (e.g., water, consumables) and energy (e.g., energy carriers), while also emitting several outputs (e.g., airborne emissions, liquid effluents and solid wastes). Thus, it is important to know and understand the metabolism of this type of service polygon to improve its environmental sustainability.
The service polygon under study here was the campus of the Autonomous University of Barcelona (UAB in Catalan), with a view to applying the MFA + LCA approach. The UAB is recognized internationally by prestigious and influential rankings due to its efforts to provide a high-level university education. In the QS World University Ranking (QS WUR, 2014), the UAB was ranked in the 176th position in the world, while the QS top 50 ranked the UAB in the 9th position worldwide and in the 2nd place in the total number of publications (QS, 2014, SIR WR, 2014). For further information, a campus map is available online as supplementary material in Appendix I.
This paper reports on the findings of a combined MFA + LCA approach which was applied to evaluate the UAB metabolism, based on a case study conducted in Catalonia, Spain.
The following specific objectives were established:
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Define a methodological MFA + LCA approach to be applied to the case study;
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Determine the most relevant flows and environmental hotspots in the study zone;
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Compare the MFA findings with those of earlier studies in the literature, also conducted in the region of Catalonia; and
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Based on the MFA + LCA highlights, to describe the ICTA-ICP building as an innovative alternative to promote environmental sustainability at the UAB campus.
Section snippets
Methodology
The research strategy adopted was the case study – an empirical, descriptive and exploratory inquiry that investigates a phenomenon in its real-life context. The object of study was an educational institution, as described in Section 2.2.
Results and discussion
Table 5 shows the overall inventory obtained in this study, considering all the direct and indirect flows. In terms of mass, most of the inputs and outputs consisted, respectively, of water consumption (69.30% of all inputs) and wastewater generation (73.00% of all outputs). A specific discussion about water flow is given in Section 3.3.
According to Table 5, Energy represented 10.90% of all inputs, ranking third in inputs after water (69.40%) and materials (19.70%). Electricity and natural gas
Conclusions
This paper reports on an MFA + LCA study of an educational institution in Spain – the UAB campus. The MFA results indicated that the UAB campus imports more than it exports, and that the stock of materials is related basically to land use. Energy consumption represented more than 50.00% of all inputs, and its associated indirect flows were very relevant to the overall metabolism, accounting for 69.30% of all energy consumption. With regard to the LCA results, the ReCiPe 2008 method was adopted
Acknowledgements
The authors are grateful for the technical support provided by the representatives from the UAB's Environmental Management Office and the Architecture and Urbanism Unit. The authors are also grateful for the financial support provided by CAPES (Federal Agency for the Support and Improvement of Higher Education) through Grants no. 288/13 (International Program for Scientific Cooperation Brazil/Spain - CAPES-DGU) and no. 9331/13-1, by Spanish Ministry HBP-2012-0216 (MECD), by FAPESP (São Paulo
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