Exploring the dynamics of urban metabolism: from theory to practice. The case study of the metropolitan city of Milan and Lombardy Region, Italy

Today, cities can be defined as highly complex non-static living organisms that are composed of dense concentrations of people, information, material, energy, and nutrients. The intense production and consumption of material and energy require vast quantities of natural resources. The world’s cities occupy just 3% of the Earth’s land but account for more than 60% to 80% of global energy use, 75% of greenhouse gas emission, and 70% of global waste (UN, 2015). Current practices are depleting the planet's finite resources, changing its climate and damaging its natural ecosystems (World Bank Group Climate Change Action Plan, 2016). Moreover, a wave of international policy visions for sustainable development has recognized the need to use natural resources more efficiently and encourage local governments to implement regulations and tools that support local resource efficiency initiatives (UNFCCC, 2015). However, there has been an insufficient discussion on whether cities and human settlements have the autonomy, capacity, tools, education, and resources to implement sustainable development policies effectively (UN, 2015). Within this context, the dissertation focus on the concept of urban metabolism to interpret the city as a living organism that is composed of a network and subsystem flows, which travel in/out, transform and release/remain in the city (Wolman, 1965; Kennedy, 2010; Zhang, 2013). Specifically, the aim of this dissertation is twofold: (A) bridge the gap between urban metabolism studies and urban planning practice; (B) develop a process of method guideline choices for future studies in material, energy and pollution flows, spatial planning and preliminary strategic environmental assessment processes. The twofold aim developed the following four phases. Phase 1, a critical literature review on urban metabolism and its relationship with the urban planning practice. Phase 2, (i) a simplified Step-by-Step Material Flow Analysis method and (ii) Metabolic Scan Sankey visualization model profiles of the Metropolitan City of Milan and Lombardy region’s 12 provinces in Italy. Phase 3, a cluster analysis to identify urban metabolism typologies of the 134 municipalities in the metropolitan area of Milan using input, product and output classification flows (material, energy, pollution and socioeconomic) and control variables. Phase 4, an urban metabolism practical nature-based application using fog harvesting technology to identify inefficient metabolism typologies in the Metropolitan City of Milan. The results from the application of this framework show that urban systems differ based on different spatial scales and metabolic profile characteristics. These findings, allow urban professionals to interpret material, energy, and pollution intensity flow in cities with the use of visualization as an urban planning tool to compare and analyze, report and monitor resource efficiencies while guiding existing/new transitioning cities towards sustainable development policies.

Oggi, le città possono essere definite come organismi viventi non statici altamente complessi che sono composti da concentrazioni di persone, informazioni, materiali, energia e sostanze nutritive. L'intensa produzione e consumo di materiali ed energia richiedono ingenti quantità di risorse naturali. Le città del mondo occupano solo il 3% della terra della Terra, ma rappresentano oltre il 60% -80% del consumo globale di energia, il 75% delle emissioni di gas serra e il 70% dei rifiuti globali (ONU, 2015). Le pratiche attuali stanno esaurendo le risorse limitate del pianeta, cambiando il suo clima e danneggiando i suoi ecosistemi naturali (Piano d'azione sui cambiamenti climatici del Gruppo Banca Mondiale, 2016). Inoltre, un'ondata di visioni politiche internazionali per lo sviluppo sostenibile ha riconosciuto la necessità di utilizzare le risorse naturali in modo più efficiente e incoraggiare i governi locali a implementare regolamenti e strumenti che supportino le iniziative di efficienza delle risorse locali (UNFCCC, 2015). Tuttavia, c'è stata una discussione insufficiente sul fatto che città e insediamenti umani abbiano autonomia, capacità, strumenti, istruzione e risorse per attuare in modo efficace le politiche di sviluppo sostenibile (ONU 2015). In questo contesto, la dissertazione si concentra sul concetto di metabolismo urbano per interpretare la città come un organismo vivente che è composto da una rete e flussi subsistemici, che viaggiano dentro / fuori, trasformano e rilasciano / rimangono nella città (Wolman, 1965; Kennedy, 2010; Zhang, 2013). Specifically, the aim of this dissertation is twofold: (A) bridge the gap between urban metabolism studies and urban planning practice; (B) develop a process of method guideline choices for future studies in material, energy and pollution flows, spatial planning and preliminary strategic environmental assessment processes. The twofold aim developed the following four phases. Phase 1, a critical literature review on urban metabolism and its relationship with the urban planning practice. Phase 2, (i) a simplified Step-by-Step Material Flow Analysis method and (ii) Metabolic Scan Sankey visualization model profiles of the Metropolitan City of Milan and Lombardy region’s 12 provinces in Italy. Phase 3, a cluster analysis to identify urban metabolism typologies of the 134 municipalities in the metropolitan area of Milan using input, product and output classification flows (material, energy, pollution and socioeconomic) and control variables. Phase 4, an urban metabolism practical nature-based application using fog harvesting technology to identify inefficient metabolism typologies in the Metropolitan City of Milan. The results from the application of this framework show that urban systems differ based on different spatial scales and metabolic profile characteristics. These findings, allow urban professionals to interpret material, energy, and pollution intensity flow in cities with the use of visualization as an urban planning tool to compare and analyze, report and monitor resource efficiencies while guiding existing/new transitioning cities towards sustainable development policies.