Material Flow Analysis (MFA)

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One of the most widely used material accounting methods is the Material Flow Analysis (MFA). This method takes a systems-perspective and quantifies the relevant inputs and outputs for these systems. MFA relies on the principles of mass balancing as a way to verify that the model is complete and accurate. One of the reasons that MFA is so widespread is the versatility in its use. MFA can be used in any reference system, which can include global, national, regional, functional, or temporal reference systems. The time horizon can range from a contemporary point in time to a time series or even involve a long-range historical perspective. Finally, depending on the aim of the work, all physical material flows can be studied, or a specific subset that is of interest. Energy flows can also be subjected to an MFA. If only a single substance is studied, then this is called a substance flow analysis instead. Many of these main features as well as a historic perspective on MFA are discussed in a great reference paper by Fisher-Kowalski and Hüttler published just over two decades ago (Fischer‐Kowalski and Hüttler 1998).

One of the strengths of MFA is the relative straightforward procedure (at the core of this method is ‘counting numbers’) that does not require advanced operations or mathematical models, and the obtained results (expressed in total weight of materials or quantity of energy flows) can be easily communicated to and understood by a wide audience.

There are some difficulties that arise depending on the chosen scope and system reference. The line between the natural and the socio-economic system is not always clear, which can lead to double counting or reporting inconsistencies. Examples include accounting for livestock and domesticated animals (and their respective nutrient intake and waste flows), defining a water balance within a reference system, accounting for the use of oxygen for respiration, and quantifying all inputs and outputs that are required to properly balance the combustion of fuels.

The method has been thoroughly described in a practical handbook (Brunner and Rechberger 2004). This handbook discussed the following procedural steps:

  • Selection of Substances
  • System Definition in Space and Time
  • Identification of Relevant Flows, Stocks and Processes
  • Determination of Mass Flows, Stocks and Concentrations
  • Assessment of Total Material Flows and Stocks
  • Presentation of Results
  • Materials Accounting

The authors also discuss data uncertainty, software to use for MFA, and relevant evaluation methods (which include a number of methods discussed further on in this report). All in all, this handbook has been a guiding reference for many MFA studies, and together with other books (e.g. Baccini and Brunner (2012)) this makes MFA one of the most strongly documented methods.

Despite the well-documented procedure and rationale behind the method, there is no single approach that is adopted across the board. Gerber and Scheidel (2018) highlight a very relevant paragraph from one of the leading books:

Baccini and Brunner (2012: 105, their emphasis) wrote that “there are no theories available to perform MFA/SFA. [...] There are many groups active in MFA/SFA using their individual techniques and accumulating their specific experience and data. [...] [However], despite the many approaches, there are only small differences between the methods of the individual schools of MFA/SFA. The main divergence is the focus.”

Specific frameworks also exist, for example for water (Kenway, Gregory, and McMahon 2011). However, within this report these were here classified as MFA with their respective material. Another related method is Material Flow Cost Accounting (MFCA). This method is seen as a management tool that has considerable uptake at a corporate level, and which has also been codified in an ISO standard (ISO 14051). This is a tool to improve economic and environmental performance (Christ and Burritt 2015). The focus of MFCA is to allocate all production costs to material flows. MFCA focuses on the costs for product and non product output (Jasch 2008)

Strengths:

  • Extremely versatile in its use and can be catered to suit many specific needs.
  • Plentiful documentation has helped define standard terms and procedures.
  • Relatively straightforward procedure around ‘counting numbers’.
  • Results can be easily communicated to and understood by a wide audience.

Weaknesses:

  • Inconsistencies or double counting need to be carefully considered when defining the exact scope and system boundaries, especially where the natural and human systems directly interact.
  • Lack of a single methodological framework has led to a multitude of specific approaches.
  • Difficult to translate results to policy interventions.

Publications

Title Type Author(s) Year
Baselining for a circular Toronto: Material Flow Analysis Report Circle Economy 2021
Cities as organisms: Urban metabolism of the four main Danish cities Journal Article Lanau et al. 2021
Circular Kongsvinger Region Report Circle Economy 2020
Circular Àmbit B30 Report Circle Economy 2020
Circular Economy Opportunities in Almaty Report Circle Economy 2019
Circular Prague Report Circle Economy 2019
Circular cities Switzerland - Bern: Material flow analysis Report Circle Economy 2019
Construction and demolition waste generation in cities in India: an integrated approach Journal Article Jain et al. 2019
Estimation of greenhouse gas reduction in waste recycling sector in Cheongju-si, Korea using US EPA WARM model Conference Paper Lee et al. 2019
Incorporating Metabolic Thinking into Regional Planning: The Case of the Sierra Calderona Strategic Plan Journal Article Daniela Perrotti Juanjo Galan 2019
The State of the Art of Material Flow Analysis Research Based on Construction and Demolition Waste Recycling and Disposal Journal Article Guo and Huang 2019
Using spatially explicit commodity flow and truck activity data to map urban material flows Journal Article Lynette Cheah Lih Wei Yeow 2019
Amstelveen Circulair: Kansen voor de circulaire economie in Amstelveen Report Circle Economy 2018
Circular Bilbao & Bizkaia Report Circle Economy 2018
Circular cities Switzerland - Basel: Material flow analysis Report Circle Economy 2018
Decentralised Organic Resource Treatments – Classification and comparison through Extended Material Flow Analysis Journal Article Bortolotti et al. 2018
Understanding the mechanism of urban material metabolism with ecological network analysis: An experimental study of Wuxi, China Journal Article Li et al. 2018
Urban Metabolism of Bangalore City: A Water Mass Balance Analysis Journal Article Paul et al. 2018
Comprehensive evaluation on industrial & urban symbiosis by combining MFA, carbon footprint and emergy methods—Case of Kawasaki, Japan Journal Article Ohnishi et al. 2017
African Urbanization: Assimilating Urban Metabolism into Sustainability Discourse and Practice Journal Article Currie and Musango 2016
Circulair Noord-Holland: Inzichten in het speelveld van de circulaire economie Report Circle Economy 2016
Circular Amsterdam: A vision and action agenda for the city and metropolitan area Report Circle Economy 2016
Circular Glasgow: A vision and action plan for the city of Glasgow Report Circle Economy 2016
Evaluating urban sustainability potential based on material flow analysis of inputs and outputs: A case study in Jinchang City, China Journal Article Li et al. 2016
Flows, system boundaries and the politics of urban metabolism: Waste management in Mexico City and Santiago de Chile Journal Article Guibrunet et al. 2016
Surveying the Environmental Footprint of Urban Food Consumption Journal Article Goldstein et al. 2016
Towards a Dynamic Approach to Urban Metabolism: Tracing the Temporal Evolution of Brussels' Urban Metabolism from 1970 to 2010 Journal Article Athanassiadis et al. 2016
An application of system dynamics for evaluating planning alternatives to guide a green industrial transformation in a resource-based city Journal Article Kuai et al. 2015
Energy and material flows of megacities Journal Article Kennedy et al. 2015
Metabolism of Brussels-Capital Region: identification of flows, economic actors and activities on the territory and tracks of reflection for resource optimisation Report Environnement et al. 2015
Urban metabolism: Measuring the city's contribution to sustainable development Journal Article Conke and Ferreira 2015
Enabling Future Sustainability Transitions: An Urban Metabolism Approach to Los Angeles Journal Article Pincetl et al. 2014
Urban Metabolism: A Tool for the Sustainability of Cities Journal Article Cristian Julián Díaz Álvarez 2014
Urban material flow analysis: An approach for Bogotá, Colombia Journal Article Alfonso Piña and Pardo Martínez 2014
Consumption based footprint of a city Conference Paper Worbe et al. 2013
Nitrogen Flow Analysis in Bangkok City, Thailand: Area Zoning and Questionnaire Investigation Approach Journal Article Buathong et al. 2013
Sustainable design of sanitation system based on material and value flow analysis for urban slum in Indonesia Journal Article Ushijima et al. 2013
Comparison of energy flow accounting, energy flow metabolism ratio analysis and ecological footprinting as tools for measuring urban sustainability: A case-study of an Irish city-region Journal Article Browne et al. 2012
Efficiency Through Proximity: Changes in Phosphorus Cycling at the Urban–Agricultural Interface of a Rapidly Urbanizing Desert Region Journal Article Metson et al. 2012
Pathways and Management of Phosphorus in Urban Areas Journal Article Yuliya Kalmykova 2012
The Development and Practice in City Level of Material Flow Analysis (MFA) in China Journal Article Wei et al. 2011
Urban Water Mass Balance Analysis Journal Article Kenway et al. 2011
Input, stocks and output flows of urban residential building system in Beijing city, China from 1949 to 2008 Journal Article Hu et al. 2010
Collaborative Problem Solving Using an Industrial Ecology Approach Journal Article Boehme et al. 2009
The food-print of Paris: long-term reconstruction of the nitrogen flows imported into the city from its rural hinterland Journal Article Billen et al. 2009
The energy and mass balance of Los Angeles County Journal Article Ngo and Pataki 2008
The flow of phosphorus in food production and consumption — Linköping, Sweden, 1870–2000 Journal Article Neset et al. 2008
Copper and zinc recycling in Australia: potential quantities and policy options Journal Article Beers et al. 2007
Metal capital sustaining a North American city: Iron and copper in New Haven, CT Journal Article Drakonakis et al. 2007
Nitrogen balance for the urban food metabolism of Toronto, Canada Journal Article Jennifer Forkes 2007
The Changing Metabolism of Cities Journal Article Christopher Kennedy and Engel-Yan 2007
The ecological sustainability of regional metabolisms: Material flow analyses of the regions of Hamburg, Vienna and Leipzig Journal Article Hammer et al. 2006
Estimating the urban metabolism of Canadian cities: Greater Toronto Area case study Journal Article Sahely et al. 2003
A material flow analysis and ecological footprint of York Report Barrett et al. 2002
Escalating trends in the urban metabolism of Hong Kong: 1971-1997 Journal Article Warren-Rhodes and Koenig 2001
Stockhome: A Spreadsheet Model of Urban Heavy Metal Metabolism Journal Article J. Hedbrant 2001
Urban Metal Management The Example of Lead Journal Article Obernosterer and Brunner 2001
Energy and material flow through the urban ecosystem Journal Article Decker et al. 2000
Material flow analysis: A tool to support environmental policy decision making. Case-studies on the city of Vienna and the Swiss lowlands Journal Article Hendriks et al. 2000
Lead and zinc flows from technosphere to biosphere in a city region Journal Article Palm and Östlund 1996
The Anthropogenic Metabolism of the City of Vienna Conference Paper DAXBECK et al. 1996
The city of Vienna's anthropogenic material balance Report H. et al. 1996
The metabolism of a city: the case of Hong Kong Journal Article Newcombe et al. 1978