REFLOW activities associated with urban metabolism, material flow analyses, and environmental impact assessment were led by Metabolic and Materiom as part of Work Package (WP) 3: Circular Engineering. The purpose of WP 3 is to map and measure each pilot city’s urban metabolism through a core set of methodologies including material flow analysis (MFA) and environmental impact assessment. The work was done in close collaboration with each pilot team and results are used to support the continual development and testing of the circular economy strategies within each pilot city. The core objectives of WP 3 are:

- To co-create principles and best process for urban circular resource flows across the pilot cities.

- To co-identify, develop, and scale innovative solutions for urban circular resource flows across the pilot cities.

- To assess the environmental performance and impacts of pilot cities, their interventions, and strategies.

Toward achieving the above mentioned objectives, the following three overarching tasks were led throughout the project:

- Circular Principles & Indicators: Co-development, with pilot cites, of a set of principles and key performance indicators (KPIs) for circular urban resource flows. The purpose of the principles is to communicate key principles and best process that partners should strive towards when building circular resource flows within cities.

- Circular key performance indicators (KPIs): Support pilot cites in setting progressive circular economy targets and goals within their REFLOW Pilot Acon Plans (REFLOW D5.1, 2020) as well as a core set of KPIs that enables pilot teams to monitor progress towards their pursuit.

- Urban metabolism: To map and measure the urban metabolism of each pilot city and support the pilot teams in devising circular strategies and intervenons that best address the unique context, challenges, and opportunities of their city