Step 3: Assessing the circularity of the city

Goal: Create understanding of the findings and outputs with respect to their local situation and circularity overall.

Situation: When an urban circularity assessment is carried out, it is necessary to not only analyse flows and stocks and calculate indicators, but also to understand the context in which they take place. This is because the context, in this case, the cities and their hinterland, provide a crucial and unique set of circumstances and situations.


Take into account the local situation in the interpretation of the various findings of material flows, material stock and overall situation. More concretely this means to consider the economic sectors and activities of the city, its geographic and geological circumstances, history, tradition and values.

Material Flow Accounting
  1. Visualise the data: Generate a Sankey diagram with the Sankey builder and drag your flows around until they are in a good legible order. You can also make single dataset visualisations (on the Data Hub) for a more in-depth interpretation.
  2. Ask yourself the exemplary questions below, reading the Sankey diagram from left to right.
  3. Note down the various insights that can be gained from the Sankey, as explained in the video. (4. If you are using the UCA online report, you can fill in the following fields 12, 13, 14, 15, 24 and 25 of the report form.)

Exemplary questions for analysis

  • What stands out to you at first sight?
  • What is the most prominent material in terms of extraction/import/export/waste?
  • Is your city consuming materials that are directly extracted from your territory or do you import (most of) them?
  • Is your city treating its waste locally or exporting it?
  • What is the quantity of materials that is staying within the material loop?
Material Stock Accounting
  1. Check that the weight of the stock material is appropriate. You can do so by making a Sanity check.
  2. State the overall weight of the city and specify the share of materials within the material stock.
  3. Observe and note down which type of buildings generate most of the mass. You can do so for the typology, age of the building, by height of the building, etc.
  4. Compare the stock to the materials flows entering and exiting the system to relate its magnitude to that.
  5. Compare your city with another case study (e.g. Brussels/Melbourne/Vienna).
  6. Verify and reflect on the quality of the data. (7. Add this information to field 18 of the UCA Report.)

Add qualitative knowledge to the data

After carrying out the diagnostic phase of the UCA by capturing all available data, processing and analysing them, the proposed indicators can give you an idea of both the material and energy dimension of the city, as well as metrics that allow you to understand the state of circularity of the region. While this is done with top-down and quantitative approaches and encourages data-driven decision-making, it is necessary to combine this with bottom-up and qualitative approaches that allow us to understand the nature and size of the problem under study. It enriches the analysis, but more importantly, it provides a better understanding in order to be able to subsequently outline the best suitable strategy to meet the local challenge.

For example, if a municipality has abundant resources, e.g. timber from new forestation and also a demand for construction materials that normally have high embodied environmental requirements, it could use local sources instead. To be more specific in the example, there could be substitution of steel beams with wooden beams in the renovation of the built environment or use for new housing to replace higher environmental impact materials with wood, where feasible. It could also have the added side-effect of bringing back into focus cultural and social aspects of vernacular architecture and traditional, less harmful building methods and materials.

Thus, when conducting an analysis and interpreting the indicators and other results, the context of a city and its associated strategy need to be taken into account. This is to say, data helps us to size the problem, but knowledge of local circumstances helps to enrich the analysis and the search for solutions

→ As a result, when the quantified stocks and flows are integrated with qualitative information, actionable knowledge is created.

Try to add this qualitative knowledge that you have on the city to the overall results and situation to write up a few paragraphs on the status quo of the city and to look into a possible future through recommendations of making the city more circular.