Generation of Sankey diagram
Goal: Build your interactive Sankey diagram.
The approach is given in 7 steps here. For more details, you can refer to the outline of the video below.
- Copy the template tab that has Table 1 and 2 to a google spreadsheet. Construction template; Biomass template
- Fill in Table 1.
- Determine if you have Case 1 (flows are known) or Case 2 (flows are unknown and allocation factors are needed).
- Case 1: Fill in all of Table 2 too.
- OR Case 2: Only fill in the waste flows, which you should know. The rest is calculated with the allocation factors.
- Upload / add your google spreadsheet as a library item (dataset type) in Layer 3.1. Extraction/Harvesting.
- Build the Sankey diagram with the Sankey diagram builder.
Outline of the video
- To visually represent the data and material quantities, visualisations are made use of. These can be split up into two main types: the Sankey diagram and other charts. In this video we will show you how you can build your Sankey diagram and select additional visualisations for your SCA report.
- Sankey diagram (see example under “Visualisations”): The goal of the Sankey diagram is to represent the material flows in your city. A Sankey diagram is made up of nodes and flows.
- In the case of our Sankeys, the nodes represent the lifecycle stages and the flows between them are the materials being transported.
- For example, it can be seen there are flows going from extraction to 4 nodes, namely manufacturing, retail and use, and even waste collection.
- The width of the flows indicate the size of the flow, which facilitates that those can be compared. A flow section that is less wide, is smaller in terms of quantities in comparison to the others.
- Different colours could represent the different materials
- Building the sector Sankey: For the SCA report, the minimum requirement is to have one Sankey that represents the sector. That means that all materials are added up.
- The building of the sector Sankey is based on the table that you have filled in for the indicators, Table 1. The added up values per lifecycle stage represent the height of the nodes.
- However, it doesn’t indicate how the nodes are linked and the different amounts flowing between them. That means, in addition, it either requires knowing which flows go from one node to other nodes, OR allocation factors which we have prepared as a back-up solution.
- In other words, just like in the example before, either it is known which amounts go from imports to all the other nodes, or we have to take existing estimations that we’ve prepared for you. We will explain what to do in both cases.
- Case (1) : You know the distribution of the node to the flows.
- You can simply fill in the quantities for the flows in Table 2a.
- Only know a single flow, but not the rest of the distribution for that node
- There is a value check embedded that allows you to check if the entered quantities add up to the total of the node. Remember: The size of the node is made up of all outflows. In = Out.
- Green = value is the same as the total of the LCS.
- Yellow = value is smaller than the total of the LCS.
- Red = value is larger than the total of the LCS.
- Case (2) : You do not know the distribution of the node to the flows and make use of allocation factors.
- For this case, we have prepared assumptions for the allocations to the different nodes as back-up solutions. They are listed in Table 2b, under the Sankey table. Nothing else has to be done then, because Table 2a is automatically generated.
- For biomass materials, the allocations are based on an article that we derived the coefficients from. The nodes are similar, but it is safe to assume that the situation is different from cities, especially on imports, because this is data from the EU.
- For construction materials, we have used our best judgement, which is really not ideal for your data and you should use your own data where possible.
- Using these allocations, since they are not based on your local situation, will therefore add some inaccuracy to the data.
- For waste collection and treatment, there are NO allocation factors. You should have this data and fill in the quantities directly.
- Building a material Sankey (single material): You can build additional Sankey diagrams, namely per each of the materials, if you want to. This can be done if you have the values for all lifecycle stages for that one material, for example, cereals or sand and know the distribution of values to different nodes.
- Once you are done with the table, you can share your data on the Data Hub.
- You will then be able to hover over the nodes to see the label of the flows and the quantity. You can add your own labels, if you wish.
- You can also drag the nodes, if you think that it makes the diagram more legible.