Sankey charts, also known as streamgraph charts or Sankey diagrams, are a unique and visually engaging way to represent the flow of quantities between different processes or entities. At first glance, they might appear complex, but fear not—this beginner’s guide aims to demystify the world of Sankey charts and equip you with the knowledge to start interpreting them like a pro.
**What is a Sankey Chart?**
A Sankey diagram is a type of flow diagram that illustrates the quantities or energy flow between systems. The width of the arrows, often called “tubes,” represents the quantity of flow. This makes it an excellent tool for analyzing processes in various fields, from energy to water usage to transportation.
**Components of a Sankey Chart**
To understand how to read a Sankey chart, it helps to know its main components:
1. **Energy or Material Flows**: These are the entities that move through the system. For example, in a process map, they could be raw materials, intermediate products, or final products.
2. **Nodes or Points**: The starting and ending points of the Sankey arrows. In a Sankey chart, these are represented by junctions where processes or entities blend, split, or converge.
3. **Tubes or Arrows**: These graphical elements represent the flow of materials or energy. The thickness of the tubes indicates the quantity or intensity of the flow.
**How to Interpret a Sankey Chart**
Now that we’ve got a grasp on the components, let’s dive into how to interpret a Sankey chart:
1. **Follow the Energy or Material Flow**: Begin at the source node, which might be an input such as raw materials or a battery. Then, watch the flow of materials or energy as it travels through the “tubes.”
2. **Analyze Nodes**: Nodes represent critical points in the flow. Notice how many tubes converge or diverge at a node. This may indicate complex processes with multiple stages.
3. **Observe the Widths of Tubes**: The wider a tube, the higher the quantity or energy flow. This makes it easy to spot which processes consume or generate the most resources.
4. **Identify Waste or Loss**: In Sankey charts, typically, a solid line along a tube indicates where no energy or material goes to waste. Thinner lines often represent losses or waste.
5. **Compare Sankey Charts**: When you have a series of Sankey charts representing different times or processes, you can observe how and why they vary. The changes could suggest process improvements or the need for further investigation.
6. **Apply Context**: Remember that while Sankey charts are a powerful visualization tool, the context of the data is crucial. Interpret the flow of materials or energy in the light of the industry or process being analyzed.
**Common Uses of Sankey Charts**
Sankey charts are used in a variety of fields, including:
1. Energy Efficiency Analysis
2. Logistics and Supply Chain Management
3. Sustainability and Environmental Study
4. Water Resource and Sanitation Engineering
5. Process Optimization and Control
**Creating a Sankey Chart**
While you might initially rely on software to create Sankey charts, it’s a good idea to understand the basics. Most data visualization programs support Sankey chart creation, allowing you to input your data and customize the chart to your needs.
By familiarizing yourself with the principles of Sankey charts, you can begin to leverage this informative and intuitive diagram in a variety of practical scenarios. So the next time you encounter a Sankey chart, whether in a report, presentation, or academic paper, you’ll be able to read it with confidence, extracting valuable insights from the flow of material or energy within the system.
