Flowing Data Visions: The Sankey Chart Enlightenment

As a powerful visualization tool, Sankey diagrams have gained popularity in recent years for their ability to illustrate the mass and energy flows in a process, system, or product. In this article, we’ll explore the origins and evolution of Sankey diagrams and delve into their creation and applications to underscore the importance of this chart in our understanding of complex and dynamic systems.

Origins of Sankey Diagrams

Sankey diagrams, named after their inventor, German engineer and engineer-inventor Maximilian Sankey, emerged in the early 20th century. Initially, these diagrams were utilitarian tools for industrial plant engineers to analyze production processes and optimize energy use. In his 1898 paper, “The Maximilian Sankey System for the Representation of the Flow of Materials in Plants,” Sankey described a method to represent the direction and magnitude of flow within complex processes, which is the basis of the Sankey chart.

How Sankey Diagrams Work

A Sankey diagram is a type of flow diagram where arrows represent the quantity of material, energy, or cost moving through a system and the width of the arrows depicts the quantity. Sankey charts connect points of input to points of output, illustrating how material, energy, or cost is used or transformed. Typically, Sankey charts start with a source at the left and end with a sink at the right, making them intuitive for visualizing the overall input-output balance of a process or system.

Here’s what makes Sankey diagrams so unique:

• Direction and Rate Representation: Arrows point in the direction of flow, and their width indicates either the rate or total amount of the flow.
• Conservation of Flow: Input at the beginning of a chart must equal output at the end.
• Efficiency Assessment: By comparing the width of an arrow to the process or system components it connects, Sankey diagrams can help analysts assess the efficiency of energy conversion.
• Scalability: Sankey diagrams can represent processes on different scales, from simple to intricate, depending on their complexity.

Creating a Sankey Chart

Creating a Sankey chart can be challenging due to the data requirements and the complexity of the chart itself. Here are the general steps in the creation process:

1. Data Collection: Gather the raw data that represents the flows involved in the process or system you wish to visualize.
2. Flow Classification: Identify the inputs and outputs and classify them based on the variable they represent (material, energy, etc.).
3. Arrow Direction: Establish the direction of the flow and connect the data points accordingly.
4. Width Scaling: Allocate width to the arrows based on the amount of flow or energy. Sankey diagram software often utilizes normalization routines to ensure that the flow and the energy dimensions are on the same scale.
5. Layout and Formatting: Determine the format for inputs, outputs, and other elements. Position the nodes and connecting arrows and adjust the flow widths to fit the chart layout.
6. Sankey Diagram Software: Use specialized software such as Sankey Diagram Editor, Sankey Diagrams, or Power BI for a more interactive and customizable experience.
7. Review and Iterate: Once the chart is created, review it for accuracy and readability. Make adjustments as necessary.

Applications of Sankey Charts

Sankey diagrams have diverse applications across various fields, including:

• Energy Use Analysis: Visualizing energy input and output in buildings, factories, or broader energy systems.
• Environmental Impact Assessment: Measuring the impact of carbon emissions and other pollutants in industrial processes.
• Supply Chain Management: Monitoring the flow of materials from providers to manufacturers and end customers.
• Financial Planning: Mapping out the inflow and outflow of resources within a company.
• Transportation Systems: Understanding the energy usage and emissions from a variety of transportation modes.

Conclusion

The evolution of Sankey diagrams as a visualization tool has significantly advanced our ability to understand the complexity of systems and processes. As an enlightening way of viewing flow in a system, the Sankey chart delivers an accessible and impactful visualization for a wide range of users and scenarios. By employing the techniques for Sankey diagram creation and understanding its applications, we can harness this chart’s full potential to unlock insights and improvements in various domains.

SankeyMaster

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