Sankey diagrams are a

data visualisation Data and information visualization (data viz/vis or info viz/vis) is the practice of designing and creating graphic or visual representations of a large amount of complex quantitative and qualitative data and information with the help of stat ...

technique or

flow diagram Flow diagram is a diagram representing a flow or set of dynamic relationships in a system. The term flow diagram is also used as a synonym for flowchart, and sometimes as a counterpart of the flowchart.Harris. (1999, p. 156) Flow diagrams ...

that emphasizes flow/movement/change from one state to another or one time to another, in which the width of the arrows is proportional to the flow rate of the depicted

extensive property Physical or chemical properties of materials and systems can often be categorized as being either intensive or extensive, according to how the property changes when the size (or extent) of the system changes. The terms "intensive and extensive ...

. The arrows being connected are called nodes and the connections are called links. Sankey diagrams can also visualize the energy accounts, material flow accounts on a regional or national level, and cost breakdowns. The diagrams are often used in the visualization of

material flow analysis Material flow analysis (MFA), also referred to as substance flow analysis (SFA), is an analytical method to quantify flows and stocks of materials or substances in a well-defined system. MFA is an important tool to study the bio-physical aspects of ...

. Sankey diagrams emphasize the major transfers or flows within a system. They help locate the most important contributions to a flow. They often show conserved quantities within defined system boundaries.

History and name

Sankey diagrams are named after Irish Captain Matthew Henry Phineas Riall Sankey, who used this type of diagram in 1898 in a classic figure (see diagram) showing the

energy efficiency Energy efficiency may refer to: * Energy efficiency (physics), the ratio between the useful output and input of an energy conversion process ** Electrical efficiency, useful power output per electrical power consumed ** Mechanical efficiency, a rat ...

of a

steam engine A steam engine is a heat engine that performs Work (physics), mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a Cylinder (locomotive), cyl ...

. The original charts in black and white displayed just one type of flow (e.g. steam); using colors for different types of flows lets the diagram express additional variables. Over time, it became a standard model used in science and engineering to represent heat balance, energy flows, material flows, and since the 1990s this visual model has been used in

life-cycle assessment Life cycle assessment (LCA), also known as life cycle analysis, is a methodology for assessing the impacts associated with all the stages of the life cycle of a commercial product, process, or service. For instance, in the case of a manufact ...

of products. Minard

One of the most famous Sankey diagrams is Charles Minard's Map of Napoleon's Russian Campaign of 1812. It is a

flow map A flow map is a type of thematic map that uses linear Map symbol, symbols to represent movement between locations. It may thus be considered a hybrid of a map and a flow diagram. The movement being mapped may be that of anything, including people, ...

, overlaying a Sankey diagram onto a geographical map. It was created in 1869, predating Sankey's diagram of 1898. Minard had used this form of diagram for visualising flow of goods and transport of people from at least since 1844.

Use in science

Sankey diagrams are often used in fields of science, especially physics. They are used to represent energy inputs, useful output, and wasted output.

Current examples

The US Energy Information Administration (EIA) produces numerous Sankey diagrams annually in its ''Annual Energy Review'' which illustrate the production and consumption of various forms of energy. The US Department of Energy's Lawrence Livermore Laboratory maintains a site of Sankey diagrams, including US energy flow and carbon flow.

Eurostat Eurostat ("European Statistical Office"; also DG ESTAT) is a department of the European Commission ( Directorate-General), located in the Kirchberg quarter of Luxembourg City, Luxembourg. Eurostat's main responsibilities are to provide statist ...

, the Statistical Office of the European Union, has developed an interactive Sankey web tool to visualise energy data by means of flow diagrams. The tool allows the building and customisation of diagrams by playing with different options (country, year, fuel, level of detail). The

International Energy Agency The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organization, established in 1974, that provides policy recommendations, analysis and data on the global energy sector. The 31 member countries and 13 associatio ...

(IEA) created an interactive Sankey web application that details the flow of energy for the entire planet. Users can select specific countries, points of time back to 1973, and modify the arrangement of various flows within the Sankey diagram. Balance of trade with the United States by country

Balance of trade with the United States by country

References

External links

* {{DEFAULTSORT:Sankey Diagram Diagrams Irish inventions British inventions

History and name

Use in science

Current examples

See also

References

External links