After my last pic of a twitter conversation on Sankey diagrams I got some thumbs up for the idea. So, here is a another one for your casual friday. Enjoy!

Back at my desk after the holiday season…. Happy New Year to all of you. To start off the blogging this year, here is a funny twitter conversation on Sankey diagrams.

Quite an impressive number of ?s and !s…. and, well, geography is more interesting anyway. 😉

This legacy article on ‘Solar Energy System and Design’ by W.B. Stine and R.W. Harrigan (published in 1985 already) has four Sankey diagrams for energy flows in a solar power system.

The old-school black&white Sankey diagrams depicted have a general vertical orientation, and some flows branch out to the left of the general flow direction. This is OK, but the first branch flow bends with an angle larger than 90° degrees, performing an almost U-turn.

In the next diagram this idea is doomed to fail as the Sankey arrow to the left is wider than the one going straight on, and the initial parallel segment is much too short.

Additionally in this second Sankey diagram the two arrows at the bottom don’t add up with their flow quantities correctly (633 kW + 244 kW is not 1008 kW).

Just to let you know that I have made some updates to the Sankey Software page. Added tamc/Sankey and Foreseer (how was it possible I hadn’t done this before?!), removed some outdated links, updated license cost for one or two tools and so on…

Had some trouble with the server that hosts the blog. There was some downtime, and I hope that you didn’t turn away from the blog annoyed… Back now!

A new blog dedicated to Material Flow Analysis (MFA) diagrams is available over at blogspot.

Material Flow Analysis (also refered to as Material Flow Accounting) is a research topic that focuses on specific substances or material flows on a macro level. Typically the system boundaries are a region or a country. Urban metabolism studies also use MFA diagrams. A key feature is the representation of stocks (storage or accumulation of material) within the system.

I have previously presented MFA diagram samples here on the blog that have Sankey diagram characteristics (i.e. arrow magnitudes proportional to flow quantities, directional arrows).

Here are two examples of MFA diagrams from the new blog for you to enjoy:


Platinum Flows in Europe. Source: Saurat, M., Bringezu, S., 2008. Platinum Group Metal Flows of Europe, Part 1 (via MFA diagram blog)


Phosphorus Flows. Source: Paul H. Brunner, 2007. MFA of regional lead flows and stocks [t/y] (via MFA diagram blog)

Make sure you visit the MFA diagram blog from time to time (I have put the link in the blogroll on the right), to see new interesting diagrams. I will also try to present some of them here…

A notice on scoop.it/visualdata led me to this fascinating video on visualnews. It shows the making of an infographic in two minutes or 3657 frames and is by Jess Bachmann for mint.com.

The central element of the infographic is a Sankey diagram on the trade flows between the United States and China (and to/from other countries).

it is interesting to see how Jess did every weighted arrow as a brush line with rounded head (the heads are neatly hidden behind the country maps, or capped at the other end). Each horizontal, vertical and curved segment is done individually.

In the YouTube comments of the long version of this video the author replied to one commenter: “After determining a metric, i.e 1 pixel width = $1M, I then stroked a line with the corresponding size brush. A $34M item would have a 34px width line. At one point you can even see a calculator popping up (0:55 into the video).

The long (7 minute) version has a lot more details on how the infographic comes to life. You can even see that Jess keeps saving his work from time to time…

Wow, what a hell lot of work – but the result sure looks gorgeous.

I calculated that Jess took more than 10h to complete this: 3657 frames, ten seconds between each frame = 36570 sec, 3600 seconds to an hour, makes 10.16 hours! I am just glad I have my Sankey diagramming software, so at least I don’t have to bother about brush sizes.

Typically it is quite difficult (read: expensive) to get hold of official ISO standards. It is by chance that I discovered the draft version of ISO 13579-1 on ‘Industrial furnaces and associated processing equipment — Method of measuring energy balance and calculating efficiency — Part 1: General methodology’ on the website of AFNOR, the French body of standards. The draft is open for comments as part of a public hearing process.

The draft standard ISO 13579-1 talks about energy balance (‘bilan énergétique’). Part 4.2 shows a sample Sankey diagram and explains that this is a tool that allows to represent the in and out flows of energy (‘outil permettant de représenter le flux d’entrée et de sortie de l’énergie’). In section 9 f on reporting the draft standard recommends that the report shall include a Sankey diagram (‘Il convient que le rapport de mesure du bilan énergétique contienne … Diagrammes de Sankey.’).

Didn’t have the original English version at hand, so I hope this is pretty much what it says in French.

Anyone aware of other ISO standards that mention Sankey diagrams?