Their 2021 update here:

https://www.sciencedirect.com/science/article/abs/pii/S01676...

Link to full paper via sci-hub:

https://sci-hub.st/10.1016/j.scico.2021.102609

This appears to be a web page where the authors have posted links to their research, data, updates, etc:

https://sites.google.com/view/energy-efficiency-languages/

For transparency, I've posted these here recently:

https://news.ycombinator.com/item?id=39286827

This is something we've been slightly interested in, as a means to reduce power consumption and the number of servers we need to operate. It's just an insane amount of work trying to rewrite software and finding the bits where produces the most results.

It's not really surprising to see C and C++ doing so well, also positive to see Rust being up there as one of the most energy efficient languages. The one language that keeps surprising me is Pascal. It often in the top 5 - 10 in terms of speed and it also does really well for energy consumption. While I haven't read the article, I could also imagine that it's good in terms of "power spend compiling" due to it's one-pass compiler. What I'm not sure of is if it's all a result of the language design, or if it's because it just had a lot of work put into it over the years by some really smart people. I presume that the tested implementation is Free Pascal.

Now we just need a follow up that takes the average dev time for each language and show which one has the optimal ratio based on these two values. It should be possible to draw a curve based on how long and how often the program will run to plot exactly when it makes sense to switch to something more efficient but also more dev intensive. Sort of in this fashion: https://xkcd.com/1205/

E.g. assembly would have very low energy use by itself, but would require an inordinate amount of human energy (~8.7 MJ/day) invested to get that end result, making it very inefficient when the whole picture is considered. Unless that code runs everywhere constantly for years of course.