As part of the commitment to be the most open, collaborative and accessible world energy model, the Global Calculator team has published the full model behind the online tool. This is built in Excel so that it can be accessed by people easily without downloading special software, and so it can be relatively easy to understand. You are welcome to examine the methodology and assumptions we have used. If you do not agree with them, you can change them and see the impact of the change.
We have also published the source code behind the online tool so that you can create and modify your own version.