Tbh, I don't remember where I got it from.

I didn't intend to publish it, it was just for personal use, so I didn't write down where it was from... 

 Found it, heatrate was the magic word to google:

https://bitcoinmagazine.com/business/introducing-cbei-a-new-way-to-measure-bitcoin-network-electrical-consumption 

 At lesat, almost. Yours is newer. 

 Yep, that's what I was going to say.
🤷