This is great. I manually monitor usage quite regularly at my meter (unfortunately not easy to get a smart meter in my country yet...) but it's just a number and you need to work out the current instantaneous usage. This just gives an intuitive sense. I really like interfaces that have this 'always-on-ness' and such a low barrier to insight.
I've actually considered making a glowing light in my office to link to the conversion rate of my SaaS app. For emergency & binary type alerts I get an immediate text alert. But for slightly softer & less urgent metrics a variable color glowing light could be a good way to get across how fast I should look into things ('this week, tomorrow, or maybe this afternoon since it's looking quite orange!').