The problem here is that no matter how many systems you want to build, and how centralized the system is, you still have to rely on the data provided by each consumer. You said it: you didn't know how much energy was used for the fridge and the stove. It's very much dependent on the willingness of each consumer to submit that data. Usually they don't give you enough data. No matter how strong the system is, the source of data is still not good enough, so you still have the same problem.
