How much of your energy are you using when nobody is there?
One site was running at 58% of its total consumption outside working hours, with nobody in the building. Here is the case written up properly, and the method for checking it on your own site in an afternoon.
Your bill tells you what you spent. It cannot tell you where it went.
Why site-level data caps you at negotiating on price, and what changes the moment you meter by machine.