Seems you already have a pretty good idea of what to do.  To quote your words, “… such as in buying power, billing for energy consumption etc and which will save money for the company.”  Life is fairly simple partner: Y = f (X ).  Of course, the Ys of corporate life are constituted by; a) your customer, b) your shareholders, and c) industry standards.  So, just start naming your important Ys, put a scale of measure to their nature, baseline their performance, establish the goals, identify the potential Xs, confirm those Xs, control the “vital few” Xs over time — that’s what its all about (plain and simple). 

Once this is understood, the rest is “just details.”  For example, consider billing and charging.  For the most part, this type of process is fairly common.  There are visual differences when comparing such processes, but the structural elements are basically the same.  So, it’s a relatively simple thing to; a) look through the literature for improvement efforts related to this type of process, b) find the threads of commonality, and c) transfer those “lessons learned” back to your own process (through training).  Sometimes, we are predisposed to “snatch defeat from the jaws of victory” simply because we “think” something is complicated or terribly difficult.

From experience, most of us have directly witnessed or participated in the circumstance where one person asks of another:  “Where are my sunglasses?”  With a perplexing tone, you reply “on top of your head.”  Seems to me, the necessary vision for your Six Sigma projects is already “on the top of your head.”