It is always interesting to read all of the various facets of "green".
From an IT perspective, one cannot truly understand what is the first steps to reducing their power costs. Here is a "simplistic" view on how to get started. You can contact me for more detailed information.

The first step is to establish a baseline of everything you have in IT. With the use of enterprise tools you will be able to capture the information about all the IT devices (servers, routers, switches, controllers, VM's, etc...). This is an important first step since you will find things you did not know you even had or you will find old redundant equipment.
Step 2, is the gather from all of the data collected during your baseline and establish the load and who the equipment is being used and configured. You will be amazed at the number of "zombie" servers you will find servers that are no longer being used.
Step 3, analyze the data, from the amount of energy each devices uses to the BTU (under your HVAC requirements) to load, who is using the system, etc...
Step 4, Roadmap on how to reduce your energy costs, many of the better "green" tools out there will do this for you. This would include purchasing / replacing old equipment, looking at 24DC devices, to changing policies and also retiring low load servers and placing the services being delivered to VM's.