I was thinking along the lines of
-List room by room, both linuxMCE connected and not linuxMCE connected, the devices and their power consumption in that room. Tedious? hell yes.
BUT
we at least have a basic power consumption tally. Then depending on what is controlled by linuxMCE can be possible scaled down / back.
I actual started working on something along those lines yesterday

What I have done so fare is make the datalogger_pugin record all state changes. I am then planing to use the information and the amount of power I know each device consume to monitor energy consumption.
At the moment I am testing to see if the information recorded is usable. I am not sure all the devices reports are reliable.