Hi dani
I don't disagree with the sentiment, and have no intention of wasting energy. However, it's more complicated than a simple annual kWh calculation (which costs me around £23 per year to run five continuous channels of CCTV recording, media server, security, heating and light control, file shares and backup - not too bad
). Right now if I run on RaspPI, I would be adding to my power charges and not reducing - I can't port everything to the platform so would need to continue to use the existing server. In addition to that, material and resource costs to manufacture and distribute new technology mean it's sometimes a good idea to use what you have, if saving the planet is what floats your boat.
I'm not trying to be antagonistic and will probably end up using RaspPI for this at some point, so this isn't a case of ignoring you!