That could include getting rid of a more than 10 year old cpu build on 22nm and opt in for a cheap, powerful and most important efficient solution. That could include something like odroid m1s which should idle at 1W and max at around 3W (without any tweaking).
So the savings for you in only one year when switching to a device with 3W power consumption is actually more then such a odroid m1s costs.
And just one day ago haos got official support for that device