When spending money to limit electricity consumption by such trivial amounts it makes sense to have a look at spending the same amount of money to generate elec

When spending money to limit electricity consumption by such trivial amounts it makes sense to have a look at spending the same amount of money to generate electricity. If you already have solar panels on a roof it is probably much more cost effective to just add a panel or two to offset the power consumption of whatever gadgetry you're running than to spend that money on more power-efficient widgets. If you don't have solar panels you can get a balcony solar installation for around €200 which easily offsets the power used by your existing NAS server assuming you're not using an ex-lease rack-mount multi-purpose server like I do. If you do use one of those you'll have to spend a bit more to get a bigger setup but even in that case it probably ends up being more cost-effective to produce your own power - a single 400W panel covers the power use of a rack-mount server after all.