Comment by hayfield

You can have an impact on power consumption at a range of levels. From choosing appropriate algorithms, to switching to different data types, to changing compiler flags. Add together a few of these 'easy' 5-10% energy savings and you've just reduced your application's energy consumption by a third (OK, it's not quite that simple, but the principle stands).

A couple of citations: http://arxiv.org/pdf/1406.0117v1.pdf (algorithms / data types) http://arxiv.org/pdf/1303.6485.pdf (compiler flags)