"From the studies that we've done, it's quite clear that fibre to the home is the most energy efficient technology. Fibre to the home has fibre all the way - it's passive.  So there's no energy consumption between the telephone exchange and the house." -- Dr Kerry Hinton - 

See more at: http://upclose.unimelb.edu.au/episode/285-how-green-your-cloud-energy-we-consume-staying-connected#sthash.9v0kBIJv.dpuf