Much effort has gone into making PCs more energyefficient, but it is not just the power used by office desktop computers that places massive burdens on electricity supplies. The networks, servers and storage resources they connect to plus the printers, scanners, photocopiers, phone handsets, and other electronic office equipment that supplement them all contribute toward increasing IT's carbon footprint. Add to this the fans and airconditioning systems that prevent all that hardware from overheating, and you don't need to be an electrical engineer to recognise that it results in a very high therm count.