Your computer and its peripherals - printers, speakers, etc. - use a energy even when idle or sleeping. So, once you have finished work for the day, be sure to switch everything off. Should you wish to go a step further, unplug the computer and peripherals as they continue to use a small amount of energy even when switched off (this will also help prevent your equipment being damaged by surges!). Remember too that computers and other electronic devices generate heat when on – and that can lead to extra spending on air conditioning!