Now I’m keen on saving the planet, but I feel you can take things too far. I set my PC to sleep after a couple of hours and sometimes I switch it off completely. But I don’t turn off my monitor – I don’t need to, because when my PC is asleep my monitor also sleeps and monitors use less than ½W when asleep. That’s about 500 pence per year.
So by all means switch it off when you go on holiday and it may even be worth saving a penny or two if you are away for a weekend, but for the rest of the time – you might as well leave it on.
Just in case you are interested flat screen monitors use about 25W – 30W when working. If you still have an old CRT type monitor then do turn it off they use about 100W! And just to make a comparison your kettle uses about 3000W – but then most of the time it is idle.