If you leave your PC and monitor on at night you’re using up 985 Kilo Watt Hours(KWH) of electricity per year unecessarily, which is 627 Kg CO2 (see below for my maths)
In the UK,Â one KWH of electricity cost around 11p per hour so leaving your PC on overnight costs Â£129 a year.Â If you have, say, 50 employees this means up to Â£6,450 ($10,500) per year is being spent on electricity you don’t use.
627 Kg C02 is also the equivalent of flying from London to Barcelona and back twice and then doing the same trip by train three more times.
Is it really that inconvenient to turn your PC off at night?
The average PC uses between 100 and 200 watts per hour (wh). The average monitor in sleep mode uses around 15wh
So if we go somewhere in the middle (150wh + 15wh for monitor = 175) we can work out:
175wh x 18 hours*Â = 3.2 kilo watt hours (KWH) per day 3.2 x 365 days** = 1168 kwh per year 985 x 0.537*** = 627 Kg C02 per year
* not at work
** assuming you don’t even turn it off at the weekend
*** Kg C02 per unit of grid electricity: http://www.carbontrust.co.uk/resource/conversion_factors/default.htm
PC watts usage info from http://michaelbluejay.com/electricity/computers.html