Save energy and money by turning off your computer at night

I save a significant amount of electricity by turning my computer all the way off at night.

My desktop computer draws about 120 watts when its on but idle with the monitors off. Assuming I only need to have my computer on 10 hours a day, if I left it on all the time annual power consumption while idle would be:

(120 watts * 14 hours * 365 days)/1,000 = 613.2 kwh a year

Here in Arizona I pay around $0.10 per kilowatt hour (kwh) so that works out to $61.32 a year.

The first step was just powering down the desktop at night. However, since I do a long backup routine every night when I end my work day it was initially inconvenient to start my nightly backup routine, and then come back later to turn off my computer. So I used http://www.autohotkey.com/ (a multipurpose utility for Windows which can map hotkeys and automate tasks using a nice scripting language) to write a script to do all the tasks of my nightly backup routine and then shut down the computer.

However, when I took my trusty Kill-A-Watt to my workspace powerstrip I discovered that between my desktop, my Cisco IP Phone 7960, my HP printer, my Linksys router, my Xerox sheet-fed scanner, my Plantronics wireless headset, etc. I was pulling 30 watts even with everything powered down.

To a normal person leaving something on all the time that draws 30 watts is no big deal, but I am not that person. I figured that this 30 watt draw works out as follows, assuming that I want my workspace power on about 15 hours a day 6 days a week:

(((9 hours * 6 days) + 24 hours) * 30 watts * 52 weeks)/1,000 = 121.68 kwh or $12.12 per year

So, I hooked up power timer I had laying around to my powerstrip and set it so it turned the power on at 04:00 and off at 19:00.