Saving Electricity

I used to leave my computer on all the time. One nice thing about Linux is that it doesn't require the nightly reboot like Windows used to (and maybe still does). The only problem with never turning off my computer was how much electricity it used. I never really quantified the numbers until recently. I was amazed at what I found.

Since I work out of town during the week and am only home on weekends (except for that one week a month that I get to work from home), I started turning off my computer on Sunday nights and didn't turn it back on until Saturday morning. The next time I got my electrical bill, it was $5 less than the previous month. Now there are a lot of things that can influence electricity usage and so I waited with anticipation for the next bill to arrive. This time it was $20 lower. Then summer hit and my electrical bill goes though the roof because of my air conditioner. However, I noticed that my electrical usage was lower for the same time over the previous year.

So how much money am I really saving by leaving my computer off during the week? Looking at my current electrical bill, I see that I am paying between 8 and 11 cents per kilowatt hour. I know that my computer sitting idle draws about 2 amps at 120 volts. Multiplying those two numbers together will give you 240 watts. So running my computer for about 4 hours is equal to 1 kilowatt hour of electricity. Doing some more arithmetic shows that my computer is off for a total of 5 days or 120 hours. Multiplying 240 watts by 120 hours equates to 28.8 kilowatt hours of electricity. If I use an average cost of 9 cents per kilowatt hour, I see that I am saving myself $2.59 per week. This works out to about $10.36 every month.

So the savings are not as huge as I originally thought. How come my bill seems so much lower? There must be other factors such as a general concern for the environment. At about the same time I started turning off my computer, I may have started working harder to turn off lights that were not in use. Looking at the electrical bill for months that I use the air conditioner, I have noticed that even though the average daily temperature is the same this year over last, I have gone from 68 kilowatt hours per day down to 43. That is huge! Not only is my computer a work device, it is also a space heater. Sometimes being "green" is a great way to save a little "green."