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Energy saving tip – How much money can you save by turning off your computer overnight?


I never realized that a large amount of money can be saved just by cutting the unnecessary wasted energy costs. I have done a little experiment with the ‘MS6115 Mains Power Meter’ on my work desktop computer to find out the effect of wasted energy in an attempt to save the company some money by generating awareness. I am pretty shocked with the results to be honest seeing how much energy is wasted every year throughout the world!

I have used the Dell Optiplex GX620 Desktop Computer for this Energy usage/cost calculation. MS6115 Mains Power Meter was used to measure energy usage. I have been doing various kinds of experiments with this power meter that i mentioned on my Essential tips to start living Green today post a few days ago.

Wasted Energy cost of a Desktop CPU (Dell Optiplex GX620)

A desktop CPU running idle with Screensaver consumes about 0.082 Kwh (What is kilowatt-hour, kWh?).
Energy Usage for overnight, 5pm-9am, 16 hours (Given an eight hours work day) = 0.082 x 16 = 1.312 Kwh
Energy Usage over five working day overnights = 1.312 x 5 = 6.56 Kwh
Energy Usage over the weekend = 0.082 x 48 = 3.936 Kwh
One working week Energy Usage = 6.56 + 3.936 Kwh = 10.496 Kwh
Energy usage over one year = 10.497 x 52 = 545.792 Kwh
Average Energy cost per Kwh = 11 cents.
Annual Energy Cost for the Desktop CPU = 545.792 x .11 = $60.04

Desktop Computer Energy Usage

Appliance name Energy (kw) Overnight energy usage 5 days energy usage Usage over the weekend Working week usage Annual energy usage
Desktop CPU running onidle with screen saver 0.082 1.312 6.56 3.936 10.496 545.79
Monitor running on screensaver 0.05 0.8 4 2.4 6.4 332.8
Appliance name Average cost per Kwh Total cost
Desktop CPU running onidle with screen saver 0.11 60.0371
Monitor running on screensaver 0.11 36.608
Total 96.6451

Wasted Energy cost of a Monitor (19 inch Dell Widescreen monitor)

A 19 inch widescreen monitor running on screensaver consumes about .05 Kwh energy. Using the calculations used for the Desktop CPU the Annual Energy Cost for the Monitor = 332.8 x .11 = $36.6

Total Wasted Energy Cost

Total Annual Energy cost of the computer (monitor and the CPU) = $60.04 + $36.6 = $96.64
For a company with 100 employees the annual energy cost = $96.64 x 100  = $9664 !!!

So, that’s a rough estimation of how much money ($9664) the company can save if the employees just turn off the computers when leaving for home at the end of the day! Imagine all the big companies out there with thousands of employees!

Does it really make any difference? I think it does.

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