Saving Energy – One Monitor at a Time

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Several times I had observed that my laptop battery lasts a lot longer if I turn down the brightness of the screen. That just seems such a common sense thing to do. But I never took power consumption of monitor that seriously till one day I almost burned my hands while trying to move the big bulky 19 inch CRT monitor. The back side of the monitor was really hot.

Boy, how much power does this one consume? A quick look at the manual and turns out that my old big bulky 19” monitor was consuming a whopping 120 Watts. It’s like having a big bright bulb burning right in your face. That figure was big enough for me to switch off my monitor while not working. But still I wondered, what is the exact relation between what is being showed on screen and how much power is being consumed by the monitor.

A really good EBay deal on P4400 KillAWatt by P3 International convinced me that God wants me to buy a power meter and investigate this in detail. For anyone interested in “watching your power”, this is a handy thing for about $30.

I ventured onto this study. I checked monitor power consumption for CRT (Cathode Ray Tube aka big, bulky, heavy, TV shaped, ugly, dinosaurs), as well as LCD monitors (Liquid Crystal Display aka thin , flat, light, cool cuties) . Since 17” monitors are the most common, I chose Compaq S710 in my office (which is CRT 17”) and Hundai Imagequest L70N, which is LCD 17” monitor for study and comparison.

I checked following things

* CRT monitor consumption vis-à-vis LCD monitor consumption
* Brightness settings varied 0, 50, 100
* Contrast settings varied 0, 50,100
* Screen background changed black, gray, white
* Soft power off (off using power settings of computer) and hard power off (off using switch) consumptions.

The results were really surprising. Following charts summarize my readings.

The Summary of the findings is below

*Sensitivity to various settings is as follows

Power Consumption Parameter	CRT Monitor	LCD Monitor
Avg. consumption	76 W	20 W
Screen color sensitivity	Extremely sensitive. Consumes lot more power (43% more) when displaying white on screen.	Completely insensitive. Consumes same power for all colors on screen.
Brightness setting sensitivity	Moderately sensitive. Consumes more power at higher brightness.	Sensitive. Consumes higher power for higher brightness
Contrast setting sensitivity	Less sensitive. (Almost insensitive when brightness setting is low.)	Completely insensitive. Consumes same power for all contrast
Consumption when turned off from computer power settings	2W	0 W

* Screen savers consume as much energy as when you are using screen. They save your screen pixels, but they burn away power.
* CRT monitor leaks power just like TV. Just FYI, a TV switched off using remote control does actually consume electricity (up to 20 Watts for some models). But the TV switched off using “OFF” switch is perfectly at rest.

Do we need our monitor at it’s brightest all the time? Do we need Microsoft Word background look like white paper? Can we write white over black instead of black over white? Can we all follow some monitor manners and save energy?

By following simple monitor manners below, in fact we can save lot of energy.

1. When not in use, simply switch off the monitor by hand.

2. If fits in your budget, buy an LCD monitor.

3. Use “blank screen” as a screen saver option.

4. If your computer allows power setting control (all laptops usually do), then change power settings to “turn monitor off” after 2-5 minutes. These setting are usually accessible somewhere around screen saver settings.

5. Right click on your desktop or background, go to properties>appearance tab>advanced. Now select “window” in the list and select a light gray color instead of white. Play around with schemes, use your creativity. Refer to the article

6. http://support.microsoft.com/default.aspx?scid=KB;en-us;q307855

7. But be careful while printing because you are not printing what you see. At such times, you can easily revert back to default scheme from display settings.

8. Reduce brightness settings, increase contrast settings.

OK, So what’s the big deal?

If you look at statistics below, you will see that it can actually be a big deal.

The USA has almost 574 personal computers per thousand population, among the highest in the world. Barring a few exceptions, each personal computer has a monitor with it. So for 292 million population, @574 per 1000, we have 177 million monitors.

Just following one or two of the above tips above, you can easily reduce your monitor’s average consumption by around 20 W. If 177 million people save 15W per monitor, it accumulates to a gigantic figure of 3500 Mega Watts, or 3.5 GigaWatts.

If you saved 3.5 Gigawatts, you just shut down four coal fired power plants in Texas, namely Gibbons creek (1 X 480 MW), Welsh (3 X 558 MW), Sandow (3 X 121, 1 X 591 MW) and Oklaunion (1 X 720 MW). That means almost 5.25 million lb CO2 emissions avoided PER HOUR. Yes, I checked my calculations twice.

This savings can be realized on your CRT monitor, not a single penny out of your pocket. A perfect conservation. If you switch to LCD, you save a lot more.

And while the environmentalists within you are drooling over the idea of closing down coal fired power plants, do not forget these additional benefits.

* If you are not saving this energy, then what is happening to it? It is getting converted to bright light and is going in your eyes. Our eyes are not designed to stare at bright white thing from 2 feet close, 8 hrs a day, whole life. They deserve a break.

With my new monitor settings, I find my eyes much more comfortable at the end of the day.

* Amory Lovins (www.rmi.org) once said “Any attempt to make the car lighter by 1 lb actually ends up in making the car lighter by 1 and half lb”. Because when you reduce body weight, you can use lighter chassis, then you need lighter suspensions and so on. Similarly any attempts to reduce monitor consumption by 100 watts actually end up saving overall 110 watts (figuratively speaking). Because to show you something on monitor, computer processor has to do work, hard disks need to be spun, video card must be fired up and fan must run faster to cool these things down. When monitor is off, all these things can take it a bit easy by a watt here and a watts there.
* Just for fun I calculated how much money I would save if I saved 15 Watts for 6 hours every day. Turns out that @ 12 cents KWH rate, I would be saving around $4.85 per year. OK, you cannot buy Lexus with this saving. But hey, at the end of the day, where would you rather put extra 5$? In Your pocket or in your utility provider’s pocket?

Moral of the story:

Just by making a small change in your computer habits, you can save some serious energy. Only thing you give up is an eye candy like screen saver. But if you consider the eye candy cost you are paying in environment terms, it is really worth it.

References:

1. www.Internetworldstats.com for 2005 computer usage statistics
2. www.Industcards.com for 2005 coal fired plants data
3. US EPA Energy information administration EGRID 2000 database as referred by www.greenmountain.com
4. US EPA National Vehicle and Fuel Emissions Laboratory EPA420-F-97-037 standards as referred by www.greenmountain.com
5. http://www.energystar.gov/index.cfm?c=pm_mmd.pr_pm_mmd

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