Wednesday, July 23, 2008

Conservation: Conquer your computers energy consumption

Here at Chicago Energy Consultants, we are no strangers to computers influencing power bills. With a long history in technology consulting, we have seen computers from the 7-foot tall multi-cabinet systems that consume many, many thousands of watts, all the way down to computers the size of a deck of cards that consume barely a couple watts.

Your home computer falls somewhere in between those two extreme cases, with most home desktop computer systems consuming from 60 to 250 watts when fully turned on. Laptops as a rule consume less power than an equivalent desktop system, because manufacturers use low-power components to allow the laptop to operate as long as possible from its battery. The Department of Energy 2001 power survey shows that computers account for 1.6 percent of a homes energy usage on average, while recent estimates put that number closer to 2%.

Before you run out and buy a new energy efficient computer, consider what the environmental impact of manufacturing the average personal computer is: 3,300 pounds of water, 529 pounds of fossil fuels, and 48 pounds of chemicals (often very toxic, like the cyanide baths used to deposit gold traces on circuit boards). So, lets focus on making your current computer more energy efficient!

A question we often receive is "Should I leave my computer on all the time?". Turning the system on and off does add the slightest bit more wear and tear on the parts of the computer, but lets see what we would be paying to leave an 'average' (155 Watt) computer on constantly for one month:

155W / 1000 = .155 KWH
.155 KWH * 24 Hours = 3.72 KWH per day
3.72 KWH per day * 30 days = 111.6 KWH in a month
.10 cents per KWH * 111.6 KWH = $11.16

So we pay more than eleven dollars a month to keep our 'average' computer running 24/7. If that computer were to remain turned on for 4 years, it will end up costing you over 535$! In the winter the waste heat that the computer produces will be doing you a little favor by heating your house, but in the summer you might not appreciate the added heat. If you want to find out just how much electricity your computer uses, grab a load meter like the Kill-A-Watt:



To save energy, there is a better choice than turning on and off the computer: that is to use your computers built-in power saving settings. If running Windows, open your Control Panel and look for 'Power Options' - you want to enable either the standby, or suspend modes. If this is over your head, you can download Google's Energy Saver gadget that automatically optimizes your computers power saving settings, and even tells you how much power you have saved (the Gadget requires Google Desktop software to work).

Another great trick you can use to save energy is to use an auto-switching power strip. This specialized power strip is setup to detect when a 'master' device plugged in to the strip turns on, and then automatically turns on the other switched outlets. With this tool, when your PC is switched off or goes to sleep, it is possible to turn completely off any computer peripherals you have plugged in along with your computer. So if you plug in your monitor, printer, DSL or cable modem, and speakers into this strip, you could be saving an extra 5-50 watts of 'always-on' vampire loads, in addition to your computers already significant power savings. These power strips are also great for use on entertainment centers.



Another big power consumer in desktop PC's is the graphics card. In newer high-end gaming systems, 2 and even 4 graphics cards can be installed into a system,. When each video card can draw 200 watts, you could be looking at a PC with the ability to pull upwards of 1000 watts! On the other hand, some systems have built-in video on the motherboard (like most laptops), these systems use much less power, and are adequate for most tasks other than gaming.


A desktop PC with energy saving settings enabled will save a significant percentage of money, but what about a server that has to remain on 24/7? The power supply unit (PSU) that all computers use to convert voltage at the plug (110/220V AC) into levels that the computer needs to operate (3.3V,5V,12V DC) is usually around 55-75% efficient ,but can range from 20-90% efficient. That means that if the components of your computer use 200 Watts, a 65% efficient PSU will use another 70 Watts, pulling 270 watts from the plug. Numerous companies who use lots of computers (like Google) are pushing to re-design PSU standards to provide only 12V DC, allowing much more efficient supplies to be built. Currently you can look for a PSU certified as "80 Plus" to be guaranteed that the unit will always operate at 80% efficiency or better.



In a large computer data center, there are many tricks to reducing power and cooling requirements. If you are interested in talking to us about any of these techniques or technologies, please contact us with the information provided on the Chicago Energy Consultants web page!

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