Columbia's Guide to Green Computing
Myth vs. Fact
Common Computing Myths
I should never turn off my computer
No harm will come from shutting your computer down when it is not needed. Manufacturers report that turning a computer on and off will have no detrimental effects over the useful lifetime of the equipment. What good will come from shutting your system down? Reduced energy consumption.
My screen saver saves energy
A screen saver does nothing to reduce the energy consumption of your computer. (Modern monitors don't even benefit from the screen saver's original purpose -- preventing image burn-in.) Enabling power management is the only means of consuming less energy when your computer is turned on but isn't being actively used.
My computer consumes a lot less energy when I’m not using it
Sorry, but the difference in energy consumption between an idling computer and one that is being actively used is neglible. Properly configured power management settings are necessary to lower energy use in inactive computers.
Computer Energy Consumption
Each part of your computer system with its own power cable requires energy. The energy requirement at any given time is measured in watts, just as with a light bulb. The larger the number of watts, the more power needed. When you multiply the number of watts required at any time by the length of time you use your computer, the result is the total amount of energy consumed by your system. The most familiar measure of energy use is the kilowatt-hour (kWh), as seen on your home electricity bill. This is the amount of energy required to power a 1000-watt device (the equivalent of ten 100-watt light bulbs) for one hour.
A typical desktop PC with a 17" flat panel LCD monitor requires about 100 watts -- 65 for the computer and 35 for the monitor. Doesn't sound like much? Left on 24/7 for one year, the system will consume a whopping 874 kWh of electricity. That's enough to release 750 lbs. of carbon dioxide into the atmosphere -- the equivalent of driving 820 miles in an average car. To reduce power usage by as much as 75 percent, turn off your computer when you won't be using it for an extended period of time and enable power management features during shorter periods of inactivity.
Computers are a mixture of engineered materials including metals, plastics and several types of toxic substances. Both desktop and laptop computers can contain substantial amounts of metals such as lead, aluminum, iron, copper, zinc, nickel and tin, as well as smaller amounts of metals such as germanium, gallium, beryllium, manganese, silver, cobalt, titanium, mercury and others.
When disposed of improperly, these materials damage the environment. And the problem is growing. Estimates are that 70 million computers have already been sent to landfills, and in this decade, another 500 to 600 million more computers may become obsolete and require disposal. Be aware of this environmental hazard. Follow the recommendations on this site in order to conserve natural resources and to protect public health and the quality of the environment.
Learning about Your Computer or Printer
Many manufacturers provide fact sheets that include power consumption figures and information on any toxins contained in their products. Links to three of the most popular vendors can be found below. Note, however, that the fact sheets often provide maximum power consumption figures, which can be quite a bit higher than figures for standard operating circumstances. The fact sheets are very useful in revealing just how little power your system uses when in standby or sleep mode under power management. The fact sheets also tell you whether your system continues to draw a small amount of power even when it is off. Use the information from your vendor in Columbia's Computer Energy Usage Calculator (Excel) to estimate your current energy use and make a reduction plan.