Personal
Computers
When we think about our personal contributions to climate change we may think about home heating, cars, and incandescent light bulbs; we should also consider our computers and computer usage. A personal computer running for ten hours per day is responsible for producing approximately 1,200 pounds of CO2 emissions in one year, or about a tenth of the CO2 emissions of a car over the same period. However, there are an estimated 600 million cars and trucks and over 2 billion computers worldwide [19]. So the contribution of the personal computer to climate change is too great to be ignored.
Of course, ten hours per day is just an average time. Many businesses and individuals leave their computers running continuously even when they are not running any applications. This is done for various reasons, but the most common reasons are the belief that multiple power cycles (turning a computer off, letting it cool and then rebooting it) reduces the lifespan of the computer and secondly a desire to save time by not having to wait for the computer to boot up when resuming work after a pause. When a computer is running, the circuits expand as they heat up and when it is powered down the circuits cool and contract. The belief is that frequent expansion and contraction can cause circuits to break down. This is a common misconception; computer manufacturers design circuits to survive thousands of power cycles, it is the cumulative operating time and temperature which are responsible for wearing out electronics. Thus, the best way to prolong the life of your computer is to turn it off when not in use [20]. Furthermore, given that many people replace their computers every four to five years – more often for businesses – it is unlikely that one would experience computer failure from normal use within a five year span. Therefore, if you wish to save money, the best option in the long run is to power down your computer when not in use, thus saving money on your electricity bills rather than leaving it running in the hopes of postponing the replacement of your computer.
The other reason is a fear of losing productivity while waiting for a computer to boot up. Again, this fear is unfounded: personal computers have a standby mode or sleep mode which allows the computer to go into an energy saving mode from which it can be rebooted in a matter of seconds. When a computer is shutdown completely, all information that was stored in the RAM is dumped and the computer must then boot up from the hard drive. Standby mode saves the current system settings to the RAM and keeps that data stored there with a small electrical current so that the computer can then boot from the RAM, which is much quicker than booting the entire operating system from the hard drive. The EPA estimates that using the sleep mode setting on a computer can reduce its energy consumption by as much as 60-70%. In terms of GHG emissions, that is equivalent to taking 5 million cars off the road [21]. Using the standby mode on a computer is a good way to conserve energy while away from the computer for short periods of time and should not impact productivity.
What if you are going to be leaving your computer for a long period of time, should you use standby or turn the computer off entirely? Although shutting down your computer uses less energy than putting it in standby mode, most electronic equipment including computers, consume electricity even when turned off. This is referred to alternatively as vampire power, phantom load, and leaking electricity. For the sake of consistency I will use the term vampire power throughout this website. It is estimated that the average electronic device consumes between 10-15 watts per hour while turned off [22]. While this may seem like a small amount it can add up to significant cost – both fiscally and environmentally – over the course of the device’s lifetime. As we have learned from non-linear mathematics small changes over time can have large consequences in dynamic systems; this is better known as the butterfly effect (click to link to Wikipedia for more information on the butterfly effect). When we multiply all of the devices that we as individuals own by the national population, the amount of GHG emitted and energy wasted each year due to vampire power becomes staggering.
An easy solution to this problem is to plug your computer equipment into a surge protector (which you have probably done, already) and shut the surge protector off after shutting down your computer. This will effectively drive a stake through the heart of your vampire power problem, reduce your personal GHG emissions and save you money on your electricity bill.
LIBR 500: Foundations of Information Technology, School of Library, Archival and Information Science, University of British Columbia
Neil MacDonald
November 17th, 2008