Tech Features

The computer helper: Going green

By Jay Dougherty Jan 6, 2007, 11:06 GMT

Washington - Greenhouse gases. Global warming. High energy bills. Take your pick: There are plenty of reasons to think 'green' when it comes to using your computer.

But which energy-saving measures make sense while still allowing you to get your work done? Read on for some answers.

Q: I prefer to leave my computer on all the time because it takes so long to boot up if I turn it off. I'm concerned about my electric bill, though. How much electricity does the computer actually use?

A: An average desktop computer uses between 60 and 300 watts of electricity. Some computers use even more. If you look on the back of your computer, on the power supply, you'll typically find a label that provides a wattage number, such as '300 watts.'

That number can be misleading, however. While the power supply might be rated for 300 watts, that doesn't mean your PC is drawing that much power at all times.

The power supply's wattage rating is a maximum value. The actual power usage of your computer may be much lower, depending upon the components you have in your computer. The number of hard drives, the speed and energy features of your microprocessor, the memory, and even the type of software you use will affect how much power is actually needed. When your computer is working hard - processing files, copying data, crunching massive spreadsheets - energy use will rise.

But your computer itself isn't the only thing drawing power. Your monitor can be a consideration as well. A typical cathode ray tube (CRT) monitor can draw from 80 to 120 watts of electricity, while the newer LCD flat panel monitors use around 35 watts. The exact wattage rating should be listed with the technical details of your screen. Other external devices, including modems and hard drives, add to the electricity drain, of course.

Using your computer's standby mode is a good compromise if you don't want to shut the PC off entirely. In standby mode, a typical computer's power usage dwindles to between 1 and 6 watts, and you can turn your monitor completely off to eliminate its power usage. Waking a PC up from standby mode should be considerably faster than turning it on from an off state.

Q: Our family has decided to get rid of all of our desktop computers and move to notebooks. We're thinking that our energy consumption will be much lower this way. Is this correct?

A: Yes. Notebook computers use about 15 to 45 watts of electricity. Compare that to as much as 300 or 400 for desktops, and you're talking considerable savings, especially if you have several desktops running in the same household. Like desktops, notebooks can also, of course, be set up to power down after a period of inactivity, making their energy consumption even lower.

The downside of notebooks is that they're not as expandable as desktops. To add more storage, for example, will require that you hook up an external drive or two, and these will bring your energy consumption back up a bit.

Q: Is there a way that I can calculate exactly how much money it costs me to run my computer each year?

A: Yes. There are some handy electricity usage calculators online that will give you a good estimate of how hard your computer is hitting you in the wallet when it comes to your electricity bill.

Michael Bluejay's Saving Electricity page (http://michaelbluejay.com/electricity) has a 'Calculate your electricity cost' section toward the bottom that allows you to plug in the variables that make up actual electricity cost for different household appliances, including the computer.

To use the calculator accurately, you will need to know how much your electricity company charges per kilowatt hour of usage. Even if you don't know the precise figure, however, it's still informative to use the calculator. In the United States, for example, the calculator shows that having an average computer on all day, every day, for a year costs over 200 dollars, compared to just 40 dollars for a notebook.

The U.S.-based Cadmus Group provides another take on the same theme. Its Calculate Potential Savings Web page (http://pmdb.cadmusdev.com/powermanagement/quickCalc.html) shows you approximately how much money you'll save by using the energy saving features of your computer and monitor. Typical savings are as much as 80 per cent.

--- Have a computer question? Send it to the Computer Helper at jayd@csi.com.