Top 5 Things You Can Do to Compute Greener

Computing greener is as easy as tweaking your settings.
Computing greener is as easy as tweaking your settings.

If you were to rank your home appliances by how many watts they use in a year, your computer probably wouldn't rank in the top 10. That honor is typically reserved for things like air conditioning and anything that produces heat. But computers still rank high up there. For a typical PC and monitor setup and a four-hour-a-day computer habit, you're looking at about 400 kilowatt hours per year [source: Energy Savers].

You can run a high-efficiency refrigerator for just a bit more than that [source: ToolBase].


If you spend more than four hours a day computing, of course, as many people do, the numbers get higher. Computer energy use and the accompanying greenhouse-gas emissions become more significant when you figure in the rising number of people who work from home -- 4.2 million in the United States in 2000 [source: Energy Savers]. In that case, you can count on using more like 800 kWh per year -- and now we're into electric range territory [source: Energy Savers].

But the thing is, there's a broad efficiency range for computers. A high-efficiency model can cut energy use by 70 percent [source: Energy Savers]. And green computing habits can cut that even more. With that type of potential reduction, it makes sense to hone your green-computing skills, especially because some of the steps you can take cost nothing at all and will help save not only the polar bears, but also your money.

In this article, we'll talk about five of the most effective ways to reduce your computing footprint -- all without interfering with your work or play. The first method on our list is as simple as a few clicks and can make a significant dent in energy use.

5. Check Your Settings

It doesn't get much simpler than this: Check your settings. Activating your computer's power-saving features can cut your computer's energy consumption by 50 percent or more.

Most computers come with power-saving modes (if yours doesn't, it's probably time for a new computer). But lots of those computers ship without the settings activated, so you have to take a minute to turn them on in order for them to work.


In a computer without power-saving features, there are only two power modes, on and off. In on mode, the computer is using its full number of watts. Energy-efficient settings set up additional modes, so instead of just on and off, you've got on, sleep, hibernate and off, plus a mode that just dims or shuts off the display (which typically consumes the most power). Each successive mode uses less energy, and you only have to hit a key to reactivate the computer out of sleep or hibernate mode, instead of having to boot up all over again.

All you need to decide is how long you want the computer to wait before activating a lower-power mode when there's been no activity. If you often spend long chunks of time staring at your computer screen and not touching anything, you may want to set sleep mode to activate after a good while, like 20 minutes. If long periods of inactivity are rare for you, you could save even more watts by setting sleep for something like four minutes.

Each computer works slightly differently, but you can usually access your power settings through the control panel. It takes about 30 seconds to make some high-efficiency changes.

Up next is perhaps the most underused, supremely logical power-saving method out there.

4. Turn It Off

Turning off your computer and switching off the power strip is a great way to save energy.
Turning off your computer and switching off the power strip is a great way to save energy.

How often do you leave your TV on overnight? Or your clothes dryer? It makes only slightly more sense to leave your computer on when you're not using it.

Once you set up your sleep mode, you've made the most significant dent. But off mode still uses less energy, and those small savings can add up.


As a general rule of thumb, shut off your monitor if you plan to be away from your computer for at least 20 minutes; and shut of the CPU if you know you'll be away for 2 hours [source: Energy Savers]. As an added bonus, shutting down will stop your computer from generating heat, saving both your cooling components and some kWh on your air conditioning bill.

Of course, there are a few circumstances in which shutting down is not a great option, like when you need to be able to access your machine remotely or you're in the middle of a big download. However, even these complications have some solutions that allow you to take full advantage of your computer's power-saving features. For example, the BitTorrent client uTorrent can turn your computer off when a download completes; and an application called Wake-On-LAN can let you power-on your computer remotely [source: Pash].

And while you're getting in the habit of shutting down, go ahead and plug all of your components into a power strip that you can unplug overnight to eliminate that pesky "phantom" power draw.

Up next, if you already practice green computing and you're still looking to save energy, it may be time to upgrade.

3. Upgrade the CPU

Upgrading your CPU will save you some watts.
Upgrading your CPU will save you some watts.
Photo courtesy of Vermont BGS

You can do a lot with settings and new habits, but at some point, you've got to start looking at the hardware. After all, computer manufacturers have made huge gains in energy efficiency in recent years.

The CPU, also known as the microprocessor, is one of the top energy users in a computer setup. It makes sense, since it's basically the hub of the system. If you're still running a Pentium 4, upgrading to a newer model can make a big difference. Here are few approximate CPU wattages, for comparison (comparing apples to apples within Intel, because different companies can use different criteria to report wattages; note that AMD processors have also increased in efficiency):


  • Intel Pentium 4: 100 watts
  • Intel Core 2 Duo E6600: 50 watts
  • Intel Core 2 Duo E8500: 35 watts
  • [source: Won]

Upgrading a processor will run you in the area of $200, so it's not a tiny investment. But cutting your CPU's energy consumption by two-thirds can make a significant difference in your system's overall power draw, and you'll make up some of that investment in energy savings, especially if you work from home and have your computer on all day.

Up next, an obvious but often overlooked system upgrade for improving energy efficiency…

2. Upgrade the Power Supply

The power supply is often a huge waster of energy.
The power supply is often a huge waster of energy.
Photo courtesy of U.S. CPSC

When it comes to wasting power, perhaps the most logical culprit is the power supply. An inefficient power supply can cause your computer to draw more power from the wall than its wattage rating states, because a good portion of that power is lost to heat.

Before 2005, PC power supplies might have been just 60 percent efficient [source: Won]. That means that for a computer that needs 100 watts to operate, the power supply needs to pull 167 watts of power, because 40 percent of that is going to be lost as heat.


Since 2005, though, efficiency is up above 80 percent [source: Won]. So that same computer will only have to draw 125 watts of dirty grid power from an outlet in order to provide the 100 watts of power the PC needs to run. That's a 25 percent decrease in energy use just from updating the power supply to a more efficient model.

Depending on how much power you're looking for, you can spend anywhere from $30 to $100 on a new unit. It's an easier upgrade than the CPU, financially speaking.

And at No. 1 on our list, the single greatest power draw in a computer system.

1. Upgrade the Monitor

The monitor is the single biggest drainer of power in you computer setup.
The monitor is the single biggest drainer of power in you computer setup.
Photo courtesy of

More than any other single computer component, the monitor is a power drain. In a typical system, the monitor accounts for at least half the entire energy draw [source: ACEEE]. So if you have the means to upgrade to a more efficient monitor, that's the way to go for real energy savings.

The difference between a high-efficiency and a low-efficiency model can be pretty drastic. Even the difference between two efficient, Energy Star-qualified monitors can be pretty mind-blowing. For example, the Philips 150S7, a 15-inch flat panel, uses 12.8 watts in Active mode. The ViewSonic VG510s, also a 15-inch flat, consumes almost twice that: 22 watts. And both are Energy Star monitors.


Both consume about 0.8 watts in sleep mode, though, which is low, even by Energy Star standards. Sleep energy use is often where you'll see the biggest difference between high- and low-efficiency monitors. And since (if you activate your power-saving modes) your computer will be spending lots of time asleep, upgrading to an Energy Star monitor with a super-low sleep wattage makes a lot of energy sense.

For more information on energy-efficient computing and related topics, look over the links on the next page.

Lots More Information

Related HowStuffWorks Articles

  • Hewitt, Ben. "Optimize Computer Energy Settings and Save 50%." The Daily Green. March 26, 2008.
  • Home Office and Home Electronics. Energy Savers.
  • Layton, Julia. "Top 5 Energy-efficient Computer Monitors."
  • Monitors/Displays. Energy Star.
  • Pash, Adam. "Easy Ways to Go green With Your Computer." LifeHacker. April 22, 2008.
  • When to Turn Off Personal Computers. Energy Savers.
  • Won, Brian. "Ars System Guide special: it's easy being green." Ars Technica. Feb. 24, 2008.