Power Management

Last Updated: 04/08/2014

Saving energy on Computer Equipment

Saving energy with desktops, laptops and monitors is easy and only takes a few clicks. But these simple steps make a huge difference in the energy your computer equipment uses. Below are directions for setting computer management options in several popular platforms.

What is power management?

Power Management features — standard in Windows and Macintosh operating systems — place monitors and computers (CPU, hard drive, etc.) into a low-power "sleep mode" after a period of inactivity. Simply touching the mouse or keyboard "wakes" the computer and monitor in seconds. Activating sleep features saves energy, money, and helps protect the environment.

To maximize power savings, the U.S. Environmental Protection Agency (EPA) recommends setting computers to enter system standby or hibernate after 30 to 60 minutes of inactivity. To save even more, set monitors to enter sleep mode after 5 to 20 minutes of inactivity. The lower the setting, the more energy you save.

The benefits of power management

In Colorado, the energy used to power the average computer monitor for one year produces as much carbon dioxide (CO2) as a car idling for 12 days. Setting your monitor to go to sleep when not used for a period can cut energy use by up to 90%. Setting your computer to go sleep as well saves even more. And turning off all your computer equipment when you’re not using it saves the most.

Frequently-asked questions about saving energy on your computer

I have my screen saver activated. Do I need to activate power management features?

Screen savers generally do not save energy. In fact, certain graphics-intensive screen savers can cause the computer to burn twice as much energy, and may actually prevent a computer from entering sleep mode.

Do computers and monitors use more energy with power management features activated due to power surges when cycling on and off?

A popular myth holds that leaving lights, computers, and other appliances on uses less energy than turning them off and also makes them last longer. In reality, the small surge of power created when some devices are turned on is vastly smaller than the energy used by running the device when it is not needed. Source: "Eleven Energy Myths: From Efficient Halogen Lights to Cleaning Refrigerator Coils", Lawrence Berkeley National Labs.

Can sleep features wear out hardware by forcing the computer to turn on and off several times a day?

"Modern computers are designed to handle 40,000 on-off cycles before failure, and you're not likely to approach that number during the average computer's five- to seven-year life span. In fact, IBM and Hewlett Packard encourage their own employees to turn off idle computers, and some studies indicate it would require on-off cycling every five minutes to harm a hard drive." Source: Rocky Mountain Institute Home Energy Brief #7 Computers and Peripherals.

For more Frequently-asked questions about power management visit the EPA’s Energy Star website.

Saving energy on the Mac OS 10.5 and above

To turn off screen savers, go to System Preferences in the Dock. In the System Preferences window, select Desktop/Screen Saver. Select the Screen Saver window pane and move the “Start Screen Saver” slider to “Never”.

Set your computer and monitor to go to sleep when they’re idle. Go to System Preferences in the Dock. In the System Preferences window, select Energy Saver.

  • If you’re using a desktop computer, open the Sleep pane of Energy Saver preferences, and drag the sliders to set a time for your computer to go to sleep.
  • To put your computer to sleep immediately, choose Apple menu > Sleep.
  • If you’re using a portable computer, choose a power source from the “Settings for” pop-up menu, and choose the option from the Optimization pop-up menu that describes how you want to balance energy savings and performance. If you want to specify the sleep time, choose Custom. In the Options pane, you can select the option to reduce the brightness of your display automatically before the display sleeps. You can also select to reduce the brightness of the display when you are using the battery. This dims the display slightly but you can continue to work.
  • To put a portable computer to sleep immediately, close the display.

To schedule a shut down time, click “Schedule” in Energy Saver preferences to schedule a time for your computer to shut down to make sure it’s turned off when you’re not working.

In Displays preferences, turn down the brightness of your display.

Turn off AirPort when it’s not in use. You can turn off AirPort using the AirPort status menu, Internet Connect, or Network preferences.

To see how energy efficient your Mac is, as well find other information about Apple and their environmental impact please visit the Apple Environment website.

Saving energy on Windows

The Windows operating system uses “power plans” to help you save energy. A power plan is a collection of hardware and system settings that manages how your computer uses power. Power plans can help you save energy, maximize system performance, or achieve a balance between the two. Windows provides the following default plans to help you manage your computer's power:

  • Balanced. Offers full performance when you need it and saves power during periods of inactivity.
  • Power saver. Saves power by reducing system performance. This plan can help mobile PC users get the most from a single battery charge.
  • High performance. Maximizes system performance and responsiveness. Mobile PC users might notice that their battery doesn't last as long when using this plan.

Your computer manufacturer might provide additional power plans.

Saving energy on Windows 7

Creating a power plan on Windows 7

  1. Open Power Options by clicking the Start button , clicking Control Panel, clicking System and Security and then clicking Power Options.
  2. In the task pane, click Create a power plan.
  3. On the Create a power plan page, select the plan that is closest to the type of plan that you want to create. For example, if you want the plan to conserve energy, select the Power saver plan.
  4. In the Plan name box, type a name for the plan, and then click Next.
  5. On the Change settings for the plan page, select the display and sleep settings that you want the computer to use when it's running on battery and when it's plugged in, and then click Create. If you are using a mobile PC, your plan appears under Plans shown on the battery meter. If you are using a desktop computer, your plan appears under Preferred plans. The default plan that you based your plan on now appears under Additional plans.
  6. Make sure that the power plan that you want the computer to use is selected.

Saving energy on Windows 8

Creating a power plan on Windows 8

  1. Open the Control Panel (icons view), and click/tap on the Power Options icon. 
  2. Click/tap on the Create a power plan link in the left pane.
  3. Select a power plan that is closest to what you want for your custom plan (choose between Balanced, Power Saver, and High Performance). 
  4. Type in a name for your custom power plan, and click/tap on Next
  5. See how many minutes to wait for the Turn off display and Put the computer to sleep settings, or select never if you do not want to use that setting. Note: If your PC runs on a battery, then you will need to set this for both On battery and Plugged in
  6. When finished, click/tap on the Create button.
  7. You will now see your custom plan listed under the Preferred plans
  8. Close the Power Options window.
  9. If created, you can now change the Advanced Power Plan Settings in Windows 8 for this custom power plan if you like. 

Troubleshooting

Access Problems

If you’re using a University computer and you are unable to change your energy settings it may be because the system administrator might have disabled or even removed certain settings by using Group Policy. If you think that Group Policy is preventing you from changing a setting that you need to access, contact your system administrator or department Computing Support Representative (CSR).

Another possibility is that you might not have the required user rights to change power settings because your system administrator has changed the permissions that are associated with these settings.