Sustainable Computing
Conserving Energy with Group Policy
Mark Aggar and Pat Stemen
and Michael Walsh
Power management on a single computer can save energy and money. When you enforce your power management strategy on systems throughout your entire organization, obviously the savings can be far more substantial.
Windows Vista® is configured by default to use its energy efficiency features. But it also gives IT professionals numerous options for tailoring power management settings to optimize energy efficiency throughout their companies. In fact, Windows Vista ships with more than 35 power management settings that you can use to create the power management strategy that best suits your organization's needs. And you can quickly put your strategy into practice with minimal effort using Group Policy. Here is guidance for some of the more common settings you can enforce with Group Policy. For a quick overview of all 35 settings that are available, see the sidebar "35 Settings for Managing Power."
Using Group Policy to Enforce Power Settings
As you know, administrators can enforce specific settings using Group Policy in Windows Vista. This, of course, can be used to set power-related features, such as display and system sleep settings.
The advantage of using Group Policy to configure power settings is that Windows Vista will use the values specified by Group Policy, preventing end users from changing the settings. If the user attempts to make a change, the Windows Vista Power Options Control Panel informs him that the selected power policies may not be changed because they are enforced by the administrator.
While Windows Vista does let the user switch between power plans (such as battery saver and balanced), the administrator can use Group Policy to enforce specific settings within those power plans. Even if the user changes power plans, the Group Policy power setting is enforced.
To enforce a power setting using Group Policy, use the Group Policy Management Console to edit a new or existing Group Policy Object (GPO). The power management policies are located in Power Management, under Computer Configuration | Administrative Templates | System | Power Management. Note that there are no power management policies under User Configuration in Windows Vista.
Each power setting lets you specify separate values for when the computer is plugged-in (AC) or running on battery power (DC).
Sleep Idle Timeout
The sleep idle timeout automatically places a system into a low-power sleep state after a set period of user and system inactivity. Sleep idle timeout is enabled by default in all power plans except the High Performance power plan. However, the timeout value varies by power plan personality in the default Windows Vista power plans.
The sleep state saves all of the user's open programs and documents and allows the user to quickly resume working with the system. The power consumption of sleep on current laptops is less than 1 watt, which is comparable to the power consumption of the hibernate and shut down states on a desktop PC.
The sleep idle timeout policy is located in Sleep Settings under Power Management. To set the sleep idle timeout setting for AC power, choose Properties for the Specify the System Sleep Timeout (Plugged In) policy. Windows Vista displays the dialog box shown in Figure 1. Click Enabled and enter the value in the System Sleep Timeout (seconds) box. Note that the sleep idle timeout value is represented in seconds with a minimum of zero, which indicates never idle to sleep. In this example, the timeout value set is 1,200 seconds (or 20 minutes). Now just click OK to save the policy setting value.
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Figure 1 Specify the System Sleep Timeout (Plugged In) properties
Display Idle Timeout
The display idle timeout automatically powers off display devices that are attached to a system after a set period of user inactivity. In the default Windows Vista power plans, this timeout varies according to the power plan.
The display idle timeout can have a substantial impact on the power consumption of the display device. Energy savings that result from enforcing a display idle timeout vary by usage patterns and the specific display device, but can be significant—especially on systems equipped with CRT monitors.
The display idle timeout policy is located in Video and Display Settings under Power Management. There are separate policy objects for both AC (utility) and DC (battery) power. To set the display idle timeout power setting for AC power, choose Properties for the Turn Off the Display (Plugged In) policy. Windows Vista then displays the dialog box shown in Figure 2. Click Enabled and enter a timeout value in the Turn Off the Display (seconds) box. Again, the display idle timeout value is represented in seconds with a minimum of zero indicating to never turn off the display. Now click OK and the policy setting value is saved.
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Figure 2 Turn Off the Display (Plugged In) properties
Confirming a Display Idle Timeout Is Enforced by Group Policy
To confirm that the display idle timeout power setting has been enforced on a system by using Group Policy, you can view the setting in the Power Options Control Panel, as shown in Figure 3. The figure shows Power Options with a display idle timeout of five minutes enforced with Group Policy. The message in the yellow banner indicates that some power settings are enforced by the system administrator. Note also that the Turn Off the Display selector used to change the display idle timeout setting is disabled.
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Figure 3 Power options showing a display idle timeout enforced with Group Policy
Configuring the Screen Saver Policy
Finally, the screen saver can be configured with Group Policy using the policies available under User Configuration | Administrative Templates | Control Panel | Display. To maximize energy efficiency (as well as security), you should configure the screen saver to use the blank screen saver and require a password on resume. For user convenience, consider setting the screen saver to come on shortly after the display is blanked. This gives the user an opportunity to bring back the desktop without entering a password if they are sitting at their PC when the screen goes blank. Figure 4 lists the relevant screensaver policy settings.
Figure 4 Screen saver policy settings
| Policy |
Description |
Recommended Value |
| Screen Saver |
Enables the screen saver. |
Enabled |
| Screen Saver Executable Name |
Configures which screen saver to use. |
Scrnsave.scr (for the blank screen saver) |
| Screen Saver Timeout |
Indicates the number of seconds of user inactivity before enabling the screen saver. |
A value slightly longer than the display idle timeout setting |
| Password Protect the
Screen saver |
Specifies whether a password needs to be entered after the screen saver comes on. |
Enabled |
Mark Aggar is an Environmental Technologist at Microsoft.
Pat Stemen
is a Senior Program Manager at Microsoft.
Michael Walsh
is the Senior Environmental Product Manager at Microsoft.
© 2008 Microsoft Corporation and CMP Media, LLC. All rights reserved; reproduction in part or in whole without permission is prohibited.