UF Department of Housing & Residence Education

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Computers Off! Campaign

Conservation of resources within residence halls helps keep future rental rate increases lower. Each resident could save over $0.50 per day in electricity following these guidelines. More importantly, KWH of energy are not wasted.

Computers Need Sleep, Too!

Have you ever heard the idea that turning off your computer can be "bad" for your computer? Do you keep your computer plugged in and turned on all day and night, even if you are not using it? Computers and other electronic devices, including chargers, can draw electricity when you are not using them. The University of Florida Department of Housing and Residence Education invites you to follow the advice on this page to reduce energy usage, reduce UF's carbon footprint, promote sustainability, and help us reduce costs so that we can continue to offer low rental rates for our residence halls.

I've heard that turning off my computer is bad for it. Shouldn't I just keep it turned on?

It used to be true that computers could not handle being turned on and off repeatedly. One of the ongoing debates in computing was whether it strained computers more to leave them on or to shut them down daily. Computers today are much more robust and can handle thousands of startup and shutdown cycles.

One way to help look at this problem is to consider your television. Do you leave your TV on all the time because turning it off would stress the TV? Of course not. The fact of the matter is that if computers were this sensitive to being turned on and off repeatedly, computers would be failing all the time.

Still not convinced? Here is a webpage from the Lawrence Berkeley National Laboratory with more information: http://eetd.lbl.gov/EA/Reports/39466/39466-4#turn

How much energy can be saved by turning off my computer when I'm not using it?

Let's assume that you use your computer for four hours per day and that for the other 20 hours per day your computer is idle. The typical computer consumes approximately 300 watts. This is 300 watts per day that you could save.

What if I really don't want to turn off my computer - is there a way I can save energy?

Yes. You can reduce power consumption by turning off your monitor.

In addition, you can use the power options that come with your computer. These reduced power modes still consume a significant amount of power, but allow you to quickly access your computer.

In Windows XP, there are multiple reduced power modes. Standby puts your computer in a reduced power state and allows you to quickly resume your use of the computer within a few seconds. Hibernate turns off your computer completely, but saves your session to the hard disk so you can resume what you were doing. You can access hibernate by holding down the shift key before you push the standby button while shutting down your computer. If you're willing to wait a little longer for your computer to restart, putting your computer in hibernate mode saves more energy.

In Windows Vista, there is a sleep mode that puts your computer in a reduced power state that is better than Window XP's standby mode.

The following is a chart summarizing power management modes on computers.

How do I tell my computer to go into a reduced power mode when I leave?

If your computer has Windows XP:

Go to the Control Panel and then click on the Power Management options.

This screenshot shows the power management options window. The four options below set what happens if your computer is “idle” or left alone for a certain number of minutes. Let’s go through each one.

The turn off monitor setting will turn off your monitor(s). You can set this to a very low number of minutes (5 to 10 minutes). Turning off monitors won’t affect anything that your computer may be doing and it’s a great way to save power.

The turn off hard disks option will turn off your hard disks after a certain number of minutes, though programs on your computer can turn the hard disk back on if they need it. Many experts recommend that this option be set to “never” because this feature can increase the wear and tear on your hard disk!

The system standby option will put your computer into the standby mode after a certain number of minutes. It takes about 5 seconds for a computer to go from standby mode back to being on. This can be set to a low setting such as 10 to 30 minutes.

The system hibernates option will put your computer into the hibernation mode after a certain number of minutes. If you don’t see this option, it’s because you have to enable hibernation by clicking on the hibernation tab.

If your computer has Windows Vista:

If your computer has Windows Vista, you can go to the Control Panel and then click on Power Options. In the dialog box that appears, check the option for "Power saver".

To customize the settings for the plan you've selected, click on "change plan settings." There, you can change when to turn off the display. 5-10 minutes is a good setting to save energy. You can also adjust the setting for when to put the computer to sleep, and 20 minutes is recommended. There is also an option to change "advanced power settings" if you need to fine-tune things further.

If your computer has Windows 7:

If your computer has Windows 7, you can go to the Control Panel and then click on Power Options (you will have to change the .view by. setting in Control Panel to small or large icons in order to see the Power Options icon. In the dialog box that appears, check the option for "Power saver".

To customize the settings for the plan you've selected, click on "change plan settings." There, you can change when to turn off the display. 5-10 minutes is a good setting to save energy. You can also adjust the setting for when to put the computer to sleep, and 20 minutes is recommended. There is also an option to change "advanced power settings" if you need to fine-tune things further.

If your computer has Mac OS X:

It is generally preferable to put Mac computers to sleep rather than shut them down.  The sleep mode uses very little power, but allows near instantaneous wake up.

All the power management settings are accessed in System Preferences which can be opened under the Apple Menu (top left of the computer screen). Click on the Energy Saver option to choose when you want the screen and/or display to be put into sleep mode automatically.

The put the computer to sleep when it is inactive option will put your Mac into sleep mode after a specified number of minutes. This can be set to a low setting such as 10 to 30 minutes.

The put the display(s) to sleep when the computer is inactive option will turn off your monitor(s). You can set this to a very low number of minutes (5 to 10 minutes). Turning off monitors won’t affect anything that your computer may be doing and it’s a great way to save power.

The put the hard disk(s) to sleep when possible option will turn off your hard disks after a certain number of minutes, though programs on your computer can turn the hard disk back on if they need it. Many experts recommend that this option be set to “never” because this feature can increase the wear and tear on your hard disk!

The Mac allows for a couple of additional settings that you can customize.

The allow power button to sleep the computer option lets you easily put the computer to sleep manually as you leave your desk.

The automatically reduce the brightness of the display before display sleep option doesn't save much power, but it does give you a brief heads up that the computer is just about to go to sleep.

If you're using a laptop (e.g., Macbook) the Energy Saver screen offers different configuration settings for when the computer is plugged in with a power adaptor versus operating on a battery.  Under each of these two options, you can customize your own preferences or select from Apple's configurations for "Better Performance" or "Better Energy Savings/Battery Life."

Is there any reason I should want to leave my computer on?

If your computer acts as a server (i.e., it provides files or services for other computers), then it would need to be left on. Also, some people have "grid" programs that provide computer time for research, and this may also be a good reason to leave your computer on. However, servers and grid programs are not allowed under the DHNet Acceptable Use Agreement.

We hope that you've found this information to be useful! You can get more sustainability tips from the UF Office of Sustainability.