A few years ago a friend of mine purchased a brand new server for use in their home. While most of us might never purchase server-class equipment for home use, my friend made the decision based on a really good sale price.
He was excited the day that server arrived. We all would be. Even the most ancient of we IT administrators still get a kick out of unboxing a new server, putting it together, and hearing it power on for the first time. Being a host from where my friend could run demos and virtual machines, he planned on keeping that server powered on all the time.
Or, at least he did until he got his first power bill. Inside that first power bill he discovered how costly running even a single server can be. So costly, in fact, that he no longer keeps his server running all the time. He simply can't afford it.
While most of us don't run server-class equipment in our homes, we all have home computers. We're also responsible for the computers at work, but we haven't traditionally been responsible for the power costs of those computers.
That's a tradition that needs to end.
Have you ever sat down to calculate how much it costs just to power all those computers at your work? The numbers might surprise you. While most desktop computers advertise Low Power Consumption!, they still grow ridiculously expensive when dozens or hundreds of them add up in a single location.
Take a look at the number of watts your computer needs. That information might be printed on its power supply or within its manufacturer's specifications.
For example, an HP Compaq 8000 Elite desktop computer is configured with a 240 watt power supply. While that computer won't be using its entire power capacity all the time, we can use this number as a starting point.
Now for a little math: 240 watts x 24 hours in a day x 30 days in a month equals 172,800 watt-hours, or more usefully, 172 kilowatt-hours. At a conservative 10 cents per kilowatt-hour, powering that computer for a month costs you $17.20, or around $206 per year.
That's not a small number. It's also one that linearly scales with your number of computers. 100 computers like this costs $20,640 per year to power, and that doesn't even include the cost for their monitors, connected devices, and printers. Expensive!
If math isn't your thing, you might take a look at the handy power calculator I found at http://www.scriptlogic.com/power_management.asp. A downloadable Excel spreadsheet, this power calculator can help you determine how much power your computers use along with their CRT or LCD monitor. Plugging in information on your business' computers will tell you how much they're costing each year and over multiple years.
Cut Power Costs by Cutting the Power
All of this power consumption math gets even more disconcerting when you realize a business computer's useful period is only about nine hours a day. While every office is different, many find people arriving at 8:00 AM and leaving at 5:00 PM with an hour for lunch. That means that almost two-thirds of every day goes by with powered-on computers performing zero useful work. Weekends add even more wasted kilowatt-hours.
Wouldn't it be great if you could just cut the power to those computers when they weren't needed? Luckily, there is an answer.
Figure 1: Advanced Settings under Power Options
With Windows' native tools and some effort it is possible, if not terribly easy. Let's take a look at how you might create a power down plan for your Windows machines using the native tools alone. The first place to look is in a computer's Control Panel | Power Options | Change Plan Settings | Change Advanced Power Settings. The resulting screen looks like Figure 1.
There, you can see the option marked Sleep | Sleep after | Setting (minutes). Configuring this setting to a number of minutes will instruct the computer to power down after a period of inactivity. The value shown in the figure will set the computer to sleep after 30 minutes where no keys are pressed and where the mouse hasn't moved.
Also available in this location are settings for hibernating the computer along with a configuration called hybrid sleep. The differences between sleep, hibernate, and hybrid can be important. Sleep is a power-saving state that is designed for quickly returning a computer back to operations after you move the mouse or hit a key. With sleep, important system components like memory contents and open documents remain resident. This enables the computer to be returned back to full operation only a few seconds after a mouse move or key press.
Hibernate is somewhat different. With it, memory contents and open documents do not remain powered on once hibernate is invoked. Instead, they are transferred to disk. After the transfer, the computer is then powered down completely. As a result, hibernation uses less power than sleep, but requires quite a bit more time to return the computer back to operations.
Hybrid sleep is, as you can expect, a combination of the other two states. With it, memory, open documents, and programs are transferred to the hard disk, but they remain powered on. This transfer to hard disk is done so that the computer can return to its earlier state should power be lost completely.
Any of these three states can be configured within the Power Options | Advanced Settings control panel. There, you can also set an amount of idle time for turning off the computer's hard disk and monitor. Most people tend to configure these settings so that the monitor is powered down first, then the hard disk, and finally the computer is put into sleep or hibernate mode. This tiered setting tends to present the lowest impact to users, while still shutting down portions of the computer when they're unused.
Group Policy for Power Settings
Configuring these settings on a single computer is trivial, but doing so across every computer gets much harder. One solution for accomplishing this is through Group Policy. Create a new policy and navigate to Computer Configuration | Administrative Templates | System | Power Management | Sleep Settings and you'll see a screen that looks similar to Figure 2.
Figure 2: Power Options in Group Policy
In that screen you'll find up to 18 different Group Policy settings for power management. The highlighted one in Figure 2 specifies the system sleep timeout for when the targeted computer is plugged in. Double-clicking this setting brings forward a configuration page where you can enable the policy and set the System Sleep Timeout in seconds.
Digging through the options, you'll find up to 46 different Group Policy settings that relate to power. Just like with the Power Options | Advanced Settings page, these configurations can adjust when monitors, hard drives, and other components will eventually power down.
One setting related to power is not found under Computer Configuration, but instead under User Configuration. In the same path as for the Computer Configuration settings, you'll find the Group Policy setting titled Prompt for password on resume from hibernate / suspend. This is an important security setting to ensure that an inappropriate person can't wake a computer and see what's happening on that computer. You'll probably want to configure this setting along with the others and target it to the correct set of users (while you're targeting the Computer Configuration setting to the correct set of computers).
Group Policies aren't the only place where you can configure settings globally. You can also use a Group Policy Preference. You can find the GPP under Computer Configuration | Preferences | Control Panel Settings | Power Options. There you'll create a new Power Plan for Windows Vista and Windows 7 or Power Options for Windows XP.
Figure 3: A GPP Power Plan
As you can see in Figure 3, creating a Power Plan using a GPP uses a wizard page that looks very much like the page inside Windows 7. It's a little easier to use than a Group Policy. In Figure 3 I've set the same sleep setting to 30 minutes just like I did on the local computer in Figure 1.
Don't Make Mistakes Here
As you can imagine, a mistake here can have painful consequences on your users, powering down their computers in the middle of the day. They'll most assuredly complain.
Also, a misplaced setting could accidentally target power down settings to the wrong computers ' like conference room computers in the middle of a big presentation or even your servers. That's why the steps necessary to correctly target Group Policy and Group Policy Preferences can sometimes be a big challenge. If the thought of a mistargeted Power Plan, or one that gets accidentally changed at some point in the future, gives you the heebie-jeebies, consider looking at alternate solutions with better validation logic and improved administrative control.
There's another very important limitation here that I'll bet you've already thought of. Namely, adjusting those power settings based on time of day and day of week. You might consider looking at those same alternate solutions, as they can help out in when Group Policy and GPPs fall short.
Here's the problem: You know now that you can set a power policy to sleep a computer after a certain number of minutes. But setting that sleep value too low will impact your users. While you could sleep your computers after 30 minutes of non-activity, users will quickly start complaining as their computers are constantly powering down throughout the day.
What you really want is a way to set power settings to a much larger (and less impactful) value during work hours, perhaps 120 minutes during those hours. Then, at the end of the day, you want to reset those values to a much smaller amount such as 15 or 30 minutes. Doing this gets those computers powered down faster when no one's using them. The same holds true with weekends, where you don't want big timeout values to impact how much power you're saving. Third-party tools can help you do that, because it's difficult to get that level of granularity out of Group Policy or Group Policy Preferences alone.
Save Power. Save the Earth.
The default settings with Windows computers can indeed be a big cost to your company. But, they're also settings that can be easily remedied with the right tools. By configuring your computers to sleep or hibernate after a certain number of minutes, you can very quickly save your company very real dollars when the monthly power bill comes in the door. And, in the end, who doesn't want to be just a little more green with the power we're consuming, particularly when that power is being used for little more than idly flipping 1s and 0s while screensavers move around the screen.