Computer Power Conservation
Desktops and Laptops consume significant amounts of energy and many of these devices are left on 24 hours a day, 7 days a week. Over the course of a year, that usage can add up. The table below give two examples of costs to leave a laptop or a desktop powered on and idle for an entire year. When these devices are under load such as watching a DVD, browsing the internet, playing games, the energy usage roughly doubles.
| Device | Idle Usage | Electrical Usage per year | Financial Cost per year1 | Environmental Cost per year(Carbon Dioxide) 2 |
|---|---|---|---|---|
| Dell 3.4Ghz Desktop w/ 17" LCD | 85 Watts | 744 kWhrs | $82 | 580 lbs |
| Dell D610 2.0Ghz Laptop | 25 Watts | 219 kWhrs | $24 | 170 lbs |
| 1. Cost based on $0.11/kWhr for 2005/2006 2. CO2 emissions based on 0.78/lbs CO2/kWhr from NYSEG in 2005. |
||||
There are two things you can do to reduce the energy usage of these devices. The most obvious one is turn them off when they are not in use. We find that many users leave these devices idle most of the day out of convenience. If the entire Cornell staff, faculty and student population (~32000 people) had desktops powered on 24/7, it would cost the university a little over $2.6 million in energy costs and generate over 18.5 million pounds of Carbon Dioxide every year. By powering those machines off when they are idle, a significant savings could be realized.
The other alternative is to turn on power saving features. Although the energy savings are significantly less that turning a machine off when it is not in use, adjusting your settings is better than doing nothing. Below you will find instructions on adjusting power save features on Windows and Mac platforms.
Windows
- Open "Display" under your Windows Control Panel.
- Select the "Screen Saver" tab at the top of the Display Properties window.
- Select the "Power..." button at the bottom of the Screen Saver tab.
-
Suggested Settings:
Turn off monitor: After 15 mins
Turn off hard disks: After 15 mins
System standyby: Never
System Standby has been known to cause occasional problems and data loss when a device comes out of standby. We suggest that you use this feature with caution.
Laptop users may have two sets of power saving options. One for when the device is plugged in and one when the device is running on batteries. You should adjust the "on batteries" setting with timeouts equal to or less than when plugged in.
- Click on the Apple in the top left corner and select "System Preferences"
- Select the "Energy Saver" icon in the Hardware section
-
Suggested Settings:
Put the computer to sleep when it is inactive for: Never
Put the display to sleep when the computer is inactive for: After 15 mins
Check put the hard disk(s) to sleep when possible
System Standby has been known to cause occasional problems and data loss when a device comes out of standby. We suggest that you use this feature with caution.
Sources:
http://www.sustainablecampus.cornell.edu
http://www.cornell.edu/visiting/ithaca
http://computing.fs.cornell.edu/fsit/Forms/ComputingEnergyConservation.pdf