Recommended Approach to Desktop Computer Power Management

Energy costs continue to rise. It's important for the campus community to understand how it can help control energy costs. The following are recommendations for desktop computer users to reduce needless power consumption; a chart indicating how much energy is directly consumed in using various Dell and Apple brand desktop and laptop computers used on campus; and a list of peripherals and their direct energy consumption recommendations.

Recommendations

  1. Purchase equipment that has the ENERGY STAR rating.
  2. Promote the use of shared network printers. Check to make sure that Energy Saver functions (if available) are enabled on printers.
  3. Enable Energy Saver functions to reduce power consumption during the workday. We recommend putting displays into Energy Saver Mode when idle for 20 minutes, with hard drives set at 30 minutes. For assistance in adjusting your Energy Saver function, send an email to greenit@uh.edu.  
  4. Unless otherwise directed by your department or IT group, users should power off their machines at the end of the workday. Check with your department for scheduled backups. 
  5. Computers and peripherals should be plugged into a power strip. At the end of the workday, shut down your computer and peripherals and then turn off the power strip. Otherwise, devices such as speakers, scanners, printers, etc. will continue to draw power even when not in use.

Results

The following chart shows potential cost savings for varying computer configurations, based on an energy cost of 8.5 cents per kilowatt hour. In both cases, no energy saving settings are configured. So, with more of the recommendations in place, further cost reductions can be realized. The dollar amounts reflect a single, 12-month year.

Computer ConfigurationPowered@168 hrs/wkPowered@60 hrs/wk
Desktop w/ 24" LED backlit LCD [290 Watts]
Power Range: 180-540 Watts
$2748.72 $981.76
Laptop (15" or 17" display) [85 Watts]
Power Range: 45-90 Watts
$805.48 $287.56

Printers

Ink Jet Printers:
25 W/hr. Power consumption measurement is the external power supply, not the printer itself.
Laser Jet Printers:
825 - 1100 W/hr.

Wear and Tear

Hard drives and other components are now better built, so wear and tear through daily powering on and off of desktop computers is no longer a consideration.

Shutting the machine off extends the overall life of the machine as cooling fans run less, and thus less dust and dirt are pulled into the machine. Less dust and dirt lead to both a lower operating temperature (so H/VAC works less) and less wear and tear on the system due to heat.