Energy Conservation Tips – Computer

If you’re wondering when you should turn off your personal computer for energy savings, here are some general guidelines to help you make that decision. Personal computers use about the same amount of energy to startup as they use when they are on for about two seconds. For energy savings, consider turning off

  • The monitor if you aren’t going to use your PC for more than 20 minutes
  • Both the CPU and monitor if you’re not going to use your PC for more than 2 hours.

Make sure your computer is on a power strip/surge protector. When the PC is not in use for extended periods, turn off the PC with the switch on the power strip. Even when you turn some PCs off with the switch on the PC  itself, it may consume a small amount of power. 
If you don’t use a power strip, unplug the CPU and monitor.

Most PCs reach the end of their “useful” life due to advances in technology long before the effects of being switched on and off ten or more times have a negative impact on their service life.  The less time a PC is on, the longer it will last.  PCs also produce heat, so turning them off reduces building cooling loads.

Here are some tips on energy saving for computer equipment:


 ENERGY STAR® labeled computers

Most computers come with power saving features (look for the ENERGY STAR® label). Enable the computer’s APM (Advanced Power Management) and ACPI (Advanced Configuration and Power Interface) can reduce power consumption up to 40 watts when in idle state. This also results in less heat dissipation and reduces the cooling load on the air-conditioner and thereby saving more energy.


  • Set your printer to enter power-saving mode after being idled for 30 minutes.
  • Remember to power off your printer after office hours.  It’s a good idea to use a timer switch to turn on/off the printer automatically.


  • USE LCD panels
  • Select darker screen background.  LCD panels consume up to 90% less energy than CRT monitors, especially those labeled with ENERGY STAR.
  • Use dark screen saver.  Select darker background colors and you’ll save 20% more energy than a light and bright background.
  • Enable the Turn Off Monitor feature.  Select a dark screen saver that launches after 15 minutes of inactivity.

The suspend state of the Turn Off Monitor box in the Screen Saver tab should be set for 20 minutes, so that
the monitor will be automatically turned off after being idled for 20 minutes.