Save Energy and Cut Costs: Use Sleep Mode on Your Computer

Together we can save money and reduce our energy footprint!

  • FACT 1: Flat screen monitors use less power than CRTs.
  • FACT 2: Laptops use less power than desktops.
  • FACT 3: There is no longer any technical reason to be concerned about turning your computer off.
  • FACT 4: Computers that are in sleep mode use a tiny fraction of the power used by computers which are on but sitting idle.

Scenario 1:

A 17″ iMac uses 78 watts/hour when sitting idle and only 2 watts/hour when in “sleep” mode. Leaving it on all day, every day, costs $67/year more than leaving it in sleep mode all day, every day (at our current rate of 10 cents a kilowatt hour). Having the computer be off or in sleep mode half the time would save half as much.

Scenario 2:

A Dell Optiplex GX 280 uses 96 watts/hour when on but sitting idle and only 1 watt/hour when
in “sleep” mode. Leaving it on all day, every day, costs $83/year more than leaving it in sleep mode all day, every day.

Together, we can have a big impact on College energy use and energy costs. Depending on your settings and the model of the computer, the college could realize $50 – $200 in savings per computer and monitor, per year, if you put your computer(s) and monitor(s) in sleep mode when they are idle.

The college owns almost 1,500 computers. The public area computers are already set to minimize energy consumption. That leaves about 1,200 computers that are managed by individuals. The total savings is hard to predict since everyone’s usage patterns are different, but even a $50 savings for each of 1200 computers would be $60,000 per year.

The government’s Energy Star page has details on how to configure your computer’s power settings:

Please contact the helpdesk ( for more information.


Gayle Barton, Chief Information Technology Officer
JJ England, ’09, for EarthLust

Here are a few related web pages that may be of interest:

An FAQ on computer energy usage from Energy Star:

From “How Stuff Works”

Apple’s Energy Usage Calculator:

MIT’s Guidelines for Personal Computer Energy Savings:

including myth-busting related to never turning your computer off.

The University of Pennsylvania site on energy-savings by model:

Notes to go with the Facts:

NOTE 1: If you have a CRT instead of a flat-screen monitor, let us know and we’ll see about replacing it.

NOTE 2: Most student computers are laptops, so there is less energy savings to be gained by students than by faculty and staff using the larger computers. It’s up to us!

NOTE 3: When you are done for the day, turn off your computer.

NOTE 4: Sleep mode is almost as good as turning off your computer, but there are other advantages (including security advantages) to turning it off on a regular basis.