The best way to save power used by computer monitors is setting them to go into sleep mode or manually turning them off when not in use, which saves more energy than using screen savers. Turn off a monitor if you’re going to be away for 20 minutes or more, and shut down the computer, too, if you’ll be away for two hours or more.

Skill Level: Basic
It’s easy to learn and use power-management settings. And when it’s time to replace a computer, consider a laptop, which is generally more energy efficient than a desktop model. Save energy with a laptop by plugging the AC adapter, which draws power even when not connected to a computer, into a power strip that can be turned off.
Cost Range: Free
It doesn’t cost anything to learn how to maximize energy efficiency by using power-management settings.
Savings: Up to 70% in electricity
Using power-management settings on computers and monitors, along with choosing energy-efficient equipment, can result in savings. ENERGY STAR® computers power down to a sleep mode that consume 15 Watts or less power, which is around 70% less electricity than a computer without power management features.