Chapter 9. Conserving Energy While Using Your Macintosh

If you're concerned about global warming, you can do something about it with your Macintosh. Every computer needs electricity to work, but too often people leave computers running when they're not using them, which gobbles up power unnecessarily. While you could turn your computer off and then on again when you need it, doing so several times a day can actually harm your computer since every time you turn it back on again, it receives a jolt of electricity to start it up.

As a safer alternative to turning your Macintosh on and off repeatedly, you can let it go to sleep when it's not in use. This reduces the amount of power consumed by your Macintosh, yet keeps it turned on so it's ready for use at the touch of the keyboard.

When your Macintosh is turned on, it needs power to spin its hard disk, display images on the screen, and do actual work with its processor. Such normal use typically consumes 60 to 120 watts, which is about the same amount of power used by an ordinary light bulb. However, if you let your Macintosh go to sleep, you can reduce the amount of power it uses to 5 watts or less.

Project goal: Learn how to conserve power by letting your Macintosh go to sleep.

To make a Macintosh sleep and wake up, you need only the following: