1. From the Apple menu choose System Preferences.
2. Choose Energy Saver.
3. The default settings are in the illustration below. You can adjust the time to turn the display off by clicking and dragging the slider button. If you are going to be doing a presentation, you might want to temporarily set the display to never turn off. You can readjust the time when your presentation is over.
If you have environmental questions regarding the amount of time you should choose, please email email@example.com.