Lower Your Display Brightness

April 2011 — Tip of the Month

Last month, I highlighted the importance of using your computer's sleep mode to conserve energy. This month, I have another simple and practical way to save energy: dim the brightness of your computer screen.

You may be surprised how much energy your computer monitor uses. While flatscreen LCD screens use less energy than those clunky old CRTs, they can still consume a lot of electricity. Fortunately, you can substantially reduce the amount of energy your monitor uses by dimming your display.

My current workstation is a Mac Pro with two 20" LCD displays. When both displays are set to the highest brightness setting, my computer and the two screens use a total of 305 watts (measured with my APC XS 1500 UPS). When I set one screen to the lowest brightness setting, the wattage drops to 278 W, saving 27 watts. When I set both screens to the lowest wattage, the wattage falls another 27 watts to 251 W. When the displays enter sleep mode (while the computer is still running), the wattage drops to 207 W.

Below is a summary of the tests I ran on my computer with two displays.

Both screens set to highest brightness: 305 W
One set to highest brightness, one set to lowest brightness: 278 W
Both screens set to lowest brightness: 251 W
Both screens turned off: 207 W

According to these results, each screen uses 22 W of power on the lowest brightness setting and 49 W of power on the highest brightness setting. Therefore, each screen uses more than twice as much power when set to the highest setting. That means one 20" monitor with the brightness maxed out actually consumes more power than two 20" monitors set to the lowest brightness.

Since my eyes are highly sensitive to light, I naturally prefer the lowest brightness setting. In fact, my primary complaint with most monitors is that their lowest brightness setting is still to bright! The only time I crank up the brightness is when I am doing certain types of graphics editing or when the room I am working in is filled with sunlight. Most of the time, the lowest brightness setting is just fine. If you typically run your screen(s) on the highest brightness level, I recommend trying a dimmer setting. The display may seem dark at first, but after a few minutes you probably won't notice the difference.

Setting your computer monitor to a low brightness setting is better for your eyes and will save you some money on your energy bills. If you use a laptop, it will extend the life of your battery. This is also true for other portable electronics, such as tablets and smartphones. You may find it is worthwhile to sacrifice a little bit of brightness for a longer battery life.

Finally, if you don't want to dim your screen to the lowest setting, even toning down the brightness a little bit helps. In most cases, the power usage increases exponentially as your crank up the brightness. Therefore, even if you dim your display a small amount, you might save a lot of energy.

- Per Christensson