A look at how LCD and plasma compare for power consumption

If youre on the hunt for a big flat-screen television, but youre worried about how much electricity theyre going to suck back, you may be confused as to which technology to look for. The prevailing wisdom is that plasma screens are power-hungry monsters, but thats not necessarily true in all circumstances.

The reason for this is the different ways that plasma and LCD bring the picture to the screen. With a plasma screen, each pixel element is an individual light source that is illuminated as needed. LCD, on the other hand, always has a backlight running, and rather than lighting up pixels, an LCD monitor will BLOCK them, so the light doesnt get through. That means a relatively steady power consumption for LCD screens, while plasma varies wildly depending on what happens to be on the screen at that given moment.

CFH Labs got in two large-screen televisions of roughly the same size, one LCD (40-inch) and one plasma (42-inch), and hooked them up to a pair of Kill A Watt electricity meters. We then tested the power consumption of these monitors under a variety of conditions, including several solid colours (white, black, red, blue and green), TV static, watching a DVD with a lot of white backgrounds (Atanarjuat), and watching a DVD with a lot of black backgrounds (Battlestar Galactica miniseries). We also tested the two screens overnight, tuned to the same station. Both screens used out-of-the-box colour and brightness settings.

As prevailing wisdom suspects, the plasma monitor consumed more energy under all of the different real-world viewing tests, but the Battlestar Galactica test showed the difference narrowing. Under the solid colour testing, the plasma ate up more energy than the LCD screen except when displaying a solid black screen, where the power consumption of the plasma screen plummeted to about a quarter of its usual use. The plasma screen used the most energy showing a screen with TV static on it, because theres a lot of white, and its rapidly moving.

For part two of the test, we reset the plasma screen to super savings energy mode, and then adjusted the brightness of the LCD screen to match.

Kill A Watt


The Kill A Watt is designed to show you how much power youre using on any particular outlet, by sitting between the outlet and the item youre plugging into it. The Kill A Watt measures the voltage, amperage, wattage, Hz and kilowatt hours. We used the Kill A Watt to measure the power draw of our large screen televisions, to see which ones were more efficient, using the watts (current power draw) and kilowatt hours (cumulative power draw over time).

Samsung SP-R4212


Consumption rating: 280 watts

The SP-R4212 is a 42-inch plasma display, and while its HD-ready, its only a 480p display (852×480 pixels). That means 1,226,880 individual pixel elements to turn on and off, each of which requires power. Theoretically, that would mean that an all-white screen would consume the most powerbut is that the case?

Samsung LN-R408D


Consumption rating: 285 watts

This 40 inch model has a slightly smaller picture than our 42-inch plasma, but it comes with 720p resolution (1366×768).

Samsung plasma:

standby: 1 watt, 0.06 amps

black screen: 65 watts, 0.58 amps

white screen: 256 watts, 2.23 amps

red screen: 232 watts, 2.02 amps

blue screen: 231 watts, 2.13 amps

green screen: 208 watts, 1.80 amps

static: 311 watts, 2.71 amps

Atanarjuat (2 hr 30 min): 0.69 kilowatt hours

Battlestar Galactica (2 hr): 0.49 kilowatt hours

CNN (overnight): 4.3 kilowatt hours

Samsung plasma (super power saver mode):

standby: 1 watt, 0.06 amps

black screen: 65 watts, 0.58 amps

white screen: 203 watts, 1.76 amps

red screen: 191 watts, 1.7 amps

blue screen: 190 watts, 1.67 amps

green screen: 180 watts, 1.56 amps

static: 251 watts, 2.21 amps

Atanarjuat (3 hr): 0.64 kilowatt hours

Battlestar Galactica (3+ hr): 0.67 kilowatt hours

CNN (overnight): 3.97 kilowatt hours

Samsung LCD

standby: 10 watts, 0.17 amps

black screen: 200 watts, 2.55 amps

white screen: 199, 2.58 amps

red screen: 199 watts, 2.57 amps

blue screen: 198 watts, 2.57 amps

green screen: 198 watts, 2.96 amps

static: 264 watts, 3.23 amps

Atanarjuat (2 hr 30 min): 0.57 kilowatt hours

Battlestar Galactica (2 hr): 0.49 kilowatt hours

CNN (overnight): 3.41 kilowatt hours

Samsung LCD (lower-brightness mode)

standby: 10 watts, 0.17 amps

black screen: 196 watts, 2.50 amps

white screen: 195 watts, 2.52 amps

red screen: 196 watts, 2.51 amps

blue screen: 196 watts, 2.52 amps

green screen: 195 watts, 2.51 amps

static: 235 watts, 3.0 amps

Atanarjuat (3 hr): 0.65 kilowatt hours

Battlestar Galactica (3 hr+): 0.72 kilowatt hours

CNN (overnight): 3.84 kilowatt hours

old Samsung plasma:

Windows Longhorn screen: 192 watts, 1.63 amp

Windows longhorn, mostly whit: 291 watts, 2.49 amps

Windows Longhorn, mostly black: 114 watts, 0.98 amp

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