Reader Question: Plasma vs. LCD Energy Use

Q: Is there a difference in energy consumption between plasma and LCD? And does size make a difference; how much more energy do you use as sets get larger?
John Kin

A: As I’ve said, I expect that consumers will start paying more attention to environmental issues for all sorts of products, including HDTV, so this is a very timely question.

First, LCDs tend to draw less power than plasma. At random, I took specs for two 42″ plasma sets; a Panasonic model is rated at 395 watts, and an LG model at 329 watts. Two 42″ LCD sets selected at random are a Sharp model rated at 247 watts, and an LG model rated at 210 watts.

However, you can’t just use the specs to make comparisons. The largest power draw on an LCD comes from its backlight, which is on all the time whether the image is light or dark. The power draw with a plasma panel comes from actually creating the image on the screen; more light requires more power, so the power consumption for a dark movie scene will be lower than for a bright one. So depending on what you’re watching, the LCD may or may not require less power. I suspect that there is less than 100 watts of difference, which is the amount drawn by a bright household lightbulb.

Size does make a difference. Sharp shows the following specs for a series of LCD TVs:

Size 32 37 42 46 52
Watts 165 203 247 270 302

It appears that the power consumption increases faster than the linear diagonal for smaller sizes, but then increases at a slightly lower rate for the larger sizes. I don’t know why this would be, except that perhaps the backlights are more efficient in larger sizes.