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WilliamR's Avatar WilliamR 09:03 AM 01-04-2007

Part II: Which Is More Energy Efficient, Plasma or LCD?
Tue Jan 2, 2007 11:33PM EST

In my last post I told you what I found out about the power consumption by our new TVs versus our old analog sets. It's not a very pretty picture. But what about plasma versus LCD? Is one of these more energy efficient than the other?

The prevailing wisdom is that plasma screens are the bigger consumers of power. That's because a plasma screen is made up of pixels, each of which has an individual light source that gets illuminated as needed. An LCD always has a backlight illuminating the entire screen. LCDs are sort of the reverse of plasma screens in that you create the picture not by illuminating the pixels, but by blocking light from getting through to certain pixels. The LCD backlight provides a steady source of power, while plasma pixels turn on and off. Because of this, energy consumption varies depending on what you're watching.

Call for Help, a TV show that covers technology, conducted a test that measured the electricity consumed by similar-sized plasma and LCD TVs. It found that most of the time LCD screens did, in fact, consume less power. However, that changed during certain conditions, such as when they displayed a solid color background on the screen or when there was static electricity. These situations taxed the LCD more heavily and resulted in more evenly matched results between LCD and plasma TVs.

It's not just what you're watching, either. Size has something to do with it as well., a site that rates energy-efficient products, recommends that for smaller screens (less than 40 inches), an LCD is generally more efficient than a CRT television. In large screen sizes (50 inches and above), the site reports that a projection TV is probably the most efficient TV you can buy. It consumes half as much electricity as comparably sized LCDs and plasmas. (But remember, the picture is not as bright.) At the intermediate sizes (40- to 50-inch range), things get even muddier in picking the winner, in part because the technologies are evolving so quickly and because of the difference in how they are used.

And if you think you can answer the question by heading over to the EPA's site on Energy Star ratings, well, you can't. The EPA's Energy Star program has been labeling energy-efficient TVs based on the amount of electricity they use in standby mode (when the user has turned off the TV, but the set is still plugged into an AC outlet). Currently, a TV receives an energy-efficient rating if it consumes less than one watt when switched off if it's an analog TV, and less than three watts if it's a digital TV. But it's really not enough to look at the ratings for TVs in the off mode. Many argue that to be meaningful at all, Energy Star ratings for TVs need to look at how efficient they are when they're active, too.

From my look at all the data across multiple sources, you're going to save electricity most of the time by buying an LCD. (You'll also spend more on the initial purchase.) Meanwhile, the one loud and clear takeaway is that no matter which flat-screen TV you've bought, you will save power if you unplug it from the wall when you're not using it. Those savings increase if you've got DVD players, tuners, and other systems hooked up to your TV since they typically remain in a low-powered but standby mode when you shut them off as well.

WilliamR's Avatar WilliamR 09:05 AM 01-04-2007

Part I: Do Flat-Screen TVs Consume More Power?

Why is it that there's no such thing as an easy answer to a simple question when it comes to technology? Over the warm holiday weekend we had one of those "green" discussions, as I'm sure so many of you did. The questions posed were simple: Are the new LCD and plasma displays more energy efficient than old CRT screens? And, which is more energy efficient: plasma or LCD? (I'll cover this question in part II of my post.)

The answer depends on many things, including how you use your TV, when you bought it, andmost of allhow TV power consumption is measured today.

First, the question of new flat-screen TVs versus old cathode-ray TVs. Generally speaking, large-screen TVs consume more energy than the smaller-screened CRT-based TVs they replace. And most people are adding TVs. That is, they tend not to replace old TVs with new ones but add a second or third TV. And since TVs consume power even when they're not on, just adding a TV set or two can add dramatically to your power consumption.

A recent report by the BBC found that in the United Kingdom, plasma televisions, which it says are about 50 percent bigger than their cathode-ray-tube equivalents, "consume about four times more energy according to the government-funded Energy Saving Trust." And when looking at the carbon emissions from the power plants, the same group found that old-style TVs produce 100kg of climate-warming C02 per year, while larger, plasma screens will pump out 400kg from the plant. A recent report from Panasonic, makers of both LCD and plasma TVs, said that the new TVs consume more power than older CRTs, but the company is working to get the new TVs to be more energy efficient as fast as it possibly can.

Some of the best research can be found at The site says that a typical U.S. household watches about five hours of television each day and that there are about 260 million TVs in our homes. They claim that our TVs are responsible for about 1 percent of our nation's electricity production a year (47 billion kilowatt hours). Most of this electricity is consumed when the TV is turned on (90 percent), but the remaining 10 percent is used in standby modes when the set has been turned off. It predicts that unless TV efficiency improves, the rapid growth in TV sales, increased hours of TV viewing, and multiple TVs per household will ultimately contribute to a rise in TV energy consumption by about 50 percent before 2010.

OK, so much for new TVs replacing cathode tubes. It seems the new TVs consume more power. Now what about the different types of flat screens? Do you know which consumes more power? LCD or plasma? Keep reading to find out.
PooperScooper's Avatar PooperScooper 10:43 AM 01-04-2007
Merged threads. Only 1 discussion thread is necessary for basically the same subject.
Although I noticed I got the order wrong...sorry.

Frost147's Avatar Frost147 08:12 AM 01-05-2007
Gee, all I can go by is the hydro bill that faithfully gets delivered to my house every other month. I've been through 3 of those billing periods and there hasn't been any kind of appreciable increase in the amount charged. So, from a strictly non-scientific-seat-of-the-pants perspective, I've got to say it amounts to looking for fly **** in pepper for all the impact it has on the user level.

What HAS increased though, is our viewing on the 42" Sammy! We watch far more movies than when we had the 32" JVC CRT and now we watch HD programming on top of that. The images coming from such channels as Discovery HD and National Geographic HD are just so damn clear!
why2not's Avatar why2not 08:17 AM 01-05-2007
Originally Posted by Frost147 View Post

So, from a strictly non-scientific-seat-of-the-pants perspective, I've got to say it amounts to looking for fly **** in pepper for all the impact it has on the user level.

My electrical usage for the same periods in prior years actually dropped slightly with changing my main display to a plasma. But there are a lot of factors beyond a display going into my electrical bill. Perhaps there were less clouds this year & I didn't need to turn my lights on as often?

I would say that the difference is minisucle at best.
TreeFarm's Avatar TreeFarm 08:24 AM 01-05-2007
Originally Posted by WilliamR View Post

It found that most of the time LCD screens did, in fact, consume less power. However, that changed during certain conditions, such as when they displayed a solid color background on the screen or when there was static electricity.

Huh? Static electricity? That requires some 'splainin, Lucy.
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