Plasma TVs: Are they really killing the planet?

There's a been a surge in interest recently about an 'imminent ban' on energy-inefficient TVs. Rumours reported by several national newspapers indicate that plasma TVs could be banned under new EU rules on energy efficiency. Of course, with Russell Brand already sacked, the papers need something else to cover their pages and whip up some public outrage.

The British press does love to cause a mass panic with an overly dramatic headline, and this story is no exception. The Independent led with 'Giant plasma TVs face ban in battle to green Britain', while the Daily Mail opted for 'Energy-guzzling plasma TVs will be banned in Brussels eco blitz'. Sadly, neither headline represents the truth, either about plasma TVs or the EU rules.

Despite a liberal sprinkling of the word 'ban' in every headline, the truth is rather more mundane. It's true to say the EU is considering introducing new power-consumption criteria for 2010, which will be announced in Q3 this year. Even so, such rules won't affect any TV you buy now, or already own.

So what's all this hysteria about? How it will actually affect you, the consumer? To find out, we did some casual measurements ourselves and while we aren't claiming this is a scientific study, for the purposes of what we're talking about, our figures should help explain the reality of power consumption.

In the office, we currently have two test TVs. One is a 46-inch LCD, the Toshiba 46ZV555D, the other a 50-inch plasma, the Pioneer KRP-500A. We used the same measurement device on both, and we found that our plasma used between 250W and 350W with its standard settings. Plasmas don't draw power at a constant rate, because they draw more power when showing white, or light colours. Unlike LCD pixels, plasma pixels generate their own light. Because of this, showing a black image requires virtually no power.

During normal use, with the backlight set to 40 per cent, our LCD -- which is four inches smaller than the plasma, remember -- used about 181W. This figure doesn't change, because on this LCD TV there's a fixed amount of light coming from the cold cathode tubes behind the screen. To save power, and improve the contrast ratio, this LCD has a 'dynamic backlight' mode, which dims the backlight when there's a dark image on-screen. We turned this mode on, set the TV to an input displaying a black image and the TV dropped its power consumption to 102W by dimming its backlight.

So from what we've found so far, it may appear that LCD is more economical than the plasma. Clearly, everyone who has ever bought a PDP should be burned alive -- and have their carbon offset with some furious tree-planting. Hold your horses though! This isn't actually the case, because the plasma we tested, like many on the market, has an energy-saving mode. When we engaged it, we got a pure white image down to just 220W and a mostly black screen fell to around 75W.

We also think it's important to mention that modern plasma TVs have a longer lifespan than many LCDs. The CCFL backlights found in most LCD screens will give you around 60,000 hours of use. Most modern plasmas will last 100,000 hours before their light output is reduced by 50 per cent. Replacing the backlight in an LCD is generally uneconomical, so these TVs will almost all end up in a landfill or, at best, be recycled.

Were you to make a judgement about a television's power consumption based on the maximum amount of power it can use, you might conclude plasmas are worse than LCDs. Although there are plasmas that can theoretically drain from 550W up to 750W, their actual consumption is much lower. The only way to compare the two technologies is to measure their total consumption over a fixed period, instead of looking at the peaks. 

There is very little doubt that all large-screen TVs use a good squeeze of juice -- certainly much more than CRTs. There's also no doubt that each year, the situation gets a little better. This year's screens are certainly better than last year's, and that trend is likely to continue. In the meantime, ignore the scaremongering and remember to engage your TV's energy-saving features. If you have an LCD, make sure the backlight is reduced. If you're a plasma owner and want to keep your bills down, make sure you watch plenty of TV set in space.