The basics of TV power

Big, flat-screen HDTVs use more power than you might imagine. Now that old tube televisions are starting to disappear, replaced by much larger plasma and LCD-based HDTVs, TV watchers everywhere may be noticing an uptick in their electricity bills. And with the increasing popularity of TV-based entertainment options, such as video game consoles, digital video recorders, and streaming/on-demand video devices, more and more electricity is being spent on TV-related activity. Those devices use quite a bit of power, but typically the biggest energy hog in your entertainment center is the TV itself. This guide will help you understand the factors in TV power consumption, provide wattage and yearly cost statistics on numerous HDTVs that we reviewed since 2008 and provide tips on how to lower electricity consumption and costs while still enjoying your high-definition television.

The 'big three' of TV power: Size, type, and settings
The power used by an active television is determined by three factors: screen size; technology type, such as plasma or LCD; and picture brightness, which nearly always depends on user-selected picture settings.

Screen size: Bigger TVs use more power. A 32-inch LCD uses about half as much power as a 52-inch LCD. Of course, the 52-incher's screen is nearly three times as large as that of the 32-inch model, so the efficiency payoff for going down in screen size does tend to taper off. However, the chances are your new flat-screen TV will use more power than your old tube TV--if the new set is significantly larger.

Technology type: Plasma TVs use more power than LCD TVs. In our tests of TVs since the beginning of 2008 plasmas consume, on average, roughly two to three times more electricity to produce an image of the same brightness as LCD. In the last couple of years, plasma TV makers have made some progress--Panasonic claims improvements of 30 percent yearly, for example--but they still can't compete with LCD for energy efficiency. One problem is that in plasma TVs, each pixel is a discrete light source (think of it as a tiny light bulb), so when resolution increases, say from 720p to 1080p, power use goes up as well. The intensity of light from each pixel must be increased to brighten the picture as a whole.

With LCD-based TVs, on the other hand, a backlight shines through an LCD panel to create the image. Since the pixels reside in the panel, and not the backlight, the TV's power use is largely independent of resolution. Many LCDs can conserve additional power by automatically turning the backlight down during dark scenes and up during bright scenes.

Many newer LCD-based TVs use LED, as opposed to fluorescent (CCFL), backlights. LEDs are more efficient in general, and can also use various dimming technologies that turn down either the entire backlight or independent sections, both of which save power. LED-backlit LCDs are the most efficient type of flat-panel TV available today, although the actual savings over a standard LCD usually amounts to less than $20 per year.

Old CRT-based TVs are relatively inefficient, especially compared with LCD TVs; however, since CRT screen size is limited, they often don't use as much power as big flat-screen models. Rear-projection HDTVs are actually the most energy efficient per square inch of the TV technologies, but they're rare nowadays.

Picture settings: Brighter pictures consume more power, and since light output is primarily a function of the picture settings available on all TVs, this is the one factor that any user can control regardless of television. Reducing the light output of your TV can cut power use by as much as half, and as long as you don't overdo it, you'll still enjoy excellent picture quality.

The principal settings that matter are contrast (aka "picture") and backlight (or "cell light" on Samsung plasmas). Both directly control light output. Nearly every TV has a contrast control, but backlight is generally restricted to LCD models--and not every LCD has it. In LCDs with both backlight and contrast controls, backlight is the main determinant of light output and power use. Counterintuitively, the brightness control has less of an impact on TVs light output than the other two settings do.

Other controls are also often available, such as energy saver modes, which typically limit peak light output, dynamic settings that raise or lower the light output depending on the brightness or darkness of the picture being displayed, and room lighting sensors that increase light output in dark rooms and lower it when the lights dim. Engaging any of these controls will generally reduce the TVs power use, but it will often sacrifice image fidelity. Automatic adjustments can be distracting, for example, and aggressive energy saver modes can make images too dim.

Other features for saving power might not affect the picture quality at all. For example, many TVs provide a "picture off" setting that just plays the audio, thus greatly reducing power consumption for people who would rather listen than watch. Many TVs can be programmed to turn off automatically after a set period of time, whether via a sleep timer or just after a set period of inactivity. A couple of Sony models, such as the KDL-EX700 series take it a step further with a "presence sensor" that automatically turns off the picture, and eventually the TV itself, when you leave the room.

Other power factors

It may surprise you to hear that TVs use power even when they're not turned on. So that the TV is ready to respond to the remote in an instant, all sets use what's called phantom or standbypower. Our tests revealed that standby power consumption varied somewhat among different TVs, but in general newer models consume negligible power when turned off. Energy Star 3.0/4.0 (see below) require devices to consume less than 1 watt of power in standby mode to qualify for its certification. To put that in perspective, leaving a TV that uses 1 watt of power in standby mode turned off for a year would cost just $1 at average 2009 energy prices.
Few people have just a TV anymore, and all sorts of ancillary devices contribute to your yearly energy costs as well. Think of all that's plugged into your set, from a DVD or Blu-ray player, an AV receiver, and a gaming console to a satellite receiver, DVR, or Slingbox that never really turns off. They all need power. It may not sound like much, but a DirecTV DVR can use about 33 watts, while a Slingbox draws about 9 watts--constantly. All told, these boxes can use more power than the TV itself, especially when it comes to gaming. The original Xbox 360 draws an impressive 187 watts, but is outdone by the power-hungry PlayStation 3, which requires 197 watts of juice (newer versions of the game consoles are more energy efficient, however--thePS3 Slim uses about 96 watts during gaming, for example). A recent study by PG&E in California estimated that 10 percent of household power use is devoted to TV-related activity.

TV power standards: Energy Star, California, and the FTC

The Environmental Protection Agency got serious about certifying TVs for its Energy Star program on November 1, 2008. Prior to that date, TVs could be branded with that familiar logo without even being turned on for testing--only standby power mattered. Then came the Energy Star 3.0 standard that mandated testing with the TV turned on. Unfortunately, it wasn't very strict--nearly every HDTV you can buy today, including some of the biggest energy hogs, is Energy Star certified.
In May of 2010, Energy Star 4.0 goes into effect, meaning that any TV sold after that date must meet the new standards. The specification mandates that TVs consume 40 percent less power overall than the 3.0 spec did, and it also tries to prevent manufacturers from "cheating" because it ties light output in the default picture setting to light output in the TV's brightest setting (aka "retail" or "torch" mode). Unfortunately, however, we don't expect the 4.0 spec for TVs to provide realistic buying advice to shoppers who prioritize energy efficiency. Nearly every 2010 HDTV available or announced so far, including large plasmas TVs, qualify for Energy Star 4.0 certification. Energy Star's more stringent 5.0 version that calls for a 65 percent power-consumption improvement over its 3.0 spec and applies the same requirements to all TVs larger than 50 inches goes into effect May 2012.
Not to be confused with the voluntary Energy Star program, a regulation passed in California (FAQ) actually prevents the sale of TVs that don't meet a certain efficiency grade. However, despite stringent opposition by industry groups to the regulation, we don't know of any new TV--regardless of size or technology--that doesn't qualify. Again, a more stringent version of the California program is scheduled to go into effect in 2013.
Comparison shoppers can take heart in a new proposal by the FTC that calls for actual wattage and cost estimates--those same yellow and black Energy Guide labels found on refrigerators, furnaces, and other major appliances--to make their way to TVs. However, the FTC has neither announced timing for the move, nor has it confirmed that it's going to happen at all.

The bottom line

No discussion of TV power use would be complete without a bit of perspective. For households that pay somewhere near the average retail cost for energy--11.55 cents per kilowatt per hour in 2009--and that watch near the average amount per TV--about 5.2 hours per day--the cost to watch a 50-inch 1080p plasma TV is about $64 per year in the calibrated light output mode (see How We Test). The average 52- to 55-inch LCD TV costs about $29 per year for the same light output, and, of course, smaller TVs use less energy. Sure, both electricity costs and average daily TV use are increasing steadily every year; however, those amounts still don't take a major chunk out of most household budgets. According to the Department of Energy, for example, the average refrigerator uses nearly $90 worth of energy per year.
It's worth noting that plasma TV has many picture quality advantages over LCD TVs, so people who really prize video quality may be willing to sacrifice some efficiency to get those advantages. On the other hand, today's high-quality LCDs can balance extreme efficiency with great picture quality. As with all technologies, improvements in HDTV performance are being made with every generation of products, and we expect power consumption to continue to fall in newer models.

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