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 more than 100 HDTVs, and provide tips on how to cut down on electricity costs while still enjoying your high-def television.
The price of energy always seems to be rising, and costs can run high when just about every modern appliance can be seen as a power-hungry mass of circuits, lights, and buttons that sucks down electricity, day and night. Televisions qualify as major appliances, and especially big-screen models can make a serious dent in your electricity bill. To find out just how serious, we've put 150 TVs--old and new--to the test by measuring how much power each uses in a simulation of actual use. Our results, detailed in a chart on the next page, show that it can cost between $25 and more than $100 in electricity per year for the average American to power his TV, depending primarily on screen size, technology type, and picture settings.
Technology and size matter
There are four basic technologies that TVs use to produce a picture, and technology type has a large influence on power consumption per inch of screen. The traditional cathode-ray tube (CRT) blasts electrons onto chemical phosphors embedded on the inside of the tube, while plasma sets ionize gas to create colors in a million or more tiny pixel cells. "SpongeBob" or "American Idol" then show up on the other side of the glass, and both require more electricity to create a brighter image.
TVs:
Average plasma: 339 watts
Average rear-projection: 211 watts
Average LCD: 213 watts
Other AV gear:
PlayStation 3: 197 watts
Xbox 360: 187 watts
Average PC: 78 watts
DirecTV HR20 DVR: 33 watts
Nintendo Wii: 19 watts
Slingbox: 9 watts
Wireless router: 7 watts
On the other hand, flat-panel LCDs and rear-projection microdisplays use a powerful fluorescent backlight or bulb that either punches through an LCD panel with its three color filters or that reflects off of a digital-light-processing chip that has a million miniature mirrors and a spinning color wheel. Either way, they consume the same power, regardless of whether they're displaying a dark or a light scene. That's because the primary light source--the backlight or the bulb--is essentially always running at maximum power.
Note that many flat LCDs actually have adjustable backlights that you can turn down to consume less power and produce a dimmer image, while some newer LCDs, including ones that use LED backlights, can be set to dynamically adjust the backlight intensity and use less power in dim scenes.
Size matters as well, so we divided each set's power use by its screen area to get a watts-per-square-inch rating. This way, small and large screens can be compared. While there are plenty of exceptions, the average score of each technology type is telling:
- Microdisplay rear projector: 0.13 watt per square inch
- LCD: 0.27 watt per square inch
- Plasma: 0.34 watt per square inch
If power efficiency is all you're after, the clear choice is rear-projection technology. Of the three, plasma screens are generally the most power hungry. Flat-panel LCDs often have a good brightness-to-consumption ratio, but they're not exactly consistent. Some LCDs are as low as 0.11 watt per square inch, but some go as high as 0.37 watt. Luckily, more and more new TVs are coming with a power-saver mode, which we've found can drastically cut power consumption.
Energy Star 3.0
Partly in recognition of the growing consumer interest in TV power consumption, Energy Star, an international program overseen in this country by the Environmental Protection Agency, has devised a new 3.0 specification for TVs. It improves upon the previous Energy Star specification by actually mandating power consumption standards for TVs while turned on. Amazingly, the previous method only considered standby power (see Other power factors below).
Starting November 1, 2008, HDTVs will have to meet the new specification if they want to bear the Energy Star logo. That specification depends on screen size/area and resolution capability, and is notably technology-agnostic; it doesn't matter whether the TV uses plasma, LCD, rear-projection, or CRT technology. To qualify as Energy Star compliant, a 32-inch HDTV must consume less than 121 watts, for example, while a 50-inch HDTV must consume less than 391 watts.
To qualify for the new specification, TV manufacturers have made some major changes. One of the most noticeable is the choice between "home" and "retail" use that a TV user will select during initial setup. Choosing "home" engages a default picture mode, typically labeled "standard," that saves more power than the mode previously used as the default setting on most TVs. Those older default settings, such as "Vivid" or "Dynamic," were designed for maximum light output to compete against other TVs in a retail store environment. Energy Star testing specifies that if a TV offers the choice between home and retail, testing and qualification must occur in the home mode. Buyers of TVs will usually choose home mode as well, which should lead to less power consumption among new HDTVs.
CNET has recently implemented power consumption testing procedures modeled on those used by Energy Star. The standard is called IEC 62087, and we'll describe it in detail in the How we test TV power consumption section.
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 standby power. 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 requires power consumption of less than 1 watt in standby to qualify. To put that in perspective, leaving a TV that uses 1 watt in standby turned off for a year would cost just $1 at average 2008 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 Xbox 360 pulls down an impressive 187 watts, but is outdone by the power-hungry PlayStation 3, which requires 197 watts of juice. A recent study by PG&E in California estimated that 10 percent of household power use is devoted to TV-related activity.
