If you're of a certain age, you can remember a time when a television set had to warm up before a picture appeared. This was due to the fact that when the set was off, it was really off. Today, however, we demand instant-on satisfaction, making TVs one of many household energy vampires sucking up 10 watts of juice or more just to stay at the ready. Energy Star reports that in the U.S., TVs consume approximately 46 billion kWh per year-about 4 percent of all residential demand and equivalent to the total power use of all the households in New York State. The cost to run a typical TV: about 2 to 5 cents per hour.

New technologies are improving our viewing experience by leaps and bounds, but for the most part they're not helping us save energy. In case you haven't noticed, we're in the midst of a television revolution, with the government, the networks, the TV manufacturers, and the cable and satellite companies all urging us to move on up to high-definition wide-screen digital TV. It's the biggest upgrade push since the NBC peacock first unfurled its colorful feathers in the mid-'60s, enticing viewers to leave behind the world of black-and-white.

As a TV's screen size stretches beyond 40 inches (not an uncommon size these days), the set's power consumption rises sharply, with some of the biggest models devouring up to 850 kWh per year-more than many refrigerators (and adding $80 to $90 to your electric bill). The best energy-saving advice, of course, is to do what your mother always told you to do: Turn off that boob tube and go outside for some fresh air. But if you're going to watch-and you know you are-here are some steps to take as you first shop for your next TV and then sit back to enjoy it.

Star performers: where to begin
Basically, flat-screen television sets come in two flavors: liquid-crystal display (LCD) and plasma. While Energy Star doesn't take an official position in favoring one technology over the other, it does rate all TVs, giving its stamp of approval to those that consume 30 percent less power than the average set. You should definitely look for the Energy Star seal when you shop for a TV (or any large appliance).

One other overarching piece of advice, if saving money on your electricity bill is your top priority: Choose an LCD flat-screen model over a plasma flat-screen model, or choose a rear-projection model over both for the cheapest overall operating cost. Here's why.

It's a gas: plasma considerations
The neon and xenon gases inside a plasma flat-screen TV glow in combinations of red, green, and blue when they are electrically charged. From the get-go, plasma technology has been most useful for dazzling TVs of the largest sizes. When you see a flat-screen TV that's 42 inches or larger hanging on the wall in a store, it's most likely plasma. But all that visual excitement comes at a cost. The consumer technology website CNET, which has done a masterly job of testing and comparing the power consumption of various TV technologies, found that the average plasma screen consumes 328 watts when on. Taking size out of the equation, the technology itself consumes .34 watts per square inch.

Until recently, plasma TVs were cheaper to buy than LCD TVs on an inch-per-inch basis, because big LCD screens were harder to manufacture. That's changing now, and in the mid-range, around 40 to 50 inches, you'll find that LCD models now cost about the same as plasma models. So why choose LCD over plasma?

Crystal clear: LCD considerations
LCD screens operate more efficiently than plasma screens. Light from a single bulb passes through the screen's crystals, generating images in exactly the same manner as a laptop computer screen. CNET found that the average LCD screen consumes 193 watts, or .29 watts per square inch, a fair measure better than plasma.

Some cinephiles have complained that one drawback of LCD as compared with plasma is that its blacks aren't black enough, appearing to be more of a dark gray. That's less of an issue today than it was two years ago, and contrast can be adjusted. Still, it always make sense to scout lots of TVs in a big-box electronics store to get some of idea of what you can expect.

Behind the scenes: the rear-projection option
You can beat both plasma and LCD on power consumption and price by getting a rear-projection TV, which uses a projector and a mirror to shine the image onto the back of a large translucent screen. This technology is more like your traditional cathode-ray tube (CRT) TV, but enhanced for the 21st century to save space and sharpen the picture to high-definition standards. CNET found that this technology consumes 0.14 watt per square inch. These more energy-efficient models often have huge screens, but they aren't thin and are therefore mainly available as freestanding, space-hogging pieces of furniture. They haven't proved to be as popular as flat-screen LCDs and plasmas, which can be mounted on a wall.

There are also projection TVs that display a high-quality image on a white screen or even a wall, just like a movie projector. This compact option, essentially the same kind of device you might see in an office conference room, won't work for everyone. It requires the right kind of room and very dim lighting, and a good projector can cost more than $2,000. But because it draws only about 180 watts, a projector delivers the most bang for your energy buck by far, and you can enjoy a cinematic experience, with pictures up to 14 feet wide. Aim it out the window at a bedsheet strung between two trees, and you can host nighttime neighborhood TV parties.

Supersize me: the game of inches
Compare all these new technologies with your traditional CRT TV, which consumes about 146 watts (or .34 watts per square inch, the same as plasma) and you see that plasma, LCD, and rear-projection technologies aren't inherently or outrageously energy-hungry. So what's the problem? Simply put, it's the size of the screens. Today we're buying much larger TV sets than we used to, and are thereby consuming much more power.

It (almost) goes without saying that you shouldn't buy a TV that's too big for your room. Conventional wisdom says that, for optimal viewing, the distance from the TV to your seat should be about double the screen size. In other words, if you want to sit five feet (60 inches) from your screen, a 30-inch model will suffice. Anything bigger will be more than you probably need and may overwhelm your room.

What else should you do when you shop for and use your new TV? Here are some tips.

Educate the salesperson
While many TV manufacturers do seek and receive Energy Star approval for their most efficient TVs, often that's the only relevant energy information you'll get at the electronics store. TV manufacturers don't typically report or promote overall or standby power consumption, so it becomes a non-issue for the comparison shopper. Make it an issue. After all, TVs can consume anywhere from 45 to 500 watts of power, and that can have a big impact on your annual energy bill. Pepper the salesperson with questions about energy efficiency and power consumption. He or she probably won't have a clue, but if enough people start asking, perhaps stores will learn to direct savvy shoppers to more energy-efficient models.

Turn down the lights
Many first-time buyers don't know that the brightness of flat-screen TVs can be adjusted. Out of the factory and in the store, they're often cranked all the way up to create the most eye-popping picture. But at home, you should dial down the brightness using whatever contrast or picture controls are available to you (LCD sets are more flexible than plasma in this regard). CNET reported that reducing light output can cut power consumption by 30 to 50 percent, depending on how far you can push it. Also find out if your TV has a power-saver setting (check the manual to find out how to set it) that can reduce power consumption, usually also by cutting back on brightness.

At the same time, dim the ambient lighting in the room where you watch TV. Less light in the room makes the TV picture pop even if you've reduced its brightness, and you'll be saving even more energy.

Lobby for CableCARD
Some cable providers and TV manufacturers are introducing CableCARD technology, which essentially puts the guts of a cable box inside your TV. Cable functionality comes by way of a credit-card-size device that's inserted into a special slot in the set. The big benefit is that this kind of setup eliminates the need for a power-hungry cable box and lets you move to a new home without the hassles of installing and unstalling a box. CableCARD technology is just starting to emerge. Ask your cable company about it, and keep an eye out for it when you shop for your next TV. (Note: Energy Star refers to this technology as a "point of deployment" slot.)

Choose a TV/DVD player combo for your second set
You may remember seeing-or even owning-a TV that came with a built-in VCR. Today you can find TVs that include DVD players. While it may seem logical to buy a combo product like this as a way to save money and energy, keep in mind that you'll be making one big tradeoff: size. It's rare to find a flat-screen combo model larger than 30 inches, so if a cinematic experience is what you're hoping for, you'll be out of luck. But for a second or third TV destined for the kitchen counter or a kid's room, a TV/DVD combo makes perfect sense. It's easy to find a 20-inch model for about $400.

Keep your old set out of the landfill
About 13 million TVs in America are sent off to landfills every year, each one containing up to eight pounds of lead-not to mention other problematic materials. Try to keep your TV out of the dump by passing it on to someone who can use it. Charities and schools are always good choices. You can try to sell it, but with used TVs flooding the secondhand marketplace, it takes only a quick perusal of the online classifieds to learn that a used TV, even a relatively new one, has very little monetary value. Why not post an ad online simply offering to give it away to anyone who can manage to lug it out of your house?

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