How Energy-efficient Electronics Work

By: Dave Roos
The Xbox 360 uses 187 watts of electricity. See more pictures of video game systems.
Courtesy Microsoft Corporation

The average American household spends $1,400 each year on energy bills [source: Forbes]. Home heating and cooling systems are responsible use about 45 percent of the energy. Lighting takes up another significant chunk, especially if you're slow to switch to efficient compact fluorescent bulbs. But some of the most energy-hungry machines making your electric bill creep higher every month are your electronic devices.

Take a look at your TV, for example. Maybe you recently splurged on one of those 40-inch (102-centimeter) plasma TVs, which requires 350 watts of energy to run. Connected to the TV is an Xbox 360 (187 watts), a PlayStation 3 (197 watts) and a digital video recorder (DVR) (33 watts) [source: CNET]. Wonder where your money's going each month? Straight into that black hole of energy consumption in your living room. Luckily, electronics manufacturers are designing equipment, appliances and gadgets that are more energy efficient.


Energy conserving electronics are not only better for our wallets, but better for the environment. More than half the electricity in the United States comes from coal-burning power plants [source: American Society of Mechanical Engineers]. Even a brand-new coal-burning power plant sends out 6 million tons (5.4 million metric tons) of carbon dioxide each year, 1,200 tons (1,089 metric tons) of sulfur dioxide and 1,600 tons (1,452 metric tons) of nitrogen oxide [source: Las Vegas Sun]. These chemicals not only deplete the ozone layer but contribute to acid rain and respiratory illness in children and the elderly.

So what can you do to cut your electric bill and clean up the air? Are there government and industry resources that can tell you which products are more efficient? And what types of TVs, computers and handheld electronics give the most bang for the energy buck? Read on to find out.


Energy Star and Other Energy-conserving Initiatives

The Energy Star logo is a familiar sight on the packaging of thousands of consumer electronics.
Image courtesy Energy Star

In 1992, the U.S. Environmental Protection Agency (EPA) introduced a new program called Energy Star to show consumers how much energy the products they buy actually use. Since its inception, 12,000 electronics and appliance manufacturers have voluntarily complied with increasingly strict Energy Star standards. As a result, more than 40,000 individual products boast the highly recognizable Energy Star label [source: Energy Star].

Energy Star first began with computers and computer monitors. Over the years, the product categories and published standards have expanded to include residential heating and cooling systems, home appliances, lighting systems, and every type of office and home electronics equipment.


In 2007 alone, Americans using Energy Star products helped prevent 40 million metric tons (44.1 tons) of greenhouse gas from entering the atmosphere [source: Energy Star]. That's the equivalent of taking 27 million cars off the road for an entire year. The EPA also estimates that in 2007, Americans using Energy Star products saved $16 billion on their electric bills [source: Energy Star].

Energy Star is the most recognizable energy-conservation initiative for consumer electronics, but it's not the only one. The Electronic Product Environmental Assessment Tool (EPEAT) is a newer rating system that grades the overall environmental impact of various consumer electronics products. Among the criteria are how much of the gadget's materials can be recycled, whether any of the components are toxic and whether the product meets existing or pending Energy Star standards.

Products that meet all of EPEAT's required criteria earn a bronze label. Those that meet all required criteria plus 50 percent of optional standards get a silver label, and those that meet all required criteria plus 75 percent or more of the optional standards get a gold rating.

All computers require a power supply, a small box that converts AC power coming from the wall to the DC power that runs the device. Historically, a lot of energy was lost in this conversion process. In 2004, a new incentive program called 80 Plus was funded by American utility companies to encourage manufacturers to build more efficient power supplies for desktop and notebook computers and servers. To qualify for an 80 Plus rating, a power supply must be 80 percent efficient or greater.

Over the years, American utility companies have funded more than $5 million worth of incentives for computer makers and power supply manufacturers to improve the efficiency of their products. As a result, more than 600 power supplies that have achieved the 80 Plus rating [source: 80 Plus]. And even better, the recently published Energy Star standards for new computers requires that internal power supplies carry the 80 Plus seal of approval.

Televisions are some of the biggest energy hogs in your house. Let's look at the most and least efficient types of TVs and what's on the horizon for greening the small screen.


Energy-efficient TVs

The Philips 42PFL5603D, or Eco TV
Courtesy Philips

Television screens are getting bigger, sharper and thinner every year. While the action on the screen looks better than ever, the effect on your electric bill can be downright scary. The average American still only pays around $24 a year to power his or her TV, but that average is dragged down by all of the old CRT (cathode ray tube) TVs that will be replaced as more people upgrade to power-sucking high-definition (HDTV) models [source: American Council for an Energy-efficient Economy].

According to testing by CNET labs, the most energy-efficient HDTV costs around $30 a year to power, while the most power-hungry model adds nearly $230 to the electric bill each year [source: CNET]. Larger screen size is one of the biggest contributors to this leap in the cost of watching TV. According to a study by the Natural Resource Defense Council, an HDTV with a 40-inch (102-centimeter) screen or larger consumes more energy per year than any other device or appliance in the house, including a 22.5 cubic foot (0.6 cubic meter) refrigerator [source: Energy Star].


Different television technologies also burn through different amounts of electricity. Plasma TVs are, on average, the least efficient technology. Next come LCDs, followed by projection TVs and traditional CRTs [source: CNET]. But even within these general categories, there are many factors that can make a TV either an energy sipper or a guzzler. Incredibly, both the most efficient and the least efficient TVs on CNET's list are LCDs.

In addition to the power they use while they're on, many of these large-screen TVs don't shut off completely when you press the power button. The manufacturers felt that people wouldn't want to wait so long for their sets to warm up when they press the power button, so they have the TVs go into a standby mode rather that shut off completely. Some of them require you to press a separate button or unplug the unit entirely to totally power down the equipment.

As consumers become more energy conscious, TV makers are responding with innovative, energy-saving designs. One example is the Philips 42PFL5603D, also known as the Eco TV. When you activate the Eco TV's power saver mode, the television uses a trio of sensors to optimize the intensity of the LCD's backlight. The brighter the room, the harder the backlight needs to work. The Eco TV can detect the relative darkness and brightness of the room and adjust how much light it uses to illuminate the picture. In addition, the Eco TV boasts a sensor that constantly adjusts for the brightness of the scene being played on the TV. If the scene takes place at night, the backlight dims ever-so-slightly to save energy for the daytime scenes.

Another TV technology called organic light-emitting diodes (OLED) offers an even more energy efficient way to light a large TV screen. With OLED, light isn't provided by a backlight, but by individual molecules that light each pixel on the screen. The first small (30-inch, 76-cm) OLED TVs arrived in November 2007 and a consortium of Japanese electronics-makers are pushing to deliver large-screen versions within the year [source: Reuters].

Now let's look at the best new energy saving computer technology.


Energy-saving Computers

The Cranberry SC20 smart client computer
Courtesy Cranberry

Even the most energy-hungry home computer doesn't make much of a dent in the monthly electric bill. If you ran a desktop computer and monitor at full power for eight hours every day, it would add $30 to your annual energy costs [source: myGreenElectronics].

But imagine that you owned a business with hundreds of employees. Now imagine all of those desktop computers crowded into an office, plus the servers and storage units crammed into IT rooms. Not surprisingly, those computers eat up a lot of energy, accounting for up to 70 percent of a company's energy bill [source: Cranberry]. Computers also create heat and force the air conditioning to work even harder to keep the office cool.


Recently, several computer makers have introduced machines designed specifically to lower the energy costs of small and large businesses. One is the Earth PC and Earth Server by Tech Networks of Boston. These new PCs come with a patented power management system that keeps machines running as lightly as possible in standby mode. They also come with 80 Plus-certified power supplies which keep them cool and lower air conditioning bills by 33 percent in the process [source: Tech Networks of Boston].

The Cranberry SC20 is another new energy-conserving computer marketed toward businesses. The Cranberry isn't exactly a PC. Instead, it's something in between a full-fledged PC and what's known as a thin client. Thin clients are pared-down computer terminals that run all of their applications from a central server. Thin clients don't have hard drives and can't run their own native applications. The Cranberry is called a "Smart Client" because it's slim (the size of a paperback book), yet it can run its own software, be controlled locally and includes standard ports for connecting digital cameras, speakers and other devices. Because the applications reside on the Internet rather than on the machine, this is a form of cloud computing.

But the impressive thing about the Cranberry is that it uses just 10 percent of the power of a standard PC. That's because it has no moving parts (no fans or hard drive) and is powered by an extremely efficient microprocessor. The Cranberry consumes a mere 9 watts compared to a standard PC which burns through 175 watts [source: Cranberry].

The Mac Mini
Courtesy Apple

The Mac Mini is another desktop computer touted for its energy efficiency. The Mini is a tiny 6.5-inch (16.5-cm)-square, white box with a built-in CD/DVD drive and the standard input/output jacks for USB and Firewire devices. But since it's stuffed with highly efficient notebook computer guts -- and has an external power supply -- it runs quiet and cool at only 25 watts. The latest Mac Mini meets Energy Star 4.0 standards and earned an Electronic Product Environmental Assessment Tool (EPEAT) Silver rating.

In terms of computer monitors, smaller LCD monitors are more energy efficient than CRT monitors of the same size -- some reports say 66 percent more efficient [source:]. LCD monitors also give off less heat than CRTs and help save money on that air-conditioning bill.

Now let's look at some cool new handheld gadgets that keep going long after everyone else's batteries are drained.


Energy-saving Handhelds

The Nokia Eco Sensor Concept and wrist sensor unit
Courtesy Nokia

Since handheld gadgets like cell phones, iPods and BlackBerrys run on batteries, sometimes we forget that charging and recharging adds to the electric bill. Thankfully some forward-looking companies are developing innovative ways to power the gadgets that run our lives.

The Eco Media Player is an iPod-like handheld device that can be loaded with music and video files via a standard SD memory card. What's not standard about this media player is that you can power up the battery with a hand crank that unfolds from of the back of the unit. One minute of cranking gets you 40 minutes of audio playing power [source: TreeHugger]. The technology is based on the famous hand-crank emergency radios that inventor Trevor Baylis developed for aid workers and villagers in rural Africa.


Alternative fuels are another way to get electronics off the power grid. A company called Angstrom Power recently presented a prototype cell phone at the 2008 Consumer Electronics Show that runs on a tiny hydrogen fuel cell. The company claims that its Micro Hydrogen fuel cell platform fits right into existing cell phones with no modifications and promises twice the talk time of a lithium-ion battery. The device can be fully charged in less than 10 minutes.

A simpler way to recharge a cell phone is to rig up a standard cell phone with a small, wearable solar panel. Several companies are selling small arrays of solar panels that can plug directly into cell phones or other mobile devices. A Japanese company called Strapyanext is selling a 12-cm (5-inch) solar cell phone charger that can produce and store roughly 40 minutes worth of talk time during 6 to 10 hours in the sun [source: CrunchGear].

Solar technology isn't limited to cell phones. The Nokia Eco Sensor Concept is a futuristic personal digital assistant (PDA) prototype that comes with a separate wrist sensor unit. The wrist sensor is made out of solar cells which provide energy for the PDA. This wrist sensor can also generate electricity by capturing kinetic energy from natural arm movements, like some watches already do today. The screen of the Nokia PDA will use a highly efficient technology called electrowetting. In place of pixels on a screen, it uses tiny drops of oil that expand and contract with electrical charges [source: Nokia].

For more illuminating information on energy conservation and electronics, check out the links on the next page.


Lots More Information

Related HowStuffWorks Articles

More Great Links

  • American Council for an Energy Efficient Economy. "Energy Consumption of Household Products."
  • American Society of Mechanical Engineers. "The Need for Additional U.S. Coal-Fired Power Plants." GovRelations/PositionStatements/Need_Additional_US_CoalFired.cfm
  • Cranberry. "Cranberry Green Credentials."
  • 80 Plus. "What is 80 Plus"
  • Energy Star. "Energy Star Overview of 2007 Achievements." 204pg.pdf
  • "Power Saving Tips for Flat-Panel TVs." power-saving-tips-for-flat-panel-tvs.html
  • McLaren, Warren. "The Wind-Up iPod: Trevor Baylis' Eco Media Player." Treehugger. Nov. 12, 2007.
  • My Green Electronics. "Energy Calculator."
  • Nadel, Brian; Moscovciak, Matthew. "HDTV Power Consumption Compared." CNET. June 4, 2008.
  • Nadel, Brian; Moscovciak, Matthew. "The Basics of TV Power." CNET. June 4, 2008.
  • Nadel, Brian; Moscovciak, Matthew. "TV Power Consumption." CNET. June 4, 2008.
  • Nokia. "Nokia Eco Sensor Concept"
  • Ostendorp, Peter. "NRDC TV Energy Efficiency Research." Ecos Consulting. July 2005. revisions/downloads/tv_vcr/Ecos_Presentation.pdf
  • Sweet, Phoebe. "We all need power, but in Mequite, priority is clean air." Las Vegas Sun. Feb. 7, 2008. we-all-need-power-mesquite-priority-clean-air/
  • Tech Networks of Boston. "Earth PC."
  • Toto, Serkan. "World's first solar battery charger for cell phones." Crunch Gear. June 9, 2008. worlds-first-solar-battery-charger-for-cell-phones
  • Reuters UK. "Sony, other firms to team up in OLED panels." July 10, 2008.
  • Shiffman, Betsy. "Why Your Energy Bills are Soaring." Forbes.