lcd displays energy physics pricelist

Dear EarthTalk: I need to replace my old TV. Can you tell me which of the latest models is the greenest? I was told that the flat-screen/plasmas are real energy hogs. What do you recommend?

According to The Wall Street Journal’s Rebecca Smith, a 42-inch plasma TV set can draw more power than a large refrigerator, even if the TV is only used a few hours a day. This is partly because many newer models don’t turn off but go into “standby” mode so they can start up fast later with no warm-up period. “Powering a fancy TV and full-on entertainment system—with set-top boxes, game consoles, speakers, DVDs and digital video recorders—can add nearly $200 to a family"s annual energy bill,” she adds.

Smith recommends green consumers consider the Liquid Crystal Display (LCD) models, which typically uses less energy than comparable plasma sets. According to the U.S. Environmental Protection Agency (EPA), a 28-inch conventional cathode-ray tube (CRT) set uses about 100 watts of electricity. A 42-inch LCD set might consume twice that amount, while plasma could use five times as much, depending on the model and the programming. For the largest screen sizes (60 inches and up), projection TVs are the most energy efficient, clocking in at 150-200 watts—significantly less than the energy a plasma set would use.

For its part, the industry is taking some steps to make its products more efficient, and to improve disclosure of energy usage. In June 2008 Sony pronounced its new 32-inch Bravia KDL-32JE1 LCD model “the world’s most energy efficient television.” Slated for sale in Japan in August 2008 for around $1,400, the new set utilizes fluorescent tubes to create higher levels of brightness with less energy consumption, but still delivers large resolution, a high contrast ratio and a wide viewing angle.

Beginning in November 2008, forward-thinking manufacturers will get a little boost from the U.S. government, which will start awarding the most energy efficient new TV sets “Energy Star” labels to help consumers identify greener choices. TVs bearing the Energy Star label must operate at least 30 percent more efficiently than standard models in both stand-by and active modes. Consumers can see which models qualify by visiting the televisions section of the EnergyStar.gov home electronics page. According to the EPA, if all TVs sold in the U.S. met Energy Star requirements, yearly energy savings would top $1 billion and greenhouse gas emissions would drop by the equivalent of taking a million cars off the road.

Of course, the greenest option of all (aside from getting out from in front of that tube and spending more time outdoors) is to keep or repair your existing CRT unit (a digital-to-analog converter will be needed after February 2009 when new signal specifications go into effect). Most CRT sets use less energy than any of the LCD or plasma models, and if it ain’t broke, why fix it? Buying a new TV, even a greener one, only generates more pollution in production and transport, and creates waste in junking the old model.

CONTACTS: U.S. Environmental Protection Agency, www.epa.gov; Energy Star, www.energystar.gov; Electric Power Research Institute, www.epri.com; Sony Corp., www.sony.com.

The power consumption of computer or tv displays vary significantly based on the display technology used, manufacturer and build quality, the size of the screen, what the display is showing (static versus moving images), brightness of the screen and if power saving settings are activated.

Click calculate to find the energy consumption of a 22 inch LED-backlit LCD display using 30 Watts for 5 hours a day @ $0.10 per kWh. Check the table below and modify the calculator fields if needed to fit your display.

LED & LCD screens use the same TFT LCD (thin film transistor liquid crystal display) technology for displaying images on the screen, when a product mentions LED it is referring to the backlighting. Older LCD monitors used CCFL (cold cathode fluorescent) backlighting which is generally 20-30% less power efficient compared to LED-backlit LCD displays.

The issue in accurately calculating the energy consumption of your tv or computer display comes down to the build quality of the screen, energy saving features which are enabled and your usage patterns. The only method to accurately calculate the energy usage of a specific model is to use a special device known as an electricity usage monitor or a power meter. This device plugs into a power socket and then your device is plugged into it, electricity use can then be accurately monitored. If you are serious about precisely calculating your energy use, this product is inexpensive and will help you determine your exact electricity costs per each device.

In general we recommend LED displays because they offer the best power savings and are becoming more cheaper. Choose a display size which you are comfortable with and make sure to properly calibrate your display to reduce power use. Enable energy saving features, lower brightness and make sure the monitor goes into sleep mode after 5 or 10 minutes of inactivity. Some research studies also suggest that setting your system themes to a darker color may help reduce energy cost, as less energy is used to light the screen. Also keep in mind that most display will draw 0.1 to 3 watts of power even if they are turned off or in sleep mode, unplugging the screen if you are away for extended periods of time may also help.

An LCD panel has a background illumination which is always on if the panel is on and uses the same amount of energy regardless of what is displayed. The only way you can save energy is by dimming the panel which will dim the background illumination but not by displaying something black. The night mode is (today) primarily intended to go easy on your eyes.

For a CRT display, the story is different. There the cathode ray sweep the screen very fast, modulating its intensity to match the desired brightness. Displaying something black will save energy. That"s also why CRT give blacker blacks. What you see is really no light, not just light absorbed by the liquid crystal matrix.

On the European map inspired by the idyllic cities of Southwest Germany, you’ll find rolling hills and beautiful riversides. In Friedenberg your mission is to help design solutions for renewable energy and improve the city’s infrastructure during the campaign. Aside from these larger jobs, you’ll get assorted tasks to test out every bit of equipment that you earn. Take pride in your accomplishments as you ride through the city!