3 power-sipping monitors lower energy bills

3 power-sipping monitors lower energy bills

Today's displays must be bright, fast -- and able to use electricity intelligently.

While businesses have always been careful about how much they spent on electricity, today's displays are making it a lot easier to keep bills lower -- and the environment safer.

For example, I measured a four-year-old 27-in. Apple Cinema Display as using 101 watts of power. However, the three 27-in. displays that I've tested in this roundup of environmentally smart monitors -- AOC's E2752VH, Dell's UltraSharp 27 UZ2715H and the Philips 271S4LPYEB -- use an average of 26.4 watts.

This is also reflected in cost in electricity to use the monitor per year. Assuming the display is used for 10 hours every business day and that power costs 12 cents per kilowatt-hour (the national average), the Apple Cinema display costs $29 for the year while the three reviewed here average an annual cost of $9.32. Doesn't sound like a lot, but if you're a business with a couple of hundred employees, it can add up quickly.

In addition, all three of these displays all carry the EPA's EnergyStar logo and boast wide screens that can display full HD resolution. And according to the EPA's Greenhouse Gas Equivalencies Calculator, every kilowatt-hour of power saved equals 1.5 lbs. of carbon dioxide that isn't spewed into the atmosphere.

Interestingly, these displays have different strategies as to how they reduce their power consumption. The Dell screen relies on the computer's screen saver to signal when it's time to go to sleep. The AOC adds a built-in timer for determining when it turns the screen off. And the Philips display includes a pair of infrared sensors that continually scan to see if someone is sitting front of the screen. When you get up, it senses that the space in front is empty and shuts the screen down, reducing its power draw.

Of course, saving on electricity doesn't mean a thing if a display doesn't excel in its main purpose. To see what these displays have to offer, I used them every day for a couple of months in my office. I took turns with them one-on-one and then viewed them together showing the same material for comparison.

Saving a few kilowatts here and there might not sound like a huge savings. But, if you multiply the savings by the number of monitors in use every day in a company's offices, it adds up quickly.


If you're looking for a frugal monitor, AOC's E2752VH is not only the cheapest display of the three, but is the only one that uses no measurable power when in sleep mode. However, it falls short on creature comforts like a webcam and USB ports.

Like the others reviewed here, the AOC monitor uses a 27-in. IPS panel with a 1920 x 1080 resolution. It features an ultra-fast 2-millisecond (ms) response time, versus 5ms and 8ms for the Philips and Dell displays, respectively.

The all-black casing is broken only by a small blue light in the lower right corner to show it's turned on. On the right side of the monitor's front, there are controls for turning it on and off, raising and lowering the volume, and using the on-screen menu. The marking for each switch's function is embossed in the display's plastic case; classy, but I found the highlighted white markings on the other two displays easier to read.

Saving power

The AOC monitor has two techniques for saving power when it's not being used. First, like the Dell display, it can use the computer's screen saver to trigger its sleep mode. It can also be configured to shut down when the computer is off or goes to sleep. In addition, a timer lets you shut down the screen after a period of inactivity. Unfortunately, the time can be configured in increments of one hour only.

The AOC consumed 27.5 watts when being used, a little more than the Dell display's power profile. Unlike the others, when the AOC screen goes to sleep, it uses no discernible power, compared to 1.1 watts and 2.1 watts for the Dell and Philips displays, respectively. It took 3.1 seconds to wake up.

Assuming it is used for 10 hours every business day and power costs 12 cents per kilowatt-hour (the national average), the AOC should cost an estimated $8.30 to use per year. That makes it the cheapest of the three to use, if only about $2 a year less than the Philips monitor.

How well it worked

At 215 candelas per square meter, the AOC's light output was the lowest of the three; to my eyes, it looked visibly dimmer than the Dell monitor. Its color balance appeared accurate with strong blues and reds. Video play was smooth, with no lags or glitches.

In addition to a standard mode, the display has settings for text, Internet, games, movies and sports. For those who want to tweak the output, the monitor has adjustments for brightness, contrast, gamma and color temperature. Unfortunately, temperature settings are restricted to normal, warm, cool and sRGB settings. You can fiddle with the red, blue and green colors, but I preferred using the Philips's more extensive presets that are based on actual color temperatures.

The monitor also comes with two Windows-only apps. iMenu lets you adjust brightness, contrast and gamma, but lacks the calibration patterns of the Philips display. Interestingly, several of the program's labels are in Chinese characters, making the app hard to fathom without the manual.

The eSaver app is how you tell the monitor when to go to sleep, based on the status of your PC. For example, I set it to turn off one minute after the computer is shut down or 10 minutes after the computer goes to sleep or the screen saver comes on. Neither of the other monitors reviewed here can match this specificity.

The AOC display makes do with two 2.5-watt speakers; there is no webcam, microphone or USB hub. The speakers are on the bottom edge of the display, so that they sound thin and don't get nearly as loud as the Dell's sound system.

Other features

Its assortment of ports (one DVI, one HDMI and one VGA) lacks the Dell's second HDMI port and the Philips's DisplayPort input. But the AOC ports are all horizontally oriented, while the other two displays have vertical ports that are more awkward to plug in.

I did appreciate the addition of an analog audio input, which I used to connect to my phone's output to listen to music while working. The display also has a headphone jack in the back.

The AOC stand was the easiest of the three to set up, because the base snaps into the monitor arm. Like the others, the monitor has standard VESA mounting holes on the back for screwing it into a third-party stand. However, the only way to adjust the stand is to tilt it up to 3 degrees forward or up to 17 degrees back. It can't go up and down, swivel or rotate.

Bottom line

With a three-year warranty, the AOC is available at prices starting under $200, the least expensive of the three. If you just need a basic monitor that can offer some savings in electric bills, this is a good choice, but its lack of a webcam among other features may limit its usefulness.

Dell UltraSharp 27 - UZ2715H

The Dell UltraSharp 27 may be the most expensive of the three displays reviewed here, but it delivers the best mix of screen and multimedia accessories.

The gray and black monitor takes up the least desktop space of the three, something to consider if you're part of a company that is tight on cubicle space. Built around an IPS panel that offers 1920 x 1080 resolution, the Dell uses hardened anti-glare glass.

There are controls up front for turning the display on and off, using the on-screen menu, and turning the volume up or down; there's also a handy mute button. I was surprised and impressed by a button with a telephone receiver icon that can initiate or answer a phone call over Microsoft's Lync VoIP system. (To get this to work, you'll need to link the screen with a PC via a USB cable.)

Saving power

The Dell comes with a seductive-sounding PowerNap feature, which triggers the display's sleep mode when the computer's screen saver comes on. The monitor first dims the screen's brightness and then shuts itself down. The screen comes back on when the host computer's screen saver shuts off. In my tests, the screen woke up in 1.5 seconds.

While being used, the Dell UltraSharp 27 consumed 23.6 watts of power, the least amount of the three. This drops to 1.1 watts when in sleep mode, half what the Philips monitor uses in the same mode.

Based on a typical usage scenario (assuming it's on for 10 hours a day for every business day and in idle mode the rest of the time, and that power costs 12 cents per kilowatt-hour), this adds up to an estimated annual power cost of $9.45, halfway between the higher-cost Philips and less expensive AOC monitors.

How well it worked

The display was able to deliver 246 candelas per square meter of brightness, the brightest of the three reviewed here. Its reds and greens were spot on, but the screen's blues appeared slightly washed out. The screen was able to render smooth video; however, its video response time of 8ms is the slowest of the three.

The Dell monitor's on-screen menu has controls for tweaking brightness, contrast and sharpness as well as adjusting the display's gamma settings for using a Windows PC or a Mac. To do any meaningful customization, though, you'll need to load the included Display Manager software. This application, which only works with Windows PCs, includes the ability to change the display's color temperature as well as choose among Standard, Multimedia, Gaming or Movie modes.

The Dell is a fine all-around monitor; it excels at delivering all the audio-visual accessories that a modern desktop requires. These include an HD webcam for video conferences as well as a dual-microphone array that does a good job of capturing your voice while reducing noise.

The display's pair of speakers sounded surprisingly good and can actually get too loud for an office. There is a headphone jack on the side, but the Dell lacks the AOC's audio-in jack.

Other features

The Dell display has the best assortment of ports as well, including one VGA, one DisplayPort and two HDMI ports, both of which can work with an MHL adapter and a compatible phone or tablet. The ports are oriented vertically rather than the more convenient horizontal orientation of the AOC display.

Unlike the others, the display has two USB 2.0 ports and a single USB 3.0 port. All of its cables can be routed through a hole in the back of the monitor's stand to keep them tidy. On the other hand, the stand's adjustability is limited: It tilts forward by 5 degrees and back by 22 degrees, but it can't go up and down, rotate or swivel.

As is the case with the AOC and Philips displays, you can remove the display from the stand and use its VESA mounting holes for use with a third-party stand or mounting hardware. You just need to press a spring-loaded button to release the panel from the stand.

Bottom line

The Dell UltraSharp 27 includes a three-year warranty and it has a list price of $450, considerably more than the AOC's cost. (Note that the cost of the Dell changed several times while this review was being written and edited.) But given that, the Dell provides all the accoutrements needed for doing desktop work without wasting power.

Philips 271S4LPYEB

As minimalist as a monitor gets these days, the Philips 271S4LPYEB is not only power-aware but knows when you're is sitting in front of it and can automatically go to sleep when you're not. Too bad it lacks creature comforts like a webcam, speakers or even an HDMI port.

The all-black display houses a 1920 x 1080 IPS panel that is rated at 5ms response time.

Saving power

Perhaps the most interesting feature is pair of infrared sensors that perceive whether someone is sitting in front of the screen. Called PowerSensor, the system can be set to four different distances (user to screen) between 12 in. and 40 in. It's quite an impressive trick. One minute after the space in front of the display is vacated, the image dims; two minutes later, the screen goes black. Then, like magic, the screen lights back up when you sit in front of it. When I tried it, the screen came back to life in less than a second.

After some fiddling (to figure out which distance setting was best for me), I found it worked well and quickly responded to my absence and return. I was able to fool it, though, by leaving my desk chair with its back to the screen.

The Philips used 28.8 watts of power in Office mode, which was similar to the standard modes of the other two displays (however, power use varied only slightly with the other modes). When the PowerSensor kicked in, the power demand was initially reduced to 10.6 watts for one minute and then to 2.1 watts.

Ironically, though, the Philips turned out to be the highest power user of the three -- probably because of the overhead required to keep the PowerSensor active and ready to restart the display. All told, using my assumptions that it was used for 10 hours a day for every business day and that electricity costs 12 cents per kilowatt-hour, the display had an estimated annual operating expenses of $10.20.

How well it worked

In the front, the Philips monitor has a control for fine-tuning the PowerSensor along with others for turning the display on and off and working with the screen's menu. A large bluish-green LED shows that the display is turned on. There are also buttons for adjusting the brightness level and selecting the company's SmartImage feature.

SmartImage optimizes the display's contrast to suit what you're looking at. It has preset modes for Office, Photo, Movie, Game or Economy (which reduces its brightness by two-thirds). There's also an adjustment for the screen's color temperature with six settings available between 5,000K and 11,500K.

With the ability to deliver 221 candelas per square meter, the Philips monitor delivered rich blues and sharp yellows, but the display's greens were too light and its reds appeared dull. Its ability to show video was very good -- clear and smooth with no frame drops.

Loading the included Smart Control Premiere app (Windows PCs only) provides a deeper level of customization. It has the ability to change the screen's black level and adjust the gamma settings. A big bonus is that it has a series of test images that you can use to calibrate the display.

Other features

While the AOC and Dell monitors have built-in speakers, the Philips lacks speakers, webcam, microphone and USB ports. In other words, it is a display and nothing more -- rather unusual in today's market.

Its collection of input ports are oriented vertically rather than the AOC display's more convenient horizontal ports. The Philips has one DisplayPort, one DVI and one VGA port, but no HDMI port. As a result, I used its DVI input with an HDMI adapter.

The Philips does offer the best stand of the trio. With little effort, the display can be tilted forward 5 degrees and back by up to 20 degrees; it can also be raised or lowered by 6.3 in. and swiveled to the right or left by up to 140 degrees.

The entire display can also be easily rotated from landscape to portrait. This is useful if you want to work with a long document or a vertically oriented website without continually scrolling. The monitor's software reorients the image after the screen is rotated.

After pressing a button in the back, you can remove the display from the stand, revealing its VESA mounting holes. This allows it to be used with a third-party stand or mounting hardware.

Bottom line

The Philips display comes with a three-year warranty and starts at a retail price of about $260, between the cheaper AOC monitor and the better equipped Dell display. While I love the display's ability to sense when I'm working and when I'm someplace else -- and the well-constructed stand -- the Philips really needs some further refinement and power reduction before it's ready for my office.


After using each of these three monitors for several weeks, I would love an amalgam of the three that is built around the Philips adaptable stand, the AOC's power-saving abilities and the Dell's bright screen.

That said, the PowerSensor feature on the Philips 271S4LPYEB is impressive and works well, but it uses too much electricity to be of much use.

I love that the AOC E2752VH doesn't use a watt when it's asleep. At $240, it is also the cheapest to get and use, but that's not enough compensation for having the least bright monitor of the three.

The Dell UltraSharp 27 UZ2715H may not have the fastest display panel, but it is fine for business work and is the best equipped and brightest of the three -- and uses a reasonable amount of power. I wish that the stand were more adaptable, but no other screen here does so much.

3 power-sipping monitiors: Specifications


Dell UltraSharp 27 UZ2715H

Philips 271S4LPYEB

Screen size/Resolution

27 in. / 1920 x 1080

27 in. / 1920 x 1080

27 in. / 1920 x 1080

Width x depth x height (in.)

25.4 x 8.3 x 17.8

25.9 x 8.0 x 18.5

25.1 x 11 x 17.0 to 23.3

Adjustments: Height/Tilt/Rotate

No / 3 degrees forward, 17 degrees back / No

No / 5 degrees forward, 22 degrees back / No

6.3 in. / 5 degrees forward, 20 degrees back / Yes

Webcam/Microphone/USB hub

No / No / No

Yes / Yes / Yes

No / No / No

Graphics ports


VGA, 2 HDMI, DisplayPort

VGA, DVI, DisplayPort

User sensor/Timer/Software

No / Yes / Yes

No / No / Yes

Yes / No / Yes


On/Off, Volume, Menu

On/Off, Menu, Volume, Mute, Phone

On/Off, Menu, SmartImage


3 years

3 years

3 years

Direct price




Retail price




How we tested

To see how these 27-in. monitors compare, I set each up in my office for at least a week as my primary display. I used each of them to write emails, edit text, create spreadsheets, watch videos, nose around on the Web and work with interactive online programs.

After unpacking and putting each together, I spent some time measuring and investigating how each stand can tilt, raise or rotate the screen. Then I looked over the display's ports, speakers, microphone and webcam. I looked at the monitor's controls and tried out the device's features.

Then I connected each of the monitors to an iPad Mini (with an HDMI adapter), a Toshiba Radius P-55W notebook and a Nexus 7 phone (connecting via a Chromecast receiver). Each screen was able to work with each source; since the Philips display lacks an HDMI port, I used its DVI port with an HDMI-to-DVI adapter.

I next measured each screen's brightness with a Minolta LM-1 light meter using a white image in a darkened room. After measuring the light level at nine locations, I averaged them and converted the result to candelas per square meter. I then displayed a standard set of color bars and compared the three displays using an Orei HD104 four-way video distribution amplifier and a Toshiba Radius computer as the source.

To see how these monitors save power, I looked into their power conservation settings and software. I checked out how flexible the setting was for putting the display to sleep and measured how much electricity each monitor used with a Kill a Watt power meter.

Using the average U.S. price of 12 cents per kilowatt-hour of electricity, I estimated of how much it might cost to operate each monitor, based on the assumption that it was used for 10 hours a day over the work year (250 days) and was asleep for the rest of the time.

3 power-sipping monitors: Test results


Dell UltraSharp 27 UZ2715H

Philips 271S4LPYEB

Brightness (candelas per square meter)




Power use (watts): On/Sleep

27.5 / 0

23.6 / 1.1

28.8 / 2.1

Annual cost of use*




*Based on 10 hours a day per business day and 12 cents per kilowatt hour.

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Tags AppleDellphilipssharpperipheralsAOCmonitorsComputer Peripherals

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