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Power-Saving Web Pages: Real Or Myth?
An anonymous reader writes "Are dark webdesigns an energy saving alternative to a snow white Google? The theory is websites with black backgrounds save energy, based on the assumption that a monitor requires more power to display a white screen than black. Is this a blatant green washing ploy by Blackle.com, or an earnest energy saving tweak for a search tool we use every day? To find out, PCSTATS hooked up an Extech Power Analyzer to a 19" CRT and a 19" LCD and measured power draw — turns out there is a not insignificant difference ..."
"turns out there is a not insignificant difference "
Double negatives are not not bad.
If you wait a few seconds, your watts will turn into joules.
"Are not dark webdesigns an energy unsaving alternative to a snow white Google? The theory is that websites with black backgrounds don't save energy, based not on the assumption that a monitor requires more power to display a white screen than black. Is not this not a earnest endeavor by Blackle.com, or a not earnest not green not washing not not not not not ploy by not Blackle.com? To find out, PCSTATS didnt't not hook up an Extech Power Analyzer to a 19" CRT and a 19" LCD and measured power draw — turns out there is a significant difference ..."
Mine would have been shot down for being too readable though.
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Yes, anyone here actually believed this. I guess in your hurry to post, you misread the double-negative in the summary...
Note that their measurements apply specifically to the two models they tested, a CRT and a particular LCD.
If 'white' means you have to drive the LCD, then white takes more energy. If 'black' means you have to drive the LCD, then black takes more energy. Most LCD drivers are standardized, though - and given the prevalence of lighter content, it may be worth it to the industry (even if only so they can use it in marketing) to switch the defaults.
The link was to pcstats.com, which actually tested the claim. There was a ~25% difference between all-white and all-black screens on their test CRT, and a ~12% difference between the two on their test LCD.
They tested a lot more sites than just Google and Blackle.
This.
It is obvious that black is good for the earth and white is bad.
Why do you think we have climate change? Because of white, of course. No one has even heard of climate change before white messed everything up.
Not only is white bad, white is unhip. What do you want at your disco? White lights? No, black lights produce the right mood.
Let's fight the white and save the world!
No, it's not. It's supposed to make the screen feel like it has a higher contrast ratio than it actually does.... and has nothing to do with power consumption.
For large sets, this will be our guide even unto death, for the LORD will work for each type of data it is applied to...
The real power-saving web pages are simple and clean ones that that use the least CPU time to load, without bloated Web 2.0 javascript mashups of dozens of irrelevant sites and web bugs that keep track of you. TFA doesn't seem to mention that.
Unless the screen is OLED, the answer to "does dark sites save power?" is a flat out NO.
How you do figure, where's your data? Their data clearly shows that a CRT displaying all white uses 85W, and the same monitor displaying all black uses 63W, which sounds to me like it's using 25% less power to display the black screen. For an LCD the difference is only about 10%. The grayscale comparisons clearly show a relationship between darkness and power draw.
"Our two-party system is like a bowl of shit looking at itself in a mirror." - Lewis Black
The LCD they tested is also 8 years old.
I'm not saying newer LCD screens would perform differently (dynamic contrast, local dimming, etc. == marketing stats boosting and terrible) but basing a blanket statement like "B) Websites with darker colours tend to cause the monitor to consume less power." on a test with one LCD monitor is stretching it.
Firstly, I'm extremely skeptical of one of the conclusions - 'flash will make a CRT monitor use more power' - which I just don't believe - it will use an amount of power dependent on the average screen brightness - which may be an increase over black.
LCDs are different - the panel does actually take some energy to change state, and the lag compensation circuitry will use more in motion.
Secondly - a huge part has been missed out of this.
Power consumption of the computer.
Flash, or javascript, even in the background, can considerably increase power.
For example, I just closed all of the flash/animated things in the background on other tabs in firefox, and the CPU usage is now bouncing around 2%, with the computer using 17W.
If I start up a new tab with some flash, and gif animations, it goes up to 25W. (+8W)
Even switching away from the tab only takes it to 23W or so. (+5W)
It would be interesting to work out the total electricity wasted by common flash ads.
That's not so strange in electronics.
Take FETs - undriven they're fine, saturated they're fine, but the Ohmic region you typically (when using it as a switch) want to stay out of because the FET's just going to burn the excess off in the form of heat.
There's a bunch of reasons why some regions may take more energy than others. I wouldn't know what the reason is for the panel they used, somebody more intimately familiar with driver design and panel response would have to chime in.
Well, he probably wasn't aware exactly which model of monitor you had. Generalizations tend to be bad for this reason.
I, for example, have an LCD projector with a dynamic iris. It dims the bulb for dark scenes, and it is only for the improvement in contrast ratios. I know this, because it doesn't dim the bulb by decreasing the voltage over the filament, but by closing shutters (the iris) between the bulb and the LCD panel. It's described in more detail here
I don't know the full history of the feature on monitors, but I'd assume it was originally to increase contrast ratio. After one marketer slapped a "energy efficient" sticker on the box, the manufacturers realized the marketing benefit of the feature, and probably renamed the menu for later models.
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People still have CRTs?
How ridiculous.
Ability to display perfect black color;
Ability to display more than one resolution correctly (useful for games, old video card = new games at reduced resolution);
Ultrafast response time, no input lag;
Reliable and have long life (people saying things like "My LCD started acting weird, but it's 3 years old, time for a new one", while my 12 year old CRT works great), but can also be repaired if necessary (well, other than the failure of the tube obviously);
More affordable than a 24" LCD that can display 2304x1440 (if such a thing even exists);
Great image quality.
The only advantages of LCDs are size, weight and power consumption - all of these are not primary features of a monitor, at least for me (the same way that I don't buy a car based solely on the fuel consumption, or a computer based on its power consumption and size - I look for performance and cost first).
No, the big power draw is from CRT displays.
Both of them. They'll die someday and things will be nice and green again....
Back in my day the CRTs were green... or sometimes amber.
The only advantages of LCDs are size, weight and power consumption - all of these are not primary features of a monitor, at least for me (the same way that I don't buy a car based solely on the fuel consumption, or a computer based on its power consumption and size - I look for performance and cost first).
The LCD advantage that I prefer? Not irradiating remaining eye.
I feel fantastic, and I'm still alive.
Set your background to black, and all your text so it only displays half the time.
I eat only the real part of complex carbohydrates.
this is minutiae.....
3.8W is hardly a minute amount of power. If I did my math right, it's approximately the amount of power it takes to lift a full soda can (~390g) 1 meter in 1 second.
Let's say each Google query takes 10 seconds of viewing time, so you could save 38 watt-seconds per query by going black. Multiply this by 3 Billion queries per day, times 365 days/year. That's 12GWh (to 2 significant figures) of electricity that could be saved annually by changing a couple lines of code.
Power costs around $0.10/KWh. I don't consider $1.2M/year to be a minute amount of money.
Why is it that the proponents of "one nation under God" are so eager to get rid of "liberty and justice for all"?
The above post has incorrect assumptions.
Standard LCD screens do not alter the intensity of the backlight based on the information displayed on the screen, and the backlight and it's inverter is the majority of the power consumption. In addition, the drive circuit that aligns the liquid crystals can work opposite from how you expect in a TFT. Most TN screens, for example, are white or light gray when unpowered - refreshing the pixels to a black state takes more transistor drive than making the screen white. This is the technology you will find in most portable devices and computer monitors.
Some LED-backlit TVs use dynamic backlight, or even zone-dynamic backlight, where (mainly to create ridiculous contrast ratio specs) the backlight is reduced to the maximum temporal white level needed, or for multi-area addressable systems, the brightest backlight needed in an area.
The only portable devices where the brightness of the screen data is directly related to energy consumption would be those with OLED screens (such as the Samsung Galaxy SII line). The individual pixels are miniature LEDs, and when a pixel is black, they are turned off. On these AMOLED display phones, a black wallpaper can use far less power.
When I think of "power-saving webpages", I may be more concerned about one that runs my CPU at 100% for several seconds to display a page, Slashdot.