As noted, an all white web page uses about 74 watts to display, while an all black page uses only 59 watts. I thought I would do a little math and see what could be saved by moving a high volume site to the black format.
Take at look at Google, who gets about 200 million queries a day. Let's assume each query is displayed for about 10 seconds; that means Google is running for about 550,000 hours every day on some desktop. Assuming that users run Google in full screen mode, the shift to a black background [on a CRT monitor! mjo] will save a total of 15 (74-59) watts. That turns into a global savings of 8.3 Megawatt-hours per day, or about 3000 Megawatt-hours a year. Now take into account that about 25 percent of the monitors in the world are CRTs, and at 10 cents a kilowatt-hour, that's $75,000, a goodly amount of energy and dollars for changing a few color codes.
[ed. This got Dugg. The link to the wattage for different colors is from EnergyStar.]
[ed. There's a follow up as well.]
[ed. And now there's a FAQ too! 7/28/2007.]
[ed. OK seriously, this is the definitive piece on this, very long Wiki-esque post that covers everything to date. 8/6/2007]
it is also a lot easier on the eyes I use stylish an extension for firefox to change a lot of websites to black or darker colors at least
Fell free to digg it to the front page of digg:
You'll find a lot of pages out there that claim "many studies have shown ... that dark text on light background is easier to read". I have always suspected that this is due to the historical accident that physical writing works best with dark ink on light paper-ish stuff. I wonder how many of "those studies" studied populations that grew up unbiased -- i.e., grew up and learned to read without the historical accident of paper-based (dark on light) reading.
This is a very interesting fact. I never thought a simple change would make such a big different. Thanks for the sharing.
Only CRT displays use more energy to display brighter things. For everything else, it is completely false that a black display uses less energy than a white page. The backlight on an LCD is on for the entire LCD regardless of what is being shown. The black pixels are only black because the LCD blocks out light. Same with projectors, etc. You're article is thoughtful, but invalid.
This may be true for CRT monitors. But, LCD monitors use significantly less energy and I don't think their wattage varies much depending on the colors displayed.
thanks for responding on the LCDs. So it would seem that it applies for CRTs, but not for LCDs. Does anyone know the percentage of CRTs in use worldwide?
Something to consider: If Google were to change the color scheme to all black, Google would loose AT LEAST 50% of its user base (dare I say 80%?). The "tech Elite" could find work arounds such as using Firefox extensions (Stylish or Greasemonkey), but the vast majority would just switch REGARDLESS of the fact that functionality remained the same.
All the money Google would be saving people (assuming the accuracy of this article) would be guzzled in the end by Google's competition: Yahoo And Microsoft have lots of white on their search pages.
Fact is, this entire idea of Google saving energy by switching to "black" would lose GOOGLE money, and not be much better energy wise at then end. Not only will it never happened, but even if it did no good would come of it (for anyone).
--Jon Z | http://www.jzencovich.com
I concur that the power draw of LCDs doesn't change much when the image changes. A black Google might save some energy, but eliminating CRTs would save far, far more. Fortunately, CRTs are fading fast; almost no new systems are sold with them.
Well those comments prior to mine may be true, it is also possible for Google to allow us to customize what colours we use. This could be adding a few scripts to the homepage. An extension to Firefox or IE may achieve the same effect.
As shown on the link, white backgrounds uses the most energy (on CRT's). A silver or gray uses 7-12 Watts less, and even if it seems minisucule, it would still play a factor in the long run in the long run.
However, probably a easier method to save energy from monitor use would be to switch to LCDs or just advising people to lower the brightness/contrast of their monitor.
I think it's important to realize that Google wouldn't save any money... would likely lose business - and why would Google do this?
If everyone one on the planet had access to the internet and everyone on the planet used a CRT, this would not even equal one cent in personal savings.
thanks for the comments, there's a lot of good points here. I'm going to bed but will track down the 'rest of the story' tomorrow.
Many posts have stated that this would not save energy on lcd displays and this is true for most existing lcd displays, but newer lcds that use dynamic back lighting could to for enhanced contrast and better display of darker color schemes could also benefit. LCDs like the newly announced Samsung 275T & 245T would probably use less electricity if google used darker colors.
LCDs use an energy efficient fluorescent back light, how much energy would be saved if all CRTs were replaced with LCDs?
You may be right about the black google energy saving thing. But google doesnt pay for the power used in the monitor, whoever owns the monitor pays the bills. So google wouldnt really save anything.
your numbers are flawed. Many google queries are made by methods other than the text area on google.com
Why so much white on your site?
Why do some think that Google would lose swaths of their audience just by switching over to a black background? Are they suggesting that most people are so shallow that they care far less about the high quality of search results that Google tends to provide, and more about superficial reasons like the site's appearance?
It will actually require more energy (a minuscule amount) to display a black page on a LCD monitor. Liquid crystals BLOCK light from the lamp if a current is applied to them, although the lamp is always on regardless of whether you display a block or a white page.
That could fund 2.5 trips back to 1955 in my time machine
on the right track.. but you're going about it all wrong.. taking into consideration that CRT's would only benefit from this, then quite possibly TV commercials, events, news broadcasts, etc. should all start using darker colors/themes..
For example, those 3 seconds in every Gieco commercial at the end when they show their logo, there's a completely white background.. if they changed it to black $ millions would be saved! :)
furthermore.. CRT based TV(there's still a LOT of cheapo ones being sold and currently used) use FAR more electricity than computer based CRT(puny 15-19" monitors) as opposed to 21, 27, 32" or bigger..
you would think something as simple as this the government would have posed into some sort of energy bill/plan and put into effect as a requirement for every TV station(or at least the main broadcasters).
This is all nonsense. LCD screens (uased by over 95% of computers) use a permanently on backlight --- their energy use is constant whatever the screen colour. Therefore black or white, there would be no difference.
With plasma screens and CRT on the other hand, the energy use would fluctuate as these technologies activiate or not each individual cell. Therefore, for darker images they use less energy. Unfortunately for your theory, hardly anyone uses CRT or Plasma as PC monitors...
i don't see how a black Google would lose googlecorp money.
other options would include an alternate website (a la black.Google.com) or personalizations...
Has anyone considered getting a google employee in on this? I mean, all Google employee's get a Friday to do their pet project. Thats how Google Mail, Book search, Code search, etc., were all created. Why not ask somebody there to do it on Friday and pitch it to their bosses with all the relavent arguments? Nothing wrong with taking the direct route.
im currently looking for lcd monitors, want to repalce my old crt but one thing that ive noticed on lcds is that the text seems to appear distorted.. anyways intersting fact.
hmmm...interesting idea...i wrote up a similar idea for JetBlue airline. I was on an evening flight from boston to las vegas, half the seats were empty, i took a picture from the back fuselage of ALL the monitors blasting light all over the place, this was a 7 hour flight, ...that sure is a TON of wasted light and energy for no one to use... these screens are mega hot when "ON" and very cool to the touch when "OFF"...my question was...instead of having the screens "ON" for default, make it "OFF" and make the customers turn on the screens. People can tun the screens off manually, but trust me, no one knows how. If this change was made, Jetblue airlines would save some MUCHO Energy and money..anyone know someone at JetBlue please..
Pictures and rest of story:
Want to petition this?
Thank you for all the comments. I wrote them up in a subsequent post.
An interesting idea ... and here I was using black for my site and the google search results because I thought it looked coo.
Pues ya puedes empezar por cambiar el color de tu blog y predicar un opoco con el ejemplo.
There is a great greasemonkey script for this if anyone is interested
So I tried it:
I have an Acer 24" AL2423 monitor and a KillAWatt P3 Energy meter. I plugged the monitor directly into the meter.
I opened two tabs in firefox: the original google page, and one of the "Dark google" variants that a bunch of people have linked to (same as original, but black background). I maximized the browser window. and brought up the original google page:
I watched it for a minute and it didn't change. I then switched to dark google:
Again, this was a stable reading. Switching back and forth between dark and light reliably changed between 64 and 65 watts.
Hi Mr. Snrub,
thanks for actually doing some numbers. So, white is 65 watts, and black is 64 watts, a small penalty for black. Fat Knowledge reported 83 vs 60 (white vs black) watts for a 19 inch CRT, and 35 watts steady for a 19 inch LCD regardless of color. If this is true, them LCDs monitoris essentially fall out of the equation, and we are back to the all black background.
i guess the same idea could be applied to the google searchbar option that i use on my firefox web browser.
Saving power... YES
Counts for most sites these days, White/bright colors is the trend.
I think that iof you would change all websites from white to black that you would get a lot of depressed people in the long run
Metasearch engine Ixquick.com does have a very fashionable dark homepage for years already, and a lot of people do like it...
More important people can search in privacy with Ixquick, The search engine deletes the user related data like IP-address within 48 hours, guaranteed!
More about privacy and Ixquick on: http://eu.ixquick.com/eng/protect_privacy.html
So you're wasting my money, with a white background ;) haha
Isn't it a fact that your eyes need a bit more time to adapt at a dark screen? When you take this exces time in account, would really saved power??? Maybe it would take even more power to use a dark screen. At least this should be researched before can be said that a dark google screen can save power / money.
Very good point, Pjotr. In fact, every time people come up with these statistics about minute differences multiplied by millions, they forget that on such a scale there are gazillions of other minute differences on the same scale you can't possibly take into account. One of them is indeed the fact that people would probably spend slightly more time looking at the displayed page. But there's no telling how the mood-change of a black page influences the rest of the user's browsing session. Again a normally neglectable difference, but not when multiplied by millions.
Another much more concrete influence though, and this is forgotten almost every time "energy waste" is calculated, is that this extra power consumed by the monitor, is eventually transformed into heat which, if you have a thermostat in the same room, is deducted from the energy use of your heater. You won't notice this on either your gas bill or electricity bill of course because the differences for one person are too small to notice. The point is, that even multiplied by millions, these and other factors will continue to cancel each other out in a way you can't really predict.
All this may seem nitpicking, but the real point is that you can't just take a single neglectable difference, multiply it on a huge scale and think that you know the total effect. The world simply isn't that simple.
Use the energy for the Science.
Mark - Please clarify: Why does your headline read Google would save 750 MWh per year, but in your article it says they'd save 3,000 Mwh?
the math was wrong in the original post because I didn't take into account the LCD monitors out there. Since about 75 percent of the monitors in the world are LCDs, I had to reduce the figure accordinly. Still a hefty number though, and that's just for Google.
FYI, there is a pretty nice "black google" page at http://www.jabago.com. The search engine on this page is run by google, but the format is customized to display with light text on a black background to be easier on the eyes and save engergy.
You can use:
If you want to search Google and have the results show in black.
You can easy do it with Opera browser : view/style/High contrast (W/B)
First: brightnss does matter on LCD's, so black beats white:
Secondly, I suspect your readership is overestimating the ratio of LCD's in use globally.
Maybe LCD's represent 75% of the installed market in the US (which I suspect is an overestimate too because a lot of corporations use very old computers) but the rest of the world (especially the 3rd world) does not replace *stuff* anywhere near as often.
thanks for posting. Actually the link in the articles has it broken out by country, so 75 percent LCD penetration is correct for the world.
Another factor to consider is eyestrain and legibility for those with visual impairments. Studies in the vision field have found that a dark background with high contrast text is the easiest to read in general.
Mac users try http://nicemac.com
Saves Energy and is easy on the eyes too!
Hello all, I made some measurements. I have a Dell 21inch "UltraSharp" LCD screen. For a white google screen it consumes 45W. For a black google screen it consumes 43W. Measurements were made with a Kill-a-Watt device. So, it appears to me that there *is* a possible savings for LCD as well as CRT screens.
What you have forgotten to tell: white letters on black paper (screen) are worse for the eyes, because more concentration is needed. So you have to do some more breaks in which the PCs and maybe also the screens consume energy.
You can search in spanish language saving energy in http://www.negroogle.com, or in german language in http://www.schwarzoogle.com
Way to go dude. I really think that people think that it is a big thing to change, but it really isn't that hard to make change. Thanks for your concern. By the way, please visit my blog, blueutah.blogspot.com, it has to to with the same thing.
Blackle is a copy of the main page of:
which has offered google search in many colors since a long time.
Sanjay John G.
I have to admit, I cant stand back backgrounds. Lighter shades are the way to go in my eyes.
gracias por tu trabajo, y tu google negro, lo tengo como pagina de inicio.
Information on white back ground can be found easier than the information on the black ground. Again, here comes the time to read the things.
In short, what I mean is:
If People take 2 seconds to get their information on the white background. It may take 4 seconds for them to get the same information on the same pages with a black background.
So, ideally, I don't think it saves power. May be CRT usage is more nowadyays but they are reducing at a very very faster pace. So, end of the day what I have to say is, very good finding but not perfect.
I am happy that google had responded to this article by Blackle.com.
Great article. Like the thought process. :)
Lets c how far n wide it reaches.
Does somebody have data around what would be the power consumption on LCD monitors for different colors?
How about turning off the monitors when not in use? Won't that save a lot more? (unless you are on the machine 24 hours a day).
the white pages even strain the eyes searching on the black pages it is so comfortable to search now
i think all the sites should adopt this technique
As has been said earlier it is only relevant for the older CRT monitors.
In any case reading on a well-lit white background is in fact easier on the eyes.
i m setting my home page to blackle
I used a power meter to confirm that there is a slight INCREASE (of about one watt) in the energy required for the black background on my 19 inch LCD. I believe the extra energy goes into blocking out the backlight.
Obviously you don't know about http://www.ninja.com/
Its a great research and it looks koool in black !!!!!!!!!!!!!
I am not sure that the change in color efect the wattage.
google black would be great!!
Even http://ninja.com has got black version of Google. :)
This is a great finding. I have changed my homepage to black google already!
Good idea but I don't think this can become a reality.
A New Darker Google - http://dark.alfredfox.com
This is really a brilliant idea. I think whoever proposed this we should give all the awards available for Energy Savings in World.
See blacklys.com - The Black Google
They have a firefox Search Extension too.. Interesting..
Just add the advanced search tools and those radio buttons for the local queries and it'll be PERFECT!
keep on going:)
Muito boa a nova versão preta do google!!
cansa menos as vistas... Já sou adepta da versão!!
Flávia - Belo Horizonte - Brasil
yeah nice idea - would have been cool 5 years ago - but it's only useful for CRT monitors which is only about 25% of displays and dropping these days as most user are using LCDs, and as there is no energy difference between white or black it's not quite so cool..
It is true that the backlight in a LCD is always on. This accounts for most of the power consumption of a LCD panel. It also does take energy to turn the pixels on or off selectively (to form a picture).
There are two different modes of operation for a liquid crystal display - normally white or normally black. This determines whether a powered pixel will be dark (black) or bright (white). Either mode is used in displays depending on how the manufacturer designed the display. The technical difference between the two modes depends on if the polarizers in the display (which all displays contain two of) are parallel or perpendicular.
As such, some displays require power to display black pixels and others require power to display white pixels. Thus, if google were to change to a black background, some displays would consume less power while others would consume more. On the balance, this means there is no significant power savings to be had by switching to a different background.
I have an old Apple Studio Display running off a Lab supply.
It consumes 0.06 to 0.09 watts MORE displaying a full black page compared to displaying a white one.
I do loaded up both the Google and Backle page and flipped tabs between them, watching the ammeter.
The biggest difference in power consumption came from turning the back light brightness down. The minimum power consumption at minimum brightness was less than half that when the brightness was wound fully up.
Far more power would be saved by working in a darkened office!
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