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Power-Saving Web Pages: Real Or Myth?

timothy posted about 2 years ago | from the raise-your-hand-if-you-think-real dept.

GUI 424

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 ..."

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No shit... (-1)

Anonymous Coward | about 2 years ago | (#39738293)

No shit?

Re:No shit... (3, Funny)

Jeremiah Cornelius (137) | about 2 years ago | (#39738441)

There is a not insignificant parsing complexity.

Re:No shit... (3, Informative)

QuasiSteve (2042606) | about 2 years ago | (#39738683)

I don't really see the problem with "not insignificant".

Just because something is "not insignificant" doesn't make it "significant".

Say I give you a papercut. You'll be in a "not insignificant" amount of pain.. in fact, you'll probably curse me all day long.
But it's not exactly a "significant" amount of pain either.. it's not like you're curled up on the floor begging for somebody, anybody, to put you out of your misery or at least give you an OTC painkiller.

Perhaps a completely alternative term could have been used - suggestions?
( I used 'measurable' in another post - but while 0.01% might be measurable, it but would be insignificant. )

Re:No shit... (1)

Anonymous Coward | about 2 years ago | (#39738887)

I am more likely to say 'non-trivial' than 'not insignificant.' Based on the simple scale of "undetectable trivial minor light moderate serious" which works well enough for 4 series of D&D spells. There's another step above serious, but it always has a distinct term, and uses a slightly different mechanic than the more fundamental spells. (Haha! I will cast my level 1 spell: Mass Cause Trivial Wounds! *Rolls 1d20, gets 19* ok, you feel slightly uncomfortable, no combat effect)

Re:No shit... (0)

Anonymous Coward | about 2 years ago | (#39738889)

Yeah there's a subtle difference, but it's still kindof a pain to read.

As for the project... whatever, so making an ALL black page makes a small difference in monitor power, depending on the model, for the 2 seconds you spend on any given site. Meanwhile, nobody wants to visit your awful site.

Still no compelling reason to make your site in all black... I don't care how "green" you want to be.

Re:No shit... (5, Funny)

busyqth (2566075) | about 2 years ago | (#39738459)


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!

even more savings (0)

ch-chuck (9622) | about 2 years ago | (#39738309)

s/not insignificant/significant/
will save another few picowatts drawing 6 redundant characters.

Seriously? (3, Insightful)

Cinder6 (894572) | about 2 years ago | (#39738311)

Did anyone here actually believe this? The big power draw is from the backlight, which is still running even with black pixels.

Re:Seriously? (2, Informative)

Anonymous Coward | about 2 years ago | (#39738335)

Re:Seriously? (1)

Anonymous Coward | about 2 years ago | (#39738503)

Not to mention the GP post's basic math fail. Even if the backlight (of an LCD) used a constant and "big" amount of power other components of the monitor could vary in power usage. If the values found are between 50-60W then those components could use around 10W and vary from 0-10W (or use 11W and vary from 1-11W, etc) with the backlight using the rest.

In fact the article found power consumption values in the LCD from 38.4W to 34W. Fine, the backlight uses 33W, the other components use between one and 5.4W. The backlight could use 80%+ of the power even if it has a constant power draw. Is that so implausible?

Re:Seriously? (0)

Anonymous Coward | about 2 years ago | (#39738359)

Seriously? Modern LCDs dim the backlight when the average brightness being displayed is low.

Really? (3, Funny)

Anonymous Coward | about 2 years ago | (#39738385)

Oh god. I was wondering why my screen randomly seems to increase/decrease in brightness.

I hate this feature. It makes me think someone slipped me some acid, and then I'm disappointed, because no, it's just bad attempts at saving power.

Re:Really? (4, Informative)

X0563511 (793323) | about 2 years ago | (#39738501)

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.

Re:Really? (1)

DanTheStone (1212500) | about 2 years ago | (#39738665)

.... and has nothing to do with power consumption.

Really? My external monitor at work defaulted to "Energy Smart Mode" (until I turned it off) which means "Dynamic dimming activated". I wouldn't say it has nothing to do with power consumption.

Re:Really? (1)

X0563511 (793323) | about 2 years ago | (#39738741)

I guess then it's intended to do what marketing says it is. I wonder what the actual intent was when the idea was brought to the table?

Re:Really? (4, Informative)

uigrad_2000 (398500) | about 2 years ago | (#39738883)

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 [projectorcentral.com]

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.

Re:Really? (1)

Pentium100 (1240090) | about 2 years ago | (#39738681)

It's a poor attempt at making the monitor have the same black levels as a CRT. Of course, a CRT would have the same black level whether the rest of the screen is white or black. It is not as good, but at least it is a step in the right direction. Ideally each pixel would have its own light source that is separately controlled.

Another way of achieving good contrast ratio is increasing the maximum brightness, after all, there is a large ratio between a 100W lightbulb and the sun...

Re:Really? (3, Interesting)

billcopc (196330) | about 2 years ago | (#39738871)

You should hate it. It's a shitty hack to make it look like your LCD has better contrast on paper.

I briefly owned a display like that. If I turned the dynamic contrast off, it looked washed out, and no amount of tweaking would get it looking even halfway decent. It was a shitty LCD but it was also 1/3rd the cost of my current photorealistic dazzlers.

It's the visual equivalent of the bass and treble boost knobs on cheap stereos.

Re:Seriously? (0)

Anonymous Coward | about 2 years ago | (#39738727)

I don't think it's as simple as average brightness, as that would seriously fuck up a screen of, say, 95% black pixels and 5% white pixels. I think they basically control brightness by a time-average of the peak brightness, 95th percentile brightness, or some such measure.

Re:Seriously? (1, Interesting)

idontgno (624372) | about 2 years ago | (#39738381)

I bet "Anonymous Reader", our submitter, who probably shills for "blackle.com", "believes" it.

I can't decide if this story is an intentional slashvertisement or an astroturf.

"Blackle.com"? Really? It's only slightly clever to raise the possibility that they're trying to greenwash the issue of "website-specific power consumption", especially since TFS very conveniently refutes that. ("not insignficant?" Sheesh.)

Re:Seriously? (1, Insightful)

Shikaku (1129753) | about 2 years ago | (#39738431)

Unless the screen is OLED, the answer to "does dark sites save power?" is a flat out NO.

That being said, reading white text on a black background looks a lot better on monitors because the entire background is not light emitting.

Re:Seriously? (2)

Ferzerp (83619) | about 2 years ago | (#39738497)

You realize that CRTs use less power with darker images for basically the same exact reason?

Re:Seriously? (2)

Yetihehe (971185) | about 2 years ago | (#39738607)

I like reading black on white. With white text on black bg I have afterimages of text lines and this is sometimes rather confusing when trying to read text with another line spacing.

Re:Seriously? (5, Informative)

amicusNYCL (1538833) | about 2 years ago | (#39738623)

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.

Re:Seriously? (0)

Anonymous Coward | about 2 years ago | (#39738827)

Hey idiot, shut the hell up.

Re:Seriously? (0)

Anonymous Coward | about 2 years ago | (#39738629)

"Pardon" "me"?

Re:Seriously? (2)

ColdWetDog (752185) | about 2 years ago | (#39738409)

Did anyone here actually believe this? The big power draw is from the backlight, which is still running even with black pixels.

No, the big power draw is from CRT displays.

Both of them. They'll die someday and things will be nice and green again....

Re:Seriously? (4, Informative)

QuasiSteve (2042606) | about 2 years ago | (#39738449)

Did anyone here actually believe this? The big power draw is from the backlight, which is still running even with black pixels.

Yes, anyone here actually believed this. I guess in your hurry to post, you misread the double-negative in the summary...

turns out there is a not insignificant difference

...that actually indicates that there is at least a measurable difference.

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.

Re:Seriously? (0)

Anonymous Coward | about 2 years ago | (#39738851)

My TV does this sort of thing. Depends on the screen you have.

If it has 'dynamic power' or 'dynamic dimming' or whatever they call it (turns off parts of the cfl/led) depending on how dark it is. That would save you money. If it does not have that feature you will not notice much. As on is on and 'off' is still on but a 'black' pixel turned on. The power usage for an LCD would be constant (depending on the tech). The power savings is coming from the led/cfl panels.

For a plasma I would bet the power saving isnt too bad there either.

Want real savings? Figure out what the idle off state is. Older ones can draw as much as 20W in the 'off' state. My new 55 inch TV uses less than 1/2W.

Re:Seriously? (4, Informative)

Anonymous Coward | about 2 years ago | (#39738451)

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.

Re:Seriously? (0)

Anonymous Coward | about 2 years ago | (#39738471)

yes for those few people that still uses CRT theres a slight difference, for LCD the black light is always on so no difference
though there are LCD TVs with back light as a grid of LEDs that can dim individually to increase dynamic range

Re:Seriously? (1)

Xeranar (2029624) | about 2 years ago | (#39738577)

I've never understood this argument they had about black bakgrounds. The backlight is always on and hence why we should all be using LED or the newly available translucent monitors that use ambient light. I think the myth is due to our perception of light & dark. We fail to understand black on a monitor is a lack of color and an absorption of all light but the backlight as stated operates independently of the display's image.

Re:Seriously? (1)

Pentium100 (1240090) | about 2 years ago | (#39738595)

No, the power draw is from the heaters and the deflection circuitry, but each gun that is turned on at full intensity also adds to the total (that's why full screen yellow uses more power than full screen red or green).

Re:Seriously? (5, Insightful)

dinfinity (2300094) | about 2 years ago | (#39738635)

The LCD they tested is also 8 years old [google.com].

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.

Re:Seriously? (1)

Joce640k (829181) | about 2 years ago | (#39738729)

Did anyone here actually believe this?

I dunno...but I DO know my eyes are funny for a few minutes after I try to read any amount of white-on-black text - it causes massive afterimage.

(Yes, I have the "nostyle" Firefox plugin to deal with these websites)

Re:Seriously? (0)

Anonymous Coward | about 2 years ago | (#39738749)

How 'bout reading TFA?! On an LCD it's not relevant, but it *is* on a CRT.

        19" CRT ADI Microscan 19" LCD Samsung 192MP
Google.com 83.5 Watts 38.6 Watts
Blackle.com 65.8 Watts 34.8 Watts
PCSTATS.com 76.2 Watts 37.8 Watts

Yup; But don't start me on ads (0)

Anonymous Coward | about 2 years ago | (#39738759)

I monitor the electricity my 46" LED TV uses (even in it's most power saving mode). Dark scenes use about 20 watts, white scenes use the full 54 watts. Never actually measure my X220i ... dammit. I did it for charging, using while charging. I use much less power when the notebook is permanently plugged into a power source.

The big thing with web pages though are the fucking ads. Some of them make a cpu core shoot to 100% and stay there.

Re:Seriously? (1)

tlhIngan (30335) | about 2 years ago | (#39738787)

Did anyone here actually believe this? The big power draw is from the backlight, which is still running even with black pixels.

Actually, it can. Modern LCD displays are crap at this - they employ crap like "local dimming" and "global dimming" to get their stupid contrast ratios. As a side effect, displaying a dark screen does save power because the backlight dims to make the black blacker.

Conversly, displaying a white screen cranks up the backlight to make it brighter, which takes more power.

Since contrast ration is the difference between darkest black and brightest white, this artifically inflates the number. Some monitor specs actually list "dynamic contrast ratio" for this, but it's usually listed as "contrast ratio".

And yes, it's crap. It makes dark images harder to look at because the stuff you want to see is dimmer. And dark stuff on a mostly white screen is harder to look at as well from the retina searing brightness. In an effort to increase global contrast, they reduced local contrast.

Fun fact: a modern TFT display is really like DRAM memory - you have a transistor and a capacitor (the pixel). The only difference is an LCD is write-only electrically, and read-only optically.

If you calibrate your monitor, the first thing you do is turn off auto-dimming because it'll screw up your calibration.

Re:Seriously? (1)

tlhIngan (30335) | about 2 years ago | (#39738833)

Other thing... white on black is hard on the eyes because of "black creep". If you're a typesetter, you know this - if you have light text on dark background, you have to increase the siez of the text in order to keep its apparent size the same. Also, thin fonts sink, so you may have to apply bolding to "fatten" them so they're still legible when the black background slims them down.

Re:Seriously? (0)

Anonymous Coward | about 2 years ago | (#39738841)

Ancient shit, being regurgitated. Do it on a plasma and you'll save power. LCD no fucking chance.

Watts aren't a unit of energy. (0, Informative)

Anonymous Coward | about 2 years ago | (#39738317)

The article is about the energy efficiency of various webpages. The only problem is that all the numbers are in Watts.

Re:Watts aren't a unit of energy. (-1)

theNetImp (190602) | about 2 years ago | (#39738469)

Watts are calculated using Voltage and Amps therefore it is a unit of energy.

Voltage mutiplied by current in Amps equals Watts.

If it weren't a unit of energy why on earth is that how people for the last 100 years have chosen their lightbulbs when they want to save "energy".

Re:Watts aren't a unit of energy. (0)

Rhywden (1940872) | about 2 years ago | (#39738511)

By that line of reasoning, Voltage is also a unit of energy.

Re:Watts aren't a unit of energy. (0)

Anonymous Coward | about 2 years ago | (#39738715)

Voltage is a unit of energy (potential)...

Re:Watts aren't a unit of energy. (1)

Matt_Bennett (79107) | about 2 years ago | (#39738647)

Watt is a unit of power, energy is the integral of power over time. A common unit for energy is the Joule. Measuring power is a complex task (both the mathematical and figurative use of complex).

Re:Watts aren't a unit of energy. (1)

ninjackn (1424235) | about 2 years ago | (#39738755)

Watts is a unit of power. Multiplying voltage by current gives you power. Multiplying time by power gets you energy. More precisely integrating power over time gets you energy because power might not necessarily be constant over the duration of time.

It works for light bulbs because you assume a lot of things. If we were a more scientifically inclined society then light bulbs would be measured in Watt-hours and not watts. Light bulbs are mostly linear regarding their power usage which is why a 60 watt light bulb that runs for an hour uses less energy than a 120 watt light bulb ran for an hour.

Re:Watts aren't a unit of energy. (1, Informative)

Xeranar (2029624) | about 2 years ago | (#39738655)

Think of electricity as waves crashing against the beach. Amps are how tall they are, volts how many are arriving in a frame of time or frequency. Watts is a measurement that gives a volumetric answer to power usage. It's a perfectly valid way to measure since we pay based on wattage per hour.

Re:Watts aren't a unit of energy. (2)

capnchicken (664317) | about 2 years ago | (#39738687)

the difference is just 17.7W and 3.8W for CRT and LCD respectively. What that adds up to over the course of a year, for every second you spend doing a search on Google is anyone's guess.

That was my favorite part. I'm guessing they just hooked up a some kind of Kill-A-Watt given that:

PCSTATS has an electronic power meter which can actually measure the amount of energy it takes a monitor (LCD and CRT) to display any given website, we've actually got a valid set of criteria to look at.

Never mind the nomenclature, there is cost forecasting on those devices, and given a few basic parameters you could figure out the cost per year searching Blackle rather than Google on the back of a napkin, so its not "anyone's guess".

price_per_killowatt_hour: $0.10
hours_searching_google_per_day: 2 hrs
watts_saved: 17.7

hours_searching_google_per_year = hours_searching_google_per_day * 365
kilowatthours_saved_per_year = hours_searching_google_per_year * (watts_saved / 1000)
price_saved_per_year = kilowatthours_saved_per_year * price_per_killowatt_hour

Which comes out a little over a buck twenty five for a CRT and more than a quarter per year on an LCD using those parameters for one person.

Blackle seems all well and good... (1)

dmacleod808 (729707) | about 2 years ago | (#39738323)

Can I do an image search or a news search right from the home page? I am not sure if Google Custom Search supports these features beyond a simple web search.

Re:Blackle seems all well and good... (0)

Anonymous Coward | about 2 years ago | (#39738379)

Firefox + Stylish Add-on + Google Dark Theme (Web/Images)

God is my salvation. (-1)

Anonymous Coward | about 2 years ago | (#39738333)

Turn to God and be at peace.

Read and be healed.


Re:God is my salvation. (3, Insightful)

gmuslera (3436) | about 2 years ago | (#39738523)

That is ontopic. You try to read that page, then turn off the computer and leave internet for a few days. That is really power saving

Double Negative (5, Funny)

Anonymous Coward | about 2 years ago | (#39738337)

"turns out there is a not insignificant difference "

Double negatives are not not bad.

Outdated... (0)

Anonymous Coward | about 2 years ago | (#39738343)

TFA is super old...live.com hasn't been a search engine since Bing was introduced in June 2009.

OLEDs and readability (2)

zaibazu (976612) | about 2 years ago | (#39738349)

I am interested in black background websites because they look prettier on OLED displays (Old Samsung Galaxy here as a reserve phone) . Readability should be driving the decision on the colours, not some % power saving.

So the answer is... (3, Insightful)

fropenn (1116699) | about 2 years ago | (#39738373)

buy an LCD (or LED) screen. That will save much more electricity than changing the colors you use on it. I can never figure out why so many energy saving tips focus on such small things (e.g., turn off the water when you brush your teeth) but ignore the big issues (like my neighbors who water all afternoon in 100 degree heat and have a stream of water running directly into the sewer).

Re:So the answer is... (1)

Eponymous Hero (2090636) | about 2 years ago | (#39738545)

we get your point, but advice about not watering in the afternoon is almost always on the same list as turn off the water when you brush, along with sweep your driveway instead of hosing it down and wait til your dishwasher is full to run it.

Re:So the answer is... (1)

idontgno (624372) | about 2 years ago | (#39738549)

The time-honored metaphor for this is "carefully arranging the deck chairs on the Titanic as it sinks." We can fiddle trivial stuff and satisfy ourselves we're "DOING SOMETHING FOR <great cause>" while not actually changing the costly, momentous, or personally-significant things.

See also Matthew 7:3-5 if you're not opposed to Biblical proverbs.

Re:So the answer is... (1)

TheCarp (96830) | about 2 years ago | (#39738571)

Well if you already did that....

Frankly, I wonder why they didn't test the one thing I do as soon as I get a new LCD, which is actually recomended by several sites out there.... turn the brightness down to under 20%, sometimes, I go all the way to "0" (interesting that 0 brightness is not a black screen).

As an N=1 test, after realising that I couldn't easily tell the difference after a minute or two, was to take one of the most observant and territorial about her PC people I know, and changed the brightness all the way down while she was away.... just as I expected, she didn't even notice. I eventually told her she had been using the display with the brightness all the way down, she had no idea.

So I agree with all the people who say turn it down.... really, your brain will adjust the white levels on its own just fine.

Then... well... I like a black google...and any other site I can get. Not because of power savings but just because I always prefered dark backgrounds with light text on screens.

OLED's (3, Informative)

imgod2u (812837) | about 2 years ago | (#39738387)

The idea is valid for all of the smartphones running OLED displays. OLED's take no power (or very little) to display a black pixel. It takes full power to display white.


RedACE7500 (904963) | about 2 years ago | (#39738393)

Power is more of a concern on mobile devices and mostly dark/black displays will allow AMOLEDs to turn off some pixels to save power and extend battery life.

Off the top of my head... (0)

Anonymous Coward | about 2 years ago | (#39738395)

seems like a funny question, but my guess would be dependent on screen time:

A) CRT - white requires more than black (black pixels have no electron hitting them)

B) LCD - black requires more than white (black pixels require a stimulated liquid crystal to darken and block the backlight)

C) OLED - white requires more than black (black pixels are actually "off")

D) LED backlit LCD - white requires more than black (white pixels require corresponding backlight LED to illuminate)

And in all cases, with the possible exception of LED backlit, I'm going to guess that this accounts for little-to-no effect on the overall draw of the monitor.

Oh comeon... (0)

Anonymous Coward | about 2 years ago | (#39738405)

turns out there is a not insignificant difference ...

Did some one seriously write this? Or did slashdot's queue automatically translate it from English to stupid? Why even employ editors?

interpretation? only 17 w (0)

Anonymous Coward | about 2 years ago | (#39738423)

Sigh, find authors' schools, request revokation of diplomas. They say "only 17W" difference for the CRT -- that's 17 out of 85! which is 20%-- that's enormous when integrated over a large number of displays. The LCD difference is smaller but still potentially signficant. That being said, there are probably better places to hunt down 17W savings.

I should have submitted this too... (5, Insightful)

dyingtolive (1393037) | about 2 years ago | (#39738425)

Except I would have said

"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.

Printer Ink (0)

Anonymous Coward | about 2 years ago | (#39738447)

Think of all the wasted energy from the fact that everytime you print, you will need an entire printer cartridge!

drive 1% less (0)

Anonymous Coward | about 2 years ago | (#39738473)

try driving 1% less that will make more difference.

infact drive 20% less. then you might make a useful difference. also have a look at this (free) book http://www.withouthotair.com/Contents.html . it has a good explanation as to why the 'every little helps' motto is nonsence.

Only Applies to OLEDS; Reduces Readability (0)

Anonymous Coward | about 2 years ago | (#39738491)

First, as other commenters have already pointed out, this only applies to OLED and CRT monitors. Secondly, I would much prefer to have readable text than to save 5 minutes of battery, or to prevent half a gram of CO2 emissions.

No one ever said it did (1)

auntieNeo (1605623) | about 2 years ago | (#39738495)

Even when Google first did this, they had a disclaimer that said that black web pages don't really save power. It's just an awareness campaign. This is not news.

Real and myth... (0)

jedirock (1453977) | about 2 years ago | (#39738505)

It's real for CRTs (why do we still test these anyways?) and OLED screens. It's a myth for LCDs, including those "LED" screens everyone's touting nowadays. CRTs and OLEDs do take more power to display a white pixel because of the way they work. LCDs depend on the backlight to produce a visible image, and the backlight is always on. The only use case where the LCD had lower consumption was a totally black screen and with HardOCP: dark enough to trigger the darkening of the backlight in "dynamic" contrast (which is a farce anyways). Turn off dynamic contrast, and suddenly there will be no power savings. This isn't a story...

Re:Real and myth... (0)

Anonymous Coward | about 2 years ago | (#39738813)

It's a myth for LCDs, including those "LED" screens everyone's touting nowadays

They tested it, they showed a difference. As far as I care, it does make a difference unless another test shows something different. In that case, we need more tests.

CRTs? (0)

Anonymous Coward | about 2 years ago | (#39738513)

People still have CRTs?

How ridiculous.

The reason the CRT draws more power on a white screen is because to get a dark screen, it has a little control grid (well, actually, in a CRT it's more like a little bass drum with a pinhole in it).

With the control grid negative about 20 volts, that stops the flow of electrons to the currently addressed point on the screen. No current means no power wasted.

On the other hand, most flat-screen displays have a backlight that's always 100% on all the time, and the LCD pixels block the light as needed. The LCD pixels are flipped on and off by a very small control current, much less than the backlight current, so a LCD is going to show very small differences between a black and a white screen.

So the reasons for the results are obvious.

A better question is, should we care? The difference is only a few watts, even for a CRT. And if you want to make the difference even smaller, just turn down the CRT brightness. Or if the CRT is getting old, as most of them are, it might make energy sense to toss away the CRT and get a more efficient display.

Webpage almost crashed IE8 (3, Interesting)

cpu6502 (1960974) | about 2 years ago | (#39738527)

Maybe PCstats should apply their own power-saving strategies to themselves (less CPU-intensive flash crap).

Anyway it appears only the CRT has a significant savings with White google versus Black blackle.com. LCDs gain almost nothing.

For one person, no - but... (1)

bigattichouse (527527) | about 2 years ago | (#39738529)

I'm not really double checking my #'s here....

1 billion queries per day in 2011 (quick online search)... lets say that 1 user makes 100 queries/day (so 10 million users) and each query takes about 10 seconds to complete. 100 million seconds burning 4 watts yields 400 megawatts per day. If we average that out per hour, then we're burning 16 megawatts per hour 24/7. Each day, enough to power 8-16 households (1000-2000kwh) for a month... so over a month: 240-480 households with pretty wasteful practices.

SO, yes, 4 Watts isn't much to an individual household - but aggregated, 4 watts is a lot.

I'm finally green!!!! (2)

crazyjj (2598719) | about 2 years ago | (#39738537)

Yay! My Black Sabbath fan site is one of the most environmentally-friendly sites on the internet!!

So do I win some kind of a prize? (1)

KlomDark (6370) | about 2 years ago | (#39738543)

I've been running MessageBase [messagebase.net] with a black background because of this exact reason since the late 1990s. Everyone told me it was a stupid idea and the power savings were negligable.

Think of all the power I've saved people! I've done my part.

Re:So do I win some kind of a prize? (0)

Anonymous Coward | about 2 years ago | (#39738739)

Think how much more power you would save people by shutting the site down!

Their own number don't even agree... (1)

fahrbot-bot (874524) | about 2 years ago | (#39738567)

In the "Black & White" table they list white at 38.4 W, then in the "Greyscales" table list 0% grey (white) at 40.0W and 60% grey at 38.5W -- all for the same 19" LCD Samsung 192MP monitor showing a full-screen solid color. For fluorescent back-lights, I can't imagine the power usage to be that different for just toggling the LCD cells, but can for an LED back-light, where there are grids of LEDs that may be powered down/off for a more true "black".

Grey levels? (2)

Shagg (99693) | about 2 years ago | (#39738585)

Anyone else notice that (further down in the article) they measured 6 different levels of grey between 'white' and 'black', and 4 of the levels of grey actually measured MORE of a power draw than pure white on the LCD monitor?

Re:Grey levels? (1)

Hentes (2461350) | about 2 years ago | (#39738797)

Shadowing the backlight consumes some power in LCDs, except if the part is dark enough so they can dim the light in that sector.

Re:Grey levels? (4, Insightful)

QuasiSteve (2042606) | about 2 years ago | (#39738853)

4 of the levels of grey actually measured MORE of a power draw than pure white on the LCD monitor?

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.

The real power-saving web pages (5, Insightful)

ortholattice (175065) | about 2 years ago | (#39738617)

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.

Organic LED (0)

Anonymous Coward | about 2 years ago | (#39738641)

When people have monitors that use organic LED's then it will make a bigger difference. It will also extent the operating lifetime of organic LED's.

What about the CPU? (4, Interesting)

queazocotal (915608) | about 2 years ago | (#39738671)

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.

Mobile Applications (2)

DontLickJesus (1141027) | about 2 years ago | (#39738673)

With recent changes in browser specs to allow for monitoring of battery levels, I've really taken an interest in this debate. Consider a web based application which has a critical function to complete, yet the battery is dying. Said application could switch it's color scheme to something darker in order to conserve battery and allow that function to complete before draining the battery. It's an edge case scenario, but mobile apps offering a "low power" mode would be a great way to promote usage.

AOL (0)

Anonymous Coward | about 2 years ago | (#39738691)

I expected AOL to suck more energy.

What about the rest of the computer ? (3, Interesting)

Alain Williams (2972) | about 2 years ago | (#39738765)

It would have been interesting to include the whole computer in the power measurement. How much more electricity is drawn by a javascript infested site than one that is just static HTML and images ? How much more is drawn if there are 100 components to build the page instead of 20 (don't forget to include the consumption of your broadband modem, etc, ...) ? How much more electricity does flash use ? How much more through heavy use of AJAX ?

The biggest difference that they showed was that the use of a glass monitor was about double that of a LCD. With an LCD the CPU/... consumption would be a bigger fraction of the whole thing.

Depends on your definition of significant (1)

Hentes (2461350) | about 2 years ago | (#39738849)

A 11% difference between full white and full back is more or less insignificant to me.

I could save $0.18/mo (1)

Anonymous Coward | about 2 years ago | (#39738877)

3.8 Watt * 12 hours / 1000 (watt per kw) * 30.5 days/mo * $0.13 /kWh = $0.18/mo

Yippie. Where can I spend this enormous bounty?

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