I heard that this makes no difference for LCDs. Blackle is meant for CRTs.

timerider42

I read TFA. AND the study they cite. Blackle's claims are specious at the best, and completely wrong at the worst.

There's a difference of 1-3 watts for LCDs using a full white and full black screen. See "Table 8. Variation in Monitor On Power (W), for Selected Monitors" on page 19: [enduse.lbl.gov]

They conclude:

Among the few LCD monitors in the table, the power used to display a white screen is indistinguishable from power used to display the desktop.

So my take is that Blackle is a nice way to feel good about saving the environment without actually doing anything significant or sacrificing much besides legibility.

see also: the Blackle wikipedia entry [en.wikipedia.org] which details the criticism in greater depth.

The gist is:

However, the power consumption difference between Google and Blackle on all 23 LCD monitors was as small as you could get - an increase of 100mW (0.1Watts). So after all that testing, we're in a better position to say that anyone else that Blackle makes next to no difference, on average, with LCD monitors.([techlogg.com])

wlcrm

IT saves my eyeballs and makes my room darker :)

StackyBotrus

Actually, it depends on the LCD. If the polarizers of the LCD are parallel, then the LCD is "twisted" to show black (i.e., "ON"). If the polarizes are perpendicular in orientation, then to display white, they have to be "ON". Anyhow, LCD cells themselves are like DRAM memory - they take very little power anyhow.

The big power savings comes from the backlight, so displaying black on a recent LCD (with the super-high contrast ratios) can save power. This is because these LCDs detect you're displaying a dark image, and dim the backlight appropriately. (Advanced LED backlit models can dim regions of the screen). This is done to artificially inflate contrast ratios.

There's no standard in measurement, so manufacturers take the brightest white they can display (backlight max + white image), and the blackest black they can display (black + dim backlight), and that's the ratio. They then put in circuits to do it automatically so it isn't considered "cheating".

Dimming the backlight can save quite a bit of power. If your monitor does this (you should disable it if you game, for it can make dimly lit areas even HARDER to see)

For CRTs, it's a more interesting issue since the electron guns don't take much power at all - most of it goes into the deflection circuitry, and power savings - the guns themselves take constant power - the brightness of the pixels is done through a grid electrode that regulates the number of electrons passing through.

If you want to save real power - plasmas could benefit, since it does take a lot more power to display white than black (you have to excite all those pixels, while black is just "off").

Worf

I saw a site that explained that CRT's use so much power compared to LCD's that things like Blackle are actually effective in general... especially since I'm sure there are a ton of people in the world who can't afford an LCD monitor.

kzooguy

@Gann: It ain't Google, but nonetheless, the naming choice is quite unfortunate.

Damage

an lcd uses slightly less power to display a white pixel than a black one. to display a white pixel, it turns off each of the three subpixels. to display a black pixel, it turns them on all the way.

so if you really think the color of your search engine will do anything, you're actually better off not using blackle.

notatoad

By my count they've saved about $40 in electricity costs. 307kWh @ (generously) $0.13 per kWh. Or, at an average CO2 emissions per kWh of 600g, 184kg of carbon, which ain't too bad.

Gari N. Corp

Yea, this is way old. Google posted a blog a while back saying why it doesn't save energy, why they don't give the option of black, etc.

SnowLeopard

Actually, would this not use more power, since if I'm thinking right, the 'default' position for the LED pixels is open, right? So to make black, it's having to power all the pixels to block the light.

TVGenius

@Gann: hahahahaha thats all i could think of
and that picture is classic

dontforget

Dang your laggy commenting servers, Giz! Four minutes? Does it really have to take that long?
*Le sigh*

hughjass

"Since most LCDs use lamps that are always on, you probably will be saving a lot more energy by reducing the brightness of your monitor. Probably this will change with LED-backlighting."
Um... no, it won't. How could you think that?

Anyway, this would really only work with OLEDs and CRTs.

@Gann: Wow.

hughjass

"Since most LCDs use lamps that are always on, you probably will be saving a lot more energy by reducing the brightness of your monitor. Probably this will change with LED-backlighting."
Um... no, it won't. How could you think that?

Anyway, this would really only work with OLED and CRT displays.

@Gann: Wow.

hughjass

It's good to see google reaching out to the african american community.

Gann

spell check doesn't like "treehugging"

rockboy04

Here's some more info on the actual savings of Blackle. Seems that for LCD users it's pretty pointless...

[www.triplepundit.com]

Blu

I run 30 CRTs and keep them on 24/7/365 for the only purpose of keeping the house warm. Suck on that hippies!!

FubarGuy

People still use CRT's? Good lord I feel sorry for them. I actually had forgotten about that phenomenon.

WilCon

only good for crt's.

ronnsprocket

Since there are so many CRT monitors still in use, Blackle is a good idea on a large scale, but not necessarily on an individual level.

sumocat

HA! This is as old as the internet isn't it!?

It doesn't save any energy at all.

djheath

If only they put a link to gmail on there... I'd totally use it... I don't care if its actually saving energy or not, the darker colors are much more appealing...

leadster618

yeah, it's just as effective as putting a gallon of gas in your car trying to drive for 200 miles.

your monitor will keep sucking juice whether the screen is black or white. same with all that other crap that consumes power when you think its off. the best way is to have a power bar and flick it off when your computer is shut down.

DSaddict

LCD uses more power on Black then White I believe.

LCD (liquid crystal diode) displays, by contrast, utilize electric charges to twist and untwist liquid crystals, which causes them to block light and, hence, emit blacks. The higher the voltage passing through the liquid crystals in a given pixel, the more fully those crystals untwist and effectively block light - all of which makes these pixels darker.

WilCon

Besides the LCD lamps always being on, what about those of us who have large monitors but only open web browser screens to half or a third the size of the screen?

That number at the bottom of the screen..the one that goes three digits past the decimal... is meaningless.

know1

@DustyButt: Ooops.. I started typing before finishing the article...

Booo quick response!

DustyButt

On an LCD monitor isn't the backlight still illuminated even tho' the screen is black?

This wouldn't make a difference.

DustyButt

You know they could always save some power by turning off the servers that host their idiotic site.

John Laur

They can save more energy by turning off the server the website runs on. It's probably doing nothing pretty much most of the time, so it's wasting energy.

Herman

Google has an article on this.
[googleblog.blogspot.com]

picsel

OLD

CooperMaybe

This DOES make a difference for LCDs. I hooked my laptop up to a Kill-a-Watt and measured the number of watts it used with four settings:

1) White background, full brightness (backlight)
2) White background, lowest brightness
3) Black background, full brightness
4) Black background, lowest brightness.

In the end I think #1 was around 18watts where #3 was around 14watts with #4 coming in around 12 watts.

So case in point... it saves you energy.

mmr

This thing only works on CRT monitors.
Btw an LCD monitor is already saving a lot of energy. Check your Watt consumption in your user-manual.
So... let's recycle those old CRTs :)

Luis Neng