Gediminas Jasionis

Fact or Fiction? Black Surfing Saves Energy

by Gediminas Jasionis February 27, 2008
Blackle_and_Ninja_and_Darkoogle_search_pages.JPGArticles about "black Google" search engines and their potential for energy savings have appeared in major newspapers and websites. For example, the article "Black Google Would Save 3,000 Megawatts a Year" (link) received over 4,000 "diggs" and made Digg's front page. The estimate was later downgraded to 750 megawatts, and later in the article we will compute a different figure, but the basic question remains: is it fact or fiction that black web pages save energy?

The question is simple. Would computer monitors use less power displaying mostly black screens compared to mostly white screens? For example, could you save energy relative to the normal white Google page by using a black interface to the Google search engine, such as Blackle, Ninja, Darkoogle, or (safer idea) by customizing Google itself to black?

The answer is complicated. The most important factor is whether the display is a CRT or LCD. A comprehensive test of 27 monitors showed an average of 10.8 watts saved by using Blackle compared to Google for CRT monitors, but basically no difference for LCD overall: -0.1 watts "savings." If you break down the LCD results by screen size, it appears that that for large LCD monitors, 24 inches and above, Blackle generally does save a couple of watts, whereas smaller LCD monitors appear to use half a watt more for Blackle. So, Blackle does not save energy for LCD monitors in general.

Many have jumped on this point and dismissed the idea of black web pages. After all, most people today have LCD monitors, and black web pages might increase their energy usage.

However, this may be missing the point. The question is not so much whether you, an individual, should use a white Google or a black Google, so to speak. The question is whether Google - and indeed Hotstocked and every other environmentally conscious website in the world - should go "black," to try to save energy across its viewer base as a whole.

CRT monitors are more popular than you may think. If you walk into an average home in Eastern Europe, you are likely to find a CRT monitor, if you find a personal computer at all. Across the world, there's no way in hell the percentage of monitors that are CRT can be less than 10%, since 10% of monitors being sold today are still CRT.

(A small percentage of monitors are plasma and other technologies, but we'll ignore those.)

Remember, above we quoted 10.8 watts savings for Blackle on CRT, versus -0.1 watts "savings" for Blackle on LCD, across the population of monitors tested, which was a fairly representative sample in our opinion. Let's take the worst case assumption that 10% of monitors are CRT. Do the math: 10% of 10.8 watts is 1.8 watts, which far outweighs 90% of -0.1 watts (-0.09), for an estimated total savings of 1.71 watts. (One of the hidden assumptions here is that users with CRT screens surf as much as those with LCD screens, which is admittedly probably a flawed assumption, but this is a article, not a PhD thesis.)

Multiply that 1.7 watts saved by a million PC's, and you get 1.7 megawatts (MW.) Some estimate that there are close to a billion PC's in the world today, and it's said that the majority of PC's connect to the Internet, so that would be close to 1,700 MW saved, if most websites were to adopt a black background and PC's did nothing but surf the web. However, we need to reduce this figure, since at any given moment most personal computers are off or on screen saver or not viewing web pages. Let's say 5% of PC's have web pages on their screens at any one moment, reducing the savings to 85 MW. Remember that this was with the worst case assumption that just 10% of monitors are CRTs today. The actual percentage of monitors that are CRT is closer to 25%, according to an estimate by Display Search, which would bring the savings estimate back up to 262.5 MW. Then we need to deduct a bit, since many webpages have pictures and other things that cannot be dark. Let's call it 200 MW.

Something on the order of 200 MW energy savings would be substantial, given that all it would take to achieve it is a few changes to color codes in HTML for the most popular websites.

There is a considerable difference between our estimate of 200 MW savings for all major websites to go dark versus the 750 MW for just Google to go dark, which was the estimate in the "Black Google" article mentioned at the start. This is because our estimate is correct and the other estimate is not. Seriously, the 750 MW figure was the result of a lot of questionable assumptions, such as 10 seconds per googling, which did not have any place in our estimate.

Google has been in the news recently for its announcement that it will invest hundreds of millions of dollars into renewable energy startup companies - more than the Federal government grants! Some people point to Google's white webpage as something the company could change to help the environment.

In the article "Is black the new green?", dated August 9, 2007, Google's official blog takes issue with this assertion that Google should make its webpage black to save energy. Bill Weihl, Google Energy Czar, writes, "We applaud the spirit of the idea, but our own analysis as well as that of others shows that making the Google homepage black will not reduce energy consumption." The "others" to which he refers is a blog article on the Wall Street Journal site: "Does a Darkened Google Really Save Electricity?"

Look, it doesn't take a degree in mathematics (which I have, by the way) to see that these writers for the Wall Street Journal and Google blogs are, well, not the brightest bulbs. It doesn't matter that most monitors today are LCD. The LCD majority is swamped by the relatively huge energy savings for CRT monitors surfing black webpages.

Today, most websites, Google and Hotstocked included, remain basically white. It's a fact that if websites were to go black, significant energy would be saved.

Of course, what's important for energy usage is not just the brightness of websites but the brightness of anything that appears on CRT computer monitors. Microsoft and its default "green pasture" wallpaper is another thing that could go "Gothic" to save energy and really be "green." At the least, Microsoft could use "black" as the default screen saver for those with CRT monitors and have an appropriately short monitor-off timer to save energy.

Other sources:

Comments 1

1. Guest
March 02, 2008, 06:10PM

Quotes I can't believe I read this entire article. What a waist of human energy.

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