All the tree huggers in the world won’t save the planet using Black Google. We have the facts to prove it.

We all want to do the right thing when it comes to the environment but it’s amazing just how much questionable information is out there when it comes to cost savings in electricity.

One furphy we came across recently was Blackle (www.blackle.com). Apparently, the idea is that if Google switched from a white to a black background, they could save the world 750-megawatt-hours of electricity each year. Sounds like a great figure – that is until you dig down and find out where this figure actually comes from.

Blackle was set up by Heap Media on the basis of a blogpost at ecoIron. Blackle even goes as far as maintain a precise (although only God knows how accurate) watt-hour counter of how much energy Blackle has actually saved.

Now ecoIron claims that displaying a black page on a CRT monitor will consume 59-watts while a white page will chew through 74-watts. Of course, there’s nothing as useful as what size or brand of CRT monitor they’re talking about but the basic gist of the argument is that 15-watts of energy can be saved from using black instead of white page backgrounds.

Click on the ecoIron headline for that story and you find that the basic information comes from the US Department of Energy’s EnergyStar information page where it has a table indicating white colours use 74-watts and black using 59-watts.

What is surprising is how completely useless and unverifiable the information on this DOE page is.

Firstly, there’s no mention at all of the type of monitor used. Was it an LCD or CRT? So far, everyone basing their stories of this EnergyStar webpage is assuming CRT. But then there’s nothing mentioned about the size of the monitor either. Was it 15-inch? 17-inch? 21-inch? Power consumption of all monitors varies considerably on a number of factors, including the monitor’s size. So on the face of it, these wattage ratings are completely unusable to base any rational conclusions on because there’s no information about how those results were obtained.

Still, ecoIron uses the 15-watt differential in going from white to black, plus the fact that 25% of the world’s monitors are CRT for the basis of its 750-mega-watt-hour (750MWh) energy-saving claim per year.

Now to get the 25% portion, ecoIron used data from DisplaySearch that showed that “worldwide, as of first quarter 2006, they estimate LCD penetration at 74.7 percent.”

There are also assumptions about Google getting 200million queries per day and each query is displayed for about 10 seconds.

The problem is that most of these assumptions are vague at best, all used to make a nice pithy head-line.

The truth about black and white

While there are a number of assumptions, we decided to find out for ourselves just what is the power consumption difference between Blackle and Google. Using our own commercial AC power meter, we tested three monitors – a 19-inch LG L192WS widescreen LCD that is about two months old; a 17-inch Mitsubishi DV1770 CRT monitor about three years old; and a 15-inch LG StudioWorks 570LE LCD monitor, about four years old.

We measured their power consumption on Blackle and Google to see what actually happens.

Monitor	Google – power consumption (Watts)	Blackle – power consumption (Watts
19-inch LG L192WS	24.5W	25.1W
17-inch Mitsubishi DV1770	72.5W	65.4W
15-inch LG StudioWorks 570LE	26.2W	26.5W

First up, the 17-inch CRT power reduction between Google and Blackle was nowhere near the 15-watts being suggested and was closer to 7-watts.

But the most surprising result was from the two LCD monitors where the power consumption actually rose by an average of 0.5W. The reason is that LCD monitors consume energy to block light when creating a black screen as the backlight is on continuously. CRT monitors work on a completely different process where three cathode ray guns fire electron beams onto a phosphor coating so that the electron beam creates the light.

So at the very least, supporters of a Black-screen Google are overstating their power savings by about double. At worst, as CRT monitors are continually phased out in favour of LCD screens, the power consumption of a Black-screen Google will actually be more than what we already have with the standard white Google.

UPDATE August 1, 2007: If you want a guaranteed way to reduce monitor power consumption, try dropping the refresh rate. This works for both CRT and LCD monitors. Read the story on our testing here.

 

UPDATE August 2, 2007: We've now expanded testing to include four CRT and four LCD monitors, Read the results here.  

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3.20 Copyright (C) 2007 Alain Georgette / Copyright (C) 2006 Frantisek Hliva. All rights reserved."