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 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.
That's a pretty powerful statement and a good argument for moving to black as a background color for Web pages.
Back in the early days of the Web -- before anyone wrote the rules about Web design -- sites often used all kinds of background colors, design elements, and graphics. The white background, however, quickly emerged as the design standard and has been the defacto Web page background for the last 8 years or so.
The success of Google -- whose homepage is famously almost all white space -- has made the use of white backgrounds definitive. But as the push to reduce power consumption takes on, we could see black (and other lower power consuming colors) take off in Web design.
What do you think? Will trend to green force Google and other online publishers to move from white to black to save power?