The Numbers Guy at the Wall Street Journal has done a little digging around to investigate the real impact of switching Google’s white background to black (ala Blackle) in order to reduce power consumption. On the plus side, there really is a power saving from switching to black. On the down side, the gain is only made on older CRT monitors, rather than newer LCD monitors. As the post points out:
On LCD displays, color may confer no benefit at all. In response to my inquiry, Steve Ryan, program manager for Energy Star’s power-management program, asked consulting firm Cadmus Group to run a quick test by loading Blackle, Google and the Web site of the New York Times (which is, like Google, mostly white on-screen) on two monitors — one CRT, one LCD — and connecting a power meter to both. “We found that the color on screen mattered very little to the energy color consumption of the LCD monitor,” said David Korn, principal at Cadmus, which specializes in energy and environment, and does work for the government. The changes were so slight as to be within the margin of error for the power meter. Tweaking brightness and contrast and settings had a bigger effect. The bulkier CRT screen did see savings with Blackle of between 5% and 20%. Mr. Korn emphasized that this was a quick test, not a rigorous study.
What a shame. Still, as the Blackle folks point out, there’s still some benefit in making people think about energy issues. And the consumer interest is real: Blackle’s servers recently fell over, due to massive interest in the site after the story was picked up in the media.