A new Web site, Blackle, aims to act as a starting point for eco-conscious Web searchers. The site, which serves as a front end for Google searches, reverses the color schemes of search-result pages so users see light-colored text on a black background. It’s a trick that, allegedly, cuts the energy consumption of computer monitors, and as of yesterday afternoon, Blackle claimed it had saved more than 5,500 watt-hours of electricity since its March debut.

BlackleIn response to a page from my colleagues at WSJ.com’s Energy Roundup blog, I looked into the numbers. The federal Energy Star program, which encourages consumers to cut their energy consumption, had someone do a quick test for me and found that modern LCD computer monitors don’t see much benefit from a black screen.

Blackle is down today (because of high traffic from recent blog links, according to owner Toby Heap of Sydney, Australia). But the Google cache version of the site’s “about” page, which carries some white screen space from Google atop the black page, explains that the site was inspired by a post this past January on the blog ecoIron claiming that if Google went all-black, it could save 750 megawatt-hours a year (a megawatt-hour is one million watt-hours; you can convert these to each other and other energy units here). But as ecoIron noted, the savings are most likely to accrue from older CRT (cathode-ray tube) monitors, rather than the more-modern, more-compact, more-energy-efficient LCD (liquid crystal display) screens that have come to dominate the market (representing three quarters of all monitors world-wide as of last year, by some estimates).

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.

“Even if the energy savings are small, they are representative of the need for each of us to start taking small steps to save energy,” Blackle’s Dr. Heap (who holds a doctorate in exercise physiology) told me in an email. “My hope is that by setting Blackle as their home page people will be reminded of this need to save energy each time they go online.” Similar wording appears on Blackle’s “about” page.

Dr. Heap and his company, Heap Media, also stand to benefit from traffic to the site (assuming it comes back online). Blackle is part of the Google Co-op program, which means it shares in ad revenue from searches. A Google spokesman said, “Google is not affiliated with Blackle and we do not have any additional comments to provide at this time.”

Further reading: In a mock interview with himself, Mark Ontkush, whose blog post inspired Blackle, discussed the “shades of grey” on his black Google idea, including the potential for poor readability. Dr. Heap told me he has no plans for other colors, so someone else would have to found Greygle. Online Journal columnist Jason Fry recently measured power consumption of his home appliances for energy consumption and found that the big energy hogs were his lights and dryer.