Blackle is a custom version of the Google search engine developed by Heap Media Australia. The principle behind Blackle is based on the fact that the display of different colors consumes different amounts of energy on computer monitors The creators of Blackle cite the US Department of Energy’s Energy Star information page which states that a monitor displaying white uses 74 watts, while a monitor displaying black uses 59 watts. They also cite a 2002 study from Roberson, who tested a variety of CRT and LCD monitors and found that an all black screen consumed less energy than an all white screen on all of them.

The creators of Blackle state that the idea behind the site came from a blog, which estimated that a black Google would save 750 Megawatt-hours a year. On the Blackle homepage, the creators of Blackle provide a count of the number of watt-hours that they claim the users of Blackle have collectively saved.

Functionality. Since it is not owned by Google Inc., the Blackle site lacks many of the features of conventional Google, including the ‘Cached’ and ‘Similar Pages’ options, and it does not have as many of the corresponding links that can be found on the Google homepage. These links include items such as preferences, advanced search, language tools, images, groups, news and scholar. However just like Google, Blackle links have a visited option, where once a link is followed it turns a different color (in Blackle’s case green). The iGoogle feature is also lacking in Blackle.

Criticism. The creators of Blackle has been criticized for lack of clarity regarding the type, size and manufacturer of monitor that the power usage claims refer to. One critic, a technology journalist who reviews computer hardware, tested 4 cathode ray tube (CRT) monitors and 23 liquid crystal display (LCD) monitors, and found that power was saved by the CRT monitors, but was less than that claimed by the blog post that inspired Blackle. The LCD monitors tested showed increased power use in the majority of cases, although most of the larger (24 inch) monitors did use less power displaying a black screen.