Computer monitors use more energy to display white pixels than black. Other colours use varying amounts of energy between the limits of black and white.

This is the theory proposed by Blackle (www.blackle.com), who have come up with a black search engine. It’s a front-end to Google, but with a black background, hence the name.

Heap Media, the company behind Blackle claim that by making Google searches using a black background, Internet users could collectively save thousands of kilowatt hours in electricity.

According to EnergyStar, a typical monitor displaying a full screen of solid colour might use the following amount of energy:

But this theory doesn’t hold up. The power consumption figures correspond to old-style CRT monitors. The power consumption for new, LCD monitors does not significantly vary depending on the colour displayed. Most of the power consumption of LCDs is from the backlight, which is constant, whatever the colour.

For LCD monitors, using all-white screens and turning down the brightness of the backlight would save more energy than using Blackle.