You may not know this, but what is displayed on your computer screen influences your electricity consumption. A lit pixel costs more than a dark one; or rather, the brighter the pixel, the higher the energy consumption. Surfing the Web on a predominantly white site (like this one) uses more megawatt-hours than a predominantly black one.

The fact is a white pixel consumes 74 watts, whereas a black one only consumes 59. After poking around a bit, I came across two tools that will help you save a few drops of energy in the future.

Blackle

There’s no question that Google.com is one of the Web’s most popular sites. Taking advantage of the fact that the Google search box can be hosted on any site, Heap Media has created a black version of the world-renowned search engine as a reminder that every little bit can make a difference. At the time of writing, Blackle claimed to have saved a total of 1,712,730 watt hours and counting. http://www.blackle.com/

Greenpeace’s One Black Pixel

Greenpeace suggests instead that we spread our energy savings over our entire time on the computer, not just the time spent using a search engine. Greenpeace proposes installing an application that will display one tiny black pixel at all times over top of your applications. Place it anywhere on your screen and forget about it. The strength of numbers will do the rest—your savings will be added to the 954,385 watt-hours already saved. http://www.greenpeaceblackpixel.org/#/en

And, as is often the case with the environment, a little research goes a long way . . .

Are you still with me? Yes? Good; because there’s just a teensy little fly in the ointment. As I was researching this article, I came across this page, which left me feeling a little sceptical. While it confirmed what I wrote in the first paragraph, it also added a very interesting element: none of these energy savings apply to LCD screens! These days almost all screens are LCD (liquid crystal display—you know, those thin, flat screens like your laptop screen). Because of the fundamental difference between different types of screens, only cathode ray tube screens (CRT screens—the ones that look like big TV sets) or plasma screens (which I have never seen for computers) consume less energy for a black pixel than for a white one. For LCD screens, it makes no difference. There is some good news though. LCD screens consume one half to two thirds less energy than a CRT screen of the same size. Phew!

So if you are still using a CRT screen, maybe it’s time to start thinking about replacing it (and disposing of it in an environmentally responsible way, of course), because even with a black pixel or for the few seconds that you are on Blackle, an LCD screen is far more energy efficient.