A blogger has proposed (and the wall-street journal has disputed) an energy savings of 3000 Megawatt hours per year (10 high output nuclear power plants operating for about three hours, $75,000 per day) if Google were to publish its front page with a black background as opposed to a white one. Google’s search page is the most visited non-pornographic site on the internet as far as I know, so this sounds like a great idea! The basic physics of the situation propose that displaying a white (100% brightness, 74 watts) pixel costs more energy than displaying a black (0% brightness, 59 watts) one.
In a CRT monitor, this idea is perfectly plausible. The brightness of the screen is directly related to the energy invested in accelerating electrons at a phosphor screen. However, in a LCD monitor, the overall power consumption is dominated by the brightness of the cold-cathode tubes backlighting the screen. Therefore, with CRT monitors on their way out, the power savings is only going to be seen for those of you browsing the internet in the stone age. In case you’d like to try it out, though, a black-colored version of the popular search page has been constructed by heap media, aptly named “blackle.” The page even goes so far as to feature very dark text as well as a jet-black background. It looks cool, energy savings aside.While it is true that you will still save *some* energy by using Blackle, it should be noted that the savings on an LCD screen are negligible at best. To save energy while using an LCD screen, just turn the brightness down.
In a typical laptop computer, about 25% of the energy expended is used to backlight the screen. Earlier this year, Apple computers released their first professional laptop with a high-efficiency LED backlight conveniently timed in response to some high-profile public accusations against Apple by none-other than Green-peace. (Greenpeace listed Apple as one of the worst companies in regards to enviornmentalism for things like recycling, the use of toxic chemicals in its products, etc. and authored a clever website to encourage macintosh fan-boys and girls to put pressure on their computer (and ipod) producer of choice. Apple has since significantly improved on the GP meter by outlining concrete plans for change in their manufacturing practice, and I believe this is due in large part to Apple’s economic interest in pleasing its consumer base, for which the environment is an important issue. Nevertheless, Sony beat apple to the punch with the first LED backlit laptop screen months earlier.
Further information about the wattage required to display a specific color is published by the department of energy, who recommends setting your desktop background to a dark color in order to save energy all day long (provided you don’t open any windows!) and identifies which screen savers are the most energy efficient. The article does not tackle the discrepancy with LCD and LED monitors, however it does indicate the ultimate monitor energy saver; turn it off.
As for thingsicando.org’s testing, I am waiting to borrow a friend’s power meter so that I can test out the theory with my own displays. As I recall, a 20″ LCD screen drew about 40 watts the last time I tested it, but I didn’t give any consideration to the colors displayed. I am planning on testing a 17″, 20″ and 24″ LCD display in order to see if the hypothesis holds any water with the current technology.Where blackle could really help out are the thousands of library clusters, computer labs and internet cafes world-wide still using CRT monitors. In that spirit, I would encourage any admins reading this to give setting your desktops to a dark color a try in your lab and report back any change in energy consumption.
What to do…
So inconclusion, here is what you can REALLY do when designing a website to make it more eco-friendly: Don’t allow flash-based ads to be displayed on your pages. Yes, flash ads look really cool, but unfortunately, the plugins that drive such ads cause the processor usage in my computer to jump way beyond what is reasonable for displaying a website, sometimes hitting 100%. With many computers running power-hungry processors, consuming upwards of 80 watts, loading a page on myspace.com for instance makes my browser beg for mercy. Poorly coded flash ads are the worst, however, sabotaging processor performance and burning through precious energy at the same time. As a consumer, you have a choice to disable flash content in your browser’s preferences. There is also a plugin for firefox that allows you to set the color scheme of every webpage you visit to dark colors in the event you are still pushing your CRT to the limit.
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