1. Every monitor uses 74 watts to display a white background, and only 59 watts to display a black background.
Answer: Nope, and it's probably the biggest misconception. The original post that started this whole thing pulled these numbers from the US department of energy, but these numbers almost certainly refer to CRT monitors only.
2. Ok, well, every CRT monitor saves 15 watts then going from white to black.
Answer: The amount of energy saved here is depends on many factors, including the size, type, and manufacturer of the specific monitor. A study conducted in 2002, the infamous Roberson Study, found that different CRT monitors saved between 4 and 30 watts going from white to black, a big range. A new study by Techlogg on 4 CRT monitors found that they all did save energy, but the range was narrower and the savings was smaller (only between 7 and 11 watts). It is likely that CRT monitors are getting more efficient.
3. What about LCD monitors? I keep hearing that is makes no difference what color they display, or that they even use more energy displaying black over white.
Answer: Another big misconception. LCD monitors have a light behind the screen that is always on, so white is usually the most efficient color to produce; you just let the light shine through. Black on the hand requires the light to be completely blocked, and this takes energy. So, on the face of it, white would always be cheaper than black to create on LCD screens. Turns out this is mostly true, and on average, takes less than a watt of energy to do.
But there more, because some clever LCD manufacturers check how dark the screen is, and if it's very dark they dim the backlight; this saves energy. The Roberson study found this was true for every LCD monitor, Techlogg found it was primarily true for monitors over 24 inches wide. This doesn't save much energy, tops 4 watts, but it does save some. So, LCD technology has changed over time, and it is true that the differential between displaying white and black is much tighter than CRT monitors, a few watts at most.
4. Very interesting. So that solves it, since about 75 percent of the monitors in the world are LCD monitors, and since it doesn't really save a lot of of energy to display black over white (some even cost energy), the whole energy saving argument is a wash.
Answer: It is true that there are a large number of LCD monitors out there, and that for the majority of them it doesn't make a whole lot of difference energy wise to show black vs. white. Sites such as Techlogg and Infoworld used these numbers to demonstrate that the technique was ineffective.
In fact, this very argument proves that the technique works! The reason is that energy consumed by the LCD monitors is dwarfed by the massive savings from the other 25 percent of monitors, the power guzzling CRT monitors.
If you want, you can try this experiment to convince yourself of this fact.Get three lcd monitors and plug them into a power strip. Then get one CRT monitor, and plug that into the same power strip. Plug the power strip into your testing equipment, then plug that into the wall outlet. Now turn on all the machines and get them all connected to the Internet; show an all white screen on all of them, and take a reading from your test equipment. Now show an all black screen on all of them. Read your testing equipment again. You have two readings now, the second should be lower than the first.
For another explanation, read Pablo Paster's posting on the topic.
5. Great, so it works! Does it work on any site?
Answer: Yes, the energy saving principle will work on any site. Google is often referenced (they get over 500 million hours of use each year) but other good candidates would be Yahoo, MySpace, and YouTube. :: TriplePundit ::Infoworld