It seems the jury is out on whether the design I use for this blog is kinder to the environment than those with a white background. According to the Blackle search engine, using a black background means that monitors use less energy and they quote ecoIron saying that if Google switched its colour scheme it could save 750 megawatt hours a year.
But just as I was congratulating myself at my accidental environmentalism, I saw this page at Google quoting Techlogg.com which tested 27 monitors and only demonstrated power savings on older models. In fact, the LCD monitors they tried Blackle on actually showed an increase in power use.
Seems as with most Green issues, you’re damned if you do and damned if you don’t.