Enernetics, Inc. is offering "CO2Stats" an "easy-to-use service that makes your website carbon neutral and energy-efficient, and that provides certification that you have taken steps to make your site environmentally friendly". The logic behind this is that websites are provided by web servers which run on electricity. If the electricity is generated by burning fossil fuel (as for example in Australia where most electricity is from burning coal), the the web server, and therefore indirectly the web site, is is causing carbon emissions. CO2Stats monitor web pages served and from that claim estimate the carbon emissions for the web site.
As I teach a course in Green IT, including estimating carbon emissions from computers, I was curious how CO2Stats make their calculations. So I signed up my web site for the service, to see how it works. After entering my web site and email address I was sent a link to a "Green Friendly Site" certification at Trustmarker. That site then issued me with some code to put on my web site to allow tracking (I put it just on the web pages to do with my Green IT course). As of today 1,256 other sites has so far signed up for the mark. It should be noted that the "Green Friendly Site" does not require any more than self certification and does not indicate any particular level of energy saving or any independent certification.