According to the study, website elements that seem to consume maximum power even after the page has loaded are the Flash animations and AJAX. The least "green" technology are the Flash banner ads that animate in a cycle thus drawing power.
The researchers repeated the test after installing the two ad-blocking extensions in Firefox and found some significant improvements (see chart). To put the numbers in perspective, the energy savings were enough to power a 40 watt tube light.
While the study was conducted with a couple of websites on a simple Dell computer, this is still something worth pondering – "The best way to conserve is to unplug equipment that is not being used but while the browser is turned on, there do appear to be ways to surf in a manner that can reduce the power impact."