The experience of using your mobile phone can sometimes be spoiled by overlong download time, which can reduce effective wireless access to Internet sites. Now researchers have measured just how much energy is consumed by various different mobile websites.


The future of business is via mobile, so it's really important that the mobile device you are using works well. Now it seems that apart from the time it takes to download and render web pages from a site, many mobile sites are in fact so heavy that they use lots of battery power and thus somewhat restrict freedom of use.  A joint team of researchers from Stanford University in the USA and Deutsche Telekom R&D in Germany have discovered that the computer codes of some of the most popular websites consume an excessively high amount of energy. They tested the mobile versions of 25 sites, among themFacebook, Amazon, Gmail, AOL, eBay, BBC, Wikipedia, (Wall Street Journal) and using an Android Developer 3G Phone, connected to the Deutsche Telekom network. The energy consumption was then analysed using a high-precision multimeter.  A first test established that 1% of a fully charged battery represented 32.84 joules.

Wide variation in mobile optimisation

The research threw up a number of findings regarding websites' energy use.'s home page is by far the most power hungry. This is in part due to the fact that Apple has not built a mobile version of its site, and that the Apple home page uses an image file which is not at all optimised for mobile devices, so that the device has to make a recalculation in order to render the page on small screens. In addition, the researchers discovered that images, Javascript, and use of the style sheet language Cascade Style Sheets (CSS) also tend to use a lot of power. All the sites which use CSS for their layout, such as Yahoo!, Microsoft and Picasa, incur higher energy consumption than that those using HTML. They also observed that many web pages use unnecessarily complex - and sometimes unused - code, one example being the mobile version of Wikipedia. They therefore undertook the task of modifying the scripts of some web pages and were able for example to reduce the energy required to render the Apple mobile site by 5 joules and the power needed to consult Wikipedia by 10 joules.

'Speed and beauty' trump energy savings

This study shows that mobile sites, especially those designed for business use, are often "optimised for speed and beauty", but pay little attention to the amount of power needed to download and render the pages.Given that the freedom of using a mobile device anytime, anywhere is what most encourages greater use, higher levels of sending and receiving information, and thus provides a better overall customer experience, it’s clearly vital that site designers make it a priority to reduce energy consumption. And it's worth pointing out that downloading publicity materials is not at all a problem here. The researchers found that on all the sites they tested, advertising used small JPEG files which consume very little energy.