New Scientist links to a study conducted by Microsoft Research, in partnership with Purdue University, to be presented at next month's EuroSys conference. The researchers sought to account for energy usage within individual apps, and developed eprof, a file-grained energy profiler for Android and Windows Phones. Using eprof, the team studied energy consumption of a variety of apps, including Angry Birds, Facebook, NYTimes and web browsers. They found that, in the case of free ad-driven apps, only a small percentage of the total energy consumed is used to compute and render the app--the rest of the energy is used for determining the user's location and then receiving ads and sending user tracking data. Angry Birds, for example, uses less than 20% of its total power consumption on the core game.
The tests were just run on Android and Windows phones, so power consumption may differ on iOS devices. The researchers also blamed third-part ad software licensed and shared by developers as the main culprit for this power inefficiency. Of course, the study isn't without its own agenda, as the researchers propose and promote bundles, their new paradigm for energy accounting for developers to use to optimize their apps. You can read the full PDF of the study details and conclusions here.