Ads in free smartphone apps are draining your battery

A study of free apps on Android smartphones shows that a significant portion of the energy consumed by such apps is dedicated to sourcing and displaying targeted advertisements. That conclusion itself isn't so surprising, but the extent to which certain free apps waste their resources on serving advertisements or logging user data - in one case, as much as 75 percent of the app's total energy consumption - is certainly eye-opening.

Abhinav Pathak, a computer scientist at Purdue University, Indiana, and the author of the study's report (PDF file), said that app developers need to take energy optimization more seriously, reports the BBC. Pathak and his fellow researchers built a special tool called eprof to monitor the energy use of Android and Windows Mobile* apps. They tested popular apps like Angry Birds, Facebook, Free Chess and NYTimes as case studies and found that only 10 to 30 percent of the energy spent went toward powering the app's core functionality.

In Angry Birds, only 20 percent of the total energy cost was used to render and run the game. Forty-five percent of the energy was spent tracking the user's location with the GPS and uploading that information, then downloading location-specific ads over a 3G connection. The app kept the 3G connection open for around 10 seconds, even if the data transmission completed in less than that amount of time. This "tail energy" cost another 28 percent of the app's energy usage.

Pathak will present his team's research at the EuroSys conference in Bern, Switzerland next month.


* Note: this isn't an error on our part. Curiously, the report - hosted on the Microsoft Research website - clearly states that Windows Mobile apps were tested, rather than apps running on the more up-to-date Windows Phone OS. While this is possibly an error by the report's authors (it wouldn't be the first time that 'Windows Mobile' and 'Windows Phone' have been used interchangeably...), we obviously have to report the findings of the study as presented.

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