New tool measures mobile apps' energy efficiency

A new tool that calculates how much energy is consumed by gadgets such as smartphones when connecting to the internet to use apps and games, has been developed by a scientist in Sweden.
Ekhiotz Jon Vergara from Linkoping University showed that there is a great potential for energy savings in the software side.
"Until now, app developers did not care all that much about the energy consumption of their apps, but more and more have started to consider this issue, such as Spotify," said Vergara.
He developed EnergyBox, a tool that quantifies the energy consumption of mobile devices due to data communication.

The tool simulates the consumption of wireless interfaces considering the aspects that impact the communication from the network operator and mobile device side, he said.
Vergara compared how much energy various apps, computer games, and chat services use, and proposed energy-efficient solutions.

He found that the energy consumption does not only depend on how much data is sent, but also on how it is sent.
When two systems are to send data back and forth, they start with a 'handshake', he said.
This procedure can be long and energy-intensive or quick and energy-efficient. How often the systems shake hands with each other depends on how the data is sent and also the configuration of the network operator, he said.

For example, Vergara tested a number of different messaging services using the same conversation such as Kik, Google Hangout, Skype and Messenger.
He measured both how much data was sent to convey the content in the message, and how much energy was consumed.
"The amount of data sent is not proportional to the energy consumption. Messenger sends a lot of data and uses a lot of energy, Google Hangout sends significantly less data and is more energy-efficient, while Kik, for example, sends very little data but uses a lot of energy," he said.
According to him, one simple way of saving energy in chats is queueing the message for a second.

"Often we write, send, write, send - but if the application can queue what we are writing and then send everything at once, we can save up to 43 per cent of the energy," said Vergara.
In the next step, he tested 20 different mobile games - both online multiplayer games and games played by only one person. Some of them also contained advertisements. Each game was played 5 times for 15 minutes.
"In principle, online multiplayer games consume more energy - that is logical - but several single-player games that do not have ads are still top energy consumers. There is not any linear connection here, either," Vergara said.

All the single-player games turned out to work just as well without an internet connection, which means that there is a large potential for energy savings, he said.