Source: http://www.wired.com/design/2013/09/this...

To begin, the Stir senses a user through its thermal presence sensor. This triggers the desk to start recording your habits—when you prefer to stand, how long your average standing session is, and so on. Maybe you like to stand for an hour and sit for 20 minutes, or maybe you like to do the exact opposite. The idea is that the smart desk will learn that over time and adjust to your preferences. The desk comes with two modes: active and passive, and your preference data is constantly being gathered in both. But only in active mode (which you instigate with the push of a button) will the desk actually make the recommendation that you switch from standing to sitting.