Sorry for using the wrong term, it's not wifi sense, but just an option in the wifi settings. When this option is set, wifi turned off, Cortana turned on, favorite places set in the maps app, wifi will automatically turn on. However I did find out that wifi will not automatically turn off. For more information read this article:
m.pocketnow.com/2014/04/16/how-to-windows-phone-8-1-auto-wifi-on
However, I did find that a number of people are having problems with this feature working consistently. See this thread: forums.windowscentral.com/windows-phone-8-1-preview-developers/276838-wifi-auto-turn-off-near-favorite-places.htm