1) In the ecobee mobile app, select the Account icon in the bottom left corner of the screen.
2) Select "HomeKit" under the Integrations menu.
3) You should see the option for "Geofence"—select it
4) Select "Enable geofence."
5) Change the radius by pinching the radius-circle to increase or decrease the radius of the geofence.
6) You may select a Scene that will trigger (or choose to do nothing) when you enter the geofence boundary and another for when you leave the boundary. Once you've finished making your adjustments, select "Done" in the top right corner to save.
7) Success! You've now set up a geofence. Any time you enter or exit the set radius, your specified Scenes will trigger.