Ecobee3, set to smart away when leaving home.

160
Connect

This allows the thermostat to go into away mode as soon as you leave the house and the 2 hours is important because it then go into smart away mode.

If

Location icon
You exit an area

This Trigger fires every time you exit an area you specify.

Then

ecobee icon
Set thermostat comfort profile for X hours

This Action will set the thermostat into a hold using the settings from the specified comfort profile. This comfort profile hold will remain in effect for the specified number of hours.

Fewer details

Explore more great ways to automate Location and ecobee