A method for a building automation system to control a comfort level in a building includes tracking a building occupant's activity data using a wearable activity tracker. A smartphone is coupled to the wearable activity tracker. Activity data is collected from the wearable activity tracker using a smartphone app operating on the building occupant's smartphone, and a comfort value is determined using the smartphone app based on the activity data. A report of the comfort value is transmitted to a building automation system (BAS) app from the smartphone, and the output of a building system is controlled based on the comfort value.