Flair uses a hysteresis band - or range - around the set point to know when to open and close Smart Vents. This range is a fixed number of degrees above and below the set point.
Flair uses a 1F hysteresis band around the set point for Smart Vent operation. So if a room's set point is 72F, the band is 71F to 73F - and once the temperature dips below 71F or rises above 73F, Flair will open/close Smart Vents.
The hysteresis band is adjustable by contacting Support.
Here's an example of a room that's cooling. The AC is on and the Smart Vent is open to let in cool air. The room set point is 72F and the room temperature is 71.6F, so the room temperature is in range (71F-73F). When the room temperature goes outside of the range, the Smart Vent will close.
Here's an example of a room that's heating. The heat is on and the Smart Vent is open to let in warm air. The room set point is 72F and the room temperature is 71.2F, so the room temperature is in range (71F-73F). When the room temperature goes outside of the range, the Smart Vent will close.