No; motion detectors can NIT be set to detect breathing because if they are set to that small amount of motion then a bug crawling across the floor would trip the sensor as motion and kick the power to the A/C on.
For YOUR situation you need each person to wear a small transponder like a lapel pin that is tracked by the hub. When the pin leaves a room, the hub can turn off the lights. When the pin leaves the house it can close the garage door, turn off all electronics and set temp to higher range.
If multiple pins (people) live in the house then each person could have their preference for temp, light, etc programmed to their settings for the room they are in. Example wife likes 72 degrees and 60% lights when she walks in a room and all power off when she leaves the room but husband likes 76 degrees and 40% Lighting if he is alone in room. When both are in a room the program controls how much light they both want. If ALL pins leave the house then it locks all doors, turns a/c to 90 and activates alarm system and closes garage door. When a pin gets within 50 yards it could unlock front door, open garage door, turn a/c to that persons level, turn on lights if during hours of darkness, and even turn on coffee pot.
THIS level of 'smart home' can be done today but to buy ONE motion detector to detect breathing will NOT work,