Flexible functionality partitioning within intelligent-thermostat-controlled HVAC systems

An intelligent-thermostat-controlled heating, ventilation, and air conditioning (HVAC) system comprising:

• one or more HVAC units;
• and
• one or more intelligent thermostats that control the one or more HVAC units, each intelligent thermostat comprising:
• a visible portion;
• a concealed portion onto which the visible portion mounts by sliding the visible portion onto the concealed portion;
• and
• subcomponents, wherein each of the subcomponents is associated with one or more intelligent-thermostat functionalities, the subcomponents comprising:
• a long-distance wireless communications module that interconnects the intelligent thermostat with remote computing facilities;
• a local wireless communications module that interconnects the intelligent thermostat with environmental-condition-system components;
• a plurality of infrared sensors comprising:
• a first infrared sensor configured to detect an occupant approaching the intelligent thermostat;
• and
• a second infrared sensor configured to detect a presence of the occupant regardless of whether the occupant is approaching the intelligent thermostat;
• a microprocessor that controls an interactive user interface and additional monitoring, analysis, and communications functions, and further controls a heating, ventilation, and air conditioning (HVAC) system based at least in part an occupancy state of the home determined by the second infrared sensor;
• a microcontroller that controls low-power-consuming functions and wake-on circuitry;
• one or more environmental sensors that monitor an environment;
• a mechanical user interface;
• an optico-electrical user interface;
• a display driver;
• an electronic memory;
• a battery;
• power-management circuitry;
• power-supply circuitry;
• and
• wake-on circuitry that powers up the interactive user interface when the occupant approaching the intelligent thermostat is detected by the first infrared sensor.