Abstract: A thermostat for controlling an HVAC system is described, the thermostat having a user interface that is visually pleasing, approachable, and easy to use while also providing ready access to, and intuitive navigation within, a menuing system capable of receiving a variety of different types of user settings and/or control parameters. For some embodiments, the thermostat comprises a housing, a ring-shaped user-interface component configured to track a rotational input motion of a user, a processing system configured to identify a setpoint temperature value based on the tracked rotational input motion, and an electronic display coupled to the processing system. An interactive thermostat menuing system is accessible to the user by an inward pressing of the ring-shaped user interface component. User navigation within the interactive thermostat menuing system is achievable by virtue of respective rotational input motions and inward pressings of the ring-shaped user interface component.

Abstract: A thermostat and related methods is provided for controlling an HVAC system having one or two separate transformers for supplying power to the HVAC system. The thermostat includes isolation circuitry housed within the thermostat to safely connect to the HVAC control wires and power wire(s) whether the HVAC system has one or two separate transformers without the use of removable jumpers or manual rewiring. The thermostat can include a processor that sends DC signals for turning on and turning off each of the HVAC functions, and an isolator adapted to electrically isolate the processor from the control wires and power wire(s). The isolator can include a transformer, such as a low cost Ethernet transformer. The circuitry can include one or more field effect transistors adapted and arranged so as to open or close an electrical connections between the control and power wires, thereby turning on or off the associated HVAC function.

Abstract: A thermostat and related methods are described for controlling one or more functions, such as heating and cooling in an HVAC. According to some embodiments the thermostat includes a rechargeable battery; charging circuitry adapted and arranged to recharge the battery; and control circuitry adapted and arranged to control the one or more HVAC functions using power from the rechargeable battery. According to some embodiments, the thermostat also includes power harvesting circuitry adapted and arranged to harvest power from the HVAC system in cases where no common wire is available to the thermostat, and to supply power to the charging circuit for recharging the battery.

Abstract: A thermostat is described for controlling air temperature in a building. The time associated with causing the controlled air temperature to reach a target temperature is estimated and displayed to a user. Input from a user indicating the target temperature can be received and the estimating and displaying can be carried out in real time. The thermostat can be wall-mounted or the user input can be received and estimated time can be displayed using a remote device, for example that communicates wirelessly with other components of the HVAC system.

Abstract: A thermostat and related methods is provided for controlling an HVAC system. The thermostat includes wiring terminals adapted and configured to make an electrical connection with an HVAC system wires such as common, heating and cooling control and return wires. The making of the connection with a common wire actuates switching open a loop of an electrical circuit used for power harvesting. According to some embodiments, the wiring terminal includes actuation of a moveable part of the terminal so as to accommodate the common wire that in turn actuates the switching open the power harvesting loop. More than one other loop can be switched. According to some embodiments, the wiring terminal can be used to automatically connect and/or disconnect Rc and Rh circuits when one or both Rc and Rh wires are present. According to some embodiments, the wiring terminal can be used for electronically sensing the presence of the HVAC system wire.

Abstract: A method is described for identifying faults relating to an HVAC system, such a clogged filter. Sensor data is used to estimate HVAC system efficiency. Trends in system efficiency are then used to identify faults such as clogged filters. The sensor(s) can include one or more of the following types: optical sensor, temperature sensor, pressure sensor, acoustic transducer, humidity sensor, resistive sensor, capacitive sensor, and infrared sensor. The efficiency estimation can also be based on conditions external to the building, such as data from exterior sensors and/or data gathered from third parties such as government or private weather stations. The efficiency estimation can also be based on performance metrics such as the time used to reach a set point temperature. The fault identification includes filtering out non-fault related events. An instrumented air filter for use with an HVAC system is also described.

Abstract: Systems and methods are described for predicting and/or detecting occupancy of an enclosure, such as a dwelling or other building, which can be used for a number of applications. An a priori stochastic model of occupancy patterns based on information of the enclosure and/or the expected occupants of the enclosure is used to pre-seed an occupancy prediction engine. Along with data from an occupancy sensor, the occupancy prediction engine predicts future occupancy of the enclosure. Various systems and methods for detecting occupancy of an enclosure, such as a dwelling, are also described.

Abstract: Systems and methods for modeling the behavior of an enclosure for use by a control system of an HVAC system are described. A model for the enclosure that describes the behavior of the enclosure for use by the control system is updated based on a weather forecast data. The weather forecast data can include predictions more than 24 hours in the future, and can include predictions such as temperature, humidity and/or dew point, solar output, precipitation. The model for the enclosure can also be updated based on additional information and data such as historical weather data such as temperature, humidity, wind, solar output and precipitation, occupancy data, such as predicted and/or detected occupancy data, calendar data, and data from the one or more weather condition sensors that sense current parameters such as temperature, humidity, wind, precipitation, and/or solar output.