Developing occupant-centric smart home thermostats with energy-saving and comfort-improving goals

Occupant-centric smart thermostats (OCST) are believed to be able to improve energy efficiency and thermal comfort but their development and implementation are challenging. This study introduces the design of an OCST, highlighting its temperature control logic, heating and cooling energy-saving, and comfort improvement. A human–machine interaction interface was designed allowing occupants to conveniently set indoor temperature schedules on smartphones. Two simple yet fast methods for estimating energy savings were developed to instantly calculate heating and cooling energy-saving rates, allowing users to immediately adjust temperature schedules. Measured data from 50 households were collected and analyzed to improve indoor thermal comfort and identify potential energy savings. The results showed that 62% of the surveyed users tended to maintain a constant indoor air temperature throughout the year. Equipped with functions for schedule setting, indoor temperature fluctuation range control, and occupancy detection, the introduced OCST can reduce annual heating and cooling energy consumption in single-family houses by 7 to 25% and 15 to 40%, respectively. Additionally, the temperature control logic of the OCST with multiple connected terminals aims to ensure maximum comfort in as many rooms as possible. This work can serve as a reference for the future development of OCST.