Roomzoner: Occupancy-based room-level zoning of a centralized HVAC system

Cyber-Physical Systems (CPSs) combine low-power radios with embedded processors in order to provide high-resolution sensing and actuation over a geographic area. This revolution has begun to deliver a new generation of engineering systems and scientific breakthroughs. One area in which CPSs can have a significant impact is in energy conservation through the intelligent control of systems. In this paper we present a CPS that enables a centralized Heating, Ventilation, and Air Conditioning (HVAC) system to be retrofitted to enable room-level conditioning of a residence. This is a compelling application due to residential HVAC systems accounting for over 15% of all U.S. energy usage, making it one of the nation's largest energy consumers. Also, it has all the aspects of a complex CPS: it uses sensors to detect room occupancy and indoor climate, it actuates hardware, and it requires complex control algorithms in order to maximize energy savings without damaging the HVAC equipment or discomforting the occupants. With an implementation using commercial off-the-shelf (COTS) components and a simple control algorithm we demonstrate an almost 15% energy saving in a residence over its existing centralized thermostat. With this demonstration, we pose a challenge to control theorists with the CPS community to refine our approach which could lead to even greater energy savings.