Occupancy Sensing Adaptive Thermostat Controls: A Market Review and Observations from Multiple Field Installations in University Residence Halls

While both occupancy sensors and the Internet have been around for many decades, recently both have been applied to programmable thermostats to reduce energy consumption and to improve usability and control. This paper explores the implications of coupling these technologies, and the role the added capabilities play on the efficiency and effectiveness of building conditioning. The research focuses on various installations of occupancy-sensing meshnetworked web-programmable thermostats in university residence halls, with a focus on the results from installation in multiple dormitories at the University of California, Davis. Occupancy sensors have been used in commercial lighting controls for a few decades, but have only recently been applied to manage conditioning systems. Occupancy sensing for climate control may have the greatest impact in hotels, residence halls, and conference or assembly halls. The appropriateness of occupancy sensing thermostats in various applications depends on user motivations, regularity of occupant schedules, total occupied time, and the extent to which a space setback is already managed manually, or programmed to align with occupancy schedules. The type of mechanical system to which an occupancy-sensing thermostat is applied will have enormous effect on its potential for energy savings. We present two installations: one successfully saved energy and the other did not. In retrospect, the latter represented an inappropriate application of an otherwise functional occupancy sensing thermostat technology. Upon review of this energy savings failure, the authors were surprised to find that facility managers were keen to install the technology in many other residence halls. Added facility management services such as wireless communicability, web-based global control, and insight into residence thermal preference, user behavior, and occupancy trends were at least as motivating as the potential for energy savings.