Good to see you again: Capture and recapture method on mobile devices to estimate occupancy profiles

Occupancy based controls can save 20-50% of the energy use in buildings. Thus, various data acquisition techniques to gather occupancy information have been developed. Recent developments focus on utilizing the pervasiveness of occupants' mobile devices with enabled networking capability, i.e., WiFi and Bluetooth (BT) to infer building occupancy. The challenge with this approach is that there is still an unknown number of people with deactivated networking functions on their mobile devices. In this paper, we propose an occupancy estimator based on BT signals, that uses the capture and recapture (CRC) technique. In ecology, CRC is an established method for estimating an animal population size. We examine the viability of using CRC in conjunction with BT devices to infer building occupancy density profiles. Our simulation results show that the CRC estimator calculates accurate occupancy profiles under certain circumstances (i.e., BT ratio > 0.3). With the results, we propose recommendations for experimental studies.