“…A novel approach is proposed in [16], where, using blind system identification techniques as in [17], no training sets including occupancy measurements are required. Other types of estimators use black box models identified using, e.g., neural networks or hidden Markov models, and potentially including several sources of information (e.g., temperature, humidity, concentrations, door statuses and light status, sound and motion, electricity consumption patterns) [18], [19], [20], [21], [22], [23], [24], [25]. This literature focuses on occupancy estimation in single rooms.…”