Abstract: An apparatus, system and method that assesses the number and location of persons in a building. The invention may include none, one, two or more emitters, at least one sensor that senses reflected radiation indicative of a modification to the emitted radiation from multiple ones of the at least two emitters, and a communicative network, wherein sensing data from the at least one doppler sensor is forwarded to a remote central hub that manipulates the sensing data to an indication of the number and the location of the persons in the building. The sensors of the present invention may be, for example, doppler sensors, or any like sensor that senses biologically caused fluctuations within a monitored environment.