Abstract: A method includes receiving, with a portable occupancy unit, a first signal using a first detector, where the first signal is indicative of an occupant in a structure. A second signal is received with the portable occupancy unit using a second detector. The second signal is indicative of the occupant in the structure. The first signal and the second signal are processed to determine whether the occupant is present in the structure. If it is determined that the occupant is present in the structure, an output is provided to convey that the occupant has been detected.