A distributed occupancy detection system includes plural networked node devices configured to be spatially distributed throughout a structure. Each node device includes an occupancy sensor that senses a presence characteristic indicative of an object being in a monitored area of the structure that is associated with the occupancy sensor. Each node device also includes one or more processors that determine a probability that the object is or was located in the structure based on the presence characteristic sensed by the occupancy sensor of a first node device and based on the presence characteristic sensed by the occupancy sensor of one or more neighboring node devices. The one or more processors determine whether the object is in the structure based on the probability.