This disclosure concerns estimating the number of people within building-based device networks. Increasingly, local area network (LAN) devices are capable of sensing people (e.g. smart appliances). Features of building layout, and physical arrangement of devices provide that only a subset of sensor data patterns can be accounted for by a single user (e.g. simultaneous activation of a smart TV and a motion sensor). Over time, a central controller (e.g. LAN gateway) can gather these building-specific sensor patterns and learn single occupant characteristics for a network (e.g. features or boundaries of single occupant capability). In one embodiment, the central controller generates a single occupancy criterion (e.g. a building-specific test), comprising single occupant characteristics, operable to test a subset of sensor data for single occupancy. The central controller divides devices into a minimum number of groups, such that each group satisfies the single occupancy criterion and estimates the number of occupants accordingly.