Real time building zone occupancy detection and activity visualization utilizing a visitor counting sensor network

Demand-controlled ventilation (DCV) can be adjusted based on room occupancy levels. In this study the feasibility of a visitor counting sensor network in occupancy detection was evaluated. A network with 15 sensor spots and real time activity visualization was designed and assembled at the Aalto Design Factory building. Direction sensitive light beam and infrared (IR) camera sensors were used. Counting data was collected for one week. The sensor spots divided the building into ten zones and the zones´ occupancies were calculated in five minute intervals. The results suggest that visitor counting errors easily accumulate over time and the use of correction factors or a more sophisticated counting algorithm is needed. The operation of a visitor sensor-based DCV could also be complemented with CO₂ sensors to guarantee both sufficient ventilation and a short response time.