A green autonomous self-sustaining sensor node for counting people in office environments

Energy consumption is of critical concern in large office buildings. While office spaces are dynamically used, current building automation systems lack information on space utilisation to adaptively adjust energy spending according to actual needs. In this work, we propose an approach to count people per office space using distributed strategically placed PIR sensor nodes. We present our concept of a self-powered PIR sensor node that is using a MSP430 family processor. The sensor node can be flexibly installed in building spaces providing specific advances over existing devices. We detail the design considerations, implementation, and evaluation of this novel embedded system. Our evaluations showed that the sensor node can emit triggers at 276 nAh, thus operating for 361 triggers in complete darkness on a single charge. The approach can be used for lighting, climate, and appliances control in office spaces.