This is an IIoT product for reducing the energy consumption of buildings. It consists of smart thermostats distributed in offices, gateways distributed in floors and a web-based application, all with indigenous design. The energy required for heating and cooling of each office is determined by smart thermostats. Subsequently, the optimal set point for building boiler and chiller is determined and implemented. This results in significant reduction in energy consumption of large scale building for heating and cooling. Each smart thermostat is also equipped with motion detection sensor that identifies offices with no occupants and subsequently turns off the heating or cooling utilities of the office with no occupants.