The Internet of Things (IoT) is the network of physical objects embedded with sensors and connectivity. The ubiquitous nature of IoT nodes will allow the deployment of embedded sensors, actuators, cameras, mobile phones, and Radio Frequency Identification Devices (RFID) in buildings for monitoring the condition of the building and the well being of the occupants. The current project presents the design and implementation of a sensor network within the IoT framework, using infrared (IR) sensors to monitor the number of visitors in the building and their distribution across predetermined zones. Using IR sensor data the Demand-Controlled Ventilation (DCV) units on each floor are controlled based on zone occupancies. The occupancy data are displayed on a mobile phone or PC using a Wireless Fidelity (WiFi) module. The devices in the experimental implementation of this network include IR, temperature, and CO2 sensors, interfaced to a microcontroller. Experimental testing shows that the network performs flawlessly and reliably.