International Journal of Science, Engineering and TechnologyAuthors: Lokesh S, Sakthi Deepashika N, Dr.Saravanakumar R
Abstract: Heating, ventilation, and air-conditioning (HVAC) systems contribute significantly to total building energy consumption because conventional ventilation systems often operate continuously at fixed power levels regardless of real-time spatial demand. This paper presents the design, hardware implementation, and graphical validation of a low-cost, real-time HVAC Building Management Energy Optimizer that dynamically regulates ventilation based on room occupancy and environmental sensing. The hardware architecture utilizes an ESP32 microcontroller as the central control unit, an HC-SR501 passive infrared (PIR) sensor for occupancy detection, an MQ135 analog environmental sensor, an L298N driver module for Pulse-Width Modulation (PWM) fan control, a 6 V DC geared motor representing the ventilation fan, and an SG90 servo motor serving as a motorized HVAC airflow damper. Laboratory Virtual Instrument Engineering Workbench (LabVIEW) communicates with the ESP32 via a USB serial (VISA) interface to provide graphical real-time data acquisition, parameter visualization, decision monitoring, and dynamic power/energy estimation. The system employs a rule-based control strategy where occupancy acts as the primary gate: when unoccupied, fan speed and damper position are set to 0% and 0°, respectively. Under occupied conditions, ventilation is scaled across three demand tiers—30% (30° damper), 60% (60° damper), and 100% (90° damper)—based on analog air-quality threshold boundaries. Experimental validation confirms the full hardware-software execution chain, establishing an accessible, transparent prototype for demand-controlled ventilation (DCV) and building energy optimization
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