HVAC controls manage heating, ventilation, and air conditioning systems in buildings. Smart HVAC combines sensors (temperature, humidity, occupancy, CO2), controllers (embedded systems, cloud logic), and actuators (valves, dampers, fans) to maintain comfort while minimizing energy. Advanced practitioners design integrated systems: deploy sensor networks, integrate with building management systems (BMS), build cloud dashboards, and implement energy optimization algorithms. They work across mechanical, electrical, and software domains.