Introduction of the Air Balancing Technology -- A Hierarchical Air Balancing Method via PID Control -- A Gradient-Based Online Adaptive Air Balancing Method -- A Distributed Cooperative Control-based Air Balancing Method -- An Air Balancing Method Using Support Vector Machine -- An Air Balancing Method Using Multi-layer Feed Forward Network -- An Air Balancing Method by A Full Data-Driven Duct System Model -- An Air Balancing with Optimal Pressure Set-point for Minimized Energy Consumption.