Development and validation of online parameter estimation for HVAC systems

Heating, ventilating, and air-conditioning systems of buildings consume nearly 50 percent of the world's energy. To improve energy efficiency, to increase occupant comfort, and to provide better system operation and control for these systems, online estimation of system parameters, including system thermophysical parameters and thermal loads, is desirable. Several reported studies have presented simulation results and assumed that the thermal loads are known. A difficulty in HVAC system parameter estimation is that most HVAC systems are nonlinear, have multiple and time varying parameters, and require an estimate of the thermal load for a building zone. In this study, the building zone and variable-air-volume unit are modeled. The system parameters including the thermal load are estimated using the recursive-least-squares method with variable forgetting factor. The sensitivity of the estimation results to different factors is examined. Different experiments are used to validate the estimation results. The comparisons between the experiments and the estimation results show good agreement.