Comparison of Control Strategies for Energy Efficient Building HVAC Systems

A framework for the design and simulation of a building en-velope and an HVAC system is used to compare advanced control algorithms in terms of energy efficiency, thermal com-fort, and computational complexity. Building models are first captured in Modelica [1] to leverage Modelica’s rich building component library and then imported into Simulink [15] to exploit Simulink’s strong control design environment. Four controllers with different computational complexity are con-sidered and compared: a proportional (P) controller with time varying temperature bounds, a tracking linear quadratic reg-ulator (LQR) controller with time varying tuning parameters, a tracking disturbance-aware linear quadratic regulator (d-LQR) controller with time varying tuning parameters which incorporates predictive disturbance information and a model predictive controller (MPC). We assess the performance of these controllers using two defined criteria, i.e. energy and discomfort measured with appropriate metrics. We show that the d-LQR and MPC, when compared to the P controller, manage to reduce energy by 41.2 % and 46 % respectively, and discomfort from 3.8 to 0. While d-LQR and MPC have simi-lar performance with respect to energy and discomfort, simu-lation time in the case of d-LQR is significantly less than the one of MPC. 1