Lumped Parameter Dynamic Thermal Model of a Building Integrated with a PID-Controlled HVAC System for Maintaining Indoor Comfort Under Variable Thermal Load

This study presents a dynamic lumped-parameter thermal model of a building integrated with a heating, ventilation, and air conditioning (HVAC) system and a Proportional-Integral-Derivative (PID) controller, implemented in Matlab/Simulink, aimed at maintaining indoor comfort under highly variable conditions. The HVAC system for winter heating is comprehensively modeled, comprising a mixer, a pre-heating coil, a humidifier, and a post-heating coil. A PID controller regulates the hot water flow rates to the pre-heating and postheating coils in order to control the relative humidity (RH) and temperature of the supply air, thereby ensuring that the indoor set-points of temperature and R H} are maintained. The innovation of the proposed approach lies in its ability to achieve and sustain comfort conditions despite extreme variations in thermal loads. Specifically, a case study focused on a real test building at the University of Calabria (Rende, Italy), was analyzed. The building is characterized by a very small volume featuring a non-insulated south-facing wall which includes a window, which simultaneously causes high heat losses and significant solar gains. Simulation results demonstrate that the proposed solution is capable of maintaining comfort conditions accurately and rapidly