Air conditioning system optimization for historical building thermal comfort: a CFD analysis

This study presents a multilevel approach for the optimization of thermal comfort levels in an office room located in one of the historical buildings of the Alma Mater Studiorum, University of Bologna. In a previous study, thermal comfort indexes distribution within the office was analysed both in summer-cooling and winter-heating conditions. This study represents a baseline to compare any alternatives that could be considered for the air conditioning optimal design. The analysis of the status-quo has revealed that summer is the most critical season for achieving thermal comfort in the office. By means of detailed CFD simulations in the Starccm+ environment, some HVAC parameters, such as the characteristics of the air inlets, are varied, to obtain the optimal thermal comfort levels in all the workstations within the office during typical summer conditions. The goal is to develop a customized and dedicated conditioning approach for each workstation in the office, while minimizing energy consumption, providing a personalized thermal environment for each occupant. In this context, possible solutions to optimize thermal comfort are evaluated. The optimization strategy involves the identification of the optimal position of the fan coil unit to best address potential hot spots and cold spots. The study also wants to demonstrate the effectiveness of shading devices in reducing the solar heat gain with consequent improvement in the indoor thermal environment and energy demand reduction. Overall, the study highlights the effectiveness of using CFD analysis to optimize thermal comfort in a building, especially when due to the heritage value of historical buildings only non-invasive strategies can be adopted for the indoor environment improvement. The findings provide valuable insights for HVAC system design and operation in similar buildings and can help improve the energy efficiency and comfort of indoor spaces.