CFD analysis of fluid dynamics and heat transfer for buildings and improvement of indoor thermal comfort

Nowadays, decarbonization goals coupled with the deep understanding of the importance of Indoor Environmental Quality (IEQ), pose high goals in buildings performances standards. Heating and Ventilation Air Conditioning systems (HVAC) are responsible for about 60 % of building energy usage thus, optimizing these systems to reduce energy consumption is essential. However, HVAC also represent the key feature of IEQ in the built environment. Studying IEQ is challenging, as it requires an understanding of the spatial distribution of key parameters. In this context, Computational Fluid Dynamics (CFD) emerges as a fast and reliable tool for designing and optimizing HVAC systems. This thesis presents a framework for using CFD simulations to assess and improve IEQ, focusing on Thermal Comfort (TC) and Air Quality (AQ). Various environments, including historical and modern office spaces, apartments, and a cafeteria, are analyzed. Each environment presents unique challenges impacting IEQ and energy efficiency. For instance, simple office rooms contrast with complex apartment layouts, while cafeterias involve large, high-occupancy spaces. Optimizing airflow, system configurations, and integrating innovative technologies can balance TC with local discomfort and AQ, even in difficult settings. However, achieving both TC and AQ simultaneously remains complex, requiring well-designed HVAC systems. In new office buildings, high TC and AQ levels are only attainable in renewal air mode. In cafeterias, ceiling-mounted fan coil units utilizing the Coanda effect improve TC but may negatively affect AQ during colder seasons by limiting ventilation in occupied zones. Optimizing furniture placement, especially in historical contexts, can enhance comfort without compromising aesthetics. Air-source heat pumps paired with fan coils are becoming more common, especially in residential settings. Retrofitting projects that replace radiators with fan coils can benefit from strategic furniture rearrangement to enhance thermal comfort. This thesis provides a systematic, CFD-driven approach to HVAC system design, prioritizing occupant wellness and energy efficiency.