This thesis presents a comprehensive thermal-fluid analysis of sauna room configurations using Computational Fluid Dynamics (CFD) to evaluate heat transfer, airflow patterns, and energy efficiency. Two room layouts are compared: a traditional Glass Door (GD) setup and a modern Glass Front (GF) design, with a focus on the thermal implications of using glass versus wood paneling. The study employs the realizable k-epsilon turbulence model with enhanced wall treatment to simulate heat transfer by buoyancy-driven natural convection within the sauna environment and includes radiation modelling via the Discrete Ordinates (DO) method. First-order analyses based on the heat diffusion equation were conducted to support the simulation results and guide boundary condition setup. Validation was performed against experimental data from a real-world sauna lab, showing good agreement with an average deviation of 7%. The results reveal that the GF configuration increases energy demand by 26% compared to the GD setup, primarily due to the higher emissivity and lack of insulation in glass surfaces, despite minimal differences in flow behavior and thermal stratification. The findings suggest that design choices significantly impact operational efficiency, with implications for cost, environmental sustainability, and user comfort.