Computational Fluid Dynamics Simulation of Airflow in a Typical Nigerian Open Office Building for Natural Ventilation Design

Thermal comfort in office buildings in tropical Nigeria is typically addressed through energy-intensive air conditioning systems, yet passive natural ventilation strategies informed by computational fluid dynamics analysis can substantially reduce cooling loads and improve indoor air quality in the humid south. This study uses CFD simulation to investigate airflow patterns and thermal comfort conditions in a representative open-plan office building designed in accordance with standard construction practices in Benin City, Edo State. A three-dimensional model of the building was developed in Autodesk Revit and imported into ANSYS Fluent for CFD analysis. The k-epsilon turbulence model was applied to simulate wind-driven natural ventilation under prevailing south-westerly wind conditions at mean approach velocities of 2.5 and 4.0 metres per second. Air velocity distributions, indoor temperature fields, and predicted mean vote comfort indices were mapped across occupied zones. Simulation results identified significant low-velocity stagnation zones in interior offices distant from window openings, with predicted mean vote values exceeding the ASHRAE comfort zone boundary. Window-to-floor area ratio and cross-ventilation opening placement were parametrically varied, and optimised configurations achieving uniform airflow and comfortable predicted mean vote indices were identified. The study provides design guidelines for improving passive ventilation effectiveness in new office construction in South South Nigeria. Keywords: computational fluid dynamics, natural ventilation, office building, thermal comfort, Benin City.