Analytical Investigation of Wind-Driven Cross-Ventilation Potential in Residential Buildings in Ibadan, Oyo State

Passive cross-ventilation is a highly effective natural cooling strategy for the hot humid climate of Ibadan, Oyo State, South West Nigeria, but the extent to which current residential building layouts enable effective wind-driven cross-ventilation is analytically uncharacterised. This study analytically investigated wind-driven cross-ventilation potential in six representative residential building typologies common in Ibadan (terraced bungalow, detached bungalow, courtyard bungalow, two-storey terrace, two-storey detached, and flat-roofed commercial-residential) using computational fluid dynamics (CFD) simulation in OpenFOAM. Building geometries were modelled using field measurements of 30 representative examples of each typology. Wind data from the Nigerian Meteorological Agency Ibadan station (2015 to 2022) provided inlet boundary conditions. Cross-ventilation performance was evaluated by air change rate per hour, mean indoor wind speed, and percentage of occupied area achieving comfort-level wind speeds (above 0.4 m/s). Results showed that the courtyard typology achieved the highest mean indoor wind speed (0.68 m/s) and the highest percentage of comfort-level wind speed coverage (74%). Terraced bungalows had the lowest cross-ventilation performance, with mean indoor speeds of only 0.21 m/s. Two-storey detached buildings with through-building window apertures performed comparably to courtyard buildings at wind angles within 45 degrees of the building normal. The study provides the first CFD-based cross-ventilation assessment for Ibadan residential typologies and recommends building orientation and aperture design guidance for the Oyo State Building Regulations.

Keywords: cross-ventilation, CFD simulation, residential buildings, Ibadan, passive cooling