Reevaluating Window Design Standards in Nigerian Architecture Optimizing Width (≥1350mm) and Ventilation Efficiency for Hot-Humid Climates

Abstract

Thermal comfort and natural ventilation are important design elements in Nigeria's hot, humid climate. However, present construction trends in the country increasingly favor tiny casement windows (≤900mm width), putting aesthetics ahead of performance. This shift represents a considerable departure from traditional wide louvered windows, which have historically provided high ventilation effectiveness (up to 98%). This research reevaluates Nigeria's present window design requirements and proposes for a minimum operable window dimension of 1350mm × 1350mm to increase indoor thermal performance. The study uses a mixed-method approach that includes Computational Fluid Dynamics (CFD) models, on-site airflow measurements, cost calculations, and expert interviews to compare the ventilation and cooling possibilities of narrow casement, classic louver, and wide pivot casement windows. The results reveal that broad window layouts outperform small designs, with air change rates more than twice as high and indoor temperatures reduced by up to 4.2°C. Material study reveals that wide frames can be made at a reasonable cost utilizing locally supplied reinforced oak or recycled aluminum. The findings provide significant support for climate-responsive window regulations in hot, humid climates. The report proposes immediate changes to the Nigerian Building Code to require a minimum window width of 1350mm and a window-to-wall ratio (WWR) of at least 25%. Furthermore, it promotes the use of culturally acceptable, cost-effective, and sustainable wide-window typologies to minimize energy demand while improving habitability.