A Hybrid Bioclimatic Thermal Comfort Model for Warm-Humid Climates: Integrating Evans Scale and Mahoney Tables for Southwest Nigeria

Abstract

Thermal discomfort in warm-humid climates remains a principal driver of excessive mechanical cooling energy demand, particularly in institutional buildings across sub-Saharan Africa. Existing comfort assessment frameworks often operate in isolation; offering either diagnostic analysis or prescriptive design recommendations without providing an integrated, location-specific decision-support tool. This study presents the YetOke Bioclimatic Comfort Model (YBCM), a novel hybrid analytical framework that systematically integrates the Evans Comfort Scale with the Mahoney Tables to produce context-calibrated thermal stress diagnoses and passive architectural design strategies for warm-humid climates. The model relies on secondary station-based meteorological data and serves primarily as a pre-design decision support tool. Monthly meteorological data (2016–2023) obtained from the Nigerian Meteorological Agency (NIMET) were analysed for three climatically representative cities in Southwest Nigeria. The cities are Ibadan (Oyo State), Abeokuta (Ogun State), and Lagos (Lagos State). Applying the Evans Scale, daytime thermal stress was found to peak at 'very hot' (++) for January–April and November–December across all three cities, while wet-season months (July–September) exhibited 'comfortable' to 'hot' conditions. Night-time stress was predominantly 'cold' (−) across the year, necessitating thermally responsive nocturnal ventilation strategies. The Mahoney Table analysis produced location-differentiated recommendations: Ibadan and Lagos require light wall construction with medium-to-large openings and well-insulated roofs, while Abeokuta demands heavy thermal mass walls and roofs with extended time lags to moderate the wider diurnal temperature range (up to 13.6°C). The synthesised YetOke Model provides a five-component decision support framework; thermal stress diagnosis, climatic classification, indicator scoring, design prescription, and cross-location validation applicable to the planning, design, and retrofitting of public institutional buildings in tropical West Africa. These findings directly inform the revision of Nigeria's Building Energy Efficiency Code (N-BEEC) and contribute to the growing evidence base for passive, climate-responsive architecture in developing economies.