Analytical Investigation of the Thermal Performance of Vernacular Building Materials in the Hot Humid Climate of South South Nigeria

Vernacular building materials used in the South South geopolitical zone of Nigeria were selected by generations of builders for their empirically observed performance in the hot humid climate, yet their thermal properties have not been analytically characterised using current building physics methods. This study analytically investigated the thermal performance of four primary vernacular building materials: laterite earth blocks, palm-thatch roofing, bamboo wall panels, and timber board wall cladding, typical of South South Nigerian vernacular construction. Material thermal properties (thermal conductivity, thermal mass, and thermal diffusivity) were measured in the laboratory using the transient plane source method and heat flux plate method. Dynamic thermal simulation using EnergyPlus was calibrated with field measurements in four test room cells constructed with each material in Bayelsa State, with simultaneous indoor temperature and relative humidity monitoring over 6 weeks. Test cell measurements showed that the laterite earth block wall performed best thermally, with peak indoor temperatures 5.8 degrees Celsius below ambient during afternoon periods. Palm-thatch roofing produced indoor conditions 4.2 degrees Celsius cooler than corrugated metal roofing in an equivalent reference cell. EnergyPlus simulation predictions agreed with measured values within plus or minus 1.4 degrees Celsius (mean absolute error). Parametric simulation showed that combining laterite block walls with palm-thatch roofing reduced annual cooling energy demand by 62% compared to concrete block and metal roofing. The study recommends integration of vernacular material thermal data into the National Building Energy Code for hot humid climate zones.

Keywords: vernacular materials, thermal performance, hot humid climate, South South Nigeria, building simulation