Thermal Mass Efficiency of Kushite Mud-Brick Architecture: A Simulation-Based Assessment of Passive Thermal Performance in Hot-Arid Climates

Abstract

Growing interest in sustainable construction has renewed attention to vernacular building systems as climate-responsive alternatives for hot-arid regions. This study investigates the thermal mass efficiency of Kushite mud-brick architecture using the Western Deffufa of Kerma, Sudan, as representative case study. Despite the historical significance of this monument, quantitative evaluations of thermal performance of Kushite architecture remain limited, constituting an important gap in the existing literature. Thermal simulations were conducted using the DesignBuilder/EnergyPlus platform to evaluate five wall configurations: mud-brick walls with thicknesses of 30, 60, 100, and 150 cm, in addition to a 30 cm reinforced concrete wall representing the contemporary baseline. Simulations were performed for peak summer (27 July–2 August) and peak winter (6–12 January) conditions using Typical Meteorological Year (TMY) climatic data and were assessed according to ASHRAE Standard 55. The results indicate progressive improvement in thermal performance with increasing wall thickness. These findings demonstrate that the Western Deffufa embodies an advanced passive climate-control strategy. Furthermore, the study introduces the “Deffufa Effect”, defined as the thermal inversion phenomenon observed at wall thicknesses between 100 and 150 cm, and proposes it as measurable passive cooling threshold with potential implications for low-carbon and culturally appropriate building design in hot-arid environments.