Energy Efficiency and Temporality in Early Urban Pottery Production: Modelling Heat Transfer in Connected Pottery Firing Structures (4th –3rd millennium BCE, Southwest Asia)

Abstract Several potting areas with connected firing structures (i.e. firing structures architecturally and functionally connected between them allowing heat transfer) have been excavated in recent years. Dating from the first urbanisation and state emergence period in Southwest Asia (4th and 3rd millennium BCE), these installations define a hitherto undocumented firing technology and raise important questions regarding their operation and their role within a socio-economic context of demographic growth and increasing production pressures on the environment. Through a close interdisciplinary collaboration between archaeologists and thermodynamics researchers, we developed a numerical model of connected firing structures to test hypotheses regarding their functioning and to evaluate the potential advantages of this firing technology. The model, calibrated using archaeological evidence from the site of Logardan in Iraqi Kurdistan and experimental firings conducted at the Archéorient laboratory branch in Ardèche (France) in 2024 and 2025, enabled a detailed reconstruction of heat transfer processes between each functional component of the firing system, This model takes the form of a series of equations, each describing the temperature and hygrometric conditions within each functional unit of the structure, which evolve as the firing process progresses. The results demonstrate spatially differentiated temperature evolution within the structure and indicate that this technique achieves approximately 30% fuel savings by optimising the use of combustion energy during the drying and preheating phases of both ceramics and the firing structures itself.