Thermal performance of traditional cavity walls: Accounting for complex cavity geometry and bonding variability

As a significant feature of traditional dwellings and modern rural buildings in China, traditional Chinese cavity walls have always been valued for their material efficiency and thermal performance. However, the thermal implications of their irregular cavity geometries—shaped by diverse bond patterns—remain underexplored. This research, for the first time, aligns traditional Chinese cavity bond patterns with brickwork in international handbooks and combine experimental validation with 3D modeling to quantify the impact of bond patterns and boundary conditions on the thermal performance.

Validated simulation results, with deviations under 10 %, show that radiation accounts for approximately 60 % of heat transfer across cavities, while convection has a comparatively minor effect. Thermal resistance ranges from 0.30 to 0.43  W/m²·K for 240  mm cavity walls, with the Flemish bond showing the lowest performance. Larger cavities and increased wall thickness enhance thermal resistance, and cavity walls generally outperform solid walls, albeit modestly. Brick thermal conductivity and surface emissivity are identified as dominant factors influencing energy performance. Moreover, clay infill as a practical strategy is confirmed in improving the thermal performance. This research provides new insights into the optimization of cavity walls for historic building, providing a critical foundation for future hygrothermal simulation and conservation-informed decision-making. The findings suggest that leveraging the unique cavity wall geometry and material strategies could inspire innovative, energy-efficient solutions for building retrofit.