Thermal Performance of Mechanically Fixed Stone and Porcelain Façade Systems: A Case Study of Hebron, Palestine

Abstract

Mechanically fixed cladding systems offer a promising technological solution owing to their thermal performance and their potential to reduce building energy consumption. Recently, dry-stone and mechanically fixed porcelain cladding systems have become increasingly popular in Palestinian residential construction, primarily due to their aesthetic appeal. However, these systems remain insufficiently investigated in the Palestinian climatic context, and context-specific evidence on their effect on façade thermal performance is limited, particularly in Mediterranean climates such as Palestine. Most studies also address either the thermal bridging caused by the fixing system or building-level thermal performance, rather than the combined effect of the system components. This research aims to assess the thermal performance of mechanically fixed stone and porcelain cladding systems under local climatic conditions, examining how cladding material, insulation position, and air cavity depth affect heat transfer and thermal bridging at the component level, and further evaluating the influence on building-level performance. Field surveys, semi-structured interviews, and in situ measurements were employed to document local mechanically fixed façade construction practices in Hebron, followed by numerical simulations using COMSOL Multiphysics for thermal-bridge modeling and DesignBuilder for building-level energy analysis. A parametric framework comprising 18 wall configurations was developed to evaluate the thermal performance of these systems and determine the most thermally efficient configurations. The results show that insulation presence was the dominant variable affecting annual energy demand, reducing it by 9.5 to 16.3% at a fixed 5 cm cavity, whereas insulation position had little influence at the building scale and cavity depth acted as a secondary factor. Relative to the uninsulated reference, the best insulated configurations with a 15 cm cavity reduced annual demand by 13.8 to 23.0% across the four zones. The two cladding systems differed seasonally but balanced over the year. At the component scale, however, insulation position strongly influenced the thermal bridging penalty. The porcelain substructure increased thermal transmittance more than the stone brackets in every configuration, by approximately three times where the fixings did not penetrate the insulation, with the porcelain penalty ranging from 6.8 to 23.0% and peaking at external insulation with the 5 cm cavity.