Comparison and Design of Dry-Stack Blocks with High Thermal Resistance for Exterior Walls of Sustainable Buildings in Cold Climates

Given the increasing demand for higher construction productivity and better thermal resistance, adopting innovative building envelope systems is crucial. Dry-stack masonry blocks have emerged as a viable solution, due to their rapid assembly, mortar-free construction, and reduced dependence on skilled labor. However, there is a lack of scientific evaluation on the thermal performance of dry-stack blocks for cold climate zones and corresponding proper designs. This study addresses this gap by investigating market-available blocks and proposing two innovative block designs-a composite block and a simple block-highlighting their thermal performance and associated challenges. Using finite element modelling, the thermal resistance of these blocks was carefully assessed and compared. The results show that thermal bridging, induced by masonry ties penetrating the insulation, significantly impacts the thermal resistance of the wall made with simple blocks, resulting in an 11% decrease in the effective thermal resistance (R-value) as compared to the composite block walls. Furthermore, compared to a conventional masonry wall with the same insulation thickness, the composite-block wall exhibits a 24% higher R-value. The composite block outperforms existing market options in terms of thermal resistance, making it a superior choice for cold climate regions. Conversely, the simple block is preferred when sophisticated manufacturing facilities are unavailable. Overall, the composite block wall's improved thermal resistance can make a meaningful contribution to lowering operational energy demand (i.e., operational carbon), contributing to the shift to a sustainable building stock.