Hemp-Lime Composite Integration with Phase Change Materials and their Application in Cold Climates

Abstract

This research explores developing, characterizing, and analyzing a new low-carbon composite material combining hemp-lime (hempcrete) and phase change materials (PCMs) for enhanced thermal performance in buildings. The study is divided into four main phases. In the first phase, novel hemp-lime composites were created using recycled, locally sourced, low-embodied energy binders and pozzolans. These composites were experimentally characterized for mechanical, thermal, and moisture buffering properties. Results showed that density affects hempcrete's properties and locally sourced pozzolans like metakaolin and recycled brick performed better than traditional hydraulic lime. The second phase included developing new hemp-lime composites with metakaolin and microencapsulated PCMs (MPCM). Numerical simulations compared the energy performance of timber-frame walls with hempcrete and HPCMs. The inclusion of MPCMs enhanced the heat storage potential of the composites. Consequently, in the third phase, a novel hysteresis modelling approach was proposed to improve the accuracy of phase change simulations. The new model was validated experimentally and compared with existing hysteresis methods. The study highlighted the importance of selecting appropriate hysteresis models and PCM integration techniques. Finally, numerical simulations investigated the effect of different heating schedules on hempcrete-PCM wall assemblies. The scenarios tested included heating setback temperature and temperature ramp-up. Results indicated that changing setpoints significantly influences PCM behaviour and wall thermal performance. Overall, this research demonstrates the potential of PCM-enhanced hemp-lime composites as sustainable building materials with improved thermal mass capacity suitable for cold climates like Canada.