Hemp fines as alternative lignocellulosic material for non-woven semi-rigid thermal insulation panels

The incorporation of sustainable materials such as hemp fines, approximately 6 wt% of the byproduct generated from hemp processing, into thermal insulation panels present a promising opportunity for enhancing energy efficiency in construction. These hemp fines were characterized and incorporated with wood fibres at substitution rates of 25%, 50%, and 100% by mass to develop semi-rigid thermal insulation panels. The thermal and functional properties of the panels were evaluated to determine the optimal substitution rate. The findings revealed that shorter hemp fines have a high soluble content (23%), low thermal stability, and increased moisture sorption. A 25% substitution with short hemp fines (90th percentile length of 5.8 mm) resulted in panels that perform comparably to those made from wood fibres (90th percentile length of 6.2 mm). For applications that prioritize low thermal conductivity, a 50% substitution with either type of hemp fine (short, super-short) proved effective. Notably, panels with super-short fines (90th percentile length of 3.3 mm) exhibited the best homogeneity and internal bond strength (2.5 kPa), although the high moisture sorption, highlighted for the fines, raises concerns about panel durability. In conclusion, this study demonstrates the viability of using hemp fines in the production of sustainable insulation and recommends a 25% substitution rate for a balanced set of properties.