The built environment is accountable for approximately one third of the global energy consumption, while producing 37 per cent of worldwide carbon dioxide. The construction sector alone within Australia generates upwards of 18% of the national carbon footprint. Within this space concrete is the most commonly used material, responsible for 9% of global greenhouse gas emissions. Now more than ever, the rapidly rising demand for and depletion of finite natural resources is under the spotlight. With a focus on using alternatives to conventional building materials, recent attention has turned to bio-based aggregates - specifically hemp shiv - being combined with lime-based binders to form hempcrete. This bio-based building material is sourced from fast-growing, high-yield, highly carbon sequestering crops, and reduces the demand for the otherwise energy-intensive, lime-based, cementitious binder.
This paper explores the characteristics of hemp lime concrete, including the physical, mechanical, thermal and hygric properties as well as its acoustic insulative performance, durability and mould growth risk with reference to their performance alongside current conventional equivalents. This allows a critical evaluation of hempcrete’s contribution to the performance and longevity of the building envelope and its future as a sustainable construction material.
This investigation finds that although some earlier studies demonstrate poor compressive strength, hempcrete outperforms many other common materials in its acoustic and thermal insulative capabilities. Furthermore, novel binders provide likely improvements across almost all properties of hempcrete, including further reduction in the high carbon-cost of lime-based binders. Identified cost benefit analyses also indicate that the superior insulative properties of hempcrete provides a possible long-term advantage where-in the initial higher capital outlay for renewable materials is potentially negated by substantial reductions in the cost of heating and cooling requirements.
While identifying gaps in current literature and discussing the trajectory of hempcrete research, this review presents the need to further explore novel binders in improving hempcrete performance across all properties.The paper concludes with acknowledging that while hempcrete technology remains in its infancy there is a paucity of building scale, long-term evaluations - specifically, seasonal assessments within a clime experiencing broad fluctuations in its temperature, rainfall and humidity such as Australia.