Lime Hempcrete Composites Based on Unfired Binders. A Review

Hempcrete has emerged as a viable and environmentally sound building material based on hemp lime mixture, whose properties render it a low Embodied Energy and Carbon (EE and EC) building material. Additionally, it allows a hempcrete building to achieve low Operational Energy and Carbon (OE and OC) by moderating indoor temperature and relative humidity fluctuations through the year with minimal auxiliary heating or cooling. Hemp shives used in hempcrete are a waste product, yet lime is an energy intensive material. This paper summarizes a research project the purpose of which was to investigate the possibility of substituting the lime in hempcrete with unfired binders, in part of whole, thus lowering the EE and EC of the mixture even further. Results of this research have shown that this is possible without compromising any of the traditional hempcrete properties, e.g., compressive strength and insulating value. A comprehensive Life Cycle Energy Analysis (LCEA) and Life Cycle Carbon Analysis (LCCA) has shown total energy requirements for a prototypical building’s lifespan (50 years) to be between ~ 50–10% of an identical building with conventional materials, and total carbon emissions to be respectively ~ 50–10%.