Environmental benefits of using hempcrete walls in residential construction: An LCA-based comparative case study in Morocco

Abstract

Hempcrete is a bio-composite material with excellent environmental and thermal properties. This material has been increasingly adopted in Europe as an alternative to concrete and traditional insulation. However, hemp hurds, as the raw materials for hempcrete, are discarded in the world's largest producer (Morocco) and considered biomass waste due mainly to their association with marijuana production. Thus, research on hempcrete remained limited in Morocco, with fewer stakeholders aware of the benefits of hempcrete in green buildings. The objective of this paper is to assess the potential use of Moroccan hemp biomass in the construction industry using a life-cycle assessment comparison of a residential house in Marrakech (Morocco) with three different exterior walls systems, two insulated conventional wall systems (i.e., double hollow clay brick (DHB), composite wall (CW) with extruded polystyrene (XPS) insulation), and a bio-composite material (i.e., hempcrete) to identify environmentally preferable wall systems. Our study demonstrated that hempcrete is advantageous over other comparable conventional wall systems in terms of embodied energy and performs best in terms of the environmental performance associated with its entire life cycle achieving relatively low carbon emissions (484.42 tCO2) compared to insulated DHB and CW systems (546.27 tCO2 and 546.55 tCO2 for DHB and CW, respectively) over a lifetime of 100 years. Significant savings (i.e., 61.85–62.13 tCO2 if hempcrete is used instead of DHB and CW) can be made from the exterior wall choice for a single house. These savings become much more significant if scaled up to the national level of Moroccan homes. Consequently, by exploiting the hemp biomass currently available in Morocco, results show a reduction of 1.91 MtCO2–1.92 MtCO2, equivalent to 2.81%–2.83% of overall Moroccan emissions. Thus, strong policy support and hemp legalization in Moroccan are essential to boost and expand hempcrete utilization for a greener construction industry.