Thermal insulation potential of non-industrial hemp (Moroccan cannabis sativa L.) fibers for green plaster-based building materials

Hemp, or industrial cannabis, is on a massively growing trend as a natural additive for high-performance bio-based building materials. However, thousands of stems from vernacular cannabis cultivation in developing countries, such as Morocco, are overlooked and regarded as biomass waste used for rural household purposes. The objective of this paper is to assess the potential use of Moroccan cannabis fibers in the manufacture of local bio-insulating plasterboards. Firstly, the study focuses on the mineralogical, morphological, and chemical characterization of used fibers using X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Secondly, the impact of fiber addition on the thermal performance of plaster was experimentally studied using Hot Disk and flash methods. For this study, one hundred local fibro-plasterboards were developed by adding Moroccan Hemp Fibers (MHFs) to local plaster at different weight replacement ratios: 0, 2, 4, and 6% in order to evaluate the effect of fiber content on the thermal insulation quality of plaster and the variation of the thermal capacity of developed bio-composites. The experimental tests demonstrate the effectiveness of Moroccan hemp stems in improving the thermal transport properties of plaster and making it more thermally efficient. The incorporation of 6% in weight of MHFs in plaster matrix considerably reduced the density, enhanced the thermal insulation and slowed the heat transfer rate respectively by 24.5%, 31.3% and 8.5% when compared to plaster without fibers. The addition of 2% in weight of MHFs showed the best results in terms of thermal heat capacity. Finally, to evaluate the energy performance of developed plasterboards at building scale, annual simulations using EnergyPlus for a residential building located in two different semi-arid climates of Morocco were carried out. The results indicate that buildings with 40 mm Moroccan hemp plasterboard (MHP) have a considerable potential to reduce the energy consumption of buildings and provide passive thermal comfort for occupants, especially during summer periods. Therefore, non-industrial hemp is a good candidate for the development of local lightweight low-environmental impact (LLL) construction materials with contributions for building energy efficiency.