Energy efficiency and hygrothermal performance of hemp clay walls for Moroccan residential buildings: An integrated lab-scale, in-situ and simulation-based assessment.

Hemp-based building envelopes have gained significant popularity in developed countries, and now the trend of constructing houses with hemp-clay blocks is spreading to developing countries like Morocco. Investigating the hygrothermal behavior of such structures under actual climate conditions is essential for advancing and promoting this sustainable practice. This paper presents an in-depth experimental characterization of a commercial hemp-clay brick that has been exposed to the outdoor environment for four years, in addition to field measurements on a building scale demonstration prototype. Additionally, the study simulates 17 representative cities to assess the hygrothermal performance and energy-saving potential in each of Morocco's six existing climate zones, using the EnergyPlus engine. The experimental campaign's findings demonstrate excellent indoor air temperature and relative humidity regulation within the hemp-clay wall building, leading to satisfactory levels of thermal comfort within hemp-clay wall buildings. This is attributed to the material's good thermal conductivity and excellent moisture buffering capacity (found to be 0.31 W/mK and 2.25 g/m2%RH), respectively). The energy simulation findings also point to significant energy savings, with cooling and heating energy reductions ranging from 27.7% to 47.5% and 33.7% to 79.8%, respectively, as compared to traditional Moroccan buildings. [Display omitted] • Experimental characterization of thermal conductivity, sorption isotherm, and moisture buffering capacity of hemp bricks. • Assessment of indoor thermal comfort and energy demand in a hemp-based building across 17 cities in Morocco. • Hemp-clay bricks demonstrated excellent humidity regulation with a moisture buffer capacity of 2.25 g/m2%RH. • Hemp-clay walls can achieve energy savings ranging from 27.7%–47.5% for cooling and 33.7%–79.8% for heating in Morocco. [ABSTRACT FROM AUTHOR]