Abstract
<jats:p>Building materials based on natural renewable resources are a key factor in reducing the environmental footprint of the construction industry. Among them, hempcrete stands out – a biocomposite obtained by mixing hemp fibers with a binder based on building lime and water. Its natural origin, good thermal and acoustic insulation properties, and excellent vapor permeability ensure an optimal indoor environment. Nevertheless, broader application of hempcrete in construction requires addressing challenges related to its hygrothermal behavior. The aim of the present study is to assess the conditions under which there is a risk of condensation within walls made of hempcrete and to formulate guidelines for their optimal design and implementation. The enclosing wall structures are designed so that the maximum thermal transmittance coefficient U does not exceed 0,26 W/m2.K. The hygrothermal regime is analyzed in accordance with the Bulgarian regulatory standards, under steady-state conditions, for Climate Zone 7. Several structural solutions for hempcrete enclosing walls with different combinations of internal and external plaster coatings are considered. The influence of various indoor microclimate parameters is also analyzed. It was found that under high indoor relative humidity and certain combinations of coating types, conditions may arise in the enclosing structure that favor moisture accumulation. In most cases, this moisture, accumulated during the condensation period (winter), evaporates completely during the evaporation period (summer). The humidity level is considered relatively low, posing no risk of mold growth or significant deterioration of the structural and thermal insulation properties of hempcrete. Given the lack of sufficient data on the equilibrium and maximum allowable moisture content of hempcrete, guidelines are proposed to prevent condensation within hempcrete walls.</jats:p>