Hempcrete as a substrate for fungal growth under high humidity and variable temperature conditions

Abstract

Bio-based alternatives for existing construction materials can be used to reduce the carbon footprint of the built environment. Hempcrete is one of these materials and is both an excellent hygric/thermal regulator and is carbon negative. However, this novel material is still incompletely researched, especially its fungal growth potential specifically within warm and humid environments. The incorporation of significant biological material within hempcrete can enable it to act as a microbial growth medium, with the corresponding potential for the release of bioaerosols. The aim of this research was thus to investigate the overall practicality of hempcrete implementation in a humid climate. To achieve this, the endogenous fungal genera on a sample of hempcrete were identified, fungal propagules aerosolized from a hempcrete sample enumerated, and a range of temperatures tested to determine their effect on fungi growth determined. Trials were performed to determine whether hempcrete can be effectively decontaminated with common materials to manage microbial growth. Under high humidity, fungal propagule emissions were high with low diversity, with potentially allergenic fungi detected. Disinfection of high fungal load hempcrete samples was able to reduce ∼94% of the fungal observations and reduce aerosolized counts to average background tropical fungal counts. The range of temperatures tested were not found to effect fungal growth, contrary to the consensus of the literature. Overall, these properties make hempcrete suited to humid areas, however, further research to investigate the potential effects of fungi on the material remains lacking.