The effectiveness of hempcrete in the reduction of the environmental and financial costs of residences

Abstract

The aim of the current graduation project is the investigation of the potential of using hempcrete for the construction of residences in the Netherlands. The research focuses on the prefabricated block form of the material and investigates different aspects that can play a major role and eventually affect the choice for the selection of the material in building applications. Such aspects are: the regulation and performance proofing requirements which are associated with the application of an unstandardised material, the application methods, the strengths and limitations related to the nature of material, the current industry barriers, its hygrothermal, energy and environmental performances according to the Dutch building regulation in comparison to popular industrialised materials in the Netherlands and the related costs. The compared industrilised options were two: the Aerated Autoclaved Blocks, which account for an industrialised option with equivalent properties as these of the hempcrete blocks, and the option of Sand-lime bricks in combination with Fiberglass insulation, which is currently a widely used construction option in the Netherlands. Dynamic hygrothermal simulations were performed in WUFI software, whereas available EPDs were used for the investigation of the environmental impacts of the materials under scrutiny in a life cycle analysis. Available literature, interviews with parties characterised by different roles and high experience regarding the use of biobased materials in the building industry were also used as a means for the completion of the current graduation project.
Apart from the available literature, the research methods followed in the current graduation project were influenced by the results of the performed interviews, which indicated aspects that could be further explored. The results of the research show that in terms of performances, the material is able to satisfy the requirements of the modern Dutch building regulation and therefore the later does not account for the reason behind the limited propagation of the material in the Dutch building industry. Nevertheless, the current Dutch regulation is currently a barrier that discourages the international material supply and disregards important properties of hempcrete as its moisture buffering capacity and specific heat capacity which can play an important role. The Sand lime brick option has been proved more competitive in comparison to the Autoclaved Aerated option, as hempcrete outperformed its industrialised version AAC in the vast majority of the analyses performed in the current study. Hempcrete shows a better moisture buffering capacity and environmental footprint. The hygrothermal performances of hempcrete blocks were also proved beneficial in the condensation analyses, where even hempcrete walls with lower thermal resistance still reached the same performances as the better thermally designed SL walls. Hempcrete design of the residence exhibited slightly lower energy performances, which can be attributed to the lower volumetric heat capacity of the material.