Hemp made: a study on the potential of hemp-lime and hemp-clay components for indoor climate performance and climate impact

Abstract

We live in a society where people spend most of their time indoors. Buildings should thus provide safe and sound spaces to live, work and sleep in. However, the building industry nowadays is mostly relying on non-renewable, man-made materials that could badly impact the indoor quality of our built environment. Above that, these materials have a non-neglectable negative influence both on resources and on emissions, putting significant pressure on our planet. Natural materials can provide an ecological and healthy alternative to numerous conventional building components. This thesis work investigates hempcrete, a sustainable, natural, biobased material that has great potential as an insulative infill component. Hempcrete is a mixture of hemp hurds with a mineral binder, most often lime-based. The hemp plant is fast-growing, making it a particularly resource-efficient raw material. This work explains what hempcrete is, how it is made and what different construction techniques are applied nowadays. Further on, the work focusses on the material’s performances both regarding indoor climate regulation and environmental impact. Various characteristics such as vapor permeability, hygrothermal performances and thermal mass allow for hempcrete buildings to achieve a steady and comfortable indoor climate. Furthermore, hempcrete has a small carbon footprint, mainly thanks to the hemp hurds. The possibility of associating hemp with clay rather than with lime is also investigated throughout this thesis work. This would enable to create a completely sustainable, safe and sound biomaterial. Lime has non neglectable embodied energy and embodied carbon, whereas clay is a local resource, available everywhere, that does not require processing. Furthermore, hemp-clay is a zero-waste product, as both hemp and clay can be reused or recycled and are both 100% biodegradable. Both theoretical research and material testing are led to study the potential of hemp-clay, and indoor climate performances are compared. In the end, guidelines on how to implement hempcrete in design are given and exemplary construction details, with their performance, are elaborated.