Life cycle assessment of hemp concret blocks

Buildings notably contribute to global environmental negative impacts due to consumption of both embodied energy and natural resources as well as various emissions during their whole life cycle. It is therefore necessary to develop practices to reduce these impacts, mainly by reducing the part of non-renewable resource in material as well as by ensuring the lowest energy consumption possible during their lifetime. New developments in natural fibres and their use in insulating materials can lead to significant improvement in building environmental impact. For this purpose, assessment of environmental performance is needed to support both the design and the production of (new) fibre based insulation solutions.

In this context, the Life Cycle in Practice (LCiP) project helps SMEs to reduce the environmental impacts of their products and services across the entire life cycle. Within the frame of this project, Isohemp (BE) hemp concrete block impact is evaluated in a cradle-to-gate LCA.

Functional unit is a pallet of hemp concrete blocks ready for shipping. It represents about 1.3 m³ of blocks. Hemp blocks are made by pressing a mix of hemp shives, hydraulic and hydrated limes, and water. Long term carbon storage due to lime carbonation induces a large benefit in Climate Change (CC) category. The balance of the CC indicator for hemp cultivation is also favorable due to carbon dioxide uptake by the photosynthesis occurring during the plant growth.

Life Cycle Assessment of hemp concrete blocks ready to ship has also highlights some improvements that can easily be made at the packaging level in order to lower the global environmental impact and increase the sustainability of this insulation material.

Data are processed in SimaPro 8 software, with Ecoinvent 3 and ELCD 3 databases, and analyzed with the CML IA method. This method is compliant with the indicators required by EN15804 standard in order to communicate on the environmental performance of Isohemp blocks.