Environmental Life Cycle Assessment of a Novel Hemp-Based Building Material

Area of Science:

• Environmental Science
• Materials Science
• Sustainable Construction

Background:

• The construction sector is a major contributor to global greenhouse gas (GHG) emissions, with infrastructure alone accounting for 18% in Australia.
• Decarbonizing construction requires low-embodied carbon building materials to meet climate goals.
• Industrial hemp (Cannabis sativa L.) presents a viable alternative due to its carbon sequestration, rapid growth, and functional properties.

Purpose of the Study:

• To estimate the carbon footprint (CF) of hemp-based building materials produced in Western Australia.
• To identify key emission contributors in the hemp-based board production lifecycle.
• To assess the impact of energy sources on the overall CF.

Main Methods:

• Life Cycle Assessment (LCA) following ISO 14040:2006 guidelines.
• Cradle-to-gate system boundary, encompassing pre-farm, on-farm, and post-farm stages.
• Functional unit: 1 m² of hemp-based board, considering regional variations in inputs and energy mix.

Main Results:

• The estimated carbon footprint for 1 m² of hemp-based board is -2.302 kg CO₂ eq.
• Electricity for bio-based binder production (post-farm) and urea production (pre-farm) are significant emission sources.
• Sensitivity analysis reveals a 164% CF reduction when replacing grid electricity with solar power.

Conclusions:

• Hemp-based boards demonstrate lower embodied GHG emissions compared to conventional materials like gypsum plasterboards.
• Optimizing energy sources, particularly utilizing renewables like solar, is critical for maximizing emission reductions.
• Hemp-based materials are a promising solution for sustainable construction and achieving climate targets.