Sustainable materials
Hempcrete
A bio-composite building material of hemp hurds and lime binder — lightweight, insulating, vapour-open, and typically carbon-storing over its life cycle.
Definition
Hempcrete is a bio-composite construction material made by mixing hemp hurds — the woody core of the hemp stalk — with a lime-based binder and water. It is non-structural, used as infill walling and insulation, and is valued for thermal and acoustic insulation, moisture-buffering breathability, and low embodied carbon: hemp absorbs CO₂ as it grows, and lime re-absorbs CO₂ as it cures, so the material can be carbon-negative across its life cycle.
References
composition and carbon profile
properties and uses
Overview
What it means
Hempcrete illustrates the shift from high-embodied-carbon materials (cement accounts for a large share of industrial emissions) to bio-based materials that store carbon in the building stock. Its vapour-open character also regulates indoor humidity and mould risk. Limitations include low structural strength, specialist skills, and regulatory hurdles around hemp cultivation in some jurisdictions.
How it is used
Applied in low-rise residential and retrofit construction, cited in whole-life carbon assessments and bio-based materials policy.
Why it matters
Decarbonising construction needs materials that store rather than emit carbon; hempcrete is the best-known example in practice.
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