To those yet to be introduced to the wonders of hemp, this type of insulation can seem like a hippies dream, however a simple Google search will soon lead you to the world beyond students bed-sits and Pink Floyd soundtracks to textiles, biodegradable plastics and fuel.
However, we’re interested in insulating properties of hemp, so back on track…
Usually produced in batts (a precut, presized, blanket of insulation). Inorganic, non-toxic natural salts and thermoplastic binder are used to improve structure, durability, moisture, rodent & insect protection. Grown in many climates C02 is ‘locked-in’ during growth.
- Non-toxic & non-irritating.
- Locks in carbon.
- Low embodied energy. Relatively little energy is consumed in its production.
- Self-supporting. In comparison to most other light-weight fibre insulations, hemp batts do not slump and therefore maintain their structure and insulating properties over time better than other comparable products.
- Note for UK readers: Hemp insulation is often grown and / or processed outside of the UK. You may want to take that into account when considering the overall ‘green’ credentials of this product.
Hemp Batts have a thermal conductivity or K value of 0.04 W/m.K.
(Watts per meter Kelvin ~ a lower value is a better result)
As production is still relatively small scale, cost is high…
A 75mm x 575mm x 1200mm roll of batts costs approximately £50 (rounded) including VAT and covers 5.5 m2 therefore approximate cost per square metre at 75mm depth is £9.
An impressive statistic quoted often in information sources about hemp insulation is that for each kilogram of hemp insulation used instead of mineral wool, 1.4Kg of CO2 is saved.