Built from hemp

Buildings made from natural hemp can be more energy efficient than their concrete counterparts.

Buildings made from natural hemp can be more energy efficient than their concrete counterparts, according to Dr Ray Marriott of Botanix, who spoke about its use at the BA Festival of Science this week.

Hemcrete – a mixture of natural hemp fibre and lime mortar – has previously been used in the construction of housing and commercial office blocks, but a new storage and distribution facility built for a Southwold brewing company represents its most ambitious use yet, he said.

The thermal insulation properties of the new construction material mean that the facility will not require refrigeration to maintain beer at its optimum temperature, saving an estimated £60,000 per year in energy costs.

Dr Marriott predicted that once people have become used to designing and building with this new material, its use will become more widespread. However, hemp is an annual crop, so limitations in the supply of raw hemp material are likely to hinder progress.

Hemp fibres, he said, are not only valuable for construction purposes, but they are also increasingly used as thermal and acoustic insulation and in the manufacture of car parts. The body shell of Eco One, an experimental racing car designed at Warwick University, is made using hemp fibre as a lightweight replacement for fibreglass.

Hemp, or cannabis, is a genus of flowering plants within the family Cannabaceae. The most well-known species is Cannabis satvia which contains the active psychotrophic compound THC (D-9-tetrahydrocannibinol).

However, natural hemp fibres are taken from cultivars of C.satvia with little or no THC. These cultivars also yield hemp seed oil which is commonly used in personal care products such as hand creams.