Hemp: an eclectic and sustainable material
Hemp has been neglected as a valuable resource for a long time; but lately, there’s been a renewed interest in its eclectic qualities. Indeed, hemp is a truly versatile plant, able to grow at a rapid rate, adapt to different climatic conditions, remove carbon dioxide from the atmosphere and regenerate the soil by purifying from pollutants. Not bad for a plant that has been demonized for years, is it? Furthermore, its biomass can be applied to a very wide range of industrial and artisanal uses, including the production of eco-sustainable building materials.
Hemp as a building material
The first use of hemp as a building material began experimentally in France in 1986. Hemp fibers were mixed with limes ones, a practice that rapidly took hold in the construction field.
This technique was initially used mainly for the restoration of historical buildings, but started to be widely applied to new buildings in the early 90s. In Italy, the first hemp-lime house was built in 2010 in the region of Emilia-Romagna, where most of the Italian hemp was produced in the first half of the 20th century.
Through a process of mechanical separation, the fiber (external part) and the canapulo (internal part) are separated from the stem of the plant.
The most valuable component, the fiber, is mainly used in construction for the production of thermo-acoustic insulation for indoor environments.
On the other hand, the canapulo is the most used component of the plant in the construction world: crushed into flakes, it is marketed in different grain sizes, such as construction aggregates; when dry, it is used to fill structures and stratigraphies, or it’s combined with water, binders and other aggregates with a mixer, obtaining a compound of different consistency depending on the final use.
Being a highly hygroscopic material – i.e. a natural regulator of air humidity – hemp, with its molecular structure, can incorporate water vapor without significant changes in volume. This allows to keep a balanced level of humidity in the rooms, which translates into a beneficial, healthy environment. Exceptional high thermal and acoustic insulation performances are also guaranteed by the insulating properties of this mixture. This type of construction technology is simply perfect to create buildings where high energy efficiency, low consumption and living comfort are required!
Meeting between architecture and sustainability
All these characteristics make hemp perfect for sustainable construction, and one wonders why its production has been opposed for years, although it is evident that it is a miraculous plant also from a medicinal point of view. What could this tender shrub ever do to deserve the epitaph of “devil’s weed”? In recent years, its reputation in public opinion is rapidly changing, and it seems that the green revolution has found a solid ally in hemp!
From an eco-friendly point of view, the ecological footprint of the lime-hemp mixture gives great results: when measuring the CO2 released in the production and use of the material and the CO2 absorbed during the growth process of the plant, the latter is greater. Furthermore, compared to other building materials, hemp-lime has a very long life cycle, which among other things ends with its complete recyclability. In fact, a crushing process is enough to be used again as a secondary raw material or even in new construction sites, without the need for treatment of any kind.
All these characteristics make hemp perfect for sustainable construction, and one has to wonder why its production has been opposed for years, although it is evident that it is a miraculous plant also from a medicinal point of view. What could this tender shrub ever do to deserve the epitaph of “devil’s weed”? Yet, in the last few years, public opinion has shown a more positive attitude towards it: it would seem that the green revolution has found a solid ally in hemp!