Hemp lime and hempcrete: green building and less CO2

The building industry consumes about forty percent of global energy: from Brittany to Italy, hemp lime could be help the green building sector

Hemp lime and Green Building: reduced water consumption compared to cement production

Hemp lime and hempcrete are cementitious compounds made from short hemp fibers, hurd (or canapule), lime and water, which can be supplied in modular blocks similar to concrete masonry units. Carbon negative and with known earthquake-resistant properties, hemp lime saves 90 percent of the water used to produce cement. It’s precisely what is called Green Building. Today, hemp lime and hempcrete are suggested for the restoration of rural buildings in rural Italy. The plant component that can decrease the percentage of the usually used mineral component (stone and water). This practice would increase CO2 storage, that is, the sequestration of stable and permanent carbon in construction works.

From Maison à colombages to Italy: contemporary history of hemp lime in construction

Currently about 5,000 tons of hemp compound building material are used annually in construction in France, the country that first began developing hemp-based insulating building materials in the early 1990s. The use of hemp in construction is in fact quite recent: it dates back to the 1970s in northwest Brittany. Small specialized productive sites are operative in Normandy, in Belgium (in the Walloon region), and into the area of the French Pyrenees, where there are lime quarries. In Italy as well, although today the majority of hemp material for building still comes from France.

Green Building: living in hemp

The European Commission estimates that the construction industry is responsible for 40 percent of global energy consumption: this consumption could be reduced by replacing mineral aggregates with plant aggregates. We need to think in terms of Green Building only. Saving water in the process. Carbon dioxide can be stocked in the new buildings. Hemp is an insulating concrete that is needed today.

Some History: from the wood houses in Rennes to Leon Battista Alberti in 1450

In the city of Rennes, wooden houses are called colombages – dating back to the period of the 1200s. The plugging of which was done thanks to a mixture of clay, wheat straw and hemp straw.
Leon Battista Alberti in De Re Aedificatoria of 1450 enunciated the usefulness of hemp in construction because when added to mortars it improves their qualities: Hemp, when mixed with lime and applied turns into a real breathing lung, capable of absorbing moisture when it is in surplus and releasing it when the air is too dry, without the need for any ventilation or air conditioning systems-systems that can often bother people or be vehicles for infection, and move fine dust that we then breathe.

Editorial team