Home sweet (hemp) home December 5 is UN World Soil Day. The building industry has thus been called to account for its role in the massive use of mineral raw materials and environmental pollution. One solution comes from the bio-construction sector which draws on unlimited sources of natural materials such as hemp, which is a recyclable carbon sequestrator. But how comfortable is it to live in a hemp house? © Paolo Ronchetti Building with wood, straw, and hemp. Bio-based materials are seeing ever more use in the construction sector, which needs to become more sustainable as it is one of the major sources of soil, air and water pollution. "Forty percent of global raw material is consumed by the building industry. Fifty percent of CO2 emissions into the atmosphere come from the construction sector," reports Italian bio-construction expert Paolo Ronchetti. Moreover: "Traditional building and insulation materials - of mineral or synthetic origin - are rarely recyclable. At the end of their life they are disposed of in landfills. Therefore, besides having an important environmental impact for their production, they have an equivalent environmental impact for their disposal." Biodegradable and from unlimited sources. Instead of exploiting the earth's crust, and using a process that consumes energy and pollutes, the bioconstruction sector can get its materials from the field. Hemp is one of the best examples; it can be grown in crop rotation and improves the quality of the soil. The plant is also a “carbon sequestrator”: it grows very quickly and acts as a carbon store, absorbing atmospheric CO2 for as long as it continues to exist. Ronchetti adds: "You should consider that one cubic metre of a brick made from hempcrete - a hemp and lime biocomposite - instead of emitting C02, and polluting, it captures 20 kg of CO2 from the atmosphere. A cubic metre of low-density hempcrete biocomposite, which is sprayed to insulate roofs or subfloors, can remove 60 kg of CO2 from the atmosphere. So you can imagine – with the volumes and the numbers in the construction industry – how much this virtuous model of building with hemp and lime can fight climate change." To note, in the past, industrial hemp was banned in many countries because it was associated with illegal marijuana, from which it differs as the psychoactive compound 'THC' is present in proportions of below 0.2%. A thriving industry was consequently stopped. Now hemp farming is flourishing again. This material also has other advantages. It allows builders to make high-performance envelopes and offers more comfortable, healthy and energy-efficient houses. Furthermore, the traditional building industry has increasingly used synthetic and chemical products that can be toxic and hazardous to human health. Tough low-allergen design using natural materials is becoming a new trend. Northern Italy, Chiari, near Brescia. “In the Po Valley summers are terribly hot and humid. Winters are cold and damp. Humidity rules here!’’ says Sara Bordiga. Her husband, Mauro Cogi, longed for an eco-friendly home, and started studying all the available possibilities on the market. Finally, he opted for hemp and in 2015, Mauro and Sara moved into their new bio-based house with their child. "My husband’s choice really surprised me. I had never heard about hemp houses!" says Sara. Mauro, an engineer, personally followed all the building phases. “The hemp technology works very well. I wrapped the whole structure in this monobloc hemp envelope, thus avoiding thermal bridges.” It’s monobloc because they didn’t use bricks, the hempcrete was sprayed directly onto the structural walls. Read more and watch the video here: www.youris.com/energy/ecobuildings/home-sweet-hemp-home.kl Keywords bio-construction, biobased materials, hemp, buildings, sustainability, insulation Countries Spain, Italy, United Kingdom
