The properties of this plant are infinite, known for millennia
the first evidence of its technical use dates back to more than 8000 years ago, somewhere in Central Asia. In 2737 BC. in a treatise on Chinese medicine, cannabis was referred to as a medicinal plant, but it is not only known for this, in fact the properties of the fiber have been exploited for centuries: Columbus' famous caravels, the Nina, the Pinta and the Santa Maria had sails made of hemp fibre, known for their great resistance, so even the ships of the English Navy adopted the use of the fiber of this plant, which was ultra resistant even to the wear and tear of sea water. 
Many manuscripts and sacred texts derive from the fiber of the Cannabis plant, in short, it has always been there Hemp it has been used in many applications, and today as in the past we can use it in building construction, to counteract the massive and uncontrolled use of materials harmful to the environment and humans.
In the new Green Deal one of the protagonists is certainly Hemp. Climate change and the waste of useful resources are forcing us to choose solutions with less impact on the environment and more eco-sustainable.
Let's see some characteristics of this plant used in construction:
One of the most incredible properties of the cannabis plant and its great ability to absorb heavy metals present in the soil, this is called "Bioremediation", a significant problem in Italy. In recent years they have been trying to reclaim the land bordering the Ilva of Taranto with cannabis, with positive results. Once the life cycle of the cannabis plant is over (about a year), the product can be transformed into biomass for the production of material for green building made of hemp. Compared to wood, it is a noble raw material, it regenerates in a very short time, it does not need particular quantities of water and pesticides. In short, the hemp, the part indicating the hemp stem could really be a valid helper for man, and considering that Italy was the largest producer of this wonderful fiber it could be a valid help for the country in the future, if we ever decide so.
In construction, there are many materials that can be made from hemp: blocks of hemp, plasters, panels insulators and the various products derivatives.
The importance of this material in a circular economy is that these products are completely recyclable and biodegradable at the end of their life cycle. For example, in the case of a demolition of a building made of biobricks, the latter can be calcined in a furnace, obtaining lime again, or crushed and mixed with more lime and vegetable fiber to create new biobricks. Finally, they can be shredded and spread as a soil improver in acidic or arid-saline soils.
HEMP BIOMBRICK:
The hemp brick is made from Canapulo, i.e. the chopped stem of the plant agglomerated with dolomitic lime and water. Let's discover the properties of this fantastic bio material: A very important characteristic of hemp brick is the fact that it removes CO2 from the atmosphere, thanks to its ability to absorb large quantities of it. It is also able to strongly isolate internal environments from the outside, thanks to the large thermal transmission coefficient (K) that hemp biobricks have. The hemp house, or rather with walls made of biobricks, are able to balance and maintain the same humidity levels despite variations in the surrounding environment. Living comfort certainly increases with the use of these "intelligent materials", thus improving the healthiness of the environments. This aspect is becoming more important every year given the large amount of hours that each of us spends in our homes.
But there are some wait negative to take into account: certainly the size of the hemp brick (one brick is as large as three terracotta bricks), making it bulky and unwieldy. Furthermore, Canapulo is not easily available in Italy, in fact it is mainly imported from France, increasing the environmental and economic costs linked to transport.
SOUND-ABSORBING HEMP PANELS:
There are sound-absorbing fiber panels (the part that covers the stem), excellent for prefabrication in wood, to insulate the inside of walls or an attic.
LIME AND HEMP
As an alternative to the use of hemp biobricks, lime can be mixed directly on site with hemp, and used as both external and internal plaster, applied in attics it becomes optimal both for thermal insulation and thanks to its breathable and anti-humidity properties it maintains excellent air healthiness, in increasingly sealed domestic environments.
COSTS OF USING HEMP IN GREEN BUILDING
The costs for building green building houses using materials derived from hemp are higher than classic construction, due to the factors we have indicated in this article: poor diffusion of the supply chain in Italy and limited presence of distribution companies. This market seems to be evolving, and thanks to its diffusion it is hoped that prices can be calmed down in the future. Some Regions, such as Piedmont, provide incentives and tax deductions for the use of bio-derived or recycled materials, as in the case of the Regional Law, Piedmont 4 October 2018 n° 16.
