HTM: First and foremost, why hemp?

Hemp is probably one of the best natural resources we were gifted with on planet Earth. There are no other plants that can grow basically anywhere all over the world and give birth to so many beneficial products like textiles, food, paper, medicines, construction materials, animal bedding, fuel, bioplastic. In particular we decided to develop the uses of hemp as a building and insulation material in the construction industry because of its interesting hygro-thermal properties.

HTM: Any historical facts about hemp in Italy?

Hemp has always played an important role in Italy. In the early XXth century, hemp was grown all over the country with more and 100.000 hectares. Italy was the second hemp producer in the world after Russia but the first in terms of quality of its fiber because of the peculiar temperate climate and local hemp varieties like Carmagnola and Eletta Campana. Between the end of World War II and the early 1990s the cultivation of industrial hemp totally disappeared because it was outlawed as an illicit substance. It then came back and slowly started to be grown again thanks to EU agricultural subsidies. Over the past ten years the cultivation of hemp in Italy went from a few hundred to more than 4000 hectares now. The main reason for such growth is due to the rise of demand for ‘cannabis light’ and CBD extracts.

HTM: Are there any varieties of hemp that are preferable for your products?

We prefer to use shives coming from stems with 2-3cm diameter regardless of the hemp variety. Smaller stems produce shives too thin and weak with very little structure. Bigger stems produce shives too thick which are difficult to deal with when using spray machine. We learned it is important to have shives with mixed length. For example we use standard shives with a granulometry range from 0 to 25mm in terms of length for blocks and spray application as well as fine shives with a range from 0 to 6mm for finishing layers.

HTM: Could you please, give us a brief synopsis of the unpaved road “Tecnocanapa” took in this promising industry?

Tecnocanapa is the brand under which the Senini Group produces and distributes a wide range of hemp based products for green building. The history of Tecnocanapa was born in 2011 with Equilibrium, the startup company which first introduced hemp construction in Italy and later became part of the Senini Group in 2018. Hemp building was totally unknown in the country before 2011. A lot was invested in promotion, public relations, marketing, training, R&D and demonstration projects. Since then, we have been able to demonstrate the high value of such technology in terms of energy saving, comfort of living and healthy indoor environment. Little by little hemp buildings started to show up all over the country and we are now proud of our 600+ completed projects. 

HTM: Dear Paolo, we know you have been doing a lot of workshops and presentations and you are one of the pioneers of hempcrete building. Do you have any projects that stand out in Your opinion? Have you done any large- scale developments?

Since 2011 we have been involved in an increasing number of projects. Since the beginning our aim has been to bring hemp and lime construction to the industrial scale. The largest scale development we supplied our solution to is a 40 apartments building in the south of Italy, Apulia region near Bari. It is called ‘Case di Luce’ (house of light) and it the largest residential construction with hempcrete envelope in the world.  

HTM: Could you tell us a bit about the proprietary LDN Natural Dolomitic Binder you are using in terms of initial setting and other characteristics?

LDN Natural Dolomitic Binder is made of 100% dolomitic air lime naturally containing magnesium oxide which makes it extremely reactive. Our experience shows that using air lime instead of hydraulic lime binders results in much higher quality hempcrete in terms of performance, compressive strength and durability. Such biocomposite is a totally new material resulting from the carbonatation of calcium hydroxid where lime does not glue the hemp shives together but permeates and covers them. This process takes time but the result is highly qualitative. While when you work with cement or hydraulic lime, you basically glue the hemp shives together and the resulting material hardens fast in a few hours and it remains a conglomerate like cement and sand in concrete. To further improve our products, in 2015 we patented a range of hempcrete products by adding special probiotic microorganisms to the hemp-binder-water mix in order to speed up the carbonatation of lime. The yeasts living in the organic additive produce CO2 which speeds up the hardening of the material once the majority of water has evaporated.  

HTM: Do Tecnocanapa “Ambiente blocks” come in various sizes and what are the feedbacks from traditional masonry workers? What is the thickness of mortar between each block?

Our Blocco Ambiente covers a wide range of thicknesses, i.e.  8, 12, 20, 25, 30, 36 and 40 cm. Standard size is 20 cm (height) by 50 cm (length) for thickness 8, 12, 25 and 30. Only exception is the 20 cm (height) by 40 cm (length) by 36 (width) format because with one size we can cover both thickness 36 and 40 cm.

Traditional masonry workers can easily work with our hemp block. At first they are usually a bit biased by the different look of hempcrete blocks compared to what they are used to work with. But then, they get immediately comfortable because of the lightness and easiness to build walls with them. As mortar we use high density hempcrete 500 kg/m3 in order to have an homogeneous material between blocks which eliminates any thermal bridge and, in the end, allows you to have a completely monolithic wall. Average mortar thickness between blocks is 1 cm. 

HTM: Could you please explain “Bio Beton” in its essence? Is it the material for spray-on hempcrete?

Bio Beton is the name of the lowest density hempcrete mix we produce (175 kg/m3). We supply it in 1 or 2 m3 big bags already mixed with water and binder and ready to be used. Bio beton is employed as roof and floor insulation as well as an insulating infill in between panels or blocks. 

Spray-on hempcrete is called Natural Beton 200 because of its low density (200 kg/m3). It is very similar to Bio Beton in terms of hygro-thermal performance. The main difference is the production and application method. Natural Beton 200 is produced and sprayed applied on site with a special machine we engineered and patented. Such method allows you to build the highest performance walling systems in terms of energy saving and living comfort.

HTM: How does building with block differ from spraying hempcrete?

The main difference between the two methods is that any masonry worker can lay hemp blocks without any previous experience with hemp building while you need skilled labor and a special machine for sprayed hempcrete. Sprayed hempcrete is also quicker when you have to build walls larger than 300 m2. In terms of energy saving performance the two methods are very similar. However, due to its lower density, sprayed hempcrete has a lower thermal conductivity (0,05 W/mK) compared to hemp blocks (0,07 W/mK). 

HTM: Where and how is “Canafiber” being applied? What are its features?

Canafiber is an insulation material made with hemp fiber. We use it for thermal and acoustic insulation of roofs, ceilings, partitions and internal walls. It is the best natural alternative to low density synthetic and mineral insulation materials. The main features are its ability to mute sound, regulate humidity, prevent mould and reduce temperature fluctuations. The sheets are easy to use, guaranteed free from harmful substances and cause no risk of skin and respiratory irritation.

HTM: Do you believe “Tecnocanapa” solution could replace all or at least most of conventional construction?

Our solution can definitely substitute a wide range of mineral and synthetic construction or insulation materials. For new buildings, once the load bearing structure has been erected with timber, steel or concrete, the rest can be made with hempcrete (i.e.  walling systems, partitions, finishes, roof and floor insulation). In existing buildings you can insulate walls either from outside or inside, apply thermal plasters and insulate the attic or the roof.

HTM: How is your work and product perceived and commented by conventional builders and industry in general?

At the beginning, between 2011 and 2013, I must confess there was a bit of skepticism amongst the main actors in the construction industry. In some cases it was even difficult to talk with architects, builders and developers. They just did not want to waste their time in learning about innovative green solutions and did not want to believe in something they could not touch and see. However, we were able to find more openness amongst private customers who were more sensitive to environmental and health issues. It is thanks to these early adopters that we were able to prove the validity of our technology on the market. As a consequence, little by little medias started to talk about this new way of building and insulating houses and also the industry started to be more open to dialogue with us. Only a couple of years ago I found out that, according to economics research, the innovation cycle in the construction industry is pretty long and lasts on average eight years. That means it usually takes eight years before new products or solutions get accepted by the mainstream market. This explained a lot to me and it is what really happened to us. At the end of 2018, Senini Group, a major industrial company decided to invest and include hemp construction in its range of products. Now, we are still in a niche market that is growing steadily year after year. The construction industry has now accepted hemp building as a reality and it is bound to get bigger and bigger over the next few years.

HTM: Have there been any regulations or intentions in Europe towards subsidizing Carbon sequestering materials?

As far as I know, at the moment there are no EU plans to subsidize carbon sequestering construction materials. It looks EU at the moment is only funding research to prove results we have known for more than twenty years now. ISOBIO Horizon 2020 is one of the most recent research project which was completed in 2019 to promote the use of innovative materials to decarbonise construction.

HTM: Is “Tecnocanapa” open for accepting new distributors and expanding onto other markets?

Yes, I confirm we are always looking for partners in Europe for distributing our products as well as for licensing our technology. 

HTM: For the last, how do you think the outbreak of COVID-19 and urgent measures halting the economy will influence market?

I really believe the COVID-19 outbreak will give a boost to the hempcrete building industry. First of all such an emergency has forced people to become more aware of the air quality inside their homes and the resulting effects on their health. Hempcrete is made with lime which is naturally antibacterial and virulicidal.  In addition to that, we will see national policies aimed at supporting the construction industry because it has always been the driving motor in developed countries. For example, the Italian government has just decided to provide a 110% tax credit to anyone willing to improve the energy efficiency of existing buildings. Such credit can be transferred from the client to the supplying contractor and from the contractor to banks. This means house owners can get a complete insulation project for free or at little cost. This is happening right now and I am sure hemp building materials will be preferred to synthetic or mineral solutions.