Sustainable building case study: the use of rice for architecture

Published on 2021-12-16

Startup Story

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Katerina Dimova is Architect and Project Manager in Ricehouse, a startup born in Italy, that tackles the impact of the construction industry by creating new sustainable building materials from rice wastes.


The story of Ricehouse: rice for sustainable architecture

Buildings are responsible for 40% of energy consumption and create 39% of global CO2. Ricehouse is a startup born in northern Italy tackling this problem, focusing on materials innovation. In fact, 40% of all materials used in the construction sector nowadays are hazardous.

So, starting from this problem and locating it in the area where 90% of the Italian rice is produced, every autumn we noticed that the rice fields were burned, creating CO2. We asked ourselves how we could transform this problem into a source of value. We started to study what we could do with all the rice residues.  

We found out that from every hectare of rice feud, we produce 7 tons of rice and 10 tonnes of residues. It is really an enormous amount, also considering the global production of rice. In these byproducts, that are mainly the rice straw and the rice husk, we saw an opportunity: the creation of 100% natural construction materials that compose the entire house, that is wholesome, that is an energy performant very technological. 

So, the startup is born from a necessity of the construction site. Basically, we've studied the traditional construction materials and we decided to change them with 100% natural materials based on rice residues. We studied which are the most impacting materials in terms of environmental impact, the end-use and the cycle, which are the ones that impact the health of the habitants.

Afterwards, we tried them with wholesome new sustainable building materials. With that approach we are slowly substituting all layers of the traditional building, that is 90% petrol-based, made with traditional materials: we change these materials with 100% natural ones. 

We are also providers of architectural design services: we accompany the client from the concept phase of the project and to the realization of rice houses or rice buildings, which are buildings that have energy performance and produce more energy than the one they consume. What is more, they're designed under the principle of natural architecture. 

The percentage of rice in a house

All the house, except the structure, can be made with our technologies. Nowadays we're providing materials that are isolating, we usually use wooden structures for the load-bearing structure and if there is an existing building we apply our materials outside of the existing building.

If we need to talk about a percentage, 90% of the house can be constructed with our materials.

Why to become a B Corp 

When the company was founded in 2016 we immediately started to divulge our business model through different seminars, lectures, different partnerships with universities, and the public and private shareholders.   
In that way, we wanted to inspire and stimulate others, mainly other stakeholders in the construction sector, for example, architects, construction companies, and real estate companies. 

This is why we decided to become a benefit corporation.   
That was actually something that we already had in mind to do, but we decided to formalize it in 2020. The benefit corporations are companies that basically state in their statute that theyr goal is not just profit, but also to create a positive impact on the environment, on the society in general. 

In Italy, there are just around 500 companies that are benefit corporations. So, we are one of the first and part of this movement.   
Every year we need to prepare a social impact report that states what is the impact produced in the current financial year, what are the targets for the next year. In that way, we are trying to show to our clients and to our partners, what is really the impact that we're producing. 

At the beginning of 2021, we submitted the application for the certification B Corps in order to become part of the movement. The Certified B Corp companies are new kinds of companies that balance purpose and profit. So it's very important for us to be part of that movement.  
Currently, we are concluding the assessment phase, it's quite a long process, but during the audit basically, this certification is stating and confirming that the two activities we create impact both on the society and on the environment. So through these instruments, we try to be transparent and to show to our clients and partners our real impact.

The end life of a 100% natural construction material

Usually the end life of our products is considered after 70, 80, 90 years. So if you want to structure processes that are working on the end life, it's quite difficult, but it's something on which we are working.  
We're working both on an academic level and on a business level. Basically we are operating with different universities in order to study the life cycle of our products. As they're 100% natural we are sure that they can be used at the end of their life for the creation of compost or for the creation of energy.

All our products are basically based on materials that are already used in the traditional architecture and so there are historic data thanks to which we know what is happening after years from the usage. 

What we would like to do in the future is something that we're already working on, but it's not currently part of our business model: it is the idea to withdraw construction materials from the construction site and recycle them or compost them directly. So, this is something that is going to be a powerful part of our business. Currently, we are not doing that, also because mainly the end life of our products is quite long, it's 50, 70 years. So we are planning to do that, for example, for products that are used in the exhibition sector or sectors that have a shorter life value.

Innovating traditional materials for sustainable construction 

We base our new sustainable building materials on raw materials that are used in traditional architecture. For example, the main binders that we use are lime-based or clay-based. 

Lime is one of the oldest binders in the history of architecture, is extremely durable and resistant to water. We know the Great Chinese Wall is constructed from lime, so there is a lot of data regarding this material and we're quite confident that our binders are working. Of course, we have engineered them and we added the technology of nowadays, but let's say the main structure is based on the traditional binders.

Also, another binder that we use very often is clay. It has been used in traditional architecture in all five continents for ages. What is more, the rice husk and rice straw are insulating materials that can be found in the traditional Italian rural houses from the 18th century. So there is also historic data regarding the raw material. 

We innovated these traditional materials and regarding the building durability, we're very, very confident that they'll be working.   
Regarding the resistance of humidity and fire, there is a very interesting figure and it's the fact that the rice crop grows in water and it has a very high percentage of silica. Silica is a fundamental component of this material and gives a very high resistance to humidity and fire. And this is why, for example, the rice straw is very different in terms of properties compared to the other crops. This is also the reason why we decided to focus our activity on rice crops.  

Overall, the main difference between our products and the traditional ones it's the impact on the environment because most of the traditional buildings are based on petrochemical materials. And on the other hand, the fact that our materials are 100% natural, they're healthy, improve the environmental internal comfort, regulate internal humidity and reduce the internal pollution by subtracting Co2. 

There are really a lot of advantages and in terms of cost, because the raw materials are so much cheaper, we have managed to stay very close in terms of cost to traditional materials. So that is an advantage.

Sustainable short supply chain production

All our products are based on a short supply chain, we basically withdraw all the rice throw and white rice husk in the area of Lombardia and Piemonte, in Northern Italy. We have different industrial partners producing different materials and all of the production is in a range of a maximum of 300 kilometres.

Even if we think about shipments to adjacent countries, for example, France, Austria, or Germany, we are trying to consider sustainable transport, for example, trains or electric vehicles. Nowadays it's still not so easy, but we're working in order to stay as pure as possible in terms of impact. 

How to reduce CO2 emissions with houses made of rice residues

It's something that we're working on an academic level together with the University of Milan: we're commissioning a research through which we are going to find out exactly how much CO2 our products are absorbing during the lifetime. 

But in general terms, if we consider that on a global level, the rice residues nowadays are destined to be burned in order to be dismantled, what we do is to insert them in a new sector: we withdraw them, they're are not burned anymore. In that way, we extend their life cycle transforming them from a problem to a source of value. Preventing the burning during dismantling, we reduce a certain quantity of CO2.

What is more, the rice husk and straw continue to absorb CO2 during the entire life cycle of the building in which they're inserted. And this is exactly the research that we have commissioned: in order to see, for example, in 70 years, the lifetime of the building, how much is every product absorbing in total. 

From the beginning of our activity in 2016, we managed to reduce around 400 tons of CO2 just by preventing the burning of the residues. And to this data, we need to add up the CO2 that is trapped during the life cycle of the buildings. This is data that it's more difficult to be calculated and that’s why it's a part of the research that we are doing.

So, considering that rice is the most consumed food on the planet, more than 66% of the population worldwide base its diet on rice, you can imagine that the potential of these residues and the potential of the reduction of CO2 that they're creating nowadays is really really enormous.  

The challenges and potentials in the sustainable construction industry 

As in every product, also with rice construction there are limits: the main limit is actually not the technical part, it's not the supply chain, but it's the cultural limit because it's in a way a new material, even if it was used in the traditional architecture it's not something that you can find in the construction stores.  
When a client approaches us, we really need to demonstrate the technical characteristics of these materials. That's why we do a lot of work on the certificates and all the technical tests.

A positive trend that we can see, that even Covid somehow triggered some changes, is that the consciousness of the customers is growing rapidly. But still, these materials are really barely considered for the mass market and actually in order to make a change, you need to transform the mass market because if you think in the niche you can't make a difference.

From another point of view, as I said, the raw material is present in extremely big amounts, because from 1 hectare of rice fields we produce 7 tonnes of edible rice and 10 tons of residues. These residues need to be dismantled sometimes twice and even three times per year.  
Considering the raw material, there is really no problem regarding the procurement. Also regarding the industrial plants, in order to scale the whole business model, it is not a problem: because we modify and engineer existing industrial plants that were in crisis. For example, one of the technologies of our products is very similar to the technology of ceramic tiles. We found an industrial partner that was in crisis, and we asked him to modify the existing equipment with small modifications, we do not talk about creating a new plan. They're partners that are already changing their business models and to which we managed to create new products. 

In terms of scalability, it's extremely possible. Actually, it's something that we would like to do and we're already starting to negotiate with different partners in different countries, because our main focus is based on the idea not to export the product, but to export the know-how in the different continents. Imagine, for example, Southeast Asia, where there is an enormous quantity of rice: it's going to be really awesome to create locally, to replicate the whole supply chain. So to withdraw the raw material there, to produce locally in the local factory and to sell locally to the local market. This is our mission, it's not easy to be done, but we're working on that through different channels.

How to spread the know-how in sustainable construction

Replicating the technology we have created and patented is something that is feasible. Nowadays, of course, you have to transfer the know-how, but we did it in Italy and it is just a matter of transferring the knowledge.

From another point of view, all our materials are created in order to be as close as possible to the traditional construction materials in terms of the poser. So when the constructor or the construction worker receives this material on the construction site, he receives packaging and mixture very similar to the traditional one. In that way, he's not worried that it is something completely new or that he doesn't know how to approach it.

For the materials that are more particular, we always provide technical documentation and we also have internally engineers that teach the workers how to pose these materials. But in general terms, we try to create materials that are extremely simple and very easy to pose and similar to the traditional one, because this is the only way to approach the mass market. Otherwise, you can't propose something completely different.

From small to big scale sustainable constructions

As in every beginning, we started from a small scale. When the startup was born we started to work mainly on small residential houses. As the startup was born on the experience of our CEO, that is architect Tiziana Monterisi, who has more than 20 years of experience in natural architecture, we already started from a very solid base.

We started with single-family houses and from the beginning of our practice, we have used our products in more than 100 building sites. What is more, we have constructed 20 houses that are completely executed with our technology and materials. We say that these are really the Rice Houses, where we have all the materials and all the technical characteristics that follow our approach. Most of these 20 buildings are energy buildings, so they produce more energy than they consume. In the last two years, also stimulated by the incentives regarding energy efficiency and sustainability of the project, we started to work also on a bigger scale. We have several high rise buildings already constructed with these materials and we have some projects that are ongoing. 

The most important project on a bigger scale is the energy regeneration of high rise building blocks in the periphery of Milan. The envelope of these buildings will be completely renovated with our materials and, what is more, we are going to generate around 3000 square meters of green roofs with vegetable gardens and orchards that will be cultivated from the local community.

The small scale and the bigger scale are very different as projects in terms of management, but in terms of materials and technology, we're applying the same concepts. Of course, working on a bigger scale we try to prefabricate most of our panels and most of the structure in order to gain time. But in general terms, the products that we use are always the same.

Possible future application of agriculture waste

We started to work on the development of products that are outside of the construction sector. We were approached by different traditional companies that have traditional products that are in crisis, and they're asking us "How can we become sustainable, how can we substitute our products with the natural based products?".

Starting from our know-how based, of course, on rice residues -  because there's so much to do with rice that we decided not to spread the energy on other crops and other cereal -  we started our research and development activities and we're working as a consultant to different sectors. 

For example, starting always with the construction sector, we created a new material for the 3D printing industry that is based on clay and rice husk. With this material, we have printed the first 3D printed house globally with 100% natural material. We are very happy about this project and we're continuing the research on the material and together with partners that are producing the 3D printers are working on several projects. 

Always with 3D printing, we're studying a mixture that can substitute the plastic, for example, used in the design or in the product design industry. In addition, a project that we have just started is the research on the possibility to create fabric from rice residue or to create panels that substitute, for example, the medium density fiberboard or different panels for the interior design.

In general terms, our idea is to try to become the focal point regarding the use of rice residue not just in the construction sector but also in others, sharing our know-how. 

If we have the idea to create the entire rice house that is completely made in terms of the building of these materials and in addition where inside the house, we have all the objects 100% natural made of rice residue, you can imagine the table, the cup, the clothes, and so everything. This is going to be really the maximum achievement. Of course, these are really in the long term, it's something that we're focusing on.

About the author

Katerina Dimova

I am a multi-skilled Chartered Architect and Senior Project Manager committed to personal and professional growth for a more sustainable future.