Bricks of mushrooms grown in five days or residual potatoes used as insulators and acoustic absorbers for sustainable construction. Cities could tackle the global problem of increased waste and resource depletion through the use of organic waste – bananas, potatoes and corn – as sustainable building materials.
At the global level, the construction industry is one of the largest users of raw materials; alone in the United Kingdom, it accounts for 60 percent of all raw materials consumed. Capturing organic waste streams from cities and the countryside could provide the industry with sustainable low-cost building materials and less CO2 such as bricks, insulators and partition walls, says Arup, an independent firm specializing in design, planning, engineering, consultants and technicians working for sustainable construction.
Its report The Urban Bio-Loop: Growing, Making and Regenerating envisages an entirely circular system in which construction waste returns to the biological cycle at the end of its useful life returning its nutrients to the soil. It is based on the idea that the potential for the bio-economy is enormous: more than 40 million tons of organic waste from agriculture and forestry were produced in Europe in 2014 and the amount is growing every year, they claim.
In addition, one kilogram of waste incinerated for energy recovery has a value of about 0.85 euro, but the same material used for interior covering could be sold for up to six euro per kilogram, they say.
In addition to the development of alternative organic materials, comprising mushroom bricks grown in five days and residual potatoes used as insulators and acoustic absorbers, Arup has created the SolarLeaf. It is the first façade system in the world that cultivates microalgae to generate heat and biomass. They have also designed BioBuild, the first self-supporting façade panel made of biological composites.
Innovation in the manufacturing processes significantly facilitates the development of these materials, such as, for example, the increasingly common 3D printing of biopolymers. So, the report highlights products made of organic matter that are already available:
– Peanuts: Peels are used to produce low cost materials, such as partition boards that are moisture resistant and flame retardant.
– Rice: Rice husk ashes can be mixed with concrete to reduce the need for fillings. Rice can also be used as a raw material for the production of boards.
– Banana: banana fruits and leaves are used to make resistant textiles. Bananas contain high strength fiber and offer good acoustic absorption and durability.
– Potato: the potato peel can be cleaned, pressed and dried to create a water-repellent, fire-resistant and low-weight insulation material and an acoustic absorbent.
Guglielmo Carra, European Lead for Materials Consulting at Arup, explains “as one of the world´s largest users of resources, we need to move away from our mindset of taking, using and disposing. There are already sectors with producers manufacturing low CO2 content construction products from organic materials. What we need now is for the industry to come together to extend this activity and make it usual. “
“An important first step is to work with the government to rethink building codes and regulations and to consider waste as a resource, opening up the opportunity to reuse it on an industrial scale,” he adds.