Construction sector represents one of the largest raw material consumers in the world with more than 42 billion tons of materials consumed in one year. Furthermore, construction and demolition wastes comprised about 25-30% of the total waste in the EU. A circular approach could help the construction sector reduce the environmental impact of buildings. In the context of the circular economy, agricultural by-products represent a potential raw material for building applications. The low density of the materials, combined with the porous structure, could be suitable for this application. Several researches have been developed using by-products from rice, sugar, corncob, pineapple, peanuts, coffee, coconut, sunflowers, walnuts, durian. Orange is the most cultivated fruit in the world and accounts for about 50-60% of the total citrus production. In 2016, more than 124 million tons of citrus fruits were produced, of which about 50-60% was consumed fresh and the remaining 40-50% was destined for industrial processing. An enormous amount of waste derives from this production; considering that 50% is made up of peels, the waste produced is about 3.4 million tons per year. The project to reuse the citrus transformation by-products develops from these environmental difficulties.

The present invention relates to a method of manufacturing a self-supporting panel for building application. The first step is to find a volume of waste or by-products deriving from the transformation of citrus fruits; subsequently the by-products are chopped to obtain a reduced volume of waste and pressed to compact the material; this phase allow to the aqueous component of the volume of chopped waste to escape through evaporation. In fact, the evaporation phase occurs simultaneously with the pressing phase to ensure a flatness of the panel obtained. In particular, the characteristic of providing a pressing of the shredded material at the same time as an evaporation phase of an aqueous component of the material itself, allows to obtain a compacting of the panel without the need to use binders, glues and/or adhesives. Furthermore, providing for a drying of the material during pressing, allows to avoid the formation of internal tensions in the panel being formed, in such a way as to guarantee a flatness of the panel obtained. Advantageously, the method according to the invention allows to recover citrus waste and to process it in both wet and dried form, ensuring, through the storage of any excess waste material in dried form, a continuous cycle production of the panels. Furthermore, the embodiment of the method according to the invention provides for a step of hot pressing at a temperature lower than that usually used for known type processes, allowing energy savings. Other advantages are the use of unused agricultural by-products, the easy finding of the raw material, the ease and the low cost of production. From an environmental point of view, the creation of this eco-sustainable material allows a reduction of CO₂ emissions, the improvement of the energy and environmental performance of the building, as well as the development of eco-sustainable buildings. The development of the circular economy is guaranteed by the enhancement of local products and recyclability at the end of their life. Finally, the good thermal performance, in response to the growing demand for thermal insulation materials, guarantees the good economic performance of the project.

The application of the described methodology allows to obtain a self-supporting panel with aesthetic characteristics similar to the cork. The excellent thermal conductivity and sound absorption are the characteristics that make the material comparable to the products currently on the market. The product can be used as a ceiling panel or cladding panel, it can be inserted inside the walls as insulation or can be used as a suspended panel. A first application could be in the furniture sector, in particular in the creation of objects or components with a high environmental value.