Utilization of cork residues for high performance walls in green buildings

The building sector accounts for 40% of consumed primary energy, 20% of which is used to heat and cool indoorenvironments through HVAC systems. Though several intervention strategies are possible, the latest studies have highlightedthat a conscious design of the building envelope was the most suitable solution to reduce environmental burdens. Actually, itscomponents considerably affect the energy performances of buildings mitigating the effects caused by variable externalenvironmental conditions and reducing expenditure by 50%-70%. Only in the last few years, research has been targeted to thedevelopment of innovative solutions to improve the energy performances of the building envelope by studying and usingbiocompatible natural insulating materials. Cork is one of the most popular natural materials used as insulators. It isobtained from the bark of the Quercus suber and only 25% of it, the high-quality cork, which is used to produce bottle stoppers,while the remaining 75% becomes waste material of the process. This paper proposes a multilayer agglomerated cork wallwith two air cavities and a central OSB (oriented strand board) load-bearing structure that can be used as an external verticalpartition in buildings located in Mediterranean climate areas. Specific graphs were developed to rapidly establish thermalinsulation characteristics which also were taken into account ISO 13786 and the performances required from the building. Thewall, which was composed of 6.5 cm-thick external layers of agglomerated cork, for a total thickness of 20 cm, had a periodicthermal transmittance value below 0.12 W m-2·K-1. The same performances can be obtained using perforated brick walls, ofat least 50 cm of length, insulated with no less than 5 cm of rock wool, for an overall weight per unit area over 20 times higher.