Classification criteria and markers for biomimetic building envelope within circular economy principles: a critical review

The responsibilities of the building sector concerning resource consumption and waste generation, as a problem of research, require a transition from a linear to a circular model in order to obtain significant positive effects on the environment. The Biomimicry approach appears to be a promising way to move the sector towards the circular economy, to meet the increasing levels of functional and environmental requirements, which is shifting the research on building materials and products toward biomimetic solutions. Along this path, the building envelope emerges as an interesting application field concerning its adaptive behaviour towards external conditions. In this field of research, the knowledge gap concerns the need for criteria to classify the biomimetic behaviour of building materials under operating conditions and to identify their environmental effects, as well as their compliance with the principles of the circular economy. The study provides a methodology to develop a set of classification criteria applicable to biomimetic materials and products which are suitable for application in the building envelope and a related set of markers that identify the strongest environmental relationships and implications related to the aptitude for integrating circular economy principles. The mapping highlights the absence of some relationships thus highlighting potential limitations of biomimetic materials/products within circular economy principles and thus current research limits. The results obtained may be useful to evaluate and compare biomimetic materials and products for the building envelope, whilst also providing the first step for further research on their environmental implications within circular economy processes.