Building envelope systems for the circular economy; Evaluation parameters, current performance and key challenges

Abstract

The building industry is the world's largest consumer of raw materials. In an effort to reduce the rate of consumption there is an urgent need to adopt more efficient recycling and reuse practices in the building industry. Emerging to support this need is the circular economy framework (circularity) -a concept that aims to separate 'economic growth from environmental destruction'. Using the framework of circularity this research critically evaluates the 'reuse' performance of a key area of modern construction; the external envelope layers of timber framed buildings.The research collates circular assessment criteria relevant to the evaluation of building envelope layers from literature. In conjunction with real-world deconstruction tests and the aforementioned circularity assessment criteria the study identifies two key trends limiting circularity in the building envelope; the widespread presence of fixings that irreversibly damage components, and the widespread use of chemically modified materials (i.e treated and/or engineered timber). Given the prevalence of such building methods in New Zealand, Australia and North America there is a clear need for research that proposes fixing and material technologies for building envelopes that meet circular economy design criteria.

Selection Criteria for Building Materials and Components in Line with the Circular Economy Principles in the Built Environment—A Review of Current Trends

“…The resistance of materials and components to deterioration over time while meeting the minimal requirements [6,[27][28][29][30]49,78,89,90,99,107,112,113,130,137,156,169] 17…”

“…Upcycling potential Re-introducing the materials and components in the loop for a higher value [5,58,63,72,95,102,130,166,169] 9…”

Support Decision Tool for Sustainable Energy Requalification the Existing Residential Building Stock. The Case Study of Trevignano Romano

“…Another fundamental aspect for the selection of the insulation material is related to the prefabrication and therefore to the way the product is installed, which should allow a quick and dry application, in order to reduce the work site time, the environmental impacts associated with it and the possibility of future reuse. The building industry is the world's largest consumer of raw materials [29]. Therefore, the entire methodological approach is based on the principles of circular economics right from the design phase.…”

End-of-life management as a design tool: the case of a dry wood envelope

“…As is now well known, the construction sector in Europe is responsible for one-third of all waste generated and consumes between 30 and 50% of all resources (Božiček et al, 2021). A recent paper published by Finch et al (2021), dealing with the survey of studies on the integration of circularity principles in buildings, notes that the trend is to focus on identifying end-of-life post-construction impacts rather than examining design practices and new "circular" ways of building that address the problem early in the project. The study also highlights that typically in practice, buildings are not designed to be reused, but rather the approach taken is to manage their post-life through material selection and final treatment.…”

“…Come ormai noto, in Europa il settore delle costruzioni è responsabile di un terzo di tutti i rifiuti generati e consuma tra il 30 e il 50% di tutte le risorse (Božiček et al, 2021). Un recente la-voro pubblicato da Finch et al (2021), trattando la ricognizione di studi sull'integrazione dei principi di circolarità negli edifici, rileva che la tendenza è quella di focalizzare l'attenzione sull'identificazione degli impatti legati al fine vita post-costruzione piuttosto che esaminare pratiche di progettazione e nuovi modi di costruire "circolari" che affrontino il problema già dalle fasi iniziali del progetto. Lo studio mette in luce, inoltre, che tipicamente nella pratica gli edifici non vengono progettati per essere poi recuperati, ma l'approccio seguito è piuttosto quello di gestirne la post-fine vita attraverso la selezione dei materiali e il loro trattamento finale.…”